Final Report Summary - SHIELD (Development of a novel, low-cost fireproof Insulation Material)
Executive Summary:
The SHIELD project aimed to develop a novel innovative insulation material combining excellent thermal insulation performance in demanding environments requiring humidity and/or a high level of fire resistance; this combined with an excellent processabilty (adapted to high volume industrial production) and a low cost.
The concept of the Shield project was to develop an inorganic lightweight foamed material based upon geopolymer chemistry. The insulation properties could be enhanced by the incorporation of ultra light weight aeroclays in the geopolymer matrix, along with other additives to further improve cell structure, foam stability, mechanical strength and humidity resistance.
Next to the material development activities on lab scale, the Shield project focussed on developing the necessary processing equipment necessary to convert the basic chemical components into tangible 3D shaped final parts, at production rates meeting the requirements from high-volume/low cost production environments.
The material and production technology was to be validated by means of the production and testing of two actual parts from the participating companies.
Such a material and associated processing would open market opportunities for the beneficiaries throughout the value chain from material production/consultancy through the design, production and commercialisation of parts containing this innovative material.
At the project start, the new aeroclay material has been developed. The resulting aeroclay materials met the requirements to allow further incorporation in the geopolymer matrix. Thermal conductivities of aeroclay materials were between 5 and 6 mW/mK.
The main material development work performed concerned the aeroclay/geopolymer foam. Several geopolymer systems were tested of which the Potassium based system was selected as the most promising one. Best foaming of the geopolymer was achieved by using a chemical blowing agent combined with a foam stabiliser.
In order to enhance mechanical properties, different kind of fibres, polymer latex and microspheres were tested.
Processing related activities focussed on defining requirements, designing systems for storage, feed and delivery of the material to the moulds. A lab scale unit was designed and purchased, and an injector was made. Application tools were designed and build.
Unfortunately, the required material properties for the foam could not be achieved – even after a review of the requirements by the sme’s resulting in less strict demands and the lab scale processing system could not be demonstrated by the deadline.
Based upon the available results, all information, remaining project time and budget, the SME board of the project decided to stop all RTD activities as the project would not be able to yield any exploitable results.
Project Context and Objectives:
The construction industry routinely experiences environments that demand excellent insulation performance in terms of high humidity or applications demanding high fire resistance. These environments often present complex shapes and limited and difficult to reach space for such insulation materials. Whilst many insulation materials are available commercially, few combine a wide range of high level performance with a low price based upon an excellent processability (spraying/injection).
The main goal of the SHIELD project was to develop a new high-performance insulation material offering a combination of excellent temperature insulation properties, fire resistance and has to be easy processable by automated processes like spraying and injection. This new material had also to show a long term stability in humid environments, a high durability and a low cost.
With this innovative new material, the consortium believed it can serve following market opportunities:
- applications were difficult to reach spaces/parts and complex shapes need to be insulated
- applications demanding very thin insulation layers: due to its high insulation property it will become the material of choice for these systems
- demanding end-uses like insulation in high humidity environments and end-uses with high demands on fire resistance and durability.
To prove the concept, the SHIELD material was to be evaluated for it’s use in air-ducts, fire doors, high level insulation in the oil and gas industry and household appliances.
The Shield project aimed to address this market gap of low-cost, fire-resistant, low-weight insulation materials coupled with excellent processability by developping a group of novel insulation materials, which exhibit these desirable properties in industrial products by combining clay-nano-composites with supporting additives.
The developed material was envisaged to offer a combination of:
- low thermal conductivity
- excellent fire resistance
- hydrophobicity for long term stability
- high durability for demanding application
- low material cost
The Shield project aimed also to develop a suitable processing route for these clay-based insulation materials, which minimises production cost by fully automating the spraying/injection production process.
With the combination of the developed material chemistry and processing methodology, it was the intention to develop and test first prototype applications for fire doors, air ducts and samples for fire testing with applications in the oil and gas industry.
Project Results:
Workpackage1: synthesis of aeroclay powder materials.
Objectives
Technical Objectives:
To develop an aeroclay material to be used as ultra-lightweight insulating filler with the following properties:
- Low thermal conductivity (< 20. 10-3 W/mK)
- Water resistance (no condensed water absorption)
- Fire resistance (European Class A1/A2)
- Low density (<30 kg/m3) Obtain a lab scale procedure for the synthesis by freeze-drying of different aeroclay materials:
Scientific Objectives:
1. A lab scale procedure for the synthesis of at least one clay base insulation material that satisfies sufficiently the stated requirements regarding thermal conductivity <20.10-3 W/mK, density, and fire resistance.
2. A lab scale procedure for the synthesis of at least one clay base insulation material that satisfies sufficiently the stated requirements regarding thermal conductivity <20.10-3 W/mK, density, fire resistance and water resistance.
Results: Material development partner Aidico succeeded in developing aeroclays with the required characteristics to be incorporated into the Geopolymer matrix to develop the Shield material. Targeted density and thermal conductivity properties were achieved, water absorption and fire resistance characteristics had to be met on the final shield material – so the aeroclay/geopolymer combination.
Achievements for WP1 are listed below:
1) Different aeroclays based in montmorillonite clay and different polyelectrolites have been developed and characterized at a lab scale with the idea of those polyions were absorbed on several clay particles at the same time and stablish strong bridges between them.
Three polyelectrolites were selected and add to different concentrations to obtain different aeroclays:
-Acry-aeroclay: Polyelectrolite (Sodium polyacrylate) + clay (montmorillonite)
-CMC-aeroclay: Polyelectrolite (carboxymethylcellulose) + clay (montmorillonite)
-Sulpho-aeroclay: polyelectrolite (Sodium alkylnaphtalene sulphonic) + clay (montmorillonite)
2) The methodology for the preparation is described below:
Clay gels preparation: Sodium exchanged montmorillonite clay (Nanofil 16) is mixed with deionized water in a laboratory mixer for 10 min at room temperature (20 ºC). Concentration of 6 % was dispersing 24 g in 400 ml of water.
Polyelectrolyte dispersions: Polyelectrolyte salt dispersion at 1, 2 or 3% concentration were prepared.
CMC and SULPHO dispersions were prepared adding 4, 8 or 12 g of polyelectrolyte over 400ml of water.
Sodium polyacrylate (ACRY) is a hydrogel polymer with ability to absorb high amounts of water, for this reason dispersions of this polyelectrolyte became too viscous and was preferable to add directly solid sodium polyacrylate and water onto the clay gel before prepared.
Mixture of clay and polyelectrolyte dispersion were prepared in volume proportions of 1:1 or 1:2 by mixing400 ml of clay dispersion with 400 or 800 ml of salt dispersion.
Frozen dispersions: The resultant dispersions (clay+electrolyte+water) were quickly frozen in a round glass container (1 litter) by submersion in liquid Nitrogen.
When solutions or suspensions were being frozen, a small amount of the liquid was poured in the drying flask. A film of the solution was formed on the wall by rotating the flask. The flask was then submersed in the coolant and was rotated until the film was frozen. This procedure was repeated with a second quantity of liquid, and so forth, until a frozen layer about 1 cm thick was built up.
Drying step: The drying step of the operation was performed in a "VirTis" freeze-drying apparatus, FM- 25EL-85. It takes about 3-4 days the total evaporation of several flasks with a 1cm film.
3) Two different aeroclays were selected depending if they are going to be used as monolithic or as powder addition to a geopolymer foam.
3,1) For the preparation of monolithic cylinders of aeroclay:
The selected was: CMC-aeroclay (6% clay-2% polyetrectrolyte (1:2) v:v)
picture of Cylinder samples of CMC-aeroclay => see attached report
All X-ray diffraction graphs show the intensity of peaks corresponding to crystallized electrolyte salts together with the peaks corresponding to the Montmorillonite. In CMC-aeroclay there are no evidences of Montmorillonite interlayer space expansion as d-spacing values are close to 12,52 A that is typical value of Monrmorillonite, as it occurs in Acry-aeroclay. This indicates that electrolyte salt is not intercalated between the clay layers.
The FTIR spectrum of CMC samples show that the carboxyl, methyl and hydroxyl functional groups are found at wavelength of 1630, 1423 and 1300 cm-1, respectively. It is obvious that broad absorption band at 3441 cm-1 is due to the stretching frequency of the hydroxyl group (–OH). The band at 2909 cm-1 is due to carbon-hydrogen bond (C–H) stretching vibration. The presence of a strong absorption band at 1630 cm-1 confirmed the presence of carboxyl group (–COO). The bands around 1423 and 1300 cm-1 are assigned to –CH2 scissoring and hydroxyl group (–OH) bending.
By SEM it is appreciated an edge to face configurations with galleries between layers (10 µ) together with longer ones (30 µ) (left figure below)
SEM image / compression results => see attached report
The chart shows the compressive strength behaviour: samples marked as C area plot of per cent linear compression versus the weight put on the cylinder. The curves marked R represent the same data after removal of the weight. The spread between the C and R curves measures the elastic recovery of the cylinders.
Then addition of a polyelectrolites during processing improves the mechanical rigidity to a point at which the clay---based aerogel sample is capable of supporting pressures on the order of 18 kPa with maximum % of linear compression of 95% for CMC-aerolclays.
Specific area surface for CMC aeroclay as been evaluated by a BET tests: 43.56±0.22 m2/g (this was the highest value of all synthetized aeroclays).
In general, the lower values of thermal conductivity for all the synthetized aerclays were the ones obtained with CMC-aeroclay type: λ = 0,0043±0,00022 W/mK
Cost calculation: A starting clay dispersion of formula [6% clay+2% polyelectrolyte (1:2, v:v) ] contains 96.6 % of water. If a 4% water retention is assumed, from 100 kg of starting clay dispersion the final water to be removed would be 92,6 %, and the final aeroclay would be 7,4 %.
This corresponds to an energy feed of 98,080kcal and required freeze drying time of 14,25h, resulting in a production cost of 2,907€/kg produced aeroclay.
3,2) For the use of powder additions to geopolymeric foam:
The selection of aeroclay was a function mainly of compatibility with selected plain geopolymeric foam (KGP) and improvements of thermal conductivity and density with its incorporation of a 2% of addition.
In all the cases, the incorporation of aeroclay to the geopolymer foam in a 2% improved density and thermal conductivity, but increase in few minutes the hardening time. The selected aeroclay was: Acry-aeroclay (Acry-montmorillonite (6% clay+1% acry (1:1) v:v)) which improve density and thermal conductivity in a more noticeable way than other aeroclays. With a temperature of 50ºC, the hardening time is more similar to KGP plain formulation than at ambient temperatures.
Characterization results:
KGP-4HP KGP-2ACRY-4HP KGP-2sulpho-4HP KGP-2CMC-4HP
Time (min) 205 210 235 205
D (Kg/m3) 138±6 108±3 125.4±0.9 136±3
Λ (mW/mK) 42±3 36.3±0.5 39.7±0.5 40.7±0.5
All the X-ray diffraction graphs show the intensity of peaks corresponding to crystallized electrolyte salts together with the peaks corresponding to the Montmorillonite. Diffractogram shows an increase of d-spacing value (from 11.79 A to 12.52 A) what is indicative of electrolyte intercalation between the clay layers.
FTIR analyses shows a wide band corresponding to stretching vibrations of the hydroxyl group occurs in the range of wave number 3700---3000 cm-1. Characteristic absorption bands at 1637 cm-1 corresponding to deformation vibrations C-OH and two bands at 1467 cm-1 and 1221 cm-1 typical for salts of carboxylic acids. The band corresponding to stretching vibrations of C-O-H group occurs at 1046 cm-1.
SEM analysis revealed variable galleries dimensions between 10 and 40µ for compositions prepared from 1% dispersions of Sodium polyacrylate in Clay: Acry 1:1 ratios
SEM image of 6%Clay:1%Acry (1:1, v:v) => see attached report
Thermal conductivity values for the Acry aeroclay reached λ= 0,0056 W/mK
Cost calculation: A starting clay dispersion of formula [6% clay+1% polyelectrolyte (1:1, v:v) ] contains 96.5 % of water. If a 4% water retention is assumed, from 100 kg of starting clay dispersion the final water to be removed would be 92,5 %, and the final aeroclay would be 7,5 %.
This corresponds to an energy feed of 98.000 kcal and required freeze drying time of 14,24h, resulting in a production cost of 2,865€/kg produced aeroclay.
Workpackage 2: development of aeroclay/geopolymer foam.
Technical Objectives:
To develop an insulating foam composition based on the combination of aeroclay filler, geopolymer binder and foaming agents, with the following properties:
- Available for spray-wet applications
- Low Density (<60 kg/m3) => revised to 80/85 kg/ m3
- Low Thermal conductivity (< 30. 10-3 W/mK)
- Fire Resistance (European Class A1/A2)
- Sufficient mechanical properties (at least 0,05 MPa) comparable to a soft poly-urethane, while maintaining or improving: Insulation, water resistance, fire resistance, low density).
- Biocide properties by adding natural biocide additives.
Scientific Objectives:
Obtain the best geopolymer/aeroclay formulation, to ensure that the SHIELD material is self-supportive and has a minimum compressive modulus of 0.05 MPa (corresponds to a soft poly-urethane) and that is compatible with the requirements of thermal insulation and fire resistance.
Determine the best foaming agents to get the density and thermal insulation performance of the final material at its optimal value.
Determine the biocide performance of the SHIELD-material when using additional additives.
Despite the efforts from material development partner Aidico, the objectives for the Shield material were not met. No good material could be developed combining low density, low thermal conductivity and good mechanical properties for an acceptable price.
Achieved formulations and properties are listed below:
1) Formulation design:
Different Geopolymeric foams based in metakaolin with different alkali cation and formulations were obtained with different foaming agents and additives in order to improve thermal conductivity, mechanical strengths and fire performance. Selected formulation is based in a potassium metakaolin-based geopolymer (with lower viscosity), foamed with hydrogen peroxide in alkali media and surfactant agents. The properties were further improved bu the incorporation of latex, hollow glass microspheres and different kinds of fibres in different concentrations.
Geopolymer system: The starting geopolymer paste was selected as a function of initial viscosity and final properties achieved incorporating different additions. The geopolymeric pastes selected were below:
Materials Na Na K K/Na K/Na-2
Name Na-GP Na-GP-2 K-GP K/Na-GP K/Na-GP-2
Metakaolin (g) 42 37 40 43 41
M2SiO3 (aq) (g) 29 35 35 35 34
MOH (50%) (g) 20 24 25 18 18
H2O (g) 9 4 0 4 7
H2O2 (g) 4 4 4 4 4
Rheocell (g) 0,6 0,6 0,6 0,6 0,6
masa total (Kg) 0,1046 0,1046 0,1046 0,1046 0,1046
Mr(Si2O/M2O) (mol) 1 1 1 1 1
M2O/Al2O3 (mol) 1 1,2 1 1 1
SiO2/Al2O3 (mol) 3,4 3,4 3,8 3.4 3.4
w/s (wt) 0,57 0,62 0,49 0,5 0,55
viscosity (cp): t=0 s 88385 2827 2756,4 19247 9299
viscosity tendency no measureable y = 2827,7e0,0821x y = 2756,4e0,0258x y = 19247e0,054x y = 9299e0,0503x
R2 0,996 0,94 0,99 0,996
One major observation was the big differences in kinetics of sodium and potassium systems. Sodium systems are faster than potassium systems, and hybrids are between both but closely to sodium systems, which can contribute to reduce setting time but starting with a more workable paste.
The potassium system KGP has been selected, due to a lower viscosity allowing to incorporate more additives and can be easier processed. Hybrid systems could be a good solution as well but the reaction kinetics are too high and effect of additives in the final properties improvement was not so evident than in potassium systems.
Foaming system:
Foaming has been realiased by a combination of two agents:
- Hydrogen peroxide, creating foam bubbles: 2H2O2 → 2 H2O + O2 (g)
- Foaming agent for concrete based in surfactant, which act as a bubble size and foam stabilizer. Recommended amount 0,6 g/100 g of KGP
Final formulation:
The final formulation is following combination: KGP-2ACRY-XL1201-WHMS-ZF-YHP
X: 0-5g of latex/100 g GP, when it was required a high amount of air entraining (higher amount of HP) to give more elasticity to the geopolymer. It is expected with the lower amount of HMS content. For amounts of HP equal or lower than 4g/ 100g KGP, it is not necessary. Improve elastic properties but decrease fire behavior.
Y: 4-6g of HP/100 g GP. 6% was found to be the maximum amount of hydrogen peroxide that KGP system accepts with 5% of latex content. It should be adjusted depending of processing parameters. Amount recommended 4%.
W: 3 g/100 g GP. It is the minimum amount of hollow glass microspheres to notice a thermal conductivity improvement but remaing cost effective.
Z: 1-2 g/100 g GP Basaltic microfibers improve mechanical strengths and fire performance but also increase density, and then the maximum amount will be fixed in 2 g/ 100 g KGP.
2) Preparation protocol
The optimal preparation protocol has been studied and optimized different parameters as:
- Mixing protocol
- Temperature influence
- Maturing age influence
schematic overview preparation protocol => see attached report
The influence of temperature on density was studied for several formulation KGP-2ACRY-5L and different fibers content. It was observed that density decreases with an increase of temperature, but it was observed also a decrease of integrity foam if the foam grown up more than 5 times it initial volume. Recommended temperature is over 50ºC.
The relation between temperature, reaction time and foam growing has also been investigated. Based upon lab scale volumes, foaming time reduces from over 2 hours to reach the final volume at room temperature to 15/20 minutes at 60°C. This has been tested for formulations with or without fibres and microsphers and findings were analogue.
3) Characterization of selected shield formulation: multiple formulations have been tested, below a summary of the most promising ones.
Properties goals KGP-4HP KGP-2ACRY-5L1201-6HP KGP-2ACRY-5L1201-4HP- 3HMS-2F
Demoulding time (min) 15 >3h (20ºC) 48 (50ºC) 50 (50ºC)
Density (Kg/m3) 85 138 79±8 125±22
Thermal conductivity
(mW/mK) < 30 42 34±0.1 38±1
Fire Resistance
European Class A1/A2 Not flammable Fire resistant (not flames or drops) Fire resistant (not flames or drops). Better behaviour.
Water repellent yes not not yes
Mechanical properties
(KPa) > 50 20±6 5±2 19±8
Cost (€/Kg) dried paste 0.9 0,7 0,8 1,3
Additionally XRD analyses were made to verify the presence and form of the aeroclay in the final product. It was observed that the peak of montmorillonite appears in all the samples together with the broad band corresponding to the amorphous geopolymer and the peak of quartz present in the starting metakaolin (unreacted in alkaline media). That’s means that at least the aeroclay is not dissolved in the alkaline media.
By SEM it was observed if the microstructure of aeroclays and hollow glass microspheres is preserved, what is important for density and thermal conductivity properties. The microstructure of aeroclay particles embedded in the geopolymer matrix is clearly visable. In all the cases the particle size is around 10 µ. The macrostructure of aeroclays is not detected, because they are incorporated in powder but microstructure is preserved with the well organized and expanded interlaminar space between layers.
The surface of the microspheres is not affected and interface between microsphers and Geopolymer seems good, but not chemically bonded.
KGP-geopolymer matrix (without foaming) KGP-3HMS (without foaming) KGP-2ACRY (without foaming) => pictures see attached report.
Thermoanalysis on the individual ingredients and Shield material samples has been conducted to verify high temperatures stability.
It showed that the selected latex is decomposed at 420ºC, Halloisyte fibres dehydroxylated at 540ºC, acry-aeroclay has a loss of weight at 480ºC due to the decomposition of polyacrylate modifier.
The Shield foamed product has a double peak of weight loss due to the decomposition of latex content and aeroclay modifier. The geopolymeric matrix is not decomposed until temperatures higher than 1000 ºC.
Fire testing: Samples with different fibre content were tested and compared to a rockwool panel. The below graph shows the different behavior of different samples, measuring the temperature rise in the not exposed face. Samples containing halloisyte fibres (FH1 and FHCF2) presented a faster rise of temperature compared with sample without fibre content (FP). Samples with basaltic fibre ( FCF1 and FCF2) content shows better behavior than sample without fibres and samples with the higher content of fibres (2%) combined with 3% of microspheres showed the best results, even better than the Rockwool panel. This result shows that basaltic fibre content improves considerably fire behavior of samples. Also to point out that samples fail by cracking of samples, but not due to decomposition or fired of samples. Not fumes were released.
fire testing graph => see attached report
Hydrophobicity testing:
To test the influence of spraying Potassium methyl siliconate over the surface of panels after drying, a simple drop test was carried out to see if water was retain in the surface or absorbed. Picture show samples without (left) and with treatment (right).
It is clear the effectiveness of water repellent in the water drops.
pictures => see attached report
Biocide properties were not measured or incorporated to the final product because properties of density, thermal conductivity, mechanical strengths or fire performance, were not good enough for SME’s and it was decided to stop the project and do not go on with more experimental work related with this issue.
WP3 Spraying and Curing:
WP3: Spraying and Curing
Technical Objectives:
Design a process for spray / blow deposition or injection adapted to the specific requirements of new foamed material.
Selection of appropriate spray/injection equipments for proof of concept tests al lab scale (<10 ltrs) according to the material and application specification. Carry out proof of concept tests on defined lab equipment with 3 selected foam formulations in order to validate the application system.
Scientific Objectives:
According to the characteristics of the raw materials and the expected foam properties, specifications for material storage, handling, feed, and delivery must be defined.
System design for Material Storage and Handling System (Pressure system, Material level indicators, Material temperature monitoring and control, Material refill systems , Material outlet system).
System design for material feed and delivery. This will be based on the theoretical procesing parameters of the foam materials (foam density, flow rate, finish/ surface quality, adequate mix ratio, spray pattern etc)
Develop Lab Scale Storage, Feed and Delivery System and carry out proof of concept tests with that system.
Define the best curing method by thermal treatment and/or curing accelerators.
WP3 was not finalised as RTD activities were stopped before the end of the project.
Achieved Results towards technical objectives:
Design a process for spray/blow deposition or injection adapted to the specific requirements of new foamed material.
A process for the injection of the geopolymer material into application specific moulds was defined. Before injecting into the moulds a chemical foaming agent is added and mixed in the injection gun. The foaming of the geopolymer then occurrs within the moulds.
Selection of appropriate spray/injection equipment for proof of concept tests al lab scale (<10 ltrs) according to the material and application specification. Carry out proof of concept tests on defined lab equipment with 3 selected foam formulations in order to validate the application system.
A lab scale ‘proof of concept’ system has been built based upon existing, available mixing and pumping equipment to perform proof of concept tests at a lab scale. The system was based on the premix concept with all material batch mixed. The foaming agent was mixed with the other components within the dispensing gun which also controlled the geopolymer to foaming agent mix ratio. The system has been demonstrated with dyed water in place of the foaming agent and mixing Metakaolin with water in place of potassiumsilicate, to show that the system could produce a homogeneous mix. Within the project it was not used to actually produce parts with this system as the project R&D work was stopped before the end.
Results related to scientific objectives:
According to the characteristics of the raw materials and the expected foam properties, specifications for material storage, handling, feed, and delivery must be defined.
The specifications for the material, storage, handling feed and delivery system has been defined. This has been achieved by examining the characteristics of the raw materials and by performing preliminary testing of the formulation to measure the properties of the material under different processing conditions. Based on the analysis and testing, recommendations for the storage and mixing of the geopolymer system and the definition of appropriate materials to be used in the vessels, pipework and hoses required for the processing equipment were made.
System design for Material Storage and Handling System (Pressure system, Material level indicators, Material temperature monitoring and control, Material refill systems , Material outlet system).
The system design for the material storage and handling system has been completed and documented. System designs have been developed for both a premix and In-gun mix method of dispensing the geopolymer. The premix system is a batch based system where it is necessary to premix all the component materials, apart from the foaming agent, before dispensing the geopolymer material. With the In-gun mix, the materials are mixed together on demand at the dispensing head. The In-gun mixing process has the advantage that there is very little waste material and minimal flush requirements, however this method requires a more sophisticated dispensing head to control the mix ratios of the materials and to ensure the materials are completely mixed before dispensing.
Process diagrams and example industrial scale processing systems have been described for both systems. A comparison of the two processing methods has also been presented.
System design for material feed and delivery. This will be based on the theoretical procesing parameters of the foam materials (foam density, flow rate, finish/ surface quality, adequate mix ratio, spray pattern etc)
The system design for the material feed and delivery system has been completed and documented. As part of this development, work was carried on the development of both a premix based spray gun and a more complex design for in-gun mixing. This included the analysis and design of a nozzle to enable a uniform spray pattern and the concept of In-gun mixing achieved through fluidizing of the powder. Despite development efforts no working ‘in gun mixing’ system for the shield material could be designed.
Several systems for foaming the geopolymer have been evaluated as part of this development. This included mechanical air foaming, adding externally generated foam and using chemical foaming.
Develop Lab Scale Storage, Feed and Delivery System and carry out proof of concept tests with that system.
A lab scale ‘proof of concept’ feed and delivery system has been built and tested during validation trials. The system was based on premix based systems but simplified so the key elements of the design and materials processing could be validated. The main components of the processing equipment were assembled and a bespoke delivery head was developed and built. Within the project timings, the system was demonstrated using water in stead of silicate solution and a water based coloured die to replace the H2O2.
Define the best curing method by thermal treatment and/or curing accelerators.
MATRI and Aidico have focused on optimising the curing process using thermal processing and through addition of curing accelerators. It was found that the length of the cure process could be reduced significantly by increasing the temperature. The target demoulding and curing times were able to be achieved at temperatures above 60oC. However the testing performed showed that the mechanical properties of the material were severely impacted if the peak exotherm temperature of the geopolymer exceeded 500C. To achieve the target mechanical strength of the cured material the peak temperature of the material had to be kept below 50oC, but at these temperatures the cure time was extended to greater than 120 minutes. An optimum cure process was defined to achieve the best mechanical strength and was used to produce samples for testing. The process however is not suited for large scale – high volume industrial production due to complex handling and long mould residence time.
WP4. Validation and Application Studies
Technical Objectives:
Pilot scale set-up for the production of the aeroclay/geopolymer base material
Pilot scale set-up for the production of two applications (coating and injection)
Application study: report on the main performance parameters of the applied SHIELD-material.
Scientific Objectives:
Demonstration of a pilot scale level for the production and application of the SHIELD-material.
Proven performance of the SHIELD-material in at least two applications.
Up-scaling processing method of selected aeroclay has been developed:
The development of a pilot scale equipment to produce high amounts of aeroclays (task 4.2) was found out to be impossible to achieve withing the projects timelines and budget. The effects of upscaling were investigated using available higher production volume equipment (still not yielding required production outputs though)
The preparation of this product has three main steps:
1. Preparation of clay dispersion
The preparation of initial clay dispersion was exactly the same than for lab scale preparation, but increasing volumes of products.
2. Pre-freezing of clay dispersion
The dispersion was poured in plastic trays with a centimeter of thickness more or less (to assured a good sublimation of total water content) and kept in a refrigerator at -80 ºC before been introduced in the freeze-drier equipment. This is the conventional method used in industrial scale for freeze-drying processes and differs from lab scale where liquid nitrogen is employed.
3. Freeze-drying process.
It was used a freeze-drying of 35 l with higher capacity than the one at lab scale. The product was placed in trays and the capacity was limited by the space in the vacuum chamber and amount into each tray. The thickness of dispersion in the tray is an important factor to consider because the sublimation time depends of that. The water content is sublimated from the outer layer to the inner layer and if the thickness is too high this process can be no completely successful. It has been place 8 l distributed in a total of 11 trays with a thickness of 1 or 2 cm. It was needed more than one week to complete the whole process. It could be tray lower volume per batch, trying to reduce time (but also amount obtained by batch), and arrive to a compromise between time/amount. The amount also affects the freezing velocity of dispersion.
Characterization of product synthetized in lab and pilot scale.
• SEM analysis
Aeroclay synthetized in the lab and compared with aeroclay synthetized in pilot plant and starting montmorillonite were analyzed by SEM. Differences in microstructure were observed. In the lab scale microstructure is an F-E organization of sheet; meanwhile in pilot scale microstructure observed was an F-F organization, with a bigger size of sheets.
Starting montmorillonite Particle of montmorillonite pictures => see attached report
Acry-aeroclay synthetized at lab scale F-E microstructure => see attached report
Acry-aeroclay synthetized in pilot scale F-F microstructure => see attached report
It is clear that the frozen procedure is influencing in the microstructure of aeroclays. To have the exact microstructure of the aeroclay synthetized in the lab scale, it would be necessary to use N2 liquid to frozen the samples instantaneously, to keep the spongy structure with a disposal F-E of sheet.
As aeroclay is incorporated in powder and mixed together with the other components in a water media, the particle size of final aeroclay in the final product is smaller (<20 microns), spongy microstructure observed previously (in the order of hundreds of micros or few millimeters) could be not so determinant in the final foam properties as it would be expected from the beginning.
Anyway, it should be researched influence in final properties (density and thermal conductivity) of aeroclays synthetized in the pilot plant. It was not studied due to lack of time.
As it was observed an improvement on thermal conductivity and density in foams incorporating Acry-aeroclay, this effect could be also due to the spacing between clay sheets caused by the incorporation of sodium polyacrylate and interpenetration between sheets in a nanoscale (From d=138±6 to 108±3, from λ= 42±3 to λ= 36,3±0,5). For the study of this effect, and how the processing could influence in it, there was study the different aeroclays obtained in both processes, together with the starting montmorillonite by XRD.
SEM image of Shield foam with aeroclay detail. SEM image of Shield foam with aeroclay detail => see attached report
• XRD
Observing the FWHW of peak corresponding to 001 plane, this value is lower for starting clay, then for the pilot plant aeroclay and the broader is for lab scale aeroclay. This means that the aeroclay synthetized in a lab scale is more delaminated (higher separation between sheets) than the one synthetized in the pilot plant and this last more than the starting montmorillonite (not modified).
XRD analysis for montmorillonite and aeroclays synthetized at pilot plant and lab scale. => see attached report
Regarding the position of peaks (001) for aeroclays modified, it seems like there was an overlapping of peaks at d=14,3 and d=13,82 A, and even d=12.48 A (this last corresponding to the starting montmorillonite). This value indicates the spacing between sheets in the plain 001, then as higher is d-spacing, as higher is the delamination of sheets in the clay. It can be deduced that in modified aeroclays, especially in the one synthetized at lab scale, there are different grades of modification/intercalation between sheets or spacing). Due to this overlapping, the peaks are broader for aeroclays than for starting montmorillonite not modified).
• Themoanalysis
The thermoanalysis show us a loss of weight in aeroclays due to the decomposition of sodium polyacrylate intercalated between the clay sheets. This percentage indicates the amount of organic present in the aeroclay and can be an indicator of effectiveness in modification of clays. Results show that a higher amount of modifier was intercalated in the aeroclay obtained at lab scale in comparison of pilot plant (>1%). This means that the frozen process can also been affecting in some way to the effectiveness of intercalation or exfoliation of clays, what is in accordance with XRD results.
Also, it was observed differences in water content, being higher in the aeroclay obtained in a lab scale. This can be due to an incomplete secondary drying of moisture chemically bounded to the clay (>7%). This value is <2.5% for pilot scale aeroclay which is a correct value of moisture content. Those differences can be due to differences in vacuum compressor power, higher for the pilot plant.
Thermoanalysis of montmorillonite and aeroclay obtained in lab scale and pilot plant ==> see attached report
Data results from thermoanalysis of montmorillonite and obtained aeroclay.
Material Temperature (loss of weight) % (wth) ACRY % (wth)water
Montmorillonite 650 ºC-dehydroxilation of clay
Acry-aeroclay-lab scale 480 ºC-decomposition of organic modifier 9,45 7.58
Acry-aeroclay-pilot plant 480 ºC-decomposition of organic modifier 8.30 2.29
Pilot scale set-up for the production of two applications (coating and injection):
As part of this development the curing and material processing was optimized to support the requirements of the application specific samples. Application specific moulds were developed and built and release agents were investigated to allow release of the material from the moulds.
As first trials, MATRI produced three prototype samples by means of manual mixing and casting (coated air duct tube an insulated door and a panel for fire testing). Within the project, the pilot scale setup designed in WP3 has not been used to produce the parts.
Application study: report on the main performance parameters of the applied SHIELD-material.
The application study of the performance parameters was not completed as samples for testing were not completed by the time the RTD work on the project was terminated. The fire test mould was tested by AIS, but the results showed that the foamed geopolymer material is less effective as a fire insulation product compared to standard products in use by AIS today. It was thought that the performance could be improved through further optimization of the material, in particular some fibres in the formulation could have prevented the cracking that occurred in the material.
Scientific Objectives:
Demonstration of a pilot scale level for the production and application of the SHIELD-material:
Demonstration of the pilot scale system for the production and application of the SHIELD material was not completed within the project timescales. The mixing capabilities of the system were validated using a dyed water in place of the foaming agent. However, the demonstration of the pilot scale system to inject of the processed material into the application specific samples for the door and Air duct applications has not been performed when the RTD activities were stopped.
Proven performance of the SHIELD-material in at least two applications:
Within the project, application specific samples for the Door and Air duct applications could not be produced before the RTD work had been terminated, so the performance of the SHIELD material developed for these applications could not be tested.
Potential Impact:
The SHIELD project aimed to develop a novel innovative insulation material combining excellent thermal insulation performance in demanding environments requiring humidity and/or a high level of fire resistance; this combined with an excellent processabilty (adapted to high volume industrial production) and a low cost.
Such a material and associated processing would open large market opportunities for the participating SME’s Vento, Rubio and AIS – companies producing components, which are in need for such a novel insulation material. IBZ – a material research company – would benefit from the generated material and material synthesis knowledge opening investment possibilities to produce the ingredients.
Along the projects progress, it became clear that despite the RTD’s and SME’s combined efforts, the targets for the material properties could not be met on lab scale level, and could not be improved by process related influences.
Within the project, SME’s repeatedly reviewed their possible applications and exploitation possibilities resulting in lower demands towards the material properties. Unfortunately these lower material specification targets could also not be met in a combined way. The developed material was either too brittle for low densities or not performing sufficiently on insulation properties for higher strength materials. Achievable densities were also higher, generating too high material costs to allow exploitation.
The SME board reviewed all available options and decided the stop all RTD activities as no possible exploitation routes could be identified. The remaining time and budget within the project was also not sufficient to further improve the development drastically.
Consequently the Shield project did not and will not generate an impact apart from the generated knowledge by the research institutes, which might be beneficial for future research.
As no exploitation possibilities could be detected by the SME’s along the project, dissemination activities remained limited to the sharing of knowledge and results within the consortium by means of meetings and reports and the development of the Shield project website providing very general information on the project and the consortium. A dissemination plan was developed along the project assuming the project results were achieved, but has not been activated.
There are no exploitation routes for the project results. SME’s don’t see any possibilities to covert the project results into business opportunities and the findings are also considered not to be exploitable through IPR protection and licensing to other parties outside the consortium.
List of Websites:
Website address: www.shield-project.eu
Contact details: the website contains an overview of all project partners and a contact form. Individual contact data can be found on the companies websites
Main contact persons:
Project coordinator: VENTO NV – Bart Modde – www.vento.be
Project participants – companies:
IBZ-Salzchemie GmbH & Co. KG – Gerald Ziegenbalg – www.ibz-freiber.de
Rubio, CMC, S.L. – José Rubio – www.rubiomet.com
AIS advanced insulation – Sarah Rogers – www.aisplc.com
Arcelik – Asli Kalihan – www.arcelikas.com.tr
Participants – RTD organisations:
Aidico – Irene Belena – www.aidico.es
Matri – Brian Stevens – www.uk-matri.org
Sirris – Heidi Vanden Rul – www.sirris.be
The SHIELD project aimed to develop a novel innovative insulation material combining excellent thermal insulation performance in demanding environments requiring humidity and/or a high level of fire resistance; this combined with an excellent processabilty (adapted to high volume industrial production) and a low cost.
The concept of the Shield project was to develop an inorganic lightweight foamed material based upon geopolymer chemistry. The insulation properties could be enhanced by the incorporation of ultra light weight aeroclays in the geopolymer matrix, along with other additives to further improve cell structure, foam stability, mechanical strength and humidity resistance.
Next to the material development activities on lab scale, the Shield project focussed on developing the necessary processing equipment necessary to convert the basic chemical components into tangible 3D shaped final parts, at production rates meeting the requirements from high-volume/low cost production environments.
The material and production technology was to be validated by means of the production and testing of two actual parts from the participating companies.
Such a material and associated processing would open market opportunities for the beneficiaries throughout the value chain from material production/consultancy through the design, production and commercialisation of parts containing this innovative material.
At the project start, the new aeroclay material has been developed. The resulting aeroclay materials met the requirements to allow further incorporation in the geopolymer matrix. Thermal conductivities of aeroclay materials were between 5 and 6 mW/mK.
The main material development work performed concerned the aeroclay/geopolymer foam. Several geopolymer systems were tested of which the Potassium based system was selected as the most promising one. Best foaming of the geopolymer was achieved by using a chemical blowing agent combined with a foam stabiliser.
In order to enhance mechanical properties, different kind of fibres, polymer latex and microspheres were tested.
Processing related activities focussed on defining requirements, designing systems for storage, feed and delivery of the material to the moulds. A lab scale unit was designed and purchased, and an injector was made. Application tools were designed and build.
Unfortunately, the required material properties for the foam could not be achieved – even after a review of the requirements by the sme’s resulting in less strict demands and the lab scale processing system could not be demonstrated by the deadline.
Based upon the available results, all information, remaining project time and budget, the SME board of the project decided to stop all RTD activities as the project would not be able to yield any exploitable results.
Project Context and Objectives:
The construction industry routinely experiences environments that demand excellent insulation performance in terms of high humidity or applications demanding high fire resistance. These environments often present complex shapes and limited and difficult to reach space for such insulation materials. Whilst many insulation materials are available commercially, few combine a wide range of high level performance with a low price based upon an excellent processability (spraying/injection).
The main goal of the SHIELD project was to develop a new high-performance insulation material offering a combination of excellent temperature insulation properties, fire resistance and has to be easy processable by automated processes like spraying and injection. This new material had also to show a long term stability in humid environments, a high durability and a low cost.
With this innovative new material, the consortium believed it can serve following market opportunities:
- applications were difficult to reach spaces/parts and complex shapes need to be insulated
- applications demanding very thin insulation layers: due to its high insulation property it will become the material of choice for these systems
- demanding end-uses like insulation in high humidity environments and end-uses with high demands on fire resistance and durability.
To prove the concept, the SHIELD material was to be evaluated for it’s use in air-ducts, fire doors, high level insulation in the oil and gas industry and household appliances.
The Shield project aimed to address this market gap of low-cost, fire-resistant, low-weight insulation materials coupled with excellent processability by developping a group of novel insulation materials, which exhibit these desirable properties in industrial products by combining clay-nano-composites with supporting additives.
The developed material was envisaged to offer a combination of:
- low thermal conductivity
- excellent fire resistance
- hydrophobicity for long term stability
- high durability for demanding application
- low material cost
The Shield project aimed also to develop a suitable processing route for these clay-based insulation materials, which minimises production cost by fully automating the spraying/injection production process.
With the combination of the developed material chemistry and processing methodology, it was the intention to develop and test first prototype applications for fire doors, air ducts and samples for fire testing with applications in the oil and gas industry.
Project Results:
Workpackage1: synthesis of aeroclay powder materials.
Objectives
Technical Objectives:
To develop an aeroclay material to be used as ultra-lightweight insulating filler with the following properties:
- Low thermal conductivity (< 20. 10-3 W/mK)
- Water resistance (no condensed water absorption)
- Fire resistance (European Class A1/A2)
- Low density (<30 kg/m3) Obtain a lab scale procedure for the synthesis by freeze-drying of different aeroclay materials:
Scientific Objectives:
1. A lab scale procedure for the synthesis of at least one clay base insulation material that satisfies sufficiently the stated requirements regarding thermal conductivity <20.10-3 W/mK, density, and fire resistance.
2. A lab scale procedure for the synthesis of at least one clay base insulation material that satisfies sufficiently the stated requirements regarding thermal conductivity <20.10-3 W/mK, density, fire resistance and water resistance.
Results: Material development partner Aidico succeeded in developing aeroclays with the required characteristics to be incorporated into the Geopolymer matrix to develop the Shield material. Targeted density and thermal conductivity properties were achieved, water absorption and fire resistance characteristics had to be met on the final shield material – so the aeroclay/geopolymer combination.
Achievements for WP1 are listed below:
1) Different aeroclays based in montmorillonite clay and different polyelectrolites have been developed and characterized at a lab scale with the idea of those polyions were absorbed on several clay particles at the same time and stablish strong bridges between them.
Three polyelectrolites were selected and add to different concentrations to obtain different aeroclays:
-Acry-aeroclay: Polyelectrolite (Sodium polyacrylate) + clay (montmorillonite)
-CMC-aeroclay: Polyelectrolite (carboxymethylcellulose) + clay (montmorillonite)
-Sulpho-aeroclay: polyelectrolite (Sodium alkylnaphtalene sulphonic) + clay (montmorillonite)
2) The methodology for the preparation is described below:
Clay gels preparation: Sodium exchanged montmorillonite clay (Nanofil 16) is mixed with deionized water in a laboratory mixer for 10 min at room temperature (20 ºC). Concentration of 6 % was dispersing 24 g in 400 ml of water.
Polyelectrolyte dispersions: Polyelectrolyte salt dispersion at 1, 2 or 3% concentration were prepared.
CMC and SULPHO dispersions were prepared adding 4, 8 or 12 g of polyelectrolyte over 400ml of water.
Sodium polyacrylate (ACRY) is a hydrogel polymer with ability to absorb high amounts of water, for this reason dispersions of this polyelectrolyte became too viscous and was preferable to add directly solid sodium polyacrylate and water onto the clay gel before prepared.
Mixture of clay and polyelectrolyte dispersion were prepared in volume proportions of 1:1 or 1:2 by mixing400 ml of clay dispersion with 400 or 800 ml of salt dispersion.
Frozen dispersions: The resultant dispersions (clay+electrolyte+water) were quickly frozen in a round glass container (1 litter) by submersion in liquid Nitrogen.
When solutions or suspensions were being frozen, a small amount of the liquid was poured in the drying flask. A film of the solution was formed on the wall by rotating the flask. The flask was then submersed in the coolant and was rotated until the film was frozen. This procedure was repeated with a second quantity of liquid, and so forth, until a frozen layer about 1 cm thick was built up.
Drying step: The drying step of the operation was performed in a "VirTis" freeze-drying apparatus, FM- 25EL-85. It takes about 3-4 days the total evaporation of several flasks with a 1cm film.
3) Two different aeroclays were selected depending if they are going to be used as monolithic or as powder addition to a geopolymer foam.
3,1) For the preparation of monolithic cylinders of aeroclay:
The selected was: CMC-aeroclay (6% clay-2% polyetrectrolyte (1:2) v:v)
picture of Cylinder samples of CMC-aeroclay => see attached report
All X-ray diffraction graphs show the intensity of peaks corresponding to crystallized electrolyte salts together with the peaks corresponding to the Montmorillonite. In CMC-aeroclay there are no evidences of Montmorillonite interlayer space expansion as d-spacing values are close to 12,52 A that is typical value of Monrmorillonite, as it occurs in Acry-aeroclay. This indicates that electrolyte salt is not intercalated between the clay layers.
The FTIR spectrum of CMC samples show that the carboxyl, methyl and hydroxyl functional groups are found at wavelength of 1630, 1423 and 1300 cm-1, respectively. It is obvious that broad absorption band at 3441 cm-1 is due to the stretching frequency of the hydroxyl group (–OH). The band at 2909 cm-1 is due to carbon-hydrogen bond (C–H) stretching vibration. The presence of a strong absorption band at 1630 cm-1 confirmed the presence of carboxyl group (–COO). The bands around 1423 and 1300 cm-1 are assigned to –CH2 scissoring and hydroxyl group (–OH) bending.
By SEM it is appreciated an edge to face configurations with galleries between layers (10 µ) together with longer ones (30 µ) (left figure below)
SEM image / compression results => see attached report
The chart shows the compressive strength behaviour: samples marked as C area plot of per cent linear compression versus the weight put on the cylinder. The curves marked R represent the same data after removal of the weight. The spread between the C and R curves measures the elastic recovery of the cylinders.
Then addition of a polyelectrolites during processing improves the mechanical rigidity to a point at which the clay---based aerogel sample is capable of supporting pressures on the order of 18 kPa with maximum % of linear compression of 95% for CMC-aerolclays.
Specific area surface for CMC aeroclay as been evaluated by a BET tests: 43.56±0.22 m2/g (this was the highest value of all synthetized aeroclays).
In general, the lower values of thermal conductivity for all the synthetized aerclays were the ones obtained with CMC-aeroclay type: λ = 0,0043±0,00022 W/mK
Cost calculation: A starting clay dispersion of formula [6% clay+2% polyelectrolyte (1:2, v:v) ] contains 96.6 % of water. If a 4% water retention is assumed, from 100 kg of starting clay dispersion the final water to be removed would be 92,6 %, and the final aeroclay would be 7,4 %.
This corresponds to an energy feed of 98,080kcal and required freeze drying time of 14,25h, resulting in a production cost of 2,907€/kg produced aeroclay.
3,2) For the use of powder additions to geopolymeric foam:
The selection of aeroclay was a function mainly of compatibility with selected plain geopolymeric foam (KGP) and improvements of thermal conductivity and density with its incorporation of a 2% of addition.
In all the cases, the incorporation of aeroclay to the geopolymer foam in a 2% improved density and thermal conductivity, but increase in few minutes the hardening time. The selected aeroclay was: Acry-aeroclay (Acry-montmorillonite (6% clay+1% acry (1:1) v:v)) which improve density and thermal conductivity in a more noticeable way than other aeroclays. With a temperature of 50ºC, the hardening time is more similar to KGP plain formulation than at ambient temperatures.
Characterization results:
KGP-4HP KGP-2ACRY-4HP KGP-2sulpho-4HP KGP-2CMC-4HP
Time (min) 205 210 235 205
D (Kg/m3) 138±6 108±3 125.4±0.9 136±3
Λ (mW/mK) 42±3 36.3±0.5 39.7±0.5 40.7±0.5
All the X-ray diffraction graphs show the intensity of peaks corresponding to crystallized electrolyte salts together with the peaks corresponding to the Montmorillonite. Diffractogram shows an increase of d-spacing value (from 11.79 A to 12.52 A) what is indicative of electrolyte intercalation between the clay layers.
FTIR analyses shows a wide band corresponding to stretching vibrations of the hydroxyl group occurs in the range of wave number 3700---3000 cm-1. Characteristic absorption bands at 1637 cm-1 corresponding to deformation vibrations C-OH and two bands at 1467 cm-1 and 1221 cm-1 typical for salts of carboxylic acids. The band corresponding to stretching vibrations of C-O-H group occurs at 1046 cm-1.
SEM analysis revealed variable galleries dimensions between 10 and 40µ for compositions prepared from 1% dispersions of Sodium polyacrylate in Clay: Acry 1:1 ratios
SEM image of 6%Clay:1%Acry (1:1, v:v) => see attached report
Thermal conductivity values for the Acry aeroclay reached λ= 0,0056 W/mK
Cost calculation: A starting clay dispersion of formula [6% clay+1% polyelectrolyte (1:1, v:v) ] contains 96.5 % of water. If a 4% water retention is assumed, from 100 kg of starting clay dispersion the final water to be removed would be 92,5 %, and the final aeroclay would be 7,5 %.
This corresponds to an energy feed of 98.000 kcal and required freeze drying time of 14,24h, resulting in a production cost of 2,865€/kg produced aeroclay.
Workpackage 2: development of aeroclay/geopolymer foam.
Technical Objectives:
To develop an insulating foam composition based on the combination of aeroclay filler, geopolymer binder and foaming agents, with the following properties:
- Available for spray-wet applications
- Low Density (<60 kg/m3) => revised to 80/85 kg/ m3
- Low Thermal conductivity (< 30. 10-3 W/mK)
- Fire Resistance (European Class A1/A2)
- Sufficient mechanical properties (at least 0,05 MPa) comparable to a soft poly-urethane, while maintaining or improving: Insulation, water resistance, fire resistance, low density).
- Biocide properties by adding natural biocide additives.
Scientific Objectives:
Obtain the best geopolymer/aeroclay formulation, to ensure that the SHIELD material is self-supportive and has a minimum compressive modulus of 0.05 MPa (corresponds to a soft poly-urethane) and that is compatible with the requirements of thermal insulation and fire resistance.
Determine the best foaming agents to get the density and thermal insulation performance of the final material at its optimal value.
Determine the biocide performance of the SHIELD-material when using additional additives.
Despite the efforts from material development partner Aidico, the objectives for the Shield material were not met. No good material could be developed combining low density, low thermal conductivity and good mechanical properties for an acceptable price.
Achieved formulations and properties are listed below:
1) Formulation design:
Different Geopolymeric foams based in metakaolin with different alkali cation and formulations were obtained with different foaming agents and additives in order to improve thermal conductivity, mechanical strengths and fire performance. Selected formulation is based in a potassium metakaolin-based geopolymer (with lower viscosity), foamed with hydrogen peroxide in alkali media and surfactant agents. The properties were further improved bu the incorporation of latex, hollow glass microspheres and different kinds of fibres in different concentrations.
Geopolymer system: The starting geopolymer paste was selected as a function of initial viscosity and final properties achieved incorporating different additions. The geopolymeric pastes selected were below:
Materials Na Na K K/Na K/Na-2
Name Na-GP Na-GP-2 K-GP K/Na-GP K/Na-GP-2
Metakaolin (g) 42 37 40 43 41
M2SiO3 (aq) (g) 29 35 35 35 34
MOH (50%) (g) 20 24 25 18 18
H2O (g) 9 4 0 4 7
H2O2 (g) 4 4 4 4 4
Rheocell (g) 0,6 0,6 0,6 0,6 0,6
masa total (Kg) 0,1046 0,1046 0,1046 0,1046 0,1046
Mr(Si2O/M2O) (mol) 1 1 1 1 1
M2O/Al2O3 (mol) 1 1,2 1 1 1
SiO2/Al2O3 (mol) 3,4 3,4 3,8 3.4 3.4
w/s (wt) 0,57 0,62 0,49 0,5 0,55
viscosity (cp): t=0 s 88385 2827 2756,4 19247 9299
viscosity tendency no measureable y = 2827,7e0,0821x y = 2756,4e0,0258x y = 19247e0,054x y = 9299e0,0503x
R2 0,996 0,94 0,99 0,996
One major observation was the big differences in kinetics of sodium and potassium systems. Sodium systems are faster than potassium systems, and hybrids are between both but closely to sodium systems, which can contribute to reduce setting time but starting with a more workable paste.
The potassium system KGP has been selected, due to a lower viscosity allowing to incorporate more additives and can be easier processed. Hybrid systems could be a good solution as well but the reaction kinetics are too high and effect of additives in the final properties improvement was not so evident than in potassium systems.
Foaming system:
Foaming has been realiased by a combination of two agents:
- Hydrogen peroxide, creating foam bubbles: 2H2O2 → 2 H2O + O2 (g)
- Foaming agent for concrete based in surfactant, which act as a bubble size and foam stabilizer. Recommended amount 0,6 g/100 g of KGP
Final formulation:
The final formulation is following combination: KGP-2ACRY-XL1201-WHMS-ZF-YHP
X: 0-5g of latex/100 g GP, when it was required a high amount of air entraining (higher amount of HP) to give more elasticity to the geopolymer. It is expected with the lower amount of HMS content. For amounts of HP equal or lower than 4g/ 100g KGP, it is not necessary. Improve elastic properties but decrease fire behavior.
Y: 4-6g of HP/100 g GP. 6% was found to be the maximum amount of hydrogen peroxide that KGP system accepts with 5% of latex content. It should be adjusted depending of processing parameters. Amount recommended 4%.
W: 3 g/100 g GP. It is the minimum amount of hollow glass microspheres to notice a thermal conductivity improvement but remaing cost effective.
Z: 1-2 g/100 g GP Basaltic microfibers improve mechanical strengths and fire performance but also increase density, and then the maximum amount will be fixed in 2 g/ 100 g KGP.
2) Preparation protocol
The optimal preparation protocol has been studied and optimized different parameters as:
- Mixing protocol
- Temperature influence
- Maturing age influence
schematic overview preparation protocol => see attached report
The influence of temperature on density was studied for several formulation KGP-2ACRY-5L and different fibers content. It was observed that density decreases with an increase of temperature, but it was observed also a decrease of integrity foam if the foam grown up more than 5 times it initial volume. Recommended temperature is over 50ºC.
The relation between temperature, reaction time and foam growing has also been investigated. Based upon lab scale volumes, foaming time reduces from over 2 hours to reach the final volume at room temperature to 15/20 minutes at 60°C. This has been tested for formulations with or without fibres and microsphers and findings were analogue.
3) Characterization of selected shield formulation: multiple formulations have been tested, below a summary of the most promising ones.
Properties goals KGP-4HP KGP-2ACRY-5L1201-6HP KGP-2ACRY-5L1201-4HP- 3HMS-2F
Demoulding time (min) 15 >3h (20ºC) 48 (50ºC) 50 (50ºC)
Density (Kg/m3) 85 138 79±8 125±22
Thermal conductivity
(mW/mK) < 30 42 34±0.1 38±1
Fire Resistance
European Class A1/A2 Not flammable Fire resistant (not flames or drops) Fire resistant (not flames or drops). Better behaviour.
Water repellent yes not not yes
Mechanical properties
(KPa) > 50 20±6 5±2 19±8
Cost (€/Kg) dried paste 0.9 0,7 0,8 1,3
Additionally XRD analyses were made to verify the presence and form of the aeroclay in the final product. It was observed that the peak of montmorillonite appears in all the samples together with the broad band corresponding to the amorphous geopolymer and the peak of quartz present in the starting metakaolin (unreacted in alkaline media). That’s means that at least the aeroclay is not dissolved in the alkaline media.
By SEM it was observed if the microstructure of aeroclays and hollow glass microspheres is preserved, what is important for density and thermal conductivity properties. The microstructure of aeroclay particles embedded in the geopolymer matrix is clearly visable. In all the cases the particle size is around 10 µ. The macrostructure of aeroclays is not detected, because they are incorporated in powder but microstructure is preserved with the well organized and expanded interlaminar space between layers.
The surface of the microspheres is not affected and interface between microsphers and Geopolymer seems good, but not chemically bonded.
KGP-geopolymer matrix (without foaming) KGP-3HMS (without foaming) KGP-2ACRY (without foaming) => pictures see attached report.
Thermoanalysis on the individual ingredients and Shield material samples has been conducted to verify high temperatures stability.
It showed that the selected latex is decomposed at 420ºC, Halloisyte fibres dehydroxylated at 540ºC, acry-aeroclay has a loss of weight at 480ºC due to the decomposition of polyacrylate modifier.
The Shield foamed product has a double peak of weight loss due to the decomposition of latex content and aeroclay modifier. The geopolymeric matrix is not decomposed until temperatures higher than 1000 ºC.
Fire testing: Samples with different fibre content were tested and compared to a rockwool panel. The below graph shows the different behavior of different samples, measuring the temperature rise in the not exposed face. Samples containing halloisyte fibres (FH1 and FHCF2) presented a faster rise of temperature compared with sample without fibre content (FP). Samples with basaltic fibre ( FCF1 and FCF2) content shows better behavior than sample without fibres and samples with the higher content of fibres (2%) combined with 3% of microspheres showed the best results, even better than the Rockwool panel. This result shows that basaltic fibre content improves considerably fire behavior of samples. Also to point out that samples fail by cracking of samples, but not due to decomposition or fired of samples. Not fumes were released.
fire testing graph => see attached report
Hydrophobicity testing:
To test the influence of spraying Potassium methyl siliconate over the surface of panels after drying, a simple drop test was carried out to see if water was retain in the surface or absorbed. Picture show samples without (left) and with treatment (right).
It is clear the effectiveness of water repellent in the water drops.
pictures => see attached report
Biocide properties were not measured or incorporated to the final product because properties of density, thermal conductivity, mechanical strengths or fire performance, were not good enough for SME’s and it was decided to stop the project and do not go on with more experimental work related with this issue.
WP3 Spraying and Curing:
WP3: Spraying and Curing
Technical Objectives:
Design a process for spray / blow deposition or injection adapted to the specific requirements of new foamed material.
Selection of appropriate spray/injection equipments for proof of concept tests al lab scale (<10 ltrs) according to the material and application specification. Carry out proof of concept tests on defined lab equipment with 3 selected foam formulations in order to validate the application system.
Scientific Objectives:
According to the characteristics of the raw materials and the expected foam properties, specifications for material storage, handling, feed, and delivery must be defined.
System design for Material Storage and Handling System (Pressure system, Material level indicators, Material temperature monitoring and control, Material refill systems , Material outlet system).
System design for material feed and delivery. This will be based on the theoretical procesing parameters of the foam materials (foam density, flow rate, finish/ surface quality, adequate mix ratio, spray pattern etc)
Develop Lab Scale Storage, Feed and Delivery System and carry out proof of concept tests with that system.
Define the best curing method by thermal treatment and/or curing accelerators.
WP3 was not finalised as RTD activities were stopped before the end of the project.
Achieved Results towards technical objectives:
Design a process for spray/blow deposition or injection adapted to the specific requirements of new foamed material.
A process for the injection of the geopolymer material into application specific moulds was defined. Before injecting into the moulds a chemical foaming agent is added and mixed in the injection gun. The foaming of the geopolymer then occurrs within the moulds.
Selection of appropriate spray/injection equipment for proof of concept tests al lab scale (<10 ltrs) according to the material and application specification. Carry out proof of concept tests on defined lab equipment with 3 selected foam formulations in order to validate the application system.
A lab scale ‘proof of concept’ system has been built based upon existing, available mixing and pumping equipment to perform proof of concept tests at a lab scale. The system was based on the premix concept with all material batch mixed. The foaming agent was mixed with the other components within the dispensing gun which also controlled the geopolymer to foaming agent mix ratio. The system has been demonstrated with dyed water in place of the foaming agent and mixing Metakaolin with water in place of potassiumsilicate, to show that the system could produce a homogeneous mix. Within the project it was not used to actually produce parts with this system as the project R&D work was stopped before the end.
Results related to scientific objectives:
According to the characteristics of the raw materials and the expected foam properties, specifications for material storage, handling, feed, and delivery must be defined.
The specifications for the material, storage, handling feed and delivery system has been defined. This has been achieved by examining the characteristics of the raw materials and by performing preliminary testing of the formulation to measure the properties of the material under different processing conditions. Based on the analysis and testing, recommendations for the storage and mixing of the geopolymer system and the definition of appropriate materials to be used in the vessels, pipework and hoses required for the processing equipment were made.
System design for Material Storage and Handling System (Pressure system, Material level indicators, Material temperature monitoring and control, Material refill systems , Material outlet system).
The system design for the material storage and handling system has been completed and documented. System designs have been developed for both a premix and In-gun mix method of dispensing the geopolymer. The premix system is a batch based system where it is necessary to premix all the component materials, apart from the foaming agent, before dispensing the geopolymer material. With the In-gun mix, the materials are mixed together on demand at the dispensing head. The In-gun mixing process has the advantage that there is very little waste material and minimal flush requirements, however this method requires a more sophisticated dispensing head to control the mix ratios of the materials and to ensure the materials are completely mixed before dispensing.
Process diagrams and example industrial scale processing systems have been described for both systems. A comparison of the two processing methods has also been presented.
System design for material feed and delivery. This will be based on the theoretical procesing parameters of the foam materials (foam density, flow rate, finish/ surface quality, adequate mix ratio, spray pattern etc)
The system design for the material feed and delivery system has been completed and documented. As part of this development, work was carried on the development of both a premix based spray gun and a more complex design for in-gun mixing. This included the analysis and design of a nozzle to enable a uniform spray pattern and the concept of In-gun mixing achieved through fluidizing of the powder. Despite development efforts no working ‘in gun mixing’ system for the shield material could be designed.
Several systems for foaming the geopolymer have been evaluated as part of this development. This included mechanical air foaming, adding externally generated foam and using chemical foaming.
Develop Lab Scale Storage, Feed and Delivery System and carry out proof of concept tests with that system.
A lab scale ‘proof of concept’ feed and delivery system has been built and tested during validation trials. The system was based on premix based systems but simplified so the key elements of the design and materials processing could be validated. The main components of the processing equipment were assembled and a bespoke delivery head was developed and built. Within the project timings, the system was demonstrated using water in stead of silicate solution and a water based coloured die to replace the H2O2.
Define the best curing method by thermal treatment and/or curing accelerators.
MATRI and Aidico have focused on optimising the curing process using thermal processing and through addition of curing accelerators. It was found that the length of the cure process could be reduced significantly by increasing the temperature. The target demoulding and curing times were able to be achieved at temperatures above 60oC. However the testing performed showed that the mechanical properties of the material were severely impacted if the peak exotherm temperature of the geopolymer exceeded 500C. To achieve the target mechanical strength of the cured material the peak temperature of the material had to be kept below 50oC, but at these temperatures the cure time was extended to greater than 120 minutes. An optimum cure process was defined to achieve the best mechanical strength and was used to produce samples for testing. The process however is not suited for large scale – high volume industrial production due to complex handling and long mould residence time.
WP4. Validation and Application Studies
Technical Objectives:
Pilot scale set-up for the production of the aeroclay/geopolymer base material
Pilot scale set-up for the production of two applications (coating and injection)
Application study: report on the main performance parameters of the applied SHIELD-material.
Scientific Objectives:
Demonstration of a pilot scale level for the production and application of the SHIELD-material.
Proven performance of the SHIELD-material in at least two applications.
Up-scaling processing method of selected aeroclay has been developed:
The development of a pilot scale equipment to produce high amounts of aeroclays (task 4.2) was found out to be impossible to achieve withing the projects timelines and budget. The effects of upscaling were investigated using available higher production volume equipment (still not yielding required production outputs though)
The preparation of this product has three main steps:
1. Preparation of clay dispersion
The preparation of initial clay dispersion was exactly the same than for lab scale preparation, but increasing volumes of products.
2. Pre-freezing of clay dispersion
The dispersion was poured in plastic trays with a centimeter of thickness more or less (to assured a good sublimation of total water content) and kept in a refrigerator at -80 ºC before been introduced in the freeze-drier equipment. This is the conventional method used in industrial scale for freeze-drying processes and differs from lab scale where liquid nitrogen is employed.
3. Freeze-drying process.
It was used a freeze-drying of 35 l with higher capacity than the one at lab scale. The product was placed in trays and the capacity was limited by the space in the vacuum chamber and amount into each tray. The thickness of dispersion in the tray is an important factor to consider because the sublimation time depends of that. The water content is sublimated from the outer layer to the inner layer and if the thickness is too high this process can be no completely successful. It has been place 8 l distributed in a total of 11 trays with a thickness of 1 or 2 cm. It was needed more than one week to complete the whole process. It could be tray lower volume per batch, trying to reduce time (but also amount obtained by batch), and arrive to a compromise between time/amount. The amount also affects the freezing velocity of dispersion.
Characterization of product synthetized in lab and pilot scale.
• SEM analysis
Aeroclay synthetized in the lab and compared with aeroclay synthetized in pilot plant and starting montmorillonite were analyzed by SEM. Differences in microstructure were observed. In the lab scale microstructure is an F-E organization of sheet; meanwhile in pilot scale microstructure observed was an F-F organization, with a bigger size of sheets.
Starting montmorillonite Particle of montmorillonite pictures => see attached report
Acry-aeroclay synthetized at lab scale F-E microstructure => see attached report
Acry-aeroclay synthetized in pilot scale F-F microstructure => see attached report
It is clear that the frozen procedure is influencing in the microstructure of aeroclays. To have the exact microstructure of the aeroclay synthetized in the lab scale, it would be necessary to use N2 liquid to frozen the samples instantaneously, to keep the spongy structure with a disposal F-E of sheet.
As aeroclay is incorporated in powder and mixed together with the other components in a water media, the particle size of final aeroclay in the final product is smaller (<20 microns), spongy microstructure observed previously (in the order of hundreds of micros or few millimeters) could be not so determinant in the final foam properties as it would be expected from the beginning.
Anyway, it should be researched influence in final properties (density and thermal conductivity) of aeroclays synthetized in the pilot plant. It was not studied due to lack of time.
As it was observed an improvement on thermal conductivity and density in foams incorporating Acry-aeroclay, this effect could be also due to the spacing between clay sheets caused by the incorporation of sodium polyacrylate and interpenetration between sheets in a nanoscale (From d=138±6 to 108±3, from λ= 42±3 to λ= 36,3±0,5). For the study of this effect, and how the processing could influence in it, there was study the different aeroclays obtained in both processes, together with the starting montmorillonite by XRD.
SEM image of Shield foam with aeroclay detail. SEM image of Shield foam with aeroclay detail => see attached report
• XRD
Observing the FWHW of peak corresponding to 001 plane, this value is lower for starting clay, then for the pilot plant aeroclay and the broader is for lab scale aeroclay. This means that the aeroclay synthetized in a lab scale is more delaminated (higher separation between sheets) than the one synthetized in the pilot plant and this last more than the starting montmorillonite (not modified).
XRD analysis for montmorillonite and aeroclays synthetized at pilot plant and lab scale. => see attached report
Regarding the position of peaks (001) for aeroclays modified, it seems like there was an overlapping of peaks at d=14,3 and d=13,82 A, and even d=12.48 A (this last corresponding to the starting montmorillonite). This value indicates the spacing between sheets in the plain 001, then as higher is d-spacing, as higher is the delamination of sheets in the clay. It can be deduced that in modified aeroclays, especially in the one synthetized at lab scale, there are different grades of modification/intercalation between sheets or spacing). Due to this overlapping, the peaks are broader for aeroclays than for starting montmorillonite not modified).
• Themoanalysis
The thermoanalysis show us a loss of weight in aeroclays due to the decomposition of sodium polyacrylate intercalated between the clay sheets. This percentage indicates the amount of organic present in the aeroclay and can be an indicator of effectiveness in modification of clays. Results show that a higher amount of modifier was intercalated in the aeroclay obtained at lab scale in comparison of pilot plant (>1%). This means that the frozen process can also been affecting in some way to the effectiveness of intercalation or exfoliation of clays, what is in accordance with XRD results.
Also, it was observed differences in water content, being higher in the aeroclay obtained in a lab scale. This can be due to an incomplete secondary drying of moisture chemically bounded to the clay (>7%). This value is <2.5% for pilot scale aeroclay which is a correct value of moisture content. Those differences can be due to differences in vacuum compressor power, higher for the pilot plant.
Thermoanalysis of montmorillonite and aeroclay obtained in lab scale and pilot plant ==> see attached report
Data results from thermoanalysis of montmorillonite and obtained aeroclay.
Material Temperature (loss of weight) % (wth) ACRY % (wth)water
Montmorillonite 650 ºC-dehydroxilation of clay
Acry-aeroclay-lab scale 480 ºC-decomposition of organic modifier 9,45 7.58
Acry-aeroclay-pilot plant 480 ºC-decomposition of organic modifier 8.30 2.29
Pilot scale set-up for the production of two applications (coating and injection):
As part of this development the curing and material processing was optimized to support the requirements of the application specific samples. Application specific moulds were developed and built and release agents were investigated to allow release of the material from the moulds.
As first trials, MATRI produced three prototype samples by means of manual mixing and casting (coated air duct tube an insulated door and a panel for fire testing). Within the project, the pilot scale setup designed in WP3 has not been used to produce the parts.
Application study: report on the main performance parameters of the applied SHIELD-material.
The application study of the performance parameters was not completed as samples for testing were not completed by the time the RTD work on the project was terminated. The fire test mould was tested by AIS, but the results showed that the foamed geopolymer material is less effective as a fire insulation product compared to standard products in use by AIS today. It was thought that the performance could be improved through further optimization of the material, in particular some fibres in the formulation could have prevented the cracking that occurred in the material.
Scientific Objectives:
Demonstration of a pilot scale level for the production and application of the SHIELD-material:
Demonstration of the pilot scale system for the production and application of the SHIELD material was not completed within the project timescales. The mixing capabilities of the system were validated using a dyed water in place of the foaming agent. However, the demonstration of the pilot scale system to inject of the processed material into the application specific samples for the door and Air duct applications has not been performed when the RTD activities were stopped.
Proven performance of the SHIELD-material in at least two applications:
Within the project, application specific samples for the Door and Air duct applications could not be produced before the RTD work had been terminated, so the performance of the SHIELD material developed for these applications could not be tested.
Potential Impact:
The SHIELD project aimed to develop a novel innovative insulation material combining excellent thermal insulation performance in demanding environments requiring humidity and/or a high level of fire resistance; this combined with an excellent processabilty (adapted to high volume industrial production) and a low cost.
Such a material and associated processing would open large market opportunities for the participating SME’s Vento, Rubio and AIS – companies producing components, which are in need for such a novel insulation material. IBZ – a material research company – would benefit from the generated material and material synthesis knowledge opening investment possibilities to produce the ingredients.
Along the projects progress, it became clear that despite the RTD’s and SME’s combined efforts, the targets for the material properties could not be met on lab scale level, and could not be improved by process related influences.
Within the project, SME’s repeatedly reviewed their possible applications and exploitation possibilities resulting in lower demands towards the material properties. Unfortunately these lower material specification targets could also not be met in a combined way. The developed material was either too brittle for low densities or not performing sufficiently on insulation properties for higher strength materials. Achievable densities were also higher, generating too high material costs to allow exploitation.
The SME board reviewed all available options and decided the stop all RTD activities as no possible exploitation routes could be identified. The remaining time and budget within the project was also not sufficient to further improve the development drastically.
Consequently the Shield project did not and will not generate an impact apart from the generated knowledge by the research institutes, which might be beneficial for future research.
As no exploitation possibilities could be detected by the SME’s along the project, dissemination activities remained limited to the sharing of knowledge and results within the consortium by means of meetings and reports and the development of the Shield project website providing very general information on the project and the consortium. A dissemination plan was developed along the project assuming the project results were achieved, but has not been activated.
There are no exploitation routes for the project results. SME’s don’t see any possibilities to covert the project results into business opportunities and the findings are also considered not to be exploitable through IPR protection and licensing to other parties outside the consortium.
List of Websites:
Website address: www.shield-project.eu
Contact details: the website contains an overview of all project partners and a contact form. Individual contact data can be found on the companies websites
Main contact persons:
Project coordinator: VENTO NV – Bart Modde – www.vento.be
Project participants – companies:
IBZ-Salzchemie GmbH & Co. KG – Gerald Ziegenbalg – www.ibz-freiber.de
Rubio, CMC, S.L. – José Rubio – www.rubiomet.com
AIS advanced insulation – Sarah Rogers – www.aisplc.com
Arcelik – Asli Kalihan – www.arcelikas.com.tr
Participants – RTD organisations:
Aidico – Irene Belena – www.aidico.es
Matri – Brian Stevens – www.uk-matri.org
Sirris – Heidi Vanden Rul – www.sirris.be
