Periodic Reporting for period 1 - SynSilable (Synthesis and Utilization of Mesoporous Silica Nanoparticles for more sustainable and durable cementitious composites)
Período documentado: 2023-09-01 hasta 2025-10-31
SynSilable was conceived in the context of the urgent need to decarbonise the construction sector while maintaining safety, durability and affordability of infrastructure. Ordinary Portland cement is responsible for a significant share of global CO2 emissions, and many EU policies and strategies, including the European Green Deal and the Renovation Wave, call for rapid reductions in clinker content and for longer lasting, resource efficient structures. However, many low clinker or alternative binders suffer from slow early strength development and uncertainties regarding their microstructural performance, which can limit their uptake in practice.
The overall objective of SynSilable is to explore mesoporous silica nanoparticles (MSNs) as a family of nano additives tailored for cement based materials, and to clarify how they can support faster and more reliable early age performance while improving microstructural refinement. The project combines synthesis and characterisation of different MSNs with systematic testing in cement pastes, mortars and selected concretes, and with a screening life cycle assessment. This pathway allows the project to link nano scale mechanisms, such as nucleation and pozzolanic reactions, to macroscopic properties like early strength and durability indicators, and then to assess whether potential performance gains can translate into lower clinker contents and reduced embodied CO2 in realistic applications.
By generating a consistent experimental data set and clear mechanistic understanding, SynSilable is expected to help researchers and industry identify where MSNs are technically meaningful, and under which conditions their environmental and economic impact is positive. The results can support improved mix design for repair mortars, precast elements and other high performance applications where early strength is critical, thereby contributing to EU efforts to reduce emissions from cement production and extend the service life of infrastructure assets. The topic does not require formal integration of social sciences and humanities, and the work is therefore focused on materials science and engineering aspects.
The overall objective of SynSilable is to explore mesoporous silica nanoparticles (MSNs) as a family of nano additives tailored for cement based materials, and to clarify how they can support faster and more reliable early age performance while improving microstructural refinement. The project combines synthesis and characterisation of different MSNs with systematic testing in cement pastes, mortars and selected concretes, and with a screening life cycle assessment. This pathway allows the project to link nano scale mechanisms, such as nucleation and pozzolanic reactions, to macroscopic properties like early strength and durability indicators, and then to assess whether potential performance gains can translate into lower clinker contents and reduced embodied CO2 in realistic applications.
By generating a consistent experimental data set and clear mechanistic understanding, SynSilable is expected to help researchers and industry identify where MSNs are technically meaningful, and under which conditions their environmental and economic impact is positive. The results can support improved mix design for repair mortars, precast elements and other high performance applications where early strength is critical, thereby contributing to EU efforts to reduce emissions from cement production and extend the service life of infrastructure assets. The topic does not require formal integration of social sciences and humanities, and the work is therefore focused on materials science and engineering aspects.
The project was structured in three main technical stages. First, several families of mesoporous silica nanoparticles (MSNs, including MCM 41, MCM 48, SBA 15 and SBA 16) were synthesised and extensively characterised using FTIR, nitrogen adsorption, XRD, SEM and related methods. Their basic reactivity and dispersibility in cementitious environments were benchmarked against commercial nano silica products, and a subset of the most promising materials was selected for detailed testing.
In the second stage, the selected MSNs were incorporated into cement pastes at different replacement levels. Isothermal calorimetry showed that MSNs accelerate hydration and increase early heat release, with optimum contents in the order of 0.2 to 0.6 percent by mass of cement depending on MSN type. Combined analysis by XRD Rietveld and TGA confirmed enhanced portlandite consumption and increased formation of C S H, indicating that MSNs act through both nucleation and pozzolanic effects. Mercury intrusion porosimetry and SEM revealed a refined pore structure with reduced volume of critical capillary pores, particularly at early ages. Ultrasonic pulse velocity and mechanical tests demonstrated significant gains in early compressive and flexural strength, without detrimental effects at later ages.
In the third stage, the use of MSNs was extended to mortar and, on a more limited scale, to concrete. Mortar tests confirmed the acceleration of hydration, microstructural refinement and strength gains observed at paste level. For example, the mix containing SBA 16 showed an increase of around 50 percent in one day compressive strength and about 15 to 20 percent at 28 days compared to the reference. Concrete trials were carried out on a few representative mixes to verify feasibility, workability and early age strength trends, which followed the positive patterns seen in mortars. A screening cradle to gate life cycle assessment compared reference mixes with MSN modified scenarios and indicated that, when MSNs enable meaningful reductions in cement content or faster formwork turnover, a reduction in embodied CO2 is plausible, although strongly dependent on MSN production routes and scale.
The main achievements of the action are a consistent experimental data set on MSNs in cement paste and mortar, a clear mechanistic understanding of their combined nucleation and pozzolanic roles, quantified optimal dosage ranges, and feasibility evidence at concrete scale together with indicative LCA results. These outcomes provide a robust technical basis for future development of MSN based admixtures and their integration into low clinker, high performance concrete systems.
In the second stage, the selected MSNs were incorporated into cement pastes at different replacement levels. Isothermal calorimetry showed that MSNs accelerate hydration and increase early heat release, with optimum contents in the order of 0.2 to 0.6 percent by mass of cement depending on MSN type. Combined analysis by XRD Rietveld and TGA confirmed enhanced portlandite consumption and increased formation of C S H, indicating that MSNs act through both nucleation and pozzolanic effects. Mercury intrusion porosimetry and SEM revealed a refined pore structure with reduced volume of critical capillary pores, particularly at early ages. Ultrasonic pulse velocity and mechanical tests demonstrated significant gains in early compressive and flexural strength, without detrimental effects at later ages.
In the third stage, the use of MSNs was extended to mortar and, on a more limited scale, to concrete. Mortar tests confirmed the acceleration of hydration, microstructural refinement and strength gains observed at paste level. For example, the mix containing SBA 16 showed an increase of around 50 percent in one day compressive strength and about 15 to 20 percent at 28 days compared to the reference. Concrete trials were carried out on a few representative mixes to verify feasibility, workability and early age strength trends, which followed the positive patterns seen in mortars. A screening cradle to gate life cycle assessment compared reference mixes with MSN modified scenarios and indicated that, when MSNs enable meaningful reductions in cement content or faster formwork turnover, a reduction in embodied CO2 is plausible, although strongly dependent on MSN production routes and scale.
The main achievements of the action are a consistent experimental data set on MSNs in cement paste and mortar, a clear mechanistic understanding of their combined nucleation and pozzolanic roles, quantified optimal dosage ranges, and feasibility evidence at concrete scale together with indicative LCA results. These outcomes provide a robust technical basis for future development of MSN based admixtures and their integration into low clinker, high performance concrete systems.
SynSilable has advanced the state of the art on nano modified cementitious materials in several concrete ways. Previous studies on nano silica often focused on single products and limited test methods. This project systematically compared several mesoporous silica nanoparticle families (MCM 41, MCM 48, SBA 15, SBA 16) and benchmarked them against commercial nano silica, using a consistent protocol from paste to mortar and selected concrete mixes. It combined isothermal calorimetry, XRD Rietveld with internal standard, TGA, MIP, SEM, ultrasonic pulse velocity and mechanical testing, which provided a coherent mechanistic picture rather than isolated observations.
The project quantified optimal dosage ranges in the order of 0.2 to 0.6 percent by mass of cement, and showed that MSNs can deliver very significant gains in early strength and microstructural refinement at these low contents. For example, SBA 16 increased one day mortar compressive strength by around 50 percent and 28 day strength by about 15 to 20 percent, while reducing the volume of critical capillary pores in the 20 to 200 nanometre range. The work clarified that these improvements arise from a combination of nucleation and pozzolanic effects, supported by consistent calorimetry and phase analysis, and confirmed that the positive trends can be transferred, at least on a feasibility level, to concrete. A screening cradle to gate LCA indicated that MSNs can contribute to reduced embodied CO2 where they enable meaningful clinker reduction or faster construction cycles, while also identifying the key parameters that control this balance.
For further uptake and impact, several needs have been identified. First, more work is required on cost effective, scalable synthesis routes for MSNs that are compatible with industrial admixture production. Second, long term durability under aggressive exposures and performance in full scale concrete structures need to be demonstrated, including statistical variability and robustness in real production environments. Third, closer collaboration with industry will be needed to translate the findings into practical admixture formulations and to validate them in targeted applications such as repair mortars and precast elements. Finally, refined LCA studies based on specific industrial production data, along with contributions to guidelines and standardisation, would support market acceptance and regulatory recognition of MSN based solutions.
The project quantified optimal dosage ranges in the order of 0.2 to 0.6 percent by mass of cement, and showed that MSNs can deliver very significant gains in early strength and microstructural refinement at these low contents. For example, SBA 16 increased one day mortar compressive strength by around 50 percent and 28 day strength by about 15 to 20 percent, while reducing the volume of critical capillary pores in the 20 to 200 nanometre range. The work clarified that these improvements arise from a combination of nucleation and pozzolanic effects, supported by consistent calorimetry and phase analysis, and confirmed that the positive trends can be transferred, at least on a feasibility level, to concrete. A screening cradle to gate LCA indicated that MSNs can contribute to reduced embodied CO2 where they enable meaningful clinker reduction or faster construction cycles, while also identifying the key parameters that control this balance.
For further uptake and impact, several needs have been identified. First, more work is required on cost effective, scalable synthesis routes for MSNs that are compatible with industrial admixture production. Second, long term durability under aggressive exposures and performance in full scale concrete structures need to be demonstrated, including statistical variability and robustness in real production environments. Third, closer collaboration with industry will be needed to translate the findings into practical admixture formulations and to validate them in targeted applications such as repair mortars and precast elements. Finally, refined LCA studies based on specific industrial production data, along with contributions to guidelines and standardisation, would support market acceptance and regulatory recognition of MSN based solutions.