Periodic Reporting for period 1 - FRGeo-Crete (Natural Fibre Reinforced Crack-resistant and spalling-controlled sustainable Geopolymer Concrete) Reporting period: 2019-11-01 to 2021-10-31 Summary of the context and overall objectives of the project The main objective of FRGeo-Crete was to investigate the underlying mechanisms of cracking and spalling of concrete and develop a crack-resistant and fire spalling-proof sustainable geopolymer concrete using waste materials and natural fibres as reinforcement.Currently, there are no design specifications to effectively control cracking in cementitious composites or provide effective sustainable reinforcement to mitigate spalling-induced issues in an efficient manner and with sustainable materials.To fulfil this objective, six Work Packages were established to achieve the following objectives:1) Quantify the cracking potential of geopolymer concrete and identify mitigation measures at the material level2) Evaluate the effectiveness of natural jute fibre in controlling the physical and performance of FRGeo-Crete3) Establish an appropriate methodology to improve the performance of natural fibres4) Explore the crack-resisting mechanisms of natural jute in FRGeo-crete5) Develop design recommendations and disseminate project scientific and technological findings. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far The main conclusions and achievements are summarised below.Objective 1 - WP1 State of the art on FRGeo-Crete development Status: Fully achieved • An extensive literature review was carried out on the development of sustainable geopolymer concrete utilizing several mineral-waste streams.• The utilisation of cement bypass dust (or Cement Kiln Dust - CKD) was identified as an effective alternative to develop one part geopolymer concrete minimizing the use of alkalis.• All information and data collected during the project are stored in a cloud-based storage device.Objective 2 - WP2 Development of natural-jute reinforced FRGeo-CreteStatus: Fully achieved• CKD in combination with GGBS was used in 1:1 ratio to prepare mortar with a w/b ratio of 0.9 and test different curing conditions (water at ambient temperature; elevated temperature @60 °C for 24 h).• 6 M sodium hydroxide solution was used to activate the BPD-GGBS system and cured in ambient condition and elevated temperature.• An another mix design was developed in which 20% cement w.r.t weight of total BPD-BFS mixture was used to avoid the alkali activation and cured in ambient and elevated temperature.• As the water demand of the BPD-GGBS system was very high (w/b = 0.9) a polycarboxylate superplasticizer was used at a dose of 2% w.r.t weight of binder and w/b was 0.75.• CKD and GGBS mixture was found suitable for making mortar and can attain the target strength after 28 days of hydration.• Though heat curing is beneficial for early strength gain; it was found to be detrimental for long term properties.• Alkali activation of the BPD-GGBS system is found to be less beneficial for obtaining good mechanical behaviour.• The use of polycarboxylate superplasticizer is found to be very effective in reducing water demand for BPD-GGBS system without affecting mechanical performance. • Jute fibre reinforcement in the BPD-GGBS system is found to be very effective in arresting crack propagation and increase flexural strength.Objective 3 - WP3 Mechanical and crack resistant performanceStatus: Fully Achieved• Jute fibres were pre-treated with 0.5% NaOH solution for 24 h, thereafter SBR, NR and TEMS (5% emulsion) were used to modify their surface.• There was not a significant difference in mechanical strength of untreated and polymer treated jute fibres.• SBR treatment was found to be the most promising in achieving appropriate mechanical strength.WP4 Durability and spalling performance of FRGeo-Crete• From the durability study of fibres exposed to several environments, SBR treated fibres retain more strength in lime exposure.• Whilst, natural rubber treated fibres show good resistance against saline solution degradation. In fact, the tensile strength increases after exposure to the saline solution after 1000 h.• A significant difference in freeze-thaw durability of fibre reinforcement mortar was found when fibres were treated with polymers.• SBR treated jute fibre reinforced mortar shows good resistance to the free-thaw degradation and retains more flexural strength than that of other treated fibre reinforced mortar samples.Objective 4 - WP5 Bond and microstructural structureStatus: Fully achievedA complementary set of techniques was used to evaluate the bond and microstructural behaviour of the examined materials, including: X-ray diffraction, FTIR, DSC, TGA and SEM-EDS.• The alkali treatment increases the crystallinity index and the tensile strength of the fibres. • Fibres treated with SBR and TEMS show reduced moisture content and water absorption properties. However, these treatments restrain the cellulosic arrangement and decrease the crystallinity, eventually reducing the tensile strength of jute fibres as compared to that of the alkali-only treated one. Objective 5 - WP6 Management, Dissemination, and OutreachStatus: Partially achievedThe results of the project were disseminated through two journal papers and two conference contributions during the funding period. Mandal R, Chakraborty S, Chakraborty S. Concrete prepared using electrolyzed water revealed benefits in controlling the early age properties. Journal of Materials in Civil Engineering. 2021, 33(6): 04021130.Chakraborty S, Mandal R, Chakraborty S, Guadagnini M, and Pilakoutas K. Chemical attack and corrosion resistance of concrete prepared with electrolyzed water. Journal of Materials Research and Technology, 2021, 11, 1193-1205.Chakraborty S, Guadagnini M, and Pilakoutas K. Development of the natural fibre reinforced bypass dust based auto activated concrete for future sustainable infrastructural solution: challenges and remedies, International Symposium MMETFP-2021, organised by PDEU, India in association with MRS of India, Gujarat, India, November 19-21, 2021. Chakraborty S, Guadagnini M, and Pilakoutas K. Development of cement-less construction materials utilizing waste alumino-silicate precursors by hydrothermal method and alkali activation, International Online Workshop EM4SS’21, Modena, Italy, 26-28 April 2021. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) This research work implements a multidisciplinary approach (i.e. macroscopic and microscopic) to demonstrate the effectiveness of waste minerals (cement bypass dust) and natural jute fibre in developing sustainable material. Another key innovation of this project is the development of an effective methodology for improving the quality of natural fibres as well as the fibre reinforced geopolymer concrete, in particular the use of a combined alkali and aqueous polymer coating (carboxylated styrene-butadiene, Natural rubber and Triethoxy methyl silane). The use of industrial by-products (slag and cement bypass dust) combined with natural jute fibres, as the binder and reinforcement respectively, in developing sustainable crack-resistant concrete has been investigated for the first time.The work completed as part of this fellowship contributed to developing safer and sustainable infrastructure, reducing waste and minimising economic losses due to repair of cracked and spalling infrastructure. The outcome of this project also benefits directly critical infrastructure owners by improving the robustness of infrastructure for both life safety and property protection. Finding highly value-added uses for waste minerals and natural fibre will reduce the environmental impact of products manufacturing. Graphical representation FRGeo-Crete microstructure
