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Geopolymer concrete is an inorganic polymer composite which has the potential to build an eco‐friendly and sustainable construction by replacing the existing conventional concrete. Herein, cement is totally replaced by mineral admixtures rich in aluminosilicates such as fly ash and is formed by the alkali activation using alkaline activator solutions, such as sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). Fly ash, a waste material from industry, can be incorporated in the manufacture of geopolymer concrete. The replacement of cement by fly ash in geopolymer concrete reduces the huge energy consumption and restricts carbon dioxide emission to the atmosphere during its production. In this paper, experimental investigations have been carried out involving the variation of total aggregate content (viz., 74, 76, 78, 80, and 82%), NaOH concentration (8, 10, 12, and 14 M), and curing temperature (60, 70, 80, 90, and 100°C) on the strength of geopolymer concrete by keeping a constant alkaline liquid to fly ash ratio of 0.45 and a 24‐hour rest period. It is concluded that 76% of total aggregate content is suitable for producing geopolymer concrete without hindering the workability. Further, strength of geopolymer concrete has been found to be increased at 90°C having 12 M NaOH concentration.

Genetically modified spore forming B. subtilis bacterial cells for eco-friendly sustainable self-healing bio-concrete.

24A silver-silica nano composite based geopolymer mortar has been developed by 25 simple adsorption of silver in a suitable amount of colloidal silica suspension for anti-26 bacterial property development. The silver nanoparticles (3-7 nm) were attached on the 27 surface of 20-50 nm sized silica nanoparticle. The silver-silica nano-composite was 28 characterized by Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD) and 29 Energy Dispersive X-ray Spectral analysis. Mechanical strength, durability and mechanistic 30 anti-bacterial activity of the silver-silica nano composite modified geopolymer mortar 31 (GM Ag-Si ) were investigated and compared to nano silica modified geopolymer mortar (GM Si ) 32 and control cement mortar (CM). To accesses the anti-microbial efficacy of the samples, 99% 33 mortality for the Gram positive and Gram negative bacteria were calculated. Minimum 34 Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values 35 were determined from batch culture. With the addition of 6% (w/w) of silver-silica nano 36 composite in the geopolymer mortar cured at ambient temperature shows substantial 37 improvement in mechanical strength, durability and anti-bacterial property. Reactive Oxygen 38 Species (ROS) generation and cell wall rapture as observed from fluorescence microscopy 39 and Field Emission Scanning Electron Microscopy (FESEM) may be possible reason behind 40 the anti-bacterial efficacy of silver-silica nano composite modified geopolymer mortar.41 42 43 44