Geopolymer concrete possesses superior fire resistance compared to ordinary Portland cement (OPC)-based concrete; however, there are concerns regarding its vulnerability when exposed to real fire events. In the present study, the fire resistance of fly-ash-based geopolymer concrete was evaluated relative to that of OPC-based concrete. Concrete specimens of standard strength grades of 20, 40, and 60 MPa were exposed to fire at 500 and 1200 °C for 2 h to simulate real fire events. Visual observation was performed, mass loss and residual compressive strength were measured, and scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses were conducted. OPC-based concrete suffered major cracks accompanied with spalling for the high-strength specimen, while geopolymer concrete experienced minor cracks with no spalling. Mass losses of the geopolymer concrete—of 1.69% and 4%, after the exposure to fire at 500 and 1200 °C, respectively—were lower than those of the OPC-based concrete. More than 50% of the residual compressive strength for low- and medium-strength geopolymer concrete, after the exposure to fire at 1200 °C, was maintained. After the exposure to fire at 500 °C, the residual compressive strength of the geopolymer concrete increased from 13 to 45%, while the OPC-based concrete was not able to sustain its compressive strength. SEM images showed that the matrix of the geopolymer concrete, after the exposure to fire, was denser than that of the OPC-based concrete, while the FTIR spectra of the geopolymer concrete showed a minor shift in wavelength. Hence, our findings indicate that fly-ash-based geopolymer concrete has an excellent fire resistance as compared to OPC-based concrete.

Concrete in general is a poor conductor of heat, but it can suffer significant damage when exposed to fire. Investigation of concrete behaviour when exposed to fire has generated interest where most of the fire cases take place in buildings and tunnels. Incorporation of fiber in concrete can improve the mechanical performance as it acts as crack arresters, resisting the development of cracks, hence making the concrete composite matrix stronger. In this study, mechanical behaviour of basalt and carbon fiber reinforced concrete for different characteristic strengths at 28 days were investigated for its performance when exposed to fire flame. Fire flame test using methane gas was developed to simulate real fire phenomena. Concrete specimens were subjected to fire flame at the temperature of 1000 °C for a period of 90 minutes. Visual observation (colour change, cracking and spalling), loss of density and residual compressive strength of the concrete specimens were performed. The results obtained were compared with reference specimens. Test results showed that tested samples experienced cracking and spalling, reduction of mass and compressive strength. All samples experienced compressive strength loss except for G20 OPC which recovers 7.8 % compressive strength. Addition of carbon fiber showed an increased in strength before exposure compared to basalt fiber. Minor damages were observed for carbon fiber in concrete after fire exposure compared to basalt fiber.

The impact of various factors such as microbes, allergens, inadequate environmental conditions, pollutants, and suboptimal building materials on human health within indoor environments is of utmost importance due to the significant amount of time people spend inside buildings. The objective of this study was to assess the combination of Portland cement (PC) with Titanium Oxide (TiO2) nano powder for antimicrobial properties with good physical and mechanical strength. TiO2 was added to PC at various percentages (0.5%, 1.0% and 1.5% by the weight of cement) and analysis of slump flow, compressive strength and flexural strength were determined. The antimicrobial activity was evaluated by agar diffusion test, utilizing 4 bacteria strains: Escherichia coli, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa. Results showed that the addition of TiO2 increased the mechanical strength of the specimen with 1.0% TiO2 displaying the optimum result. For the antimicrobial activity, samples with 1.05% TiO2 had the highest efficiency in inhibiting bacteria growth. The findings showed that a lower percentage of TiO2 added to the PC mortar significantly enhances its mechanical properties and is efficient in inhibiting the growth of bacteria. Such mortar mixture with antibacterial properties should be utilized to enhance hygiene conditions in diverse environments, including hospitals, institutional kitchens, etc., where such properties are necessary.

In view of the increasing cost of raw materials and depleting natural resources in many developed countries, adoption of waste in construction materials has to be considered. Fibre-reinforced concrete (FRC) is a type of concrete that employs steel or synthetic fibres. Sugarcane bagasse fibre (SCBF), which is a waste material from the agricultural industry, can potentially be utilized in FRC as an alternative to steel or synthetic fibres. In light of the potential, in the present study, compressive and splitting tensile strengths of sugarcane-bagasse-fibre-reinforced concrete (SCB-FRC) at varying volumes of SCBF were evaluated. Four types of concrete samples were prepared, which are the control sample that does not contain any SCBF and SCB-FRC samples that contain 0.5, 1.0, and 1.5% of SCBF of 5-cm fibre lengths by volume of cement. Samples were cured in water for 7 and 28 days for compressive strength testing and 28 days for splitting tensile testing. Findings indicate that the optimum fibre volume is 1.0%, where the highest compressive strengths of 24.75 and 33.02 MPa were achieved at 7 and 28 days of curing, respectively, and the highest splitting tensile strength of 2.61 MPa was achieved. Formation of fibre bundles during mixing may have resulted in the decrease in strength as the fibre volume was further increased from 1.0 to 1.5%.