This research study is performed on the self-compacting geopolymer concrete (SCGC) combining coal bottom ash (CBA) and metakaolin (MK) as a substitution for GGBFS alone and combined for analysing the fresh properties (slump flow, V-Funnel, and T50 flow), mechanical characteristics (compressive, splitting tensile and flexural strengths) and durability tests (permeability and sulfate attack test). Though, total 195 SCGC samples were made and tested for 28 days. It has been revealed that the consumption of CBA and MK as a substitution for GGBFS alone and combine in the production of SCGC is decreased the workability of SCGC while mechanical characteristics of SCGC are enhanced by utilizing CBA and MK as a substitution for GGBFS alone and combine up to 10%. In addition, the compressive, splitting tensile and flexural strengths were calculated by 59.40 MPa, 5.68 MPa, and 6.12 MPa while using the 5CBA5MK as a substitution for GGBFS in the production of SCGC after 28 days correspondingly. Furthermore, the permeability is decreased by growing the quantity of CBA and MK by the weight of GGBFS alone and jointly in the production of SCGC after 28 days. Besides, the minimum change in length of the SCGC specimen is recorded by 0.062 mm at 7.5MK7.5CBA while the maximum change in length is calculated by 0.11 mm at 10CBA10MK as a substitution for GGBFS at 180 days correspondingly. In addition, the embodied carbon is recorded reduce as the addition of CBA while it is getting higher when the accumulation of MK alone or combined with CBA in SCGC. Besides, response models for prediction were constructed and confirmed using ANOVA at an accuracy rate of 95%. The models' R2 fluctuated from 88 to 99%. It has been observed that the utilization of CBA and MK alone and together up to 10% as substitution for GGBFS in geopolymer concrete provides the best results therefore it is suggested for structural applications.
The increasing demand for cement has substantially affected the environment, and its manufacturing requires substantial energy usage. However, most countries in the world recently encountered a significant energy problem. So, researchers are exploring the use of agricultural and industrial waste resources with cementitious characteristics to minimize cement manufacturing, cut energy consumption, and contribute to environmental protection. Therefore, this research is performed on roller compacted concrete (RCC) reinforced with 5%, 10%, 15%, and 20% of corn cob ash (CCA) as substitution material with different percentage of cement and 0.25%, 0.50%, 0.75%, and 1% of jute fibre (JF) together for determining the mechanical properties and embodied carbon (EC) by applying response surface methodology (RSM) modelling. The cubical samples were prepared to achieve the targeted strength about 30 MPa at 28 days and then obtained mix proportions were employed for all combinations at various water-cement ratios to maintain roller-compacted concrete's zero slump. Results showed that at 0.50% JF and 10% CCA, the flexural strength, splitting tensile strength and compressive strengths, and modulus of elasticity of RCC obtained were 5.3 MPa, 3.8 MPa, 32.88 MPa, and 33.11 GPa at 28 days, respectively. Besides, the embodied carbon of RCC is recoded reducing with combined addition of different levels of JF and CCA as compared to control mixture. In addition, the generation of response prediction algorithms was performed using analysis of variance (ANOVA) at a threshold of significance of 95%. The coefficient of determination (R2) readings for the statistical models ranged from 96 to 99%. It is observed that the use of 0.50% of JF along with 10% of CCA as cementitious constituent in RCC provides best outcomes. Therefore, this method is a superior choice for the construction industry.
Currently, chemical attacks, including acid attacks and sulphate attacks, pose a significant problem for the long-term durability of concrete infrastructures that encounter many types of water, including swamp water, marine water, sewage water, drinkable water, and groundwater. Therefore, the intention of this work is to enhance the durability and resistance of concrete against chemical attack by blending titanium dioxide (TiO2) as nanoparticles into designed cementitious composites. The purpose of current study is to obtain an appropriate TiO2 based on the cement's weight and polyvinyl alcohol (PVA) fiber in composites using multi-objective optimisation. Thirteen mixtures comprising diverse combinations of variables (TiO2: 1-2%, PVA: 1-2%) were formulated utilising RSM modelling. Seven responses were assessed for these mixtures, including weight loss, compressive strength, expansion, a rapid chloride permeability test (RCPT) and a pH test. Analysis of variance, on the other hand, was utilised to construct and assess eight response models (one linear and six quadratics in nature). The R2 values for models spanning from 88 to 99%. The multi-objective optimisation generated optimal response values and ideal variable values (1% PVA and 1.5% TiO2). Experimental verification revealed that the predicted values correlated exceedingly well with the experimental data, with an error rate of less than 5%. The outcomes indicate that a 30% rise in compressive strength was noted when 1.5% TiO2 nanomaterial was incorporated into ECC. Furthermore, the expansion caused by sulphate attack decreases when TiO2 used as a nanomaterial increases in composites. Besides, when the concentration of TiO2 in ECC increased, the pH value, and weight loss caused by acid attack reduced. In addition, the RCPT is recorded reducing when the content of TiO2 increases but it increases with addition of PVA fiber. It has been shown that including 1.5% TiO2 and 1% PVA fiber yields the optimal results for the building sector.