Vivek Deivasigamani

Pervious concrete is a special type of concrete being used in construction industry and offering a sustainable solution for storm water management and ground water recharge. This research focuses on Response Surface Methodology (RSM) with a Box- Behnken design to systematically evaluate different parameters such as aggregate size, quantities of ordinary Portland cement (OPC), Portland Pozzolana Cement (PPC) and coarse aggregate content for analysing the influence the mechanical performance of pervious concrete mixes. Through comprehensive testing and statistical analysis, the study uncovers complex interactions of the mix components, facilitating the identification of optimal formulations to achieve a balance between strength and sustainability for diverse applications. In this present study, nine mixes were performed with varying Aggregate Binder (A/B) and Water Binder (W/B) ratio ranging from 3 - 2.9 and 0.3 - 0.35. All the mixes were tried with OPC and PPC binders using aggregate sizes viz. 6.3 mm, 9.4mm and 12.5 mm respectively. Test results proved that, mix containing more binder content with higher water cement ratio (M9) showcased higher mechanical strength properties than other mixes (M1-M8) due to enriched paste coating around the aggregate surface. Mix M1 has shown higher permeability and porosity due to lesser binder quantity and the adequate water-cement ratio results in slower rate of hydration process resulting in more void formation. Better strength properties are observed in smaller size aggregates which attributed to a dense microstructure. Increase in aggregate size results in decrease in strength whereas permeability and porosity increase.

Cement production is a major industrial source of CO ₂ emissions; therefore, materials capable of partially replacing cement without compromising performance are of considerable interest. In this study, sugarcane bagasse ash (SBA) was used to replace 20% of the cement by mass, while steel slag replaced the fine aggregate at levels of 0%, 10%, 20%, and 30%. The four resulting mixes were evaluated for compressive strength, splitting tensile strength, flexural strength, accelerated carbonation, resistance to sulphate attack after six months of exposure to a combined sodium and magnesium sulphate solution, and drying shrinkage. The mix containing 20% steel slag exhibited the best overall performance, achieving the highest compressive, splitting tensile, and flexural strengths at all three testing ages, as well as the lowest carbonation depth, mass loss under sulphate attack, and drying shrinkage strain. However, increasing the steel slag replacement level to 30% resulted in a decline in performance relative to the 20% replacement level.

Greenhouse gases, namely carbon dioxide emissions, cause variations in global temperature and relative humidity (RH), which some projections show that there will be a reduction in RH in certain areas as CO2 level increases. These fluctuations in CO2, temperature and RH significantly impact on carbonation depth in current systems. However, models for forecasting carbonation depth as a function of time in concrete components are limited to the extent of implementing important factors associated with the effects of climate change. Various concrete mixes containing 10 to 30% fly ash (FA), 3% nano silica particles (NSP) with a constant water to cement (w/c) ratio of 0.34 were used to test the durability and mechanical characteristics of nano fly ash concrete (NFC). After exposing these specimens for up to 28 days, the depth of carbonation (2% (vol.) CO2, 20°C, 65% RH) were investigated. Carbonation results show that NSP incorporated concrete mixes reduce carbonation depth by approximately 73% when compared to the control specimens.

The impact of integrating Nano Silica (NS) on mechanical characteristics, resistance towards impact, and chloride penetration on concrete having Fly Ash (FA) are investigated in this research. The NS particles are subsequently mixed into concrete at one, two, three, four, and five percent of the binder’s mass, respectively. The performance of the specimens under an impact load is assessed by utilizing the drop weight impact technique, frequency on strikes, and impact force variation has been used to evaluate the specimen's impact resistance. The concrete's ability to withstand damage from chloride penetration was evaluated by determining the chloride diffusion coefficient of the samples. The test findings demonstrated that adding NS to concrete may significantly increase its mechanical characteristics as well as chloride penetration resistance. The optimum amount of NS substitution in concrete is two to three percent and it is discovered that if the proportion of NS is too large, the benefits of incorporating NS into the characteristics of the concrete are diminished, and might even have a detrimental effect on the resistance towards impact and durability of the concrete. Moreover, the experimental compressive strength and split tensile is compared with existing gene expression programming model.

Ultra-high-performance fibre-reinforced concrete (UHPFRC) is a specialized type of concrete (to create a very dense matrix) that is used for both new construction and renovation projects in order to improve the lifespan of structures. Researchers analyse and evaluate only the microstructure, porosity, and fresh and hardened concrete properties of UHPFRC but limited their exploration on the reduction of the mechanical properties of UHPFRC due to the presence of metallic particles and micro-fractures that occur during the generation of hydrogen. Hence, the present study aims to eliminate the existing problem by hybridization approach (mixing of bio-nano-silica (nS) and polypropylene) with different percentages to further improve the strength properties of UHPFRC. The result showed that the compressive strength is increased by 15.5 compared to traditional concrete due to the filling ratio of nS in the pores of the concrete; in addition, the fibres surface and roughness also contributed to the strength enhancement.

Design of Experiment-Response surface methodology approach is adopted to obtain the optimal flexural moment of ferrocement composites comprising galvanised square weld mesh with weight fraction of fine aggregate by steel slag. To get the optimal combination of progression variables on a flexural moment of ferrocement composites, the central composite design of response surface methodology was adopted. Regression models for responses were justified using analysis of variance and the Pareto chart. The test results show that a maximum ultimate load of 3.30 kN and moment capacity of 220 kNm was obtained for ferrocement with a volume fraction of 2.733% and steel slag of 25% replacement. From the analysis of variance, it is evident that the value is less than 0.005, the predicted R² and the adjustable R² are less than 20%, and the predicted values go in hand with the experimental result which indicates that the proposed models are highly suitable. Moreover, the volume fraction of galvanised square weld mesh has a higher significance on a flexural moment of ferrocement composites. Surface plot, Pareto chart, and regression analysis outcomes show that the most substantial and influential factor for a flexural moment is the volume fraction of galvanised square weld mesh.

Bending tests were conducted on ferrocement laminates containing chicken mesh and steel slag. The fundamental goal of the examination was to investigate the effects of partial substitution of fine aggregate by steel slag in cement mortar combining chicken mesh of different volume fractions as reinforcement in thin ferrocement laminates. The following variables were investigated: (a) volume fraction of chicken mesh as 0.94%, 1.88%, 2.82%, and 3.77% and (b) level of steel slag substitution from 0% to 50% by weight fine aggregate. Results show that ferrocement laminates with chicken mesh of volume fractions of 3.77% and 30% substitution of fine aggregate with steel slag display better performance in terms of load deflection behaviour, first crack load, ultimate load, energy absorption, and ductility ratio when related with other specimens. An analytical model has been proposed to predict the ultimate moment carrying capacity of ferrocement laminates under flexure to validate the experimental results.