Abstract
Producing high-strength self-compacting concrete (SCC) requires a low water-cement ratio (W/C). Hence, using a superplasticizer is necessary to attain the desired self-compacting properties at a fresh state. The use of low W/C results in very brittle concrete with a low deformation capacity. This research aims to investigate the influence of crumb rubber (CR), fly ash (FA), and nanosilica (NS) on SCC’s workability and mechanical properties. Using response surface methodology (RSM), 20 mixes were developed containing different levels and proportions of FA (10–40% replacement of cement), CR (5–15% replacement of fine aggregate), and NS (0–4% addition) as the input variables. The workability was assessed through the slump flow, T500, L-box, and V-funnel tests following the guidelines of EFNARC 2005. The compressive, flexural, and tensile strengths were determined at 28 days and considered as the responses for the response surface methodology (RSM) analyses. The results revealed that the workability properties were increased with an increase in FA but decreased with CR replacement and the addition of NS. The pore-refining effect and pozzolanic reactivity of the FA and NS increased the strengths of the composite. Conversely, the strength is negatively affected by an increase in CR, however ductility and deformation capacity were significantly enhanced. Response surface models of the mechanical strengths were developed and validated using ANOVA and have high R2 values of 86–99%. The optimization result produced 36.38%, 4.08%, and 1.0% for the optimum FA, CR, and NS replacement levels at a desirability value of 60%.
Highlights
Self-consolidating concrete (SCC) is defined as concrete that flows freely under its weight and does not require compaction or vibration during casting [1,2]
Flow, L-box, and V-funnel tests increased with an increase in the fly ash (FA) replacement due θ −the θP opposite effect was observed with crumb rubber (CR) reto its smooth spherical particles, while δ= E
The rubberized self-compacting concrete (RSCC) workability properties measured through T500, slump flow, L-box, and V-funnel tests increased with an increase in the FA replacement due to its smooth spherical particles, while the opposite effect was observed with CR
Summary
Self-consolidating concrete (SCC) is defined as concrete that flows freely under its weight and does not require compaction or vibration during casting [1,2]. Many researchers have shown that using SCC improves workability, lowers cement content, improves permeability, and increases the durability of concrete. It is favorable because of its high flow rate, cohesiveness, and good passing ability, allowing it to travel through congested reinforcements [3,5,6]. The SCC demonstrates high flexural and tensile strength than conventional concrete due to its dense microstructure [5] and improved interfacial transition zone between the individual particles [3]. SCC is brittle and has a poor yield strength because of its low
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