Application of statistical models in proportioning lightweight self-consolidating concrete with expanded clay aggregates

Abstract

A response surface method based experimental study was carried out to model the influence of key parameters on the properties of Lightweight Self-Consolidating Concrete (LWSCC) mixtures developed with expanded clay (EC) aggregates. Three key mix design parameters were selected to derive mathematical models for evaluating fresh and hardened properties. Water to binder ratio of 0.30–0.40, high range water reducing admixture (HRWRA) of 0.3–1.2% (by total content of binder) and total binder content of 410–550kg/m3 were used for the design of and testing of twenty LWSCC mixtures. Slump flow diameter, V-funnel flow time, J-ring flow diameter, J-ring height difference, L-box ratio, filling capacity, sieve segregation, fresh/28-day air/oven dry unit weights and 7- and 28-day compressive strengths were evaluated to analyze influence of mix design parameters and develop the models. Utilizing the developed models, three optimum expanded clay LWSCC (EC-LWSCC) mixtures with high statistical desirability were formulated and tested. It was possible to produce robust EC-LWSCC mixtures that satisfy the European EFNARC criteria for Self-Consolidating Concrete (SCC). The proposed mix design models are proved to be useful tools for understanding the interactions among mixture parameters that affect important characteristics of EC-LWSCCs. This understanding might simplify the mix design process and the required testing, as the model identifies the relative significance of each parameter, provides important information required to optimize mix design and consequently minimizes the effort needed to optimize LWSCC mixtures, and ensures balance among parameters affecting fresh and hardened properties. Examples highlighting the usefulness of the models are presented using isoresponse surfaces to demonstrate single and coupled effects of mixture parameters on measured properties. LWSCCs with EC lightweight aggregates can reduce the construction pollution, increase the design solutions, extend the service life of the structure and hence, promote sustainability in construction industry.