A response surface method based experimental study was carried out to model the influence of key parameters on properties of Lightweight Self-Consolidating Concrete (LWSCC) mixtures developed with various types of lightweight aggregates namely, furnace slag (FS), expanded clay (EC), and expanded shale (ESH). Three key parameters were selected to derive mathematical models for evaluating fresh and hardened properties. Water/binder ratio of 0.30 to 0.40, high range water reducing agent (HRWRA) of 0.3 to 1.2% (by total content of binder) and total binder content of 410 to 550 kg/m3 were used for the design of LWSCC mixtures. Slump flow diameter, V-funnel flow time, J-ring flow diameter, J-ring height difference, L-box ratio, filling capacity, bleeding, fresh air content, initial and final set times, sieve segregation, fresh/28-day air/oven dry unit weights and 7- and 28-day compressive strengths were evaluated. Utilizing the developed model, three optimum LWSCC mixes with high desirability were formulated and tested for mechanical, mass transport and durability characteristics. The optimized industrial LWSCC mixtures were produced in lab/industrial set-up with furnace slag, expanded clay, and expanded shale aggregates. The mixtures were evaluated by conducting compressive/flexural/split tensile strength, bond strength (pre/post corrosion), drying shrinkage, sorptivity, absorption, porosity, rapid chloride-ion permeability, hardened air void (%), spacing factor, corrosion resistance, resistance to elevated temperature, salt scaling, freeze-thaw iv resistance, and sulphuric acid resistance tests. It was possible to produce robust LWSCC mixtures that satisfy the European EFNARC criteria for Self-Consolidating Concrete (SCC).
The proposed mix design model is proved to be a useful tool for understanding the interactions among mixture parameters that affect important characteristics of LWSCC. 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.
LWSCCs with FS, EC and ESH 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.
Lightweight Self-consolidating Concrete with Expanded Shale Aggregates: Modelling and Optimization
