Empirical variance minimization with applications in variance reduction and optimal control

Abstract

The main objective of this study was to examine the combined effect of ground recycled concrete cement (GRC) and thermo-activated recycled concrete cement (TARC) on properties of mortar. The physical, chemical and microstructural tests were conducted to characterize GRC and TARC before mortar mixtures were produced. The microscopic morphology of GRC and TARC revealed uneven edges and a rough surface that is slightly porous. The GRC and TARC powders were used to replace cement in the range of 0-50% at increments of 10% by volume. The fresh, mechanical, microstructure, and durability characteristics of mortar were tested for different proportion of GRC and TARC as partial replacement of cement. The usage of GRC and TARC decreases the workability of mortar marginally. However, the mechanical performance of the mortar mixtures showed an increasing trend when GRC and TARC share increases in the mixture. Predominantly, compressive strength, bulk density, and ultrasonic pulse velocity (UPV) have all been increased by as much as 20% cement replacement. Furthermore, the incorporation of GRC and TARC enhances the mortar’s durability properties. The microstructure analysis reveals that 20% replacement (GT20) mix has superior structural compactness. In general, partially substitution of GRC and TARC by ordinary Portland cement improves several characteristics of mortar. This will help solve the most prevalent problems that concrete produces, including the high embedded carbon dioxide creation, the high resource usage, and the high waste generation after demolition.