Influence and Mechanism Analysis of Different Parent Rock Stone Powders on the Properties of Manufactured Sand High-Strength Concretes

Abstract

This study employed limestone powder (LS), dolomite powder (DM), basalt powder (BS), and granite powder (GN) in certain proportions to replace fly ash (FA) to prepare manufactured sand high-strength concrete (MSHSC). The influences of different parent rock stone powders on the fluidity, water absorption, apparent porosity, compressive strength, and splitting tensile strength of MSHSC were evaluated. The influence mechanism of each stone powder was determined using microscopic morphology and distribution of hydration products. The results indicated that 20% LS improved the fluidity of MSHSC by releasing pore water. GN caused an increase in matrix cohesion due to its adsorption effect on the water reducer. Moreover, both 5% LS and 5% DM exhibited a significant inhibitory effect on the water absorption and apparent porosity of MSHSC. In addition, LS exhibited a more pronounced enhancement effect on the strength of MSHSC at a content of 15%, demonstrating the superior filling and nucleation effects. BS and GN were suitable for coblending with FA to improve the properties of MSHSC. Microscopic morphology and hydration product analysis indicated that LS adsorbed Ca2+ ions, causing LS particles to be enveloped by calcium hydroxide [Ca(OH)2], promoted early strength improvement. A small amount of BS showed surface erosion after participating in the pozzolanic reaction. Ettringite (AFt) was stabilized by the reaction between CaCO3 in LS and tricalcium aluminate (C3A). The diffraction peak of Ca(OH)2 was lower owing to the reduction of the hydration reactions by GN, weakening the strength of the matrix. The findings of this study verified the feasibility of utilizing different parent rock stone powders in MSHSCs and provide experimental data and references for engineering applications.