Effect of Aggregate Mix Proportion on Static and Dynamic Mechanical Properties and Pore Structure of Alkali-Activated Slag Mortar with Sludge Pottery Sand

Abstract

The overexploitation of river sand will reduce the stability of the river. Using sludge pottery sand (SPS) as a substitute for fine aggregate in mortar can reduce the weight of building mortar and achieve pollution control and resource regeneration. Based on the consideration of energy-saving and carbon reduction, the combination of alkali-activated slag cementitious material and SPS with potential pozzolanic activity to prepare sludge pottery sand alkali-activated slag mortar (PSAM) can replace the traditional silicate river sand mortar. The static and dynamic peak stress of PSAM was tested, and the energy dissipation characteristics of PSAM specimens under the dynamic load were analyzed by using the wave acquisition system of a split Hopkinson pressure bar. The results show that the SPS with 0.15~2.36 mm has better mechanical properties. The increase in the mixing ratio with the SPS with 2.36~4.75 mm will gradually reduce the static and dynamic compressive strength of the specimen, and also reduce the density of the specimen. SEM images and binary pore morphology images showed that the increase in SPS size will lead to a large number of coherent pores inside the specimen, which will increase the air content of the specimen, but at the same time reduce the absorption capacity of the specimen to the wave, so the dynamic energy absorption peak of PSAM appears to decrease significantly. The image of ultra-high-speed photography revealed the mechanism of crack propagation of the PSAM specimen. The development of the crack is positively correlated with the dynamic energy absorption performance when the specimen is completely broken.