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Recycled rubber aggregate (RRA) made from ground tire rubber has been promoted for its light weight and shock resistance. The high alkalinity of alkali-activated slag mortar has a modification effect on the surface of RRA. This paper studies the performance of alkali-activated slag mortar using RRA as aggregate (RASM), which has significance for applications in low-carbon building materials. The orthogonal test analysis method was used to analyze the significance and correlation of the main variables of the test. The dynamic energy absorption capacity and crushing state of RASM under the synergistic effect of various factors were studied using the separating Hopkinson pressure bar (SHPB) test system. The energy absorption characteristics and failure modes of RASM were analyzed by SEM and microscopic pore characterization. The results show that the increase of the alkali equivalent of the mix ratio will increase the peak value of the absorption energy of the specimen. When the size of the RRA is between 0.48 mm~0.3 mm, the dynamic energy absorption of the specimen will reach its peak value. Although the increase in the total volume of RRA will reduce the energy absorption capacity of RASM specimens, its crack resistance is enhanced.

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.