Study of the anti-abrasion performance and mechanism of coral reef sand concrete

Abstract

In a marine environment, tidal waves carry coral reef blocks, which cause erosion and abrasion of breakwaters and other concrete structures, seriously affecting their stability and durability. In order to reveal the damage mechanism of coral reef sand concrete, herein the effects of admixtures such as fly ash, silica fume, polypropylene fiber and basalt fiber on the anti-abrasion performance and micro-hardness of coral reef sand concrete were studied. Additionally, the mechanisms of the abrasive damage and the increased performance of coral reef sand concrete were revealed by means of modern testing techniques, including X-ray diffraction and scanning electron microscope. The results revealed a linear relationship between the anti-abrasion strength and the compressive strength of the coral reef sand concrete mixed with fly ash and silica fume; whereas this correlation was not observed for the coral reef sand concrete containing fibers. Unlike ordinary aggregates, the characteristics of the coral aggregate such as the roughness, porosity, susceptibility to breakage, the irregularity of the shape, and the mineral composition were found to affect the anti-abrasion performance of the coral reef sand concrete. The roughness and the porous characteristics improved the micro-hardness of the aggregate-cement stone joints (0 μm) in the coral reef sand concrete, but there was still a weak Interfacial transition zone. Moreover, it was observed that the abrasion of the coral reef sand concrete can be reduced by the presence of a strong and dense interfacial transition zone, the crack resistance effect of the fibers, and the enhanced cohesive force of the cement mortar and fibers.