Analysis of milling treatments of waste clay bricks effect on density and compressive strength of cement paste

Abstract

Milling treatments for evaluating grindability of pozzolanic materials using ball mill have been employed with limited studies focused on fragmented clay bricks. Of great importance of the milling treatments are sample masses. In this paper, the effects increasing sample mass of fragmented clay bricks on fineness of resulting clay brick powder (CBP) were examined using ball milling, particle size distribution curves and scanning electron microscopy (SEM). Image analysis was then used to verify variations of particle size, particle distribution, porosity and surface roughness for different sample masses. Moreover, the influence of CBP fineness on density and prismatic compressive strength of cement paste was evaluated. The reduction of sample mass fed in ball mill corresponded to enhancement of fineness of CBP. Meanwhile, image analysis proved that significant enhancement of fineness led to reduction of surface roughness. It was observed that reduced surface porosity originated from finer CBP. Findings of shape parameters showed a strong correlation for Pearson's coefficients between solidity (SLD)-circularity (Circ) pair (r ≥ 0.900, p = 0.000) and SLD-Circ relationship revealed distinguishable clusters created for the samples. Eventually, the research established that incorporating finer CBP in cement paste significantly enhanced prismatic compressive strength among CBP-cement paste mixes without significantly affecting the density of the mixes.