Investigating the synergistic effects of internal curing and pozzolanic activity in mortar utilizing clay-burnt brick fines

Abstract

This study investigates the combined effect of internal curing and pozzolanic activity in mortar through the incorporation of clay-burnt brick fines (CBBF) as a partial substitute for sand. Simultaneously, the study explores the degree of pozzolanic reactivity by replacing a part of cement with finer clay-burnt brick fines (CBBP, particle size <75 μm). These materials are sourced from waste materials generated during brick-chip production. The 50 mm cubic mortar specimens were prepared by substituting a portion of fine aggregate with pre-wetted CBBF up to 20 % v/v and replacing cement with CBBP up to 27 % v/v. Two separate sand-to-cement ratios (S/C) of 1.2 and 1.6 were used in the mortar mixes. Samples underwent mechanical testing and were analyzed using ultrasonic pulse velocity (UPV) and accelerated carbonation tests. At a S/C of 1.6, increasing CBBF content in the mortar led to higher compressive strength. Conversely, for S/C = 1.2, the optimal replacement level was 4 % v/v of CBBF, beyond which compressive strength gradually decreased due to the porous nature of CBBF particles. Moreover, an 8 % CBBF replacement demonstrated maximum resistance to carbonation. SEM analysis revealed a denser matrix, indicating the effectiveness of CBBF in enhancing mechanical and durability properties.