Enhance the properties of concrete using pre-developed burnt clay chips as internally curing concrete aggregate

Abstract

Materials of internal curing concrete have been developed in many countries. Some of those materials are superabsorbent polymers, light weight aggregate (LWA), normal weight aggregate, recycled aggregate, bentonite clay, furnace slag and bottom ash. The most popular internal curing material is LWA. LWA are not available in most countries. Thus, the production of internal curing concrete (ICC) was limited for few countries. Consequently, this research was focused on the utilization of burnt clay chips as a new material to enhance the properties of ICC. Furthermore, water–cement (w/c) ratio and workability of ICC were investigated to develop high strength internal curing concrete (SICC). The water absorption and desorption capacity of porous aggregates are basically depends on the capillary interaction between water and the pore structure. Thus, formation of an effective pore structure within the burnt clay chips becomes the most important thing. Thus, Red clay was selected and different pore structures were developed within the clay mass by heating trough furnace. The heating temperature ranged from 800 to 1300 °C. The burnt clay chips produced at 900 °C was identified as an effective ICC aggregate. Afterwards, the pre-developed burnt clay chips (DBCC) were produced in larger scale. During the production of burnt clay chips, clay blocks (150 × 250 × 14 mm) were produced and heated at 900 °C using industrial furnace. Subsequently, heated clay blocks were crushed and sifted through 4.75 mm sieve to obtain fine clay chips. The water absorption capacity and the dry apparent density of DBCC was recorded as 15.5% and 1.8 g/cm3 respectively. Finally, grade 25, 30 and 35 concretes were prepared to study the effect of workability and w/c ratio. Moreover, three different concrete samples were prepared from each concrete grade; external curing concrete (ECC), ICC and SICC. ICC samples increased the slump value in 12%. Furthermore, the compressive strength of ICC and ECC were almost same for all three concrete grades. SICC sample increased the compressive strength in 9% while maintaining the required workability and same cement content of ECC sample. Thus, it is concluded that, DBCC can be used as an effective internal curing agent to increase the compressive strength and workability of ICC.