Selected Strength Properties of Coal Bottom Ash (CBA) Concrete Containing Fly Ash under Different Curing and Drying Conditions

Abstract

This study aims to evaluate the effect of curing and drying conditions on the strength properties of concrete containing coal bottom ash (CBA) and fly ash as substitutes for fine aggregates and cement, respectively. The strength properties of the concrete including CBA and fly ash were evaluated under two different curing and drying conditions: saturated surface-dry (SSD) conditions and oven-dried conditions at curing ages of 28 and 91 days. The natural fine aggregates of the mixtures were replaced by CBA fine aggregates at 25%, 50%, 75%, and 100% by volume. In addition, the cement in the mixtures was partly replaced with fly ash at 20% and 40%. The experimental program included the measurement of the unit weight, compressive strength, splitting tensile strength, flexural strength, and ultrasonic pulse velocity of the concrete. The test results showed that the compressive strength, splitting tensile strength, and flexural strength decreased as the CBA content increased under both SSD and oven-dried conditions. The curing and drying conditions of the concrete with CBA and fly ash considerably influenced the reduction in the compressive, splitting, and flexural tensile strengths of the concrete. Additionally, the experimental results showed that fly ash insignificantly contributed to the reduction in the strength properties under both SSD and oven-dried conditions. Finally, the relationships between ultrasonic pulse velocity and the splitting tensile strength, flexural tensile strength, and compressive strength were investigated.

On the Performance Analysis and Environmental Impact of Concrete with Coal Fly Ash and Bottom Ash

“…Despite being classified as fly ash type F and type C, the chemical composition of fly ash from various sources greatly varies, which means the classification alone could not represent the fly ash performance in a concrete mixture [12]. Moreover, several pieces of research also show that coal FABA in concrete increases the concrete drying time and reduces workability [13][14][15][16][17][18].…”

A Comparative Study of the Thermal Conductivities of CBA Porous Concretes

“…Zaetang et al [ 8 ] reported that the insulating properties of porous concrete were increased by three to four times when lightweight coarse aggregates were used. Recently, coal bottom ash (CBA) has been progressively used in the construction industry due to its ability to replace cement or aggregate in concrete [ 9 , 10 ]. According to previous studies [ 9 , 11 , 12 , 13 ], the CBA particles contain micro- and macro-pores that make the density of CBA low.…”

Fineness of Coal Fly Ash for Use in Cement and Concrete

“…Coal fly ash in concrete has several advantages, such as increasing the resistance to chloride penetration, sulphate attack, and alkali-silica reaction, lowering cracking due to drying and thermal shrinkage, improving the workability and reducing the water demand [22]. By contrast, most of the studies reported that coal fly ash provides early age compressive strength to the concrete [23,24], but at the later ages its contribution to compressive strength becomes larger. Furthermore, wet-curing periods result in lower compressive strength, and more porous and permeable concretes [25,26].…”