Abstract
Most previous studies on the strength properties of coal bottom ash (CBA) concrete have focused on concrete with a normal compressive strength, and thus, studies on the strength properties of high‐strength concrete (HSC) containing CBA are limited. Therefore, the effects of replacing fine aggregates with CBA and variations in the curing age on the strength properties of HSC with a compressive strength of greater than 60 MPa were investigated in this study. The different CBA contents included 25, 50, 75, and 100%, and the different curing ages were 28 and 56 days. The mechanical properties of the HSC with CBA incorporated as fine aggregates were examined. The experimental results revealed that CBA could be partially or totally substituted for fine aggregates during HSC production. The test results also showed that the compressive, splitting tensile, and flexural strengths of the HSC containing CBA fine aggregates slightly decreased as the CBA content increased. Moreover, useful relationships between the compressive strength, splitting tensile strength, and flexural strength were suggested, and the predictions reasonably agreed with the measurements. Compared to those of the control specimen, the pulse velocities of the HSC specimens at various CBA contents decreased by less than 3%. In addition, equations for predicting the strength values of CBA concrete by using the ultrasonic pulse velocity were suggested.
Highlights
Coal bottom ash (CBA) is an industrial waste produced at the bottom of coal furnaces in thermal power plants [1,2,3,4,5]
The unit weight, compressive strength, splitting tensile strength, flexural strength, and ultrasonic pulse velocity of the concrete were measured at curing ages of 28 and 56 days. e compressive strength of the CBA concrete specimens was measured by testing cylindrical specimens with a hydraulic testing machine in accordance with the KS F 2405 test method [33]. e splitting tensile strength test was determined by testing cylindrical specimens in accordance with the KS F 2423 test method [34]. e flexural strength of the CBA concrete was measured by testing prism specimens under four-point loading in accordance with the KS F 2408 test method [35]. e average values of the three specimens
Based on the extensive experimental results, the following conclusions can be drawn: (1) e test results showed that, at low CBA contents, the unit weight of the high-strength concrete (HSC) concrete slightly reduced by approximately 2%-3%. ese results implied that low CBA contents could be applied to fabricate HSC with a normal weight
Summary
Coal bottom ash (CBA) is an industrial waste produced at the bottom of coal furnaces in thermal power plants [1,2,3,4,5]. Ey showed that the greatest tensile strength of the self-compacting concrete containing CBA was 3.28 MPa, when fine aggregate was replaced by 10% CBA. Most studies on the material properties of CBA concrete have focused on the strength properties of conventional concrete with a compressive strength of less than 40 MPa. Recently, Kim and Lee [32] investigated the influences of replacing fine and coarse aggregates with power bottom ash on the mechanical properties of HSC. The strength properties of concrete specimens with natural fine aggregates partially or fully replaced by CBA aggregates (25, 50, 75, and 100%) and with a compressive strength of greater than 60 MPa were investigated. Cylindrical specimens with dimensions of 100 mm × 200 mm were cast to measure the unit weight, compressive strength, and splitting
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