Abstract
The utilization of coal bottom ash (CBA) and fly ash in concrete has become more common. For CBA concrete, curing conditions would influence the thermal properties of the concrete due to the high water absorption capacity of the CBA aggregate. In addition, CBA and fly ash contents in concrete affect the thermal properties of the concrete. Therefore, the effects of the drying conditions and the CBA and fly ash contents on the thermal conductivity of CBA concrete were investigated in this study. The thermal conductivity of concrete was measured under two different curing and drying conditions: oven-dried conditions and saturated surface-dry (SSD) conditions, with curing times of 28 and 91 days. The concrete mixtures also contained different levels of CBA and fly ash. Crushed sand in the concrete mixtures was replaced by CBA with replacement ratios of 25%, 50%, 75%, and 100% by volume. In addition, cement in the concrete mixture was substituted by fly ash with replacement ratios of 20 and 40% by volume. The thermal conductivity of concrete under the oven-dried conditions was much lower than that under the SSD conditions. Moreover, the thermal conductivity of the concrete decreased as the CBA content increased under both the oven-dried and SSD conditions. The material properties of the concrete, including unit weight, compressive strength, and ultrasonic velocity, were also measured in the study. Compared with the SSD conditions, the compressive strength, unit weight, and ultrasonic velocity of CBA concrete were considerably lower under the oven-dried conditions. Moreover, the relationships between the thermal conductivity and unit weight, compressive strength, and ultrasonic velocity were suggested.
Highlights
Global climate change has led to an increase in energy consumption for cooling in hot weather and for heating in cold weather
Ngohpok et al [8] investigated the material properties of pervious concrete containing recycled and bottom ash aggregates. is study suggested that the use of Coal bottom ash (CBA) in pervious concrete significantly reduced the thermal conductivity of the concrete
E thermal conductivity of CBA concrete decreased when the drying condition was changed from saturated surface-dry (SSD) conditions to oven-dried conditions
Summary
E utilization of coal bottom ash (CBA) and fly ash in concrete has become more common. Erefore, the effects of the drying conditions and the CBA and fly ash contents on the thermal conductivity of CBA concrete were investigated in this study. Cement in the concrete mixture was substituted by fly ash with replacement ratios of 20 and 40% by volume. E thermal conductivity of concrete under the oven-dried conditions was much lower than that under the SSD conditions. The thermal conductivity of the concrete decreased as the CBA content increased under both the oven-dried and SSD conditions. E material properties of the concrete, including unit weight, compressive strength, and ultrasonic velocity, were measured in the study. Compared with the SSD conditions, the compressive strength, unit weight, and ultrasonic velocity of CBA concrete were considerably lower under the oven-dried conditions. The relationships between the thermal conductivity and unit weight, compressive strength, and ultrasonic velocity were suggested
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