No abstract

The coal based thermal power plant in Malaysia produces annually around 1.7 million tons of coal bottom ash (CBA) as a discarded material which poses great environmental problems. Hence, the objective of this study is to utilize ground CBA as a supplementary cementing material in concrete. The oven dried original CBA was grinded for 20hours to achieve required fineness. The mixture of concrete was prepared with CBA proportion of 10, 20 and 30% by weight of cement. For the evaluation ofdensity, water absorption, compressive and tensile strength of concrete, 48 specimens were cast. The workability of fresh mix concrete was also evaluated, and it was found to be decreased as the quantity of CBA increased in the mixture. However, the compressive and splitting tensile strength of concrete was also reduced with the addition of ground CBA but with 10% replacement has attended the targeted compressive strength at the age of 28days.Besides that, it was also observed that the influence of CBA on concrete is obvious in density as well as in water absorption. The density of concrete gradually decreased due to addition of ground CBA, concrete containing 10% ground CBA was likely to be similar to that of control mix and the opposite performance was noticed in water absorption.Hence, experimental findings of this study indicated potentiality of ground CBA as supplementary cementing material in concrete construction which will reduces the environmental concern.

Geopolymer is an attractive construction binder owing to its ability to improve the properties of the concrete and preserves the environment from the high CO2 emission. Geopolymer technology will convert the potential hazardous industrial waste such as fly ash into valuable construction materials. However, there is a need of studying the properties of iron-based geopolymer in order to enhance the fundamental and knowledge of the geopolymer research also development in this study area. Fly ash which contains a significant amount of iron oxide (Fe2O3) was used as a precursor and tested at different curing duration (1, 3, 7, 14 and 28 days). Crystallization of iron oxide (Fe2O3) contained in the fly ash under geopolymerization process will be able to turn waste fly ash into a strong concrete materials, simultaneously creating a waste-to-wealth economy. Furthermore, the formation of fayalite detected from the microstructure characterization is mainly contribute to the strength development of the fly ash after 28 days curing.

Concrete construction offers a great opportunity to replace the cement with a coal-based power plant waste—known as coal bottom ash (CBA)—which offers great environmental and technical benefits. These are significant in sustainable concrete construction. This study aims to recycle CBA in concrete and evaluate its particle fineness influence on workability, compressive and tensile strength of concrete. In this study, a total of 120 specimens were prepared, in which ground CBA with a different fineness was used as a partial cement replacement of 0% to 30% the weight of cement. It was noticed that workability was decreased due to an increased amount of ground CBA, because it absorbed more water in the concrete mix. The growth in the compressive and tensile strength of concrete with ground CBA was not significant at the early ages. At 28 days, a targeted compressive strength of 35 MPa was achieved with the 10% ground CBA. However, it required a longer time to achieve a 44.5 MPa strength of control mix. This shows that the pozzolanic reaction was not initiated up to 28 days. It was experimentally explored that 10% ground CBA—having particle fineness around 65% to 75% and passed through 63 µm sieve—could achieve the adequate compressive and tensile strength of concrete. This study confirmed that the particle fineness of cement replacement materials has a significant influence on strength performance of concrete.

The prevalence of AF in the Malaysian population was low at 0.54% compared to the global average of 1%. We found that AF was associated with older age, male sex, hypertension, and ischaemic heart disease.