Acoustic emission (AE) has been widely used for monitoring of the structure performance. However, identification of structure’s characteristic is still limited assess. Hence, this paper presents the characteristic of AE of different thicknesses of reinforced concrete (RC) slabs. Two different thicknesses of grade C25/30 RC slabs which are 125 mm and 175 mm were prepared and designated as S125 and S175, respectively. The slabs were designed based on Eurocode 2 with the size of 500 mm width x 1000 mm length were tested under three-point loading in conjunction with the AE monitoring. The maximum loads of the slabs were identified. The acoustic signal strength was analyzed and discussed. It is found that the maximum load of the RC slabs is increased as the thickness of the slab increases. Moreover, the signal strength of S175 is greater than the S125. Hence, this study is beneficial to provide factual data on the maximum load and AE characteristic of different thicknesses of slab.

No abstract

Concrete performance and workability can be improved by using an optimum amount of fly-ash. This leads to the purpose of analysing the percentage of fly-ash that can replace a certain amount of Portland cement in the concrete until it reaches the maximum strength. The experiment was conducted using G25 and G45 concrete supplied by a local ready-mix concrete plant in Kuching, Sarawak. The cement content of each concrete grade was replaced with various fly-ash percentages of 20, 30, 40, 50 and 60 collected from waste materials in Pending Sarawak. The specimens used in the studies were made of 150mm concrete cubes. Specimens were tested for compressive strength at the ages of 3, 7, 14, 28, 56 and 90 days. The curing age extended to 56th and 90th-day to participated slow pozzolonic reaction process contributed by fly-ash. Based on the test results for both concrete grades with enhancements, the compressive strength significantly increases from 7 days to 56 days, and then slightly increases on the 90th-day. The G25 concrete has an optimum strength with a fly-ash replacement of 30% cement content, followed by 40%, 20% and 50%. Similarly, the G45 concrete achieved an optimum strength with a fly-ash replacement about 30% cement content, followed by 20%, 40% and 50%. In addition, both grades of concrete tested have a cut-off cement replacement level of 60%, beyond which the compressive strength falls below that of the control mixtures.

Development and testing of other foam concrete materials, as well as the inclusion of a marine-based filler, cuttlefish bone powder, may be one of the most advanced products suitable for cementitious materials to be added in concrete to provide a sustainable environmentally friendly alternative solution on construction industry in Malaysia. Cuttlefish bone will have some advantages and benefits in foam concrete since it contains high amounts of calcium carbonate, which is believed can improve the concrete’s strength and encourage foam concrete to achieve an early strength. The objectives of this research is to determine the optimum percentage of cuttlefish bone additive towards increasing the strength properties of foam concrete. In this research, there were 42 foam concrete cube samples prepared, each group of samples containing different amounts of cuttlefish bone additive (1%, 2%, 3%, and 4%). All the samples were tested for compressive strength at 1, 3, and 7 days of age. According to the findings, an improvement in the foam concrete when the cuttlefish bone additive content from 1% to 4% added which result in the enhancement of the behavior of foam concrete. In addition, this research reveals that cuttlefish bone additive has better characteristics to normal OPC, making it an effective addition to concrete.