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Investigation of CO2 Laser Treated Concrete in Terms of Water Absorption through Dissimilar Layers
J. Lawrence, C.B. H0 and L. Hao

A comprehensive investigation of the effectiveness of a CO2 laser generated glaze on the absorption characteristics of OPC has been conducted. The experimental results from the absorption tests confirmed that the CO2 laser generated glaze surface on the OPC had successfully reduced the absorption rate by 77% as compared to the untreated OPC. The presence of dissimilar layers on both the untreated and CO2 laser treated OPC was established. Two dissimilar layers, which were the OPC material and the concrete material respectively were identified for the untreated concrete. As for the CO2 laser treated OPC, four dissimilar layers were identified. These were the glaze, the HAZ, the OPC and the concrete aggregate respectively. For the CO2 laser treated OPC, the sorptivity of the first layer (CO2 laser generated glaze) was 0 mm min–1/2 on account of the fact that it is an amorphous structure. The sorptivity of the second layer (HAZ) was 0.057 mm min–1/2, which was 42.5% higher than the third layer (OPC) where the sorptivity value was 0.040 mm min–1/2. Consequently, it was concluded that reduction in the thickness of the HAZ layer and improvement in the quality of glaze layer would further enhance the effectiveness of the CO2 generated glaze on the OPC surface of the concrete.

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