Effect of Mixed Recycled Aggregate on the Mechanical Strength and Microstructure of Concrete under Different Water Cement Ratios |
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Authors: | Tao Meng Huadong Wei Xiufen Yang Bo Zhang Yuncai Zhang Cungui Zhang |
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Affiliation: | 1.College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China; (H.W.); (X.Y.);2.Ocean Research Center of Zhoushan, Zhejiang University, Zhoushan 316021, China;3.Zhoushan Jinke Resources Recycling Co., Ltd., Zhoushan 316000, China;4.Shanxi Sixth Construction Group Co., Ltd., Taiyuan 030024, China; |
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Abstract: | Mixed recycled aggregate (MRA) is a kind of recycled aggregate containing discarded bricks and other impurities that is inferior to ordinary recycled concrete aggregate. To study the effect of MRA in concrete, specimens with 100% MRA under different water–cement ratios (W/C) of 0.50, 0.42, 0.36 and 0.30 were prepared, and the mechanical properties and microstructure were tested. Results show that compared with ordinary concrete, the compressive strength of mixed recycled aggregate concrete (MRAC) with the same W/C was reduced by more than 50% at 28 days, but the axial compression ratio was relatively high, reaching over 0.87. Affected by the high water absorption of MRA, the hydration rate of cement slowed, which was beneficial to the long-term development of the properties of MRAC. An appropriate increase in cement content could strengthen MRA and densify the pore structure of MRAC. The research results of this article prove that MRA has high utilization value and could be used to prepare MRAC with application potential using optimal gradation, which is of positive significance for promoting the consumption of construction waste. |
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Keywords: | mixed recycled aggregate, water– cement ratio, mechanical properties, hydration process, microstructure |
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