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| Effects of recycled aggregates gradation on mechanical performance of concrete and microscopic performance analysis |
| School of Civil Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China |
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Abstract To investigate the influence of recycled coarse aggregates on the mechanical properties of concretes, various compressive strength tests of the cube at different ages were carried out using the concretes with a single gradation of 5.0 mm to 10.0 mm, 10.0 mm to 20.0 mm, 16.0 mm to 31.5 mm and continuous gradation from 5.0 mm to 31.5 mm and with the replacement rate of 30%，50% and 70%. The effects of aggregate on the mechanical properties of recycled concrete were revealed at microscopic level by scanning electron microscopy(SEM) and Xray diffraction(XRD). The results show that for low dosage, the strength at 112 d is almost the same as that of ordinary concrete when the size of aggregate content ranges from 5.0 mm to 10.0 mm. No matter how many dosages are selected, all the compressive strengthes of different age cubes are low when the aggregate content size ranges from 10.0 mm to 20.0 mm. When the aggregate content size ranged from 16.0 mm to 31.5 mm and 5.0 mm to 31.5 mm, the strength of recycled concrete is increased with an appropriate dosage.
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Received: 28 April 2018
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2019, Vol. 40 
