Research On The Basic Properties Of Recycled Aggregate And Recycled Concrete

The research on the recycled concrete technic is inchoate in China. Most of the reseach are constrated on the basic properties of recycled aggregate and recycled concrete, but the resules do not agree with each other. No law which is essential and can direct the production can be draw from the existing reseach reports. In this paper, the overseas productions are consulted, and the emphases are placed on the internal actuality, the leitmotiv of sercing for production is insisted on. In this paper, the basic properties of recycled aggregate and rectcled concrete and the mix proportion designing of recycled concrete are experimentally reseached on. Main reseachful contents are as follows:(1) The antiquated concrete specimens of Srucure laboratory of Dalian University of Technology are collected as original concrete. Those speciments are broken up manully and sifted, and the the recycled aggregates are gained. After the absorption, apparent density and crush index experiments on the recycled aggregates of different size, the relationships between the basic properties of recycled concrete and the compressive strength and gradations of coarse aggregare of original concrete are found, the advice on the producing and quality assessing of recycled concrete is presented;(2) The influence of kind, displacing ratio, gradations of recycled aggregate on the mechanics properties and workality of recycled concrete is taken into account. Recycled concrete specimens are made and their compressive strength, flexural strength and splitting tensile strength are measured. The relationship between different mechanics indexes is gained;(3) Experiments are made on the unit water use of recycled concretes which contain recycled concrete coarse aggregate and natural sand. The quantities of additional water use of recycled concrete to obtain the same slump and strength as ordinary concrete with the same water cement ratio are confirmed. The formula of unit water use of recycled concrete is established. And the method of mix proportion designing of recycled concrete is presented;(4) The absolute cement water ratio curve and free cement water ratio curve are drawn based on the experiments. These curves can be consulted when the recycled aggregates have the similar properties to those of this paper.