Of Construction Waste Recycled Concrete Pilot Study

With the quick development of building industry, the value of construction wastes is also soaring to unprecedented to heights. Besides the handling charges construction waste is very high, it also causes a lot of environmental problems and social harmful effects. Therefore, attention has been paid greatly the reuse of construction wastes by building industry and environmental protection department of all countries in the world. Recycled concrete is one of new type concrete that mixed with recycled aggregate at a certain proportion after cleaning, crushing, grading wasted concrete. It is helpful in dealing with rejectamenta of concrete and a bad influence on environment because of castoff. At the same time, this concrete can save on the large number expenditure of cleaning, transportation and disposing. On the other hand, it will reduce the exploitation of natural stone and sand, protect environment, and safeguard durative development of social. Recycled concrete meet three meanings of "green" fully, which putted forward by World Environment Organization: (l)saving resource and energy sources; (2)don't destroy environment, while in favor of environment; (3)durative development, not only meet the request of men of moment, but also not hurt the faculty of meeting unborn generation's requirement . So the Recycled Concrete belongs to durative developed "green concrete". Concrete's production and construct technology must develop in the most management way of saving resource, alleviating the burthen of environment, maintenancing zoology balance. It is representing the up to the minute development in the future.In this article, the concepts concerning recycled aggregate concrete are defined and the characters of recycled aggregate concrete are discussed. The author also points out the issue of the mix design method based on water binder ratio in order to solute the problem of larger water absorption and analyze its advantages on developing the compressive strength of recycled aggregate concrete, and compared with the mix design method of common concrete. The author also suggests this method of mix design should be widely used in other concretes. In the part of the experiments the author carried out test complying with orthogonal test-schema. The effect of the factors (the w/b ratio, sand content by mass of aggregate, the percentage of silica fume and superplasticizer) on the recycled capability of the mass is analyzed. And then, the optimum value of every effect factor is acquired according to the comprehensive-equilibration theory. Based on this, by using RO. 42.5R cement and recycled aggregate from artificial wasting concrete, RCA which reaching 50MPa strength are mixed successfully. Simultaneously, regressive analysis is carried out between the 28d compressive strength of recycled concrete and the w/b ratio with no variation of other factors. The optimum mix proportions of the recycled concrete are recommended.