Experimental Research Of Mix Design Method Of High Performance Recycled Aggregate Concrete

Along with the raising advancement of construction industry, the grim situation of this industry because of the shortage of natural resources such as sand, stone etc, and the increase of construction wastes, the research and application of recycled aggregate concrete is becoming a crucial development direction of civil engineering. The current recycled aggregate concrete research mainly focused on the basic mechanical properties of recycled concrete. But the study of mix design method of high performance recycled concrete is rarely reported. As the recycled coarse aggregate and natural aggregate has the remarkable difference, therefore the mix design method of ordinary concrete is no longer suitable for that of recycled aggregate concrete. This paper mainly on the recycled aggregate concrete Bolomey formula regression and correction, to ensure stable paste aggregate ratio is proposed for high performance of recycled aggregate concrete mix ratio design method.In this paper,the main work done is as follows:1. Produce recycled coarse aggregate by using waste briquette in experiments and waste concrete on the road,the experimental study of basic performance of recycled coarse aggregate concrete and natural one. The results show that various performances of recycled are worse than the natural, for example the surface of recycled is rough and it has smaller apparent density, smaller stacking density, bigger bibulous rate and bigger crushing index.2.The paper studies the effects of different crushed value and replacement rate of recycled coarse aggregate on Bolomey formula. Test results show that:crushing value of coarse aggregate had less influence on the aggregate parameter αa, but had good linear correlation with the other aggregate parameter αb\different substitution rate αn also showed a good linear relationship with the replacement rate of coarse aggregates. Through comparing the measured values with the Bolomey formula calculated value in the experiments, The numerical error is less than 10%; this reveals that the Bolomey formula calculated with recycled aggregate crushing value and recycled aggregate replacement rate of recycled concrete strength has high reliability.3. The paper studies the different pre-processing methods and fly ash replacement on strength of recycled aggregate concrete, the recycled aggregate concrete Bolomey formula was modified. The results show that:when using the pre-processing methods of ganister sand seriflux replacement without concrete and poval liquor, the strengthening effect is the best, and it is suggested that the influence coefficient of pre-processed recycled aggregate should be 1.1. The influence coefficient of fly ash γf also has a relatively good liner relationship with fly ash replacement.4. Carry out the experimental study on the working performances and basic mechanical properties of high-performance recycled aggregate with different paste aggregate ratio. The results show that:when the recycled concrete paste aggregate ratio was 37.5/62.5, the recycled concrete slump meet the requirements, the change of small and cube compressive strength, axial compressive strength and modulus of elasticity and other mechanical properties can achieve a better value.5. By reference to genera concrete mix design method and high performance concrete mix design method, the Bolomey formula of recycled concrete is aggressed and modified, and the concrete mix ratio design method for high performance recycled aggregate is proposed on the basis of high performance of stable paste aggregate ratio of recycled concrete.