Study On Preparation And Application Technology Of Self-compacting Concrete With Recycled Coarse Aggregate

The regeneration concrete solves the transport, storage and disposing of waste building materials, so that enormous social and economic benefits are achieved and promising future is expected. Regeneration concrete technology is generally considered the most effective solution to the waste concrete. The self-compacting regeneration coarse aggregate concrete(SCRC) is a technology based on the theory of self-compacting concrete. It is in accordance with the technical route of self-compacting high-performance concrete, and waste brick recycled aggregates, waste concrete and hybrid-brick waste recycled aggregates are used to prepare the concrete with little vibration. In this paper, in order to study the workability of self-compacting concrete with discontinuous gradation recycled coarse aggregate the influence of regeneration aggregate replacement, sand rate, steel slag replacement and gradual loss are researched with the control variable method. The cubic compressive strength, axial compressive strength, elastic modulus and splitting tensile strength, mix proportion design method and construction method of SCRC under different replacement rates were experimentally researched. The properties of flexural beam, shear beam and eccentric compression members were also experimentally researched.In this paper, the main conclusions are as follows:1. The results indicate that self-compacting concrete with discontinuous gradation recycled coarse aggregate can be produced. When the coarse aggregate is replaced with 50% recycled concrete aggregates and sand rate is 45%, the workability of self-compacting concrete is best.2. The workability of self-compacting concrete declines with the extension of time. Added the right amount of polycarboxylate superplasticizer can restore the slump flow. The gradual loss of slump flow is expressed by a simple formula proposed in this paper, which can be a reference on the evaluation of gradual loss of slump flow.3. A certain amount of steel slag can improve the filling ability of fresh self-compacting recycled concrete. When the steel slag rate is 10%, the filling ability of fresh self-compacting recycled concrete is best. The amount of steel slag is not obvious influence on passing capacity. With the increase of dosage of steel slag, the segregation rate also increases, the segregation resistance decreased.4. The cube compressive strength decreases and the early strength grows quickly with the increasing replacement rate of recycled coarse aggregate, while the failure mode of cubic specimens is similar as normal concrete. The calculation of the recycled concrete axial compressive strength and cube compressive strength model is not suitable for SCRC, a new expression is proposed. The elastic modulus of SCRC is lower than that of traditional concrete, but higher than traditional recycled concrete. Expressions of elastic modulus and splitting tensile to compressive strength are proposed. It is feasible to use steel slag as cementing material to preparate self-compacting recycled concrete. A balanced amount of steel slag can improve the cube compressive strength of SCRC. When the amount of steel slag is 10%,the cube compressive strength is highest.5. The use of SCRC mix design method, cement dosage calculation value error is about 10% than the theoretical value and the use of the added mass of entrained water error is negligible.6. The ultimate bearing capacity and failure modes of flexural members, shear members and compression members which are made of SCRC is similar to ordinary concrete members. The ultimate strength decrease slightly and the calculation formulas of current design standard can be used of flexural members, shear members and compression members which are made of SCRC.7. Initially established the frame of SCRC pavement construction method and dense reinforcement area construction method.