Study On The Effect Of Lightweight Aggregate On Mechanism Sand Self-compacting Concrete

The paper adopted the fixed sand volume method which has been improved to design the mechanism sand self-compacted concrete mix reference.On this basis,the paper designed the orthogonal experiment to optimize the mix proportion so that the performance and mechanical properties of the mechanism sand self-compacted concrete can satisfy the requirements.The paper replaces the crushed stone aggregate with high-intensive lightweight aggregate to research the influence on work performance?mechanical property and the durable performance of mechanism sand self-compacted concrete.Finally,the paper utilize ANSYS numerical simulation software to simulate the effect of different substitutions of lightweight aggregates on the mechanical properties of self-compacted concrete,and verified with the experimental results.The conclusion was as follows:(1)Based on the baseline mix,the paper select the mechanism sand fineness modulus?mechanism sand MB value?stone powder content,?sand rate,?gel material dosage,?water glue ratio?dosage of admixture as the key factors of the orthogonal experiment.Selecting the orthogonal design table with three levels and seven factors to test the effect of the above key factors on the working performance and mechanical properties of the mechanism sand self-compacted concrete to modify the material consumption of the fix proportion so that the fix proportion of mechanism sand self-compacted concrete is more reasonable.The results as following:cement :420kg/m3?the fly ash:140kg/m3?the mechanism sand:800kg/m3?gravel:900kg/m3?Water:180kg/m3?water reducing agent:7.84kg/m3.(2)Using the modified mechanism sand self-compacted concrete mix reference as the reference.The paper replaces the crushed stone aggregate with high-intensive lightweight aggregate(ceramsite)to research the influence on work performance?mechanical property and the durable performance of mechanism sand self-compacted concrete.The volume replacement rate is the percentage of 0?30?60?100.The results showed that:1)With the replacement rate accumulating,the compressive strength of mechanism sand self-compacted concrete declined gradually,but the relative strength was great than the gravel self-compacted concrete and the structural efficiency wassuperior to gravel self-compacted concrete.When the rate was between 30 percent and60 percent,the various impressive strength declined slightly,meanwhile,the work performance improved evidently.2)Adding lightweight aggregate to mechanism sand self-compacted concrete can improve the micro-structure of the concrete so that the the durable performance of the concrete such as the carbonation resistance and the chloride penetration resistance got better because of the micro-pump action of the lightweight aggregate.When the replacement rate was more than 60 percent,the lightweight aggregate would have a negative effect on the mechanism sand self-compacted concrete.it was loose and porous and the combing capacity with mortar was inferior to the gravel aggregate.(3)Using ANSYS to establish the two-dimensional random aggregate model of mechanism sand self-compacted concrete to simulate the compressing test?tensile test and the bending test of concrete test cubes which have different replacement rate of lightweight aggregates.The results showed that:1)Acquiring the stress-strain relationship?modulus of elasticity and Poisson ratio of mechanism sand self-compacted concrete which have different replacement rate of lightweight aggregates.Comparing the data with trial value to verify the validity of the the results.2)By simulating the tensile process of the concrete of different replacement rate and observe the fracture development.the results agreed with the experiments.The cracks penetrated through the aggregates and break through the cracks in the mortar and accelerated the destruction of the concrete.3)By simulating the bending test of the concrete of different replacement rate and acquiring the bending destruction process of the microscopic level that have different replacement rate of lightweight aggregates.Comparing the data with trial value to verify the validity of the the results.