Durability Of High Performance Concrete With Manufactured Sand Based On Admixture And Mineral Admixture

With the depletion of natural sand resources,the use of mechanical sand instead of natural sand to prepare concrete is a trend in the development of the concrete industry,with significant economic and social benefits.Due to the difference between the mechanical sand and the natural sand,we should face the shortage of the mechanical sand itself,and face the impact of these shortcomings,using the mechanism sand to prepare high-performance concrete with good self-compacting properties,mechanical properties and durability..Therefore,it is necessary to carry out related research on the performance impact of materials on machine-made sand high-performance concrete.Based on the above research background,this paper starts from the mechanism sand material,and designs and optimizes the mix ratio of high-performance concrete for sand.In the optimization process,the optimization method of admixture with admixture and mineral admixture is adopted.Through the relevant analysis methods,the performance,mechanical properties and durability of the mechanical sand high performance concrete were analyzed,and the following conclusions were obtained:(1)Calculate the mix ratio through the specification,and at the same time,through the test and test mechanism sand concrete mixture work performance and subsequent mechanical properties,carry out the mix ratio optimization design,and finally obtain the reference mix ratio of the mechanism sand high performance concrete:the total amount of cementitious materials It is used for 550kg/m~3 and mineral admixture,which accounts for 30%of the total amount of cementitious materials,828kg/m~3 of mechanical sand,870kg/m~3 of coarse aggregate crushed stone and 145kg/m~3 of water.The polycarboxylic acid superplasticizer has a dosage of 6.6 kg/m~3.(2)Using the admixture of admixture and mineral admixture to optimize the performance and mechanical properties of the high performance concrete sand.For the mechanical properties and working performance,the addition of thickener after the admixture of admixture can effectively improve the segregation phenomenon of concrete,but it is unfavorable for the flow performance of concrete.The optimum dosage is 0.3%,and the incorporation of polycarboxylate superplasticizer Improve the working performance of concrete,the optimum dosage is 1.2%,the incorporation of expansion agent improves the mechanical properties of concrete,and the optimum dosage is 9%.In the case where the mineral admixture accounts for the total amount of the cementitious material,after the mineral admixture is compounded,the ratio of the fly ash to the slag powder is 6:4,and the compounding ratio is high on the mechanical sand high performance concrete.The improvement in work performance and mechanical properties is most obvious.(3)The method of compounding with admixture and mineral admixture can effectively improve the durability of high performance concrete sand.For the durability performance,when the polycarboxylate superplasticizer is 1.2%after the admixture,the anti-freezing property and the sulfate-resistant performance of the concrete are the best.When the dosage is 1.3%,the concrete is resistant to carbonization.The performance is the best.When the amount of expansion agent is 9%,it has the best performance against concrete frost resistance and carbonation resistance.When the dosage is 10%,the concrete has the best resistance to sulfate attack.The incorporation of thickeners does not significantly improve the durability of mechanical sand high performance concrete.After the composite admixture of mineral admixture,after the fly ash and slag powder are compounded,the durability indexes of the three concretes are obviously improved.The different blending ratios of different mineral admixtures have different effects on different durability indexes.