Study On Preparation And Properties Of Recycled Aggregate Permeable Concrete

Pervious concrete is a kind of eco-friendly porous concrete,which can effectively solve the problem of serious road water,and effectively promote the construction of"sponge city".With the continuous development of economy,a large number of construction wastes continue to emerge,waste concrete is a particularly common construction waste,the effective use of waste concrete to prepare permeable concrete is in line with the concept of sustainable development.In this thesis,different water cement ratio,different silica fume content and different recycled aggregate content are used as variables to design parallel experiments.Combined with the results of parallel experiments,the level of orthogonal experiment factors is determined.This test adopts L₉（3⁴）orthogonal test,in which three factors are water cement ratio,silica fume content and recycled aggregate content respectively.Among them,the water-cement ratio was 0.25,0.30 and 0.35,the silica fume content was 2%,4%and 6%,and the reclaimed aggregate content was 10%,20%and 30%.According to the test data of each group,the range analysis and variance analysis of the recycled aggregate pervious concrete were carried out.Through the range analysis and variance analysis,the basic rules of the apparent density,permeability coefficient,7d/28d compressive strength,28d flexural strength and sulfate corrosion resistance of the recycled aggregate pervious concrete were summarized.The test results show that:in terms of physical properties,the primary and secondary factors affecting the apparent density of recycled aggregate pervious concrete are:recycled aggregate content>water cement ratio>silica fume content;among them,when the water cement ratio is 0.35,silica fume content is 2%and recycled aggregate content is 30%,the apparent density of recycled aggregate pervious concrete is the smallest,the minimum value is 1624kg/m³.The primary and secondary factors affecting the permeability coefficient of recycled aggregate pervious concrete are as follows:silica fume content>recycled aggregate content>water cement ratio.When the water cement ratio is 0.35,silica fume content is 2%and recycled aggregate content is 30%,the permeability coefficient of recycled aggregate pervious concrete is the largest,and the minimum is 6.84mm/s.In the aspect of mechanical properties,the primary and secondary factors affecting the7d/28d compressive strength of recycled aggregate pervious concrete are:silica fume content>water cement ratio>recycled aggregate content.Silica fume content is a significant factor for the 7d/28d compressive strength of recycled aggregate pervious concrete.When the water cement ratio is 0.35,silica fume content is 4%and recycled aggregate content is 10%,the 28d compressive strength of recycled aggregate pervious concrete reaches the maximum.The maximum compressive strength is 12.14MPa.The primary and secondary factors affecting 28d flexural strength of recycled aggregate pervious concrete are:silica fume content>water cement ratio>recycled aggregate content,in which silica fume content is a significant factor.When water cement ratio is 0.30,silica fume content is 4%and recycled aggregate content is 30%,28d flexural strength of recycled aggregate pervious concrete reaches the maximum,and its maximum flexural strength is 3.66MPa.Corrosion resistance,the primary and secondary factors affecting the sulfate corrosion resistance coefficient of recycled aggregate pervious concrete are:water cement ratio>silica fume content>recycled aggregate content.The water cement ratio and silica fume content are significant factors.When the water cement ratio is 0.30,silica fume content is 4%and recycled aggregate content is 30%,the sulfate corrosion resistance coefficient of recycled aggregate pervious concrete reaches the maximum,and its maximum value is 0.851.