Experimental Research On Permeable Concrete Mixed With Mineral Admixtures

In recent years,due to the acceleration of urban construction,the ecological destruction is more serious.The traditional watertight hardened pavement suffers from obvious limitations.Due to the design defects of the structure itself,it is easy to cause rainwater accumulation and seepage damage of the pavement,and the freezing of rainwater in winter is easy to cause the road surface to be damaged by freezing,so the "sponge city" gradually enters the field of vision.Pervious concrete with high permeability and ecological environmental protection can effectively improve this situation,alleviate urban heat island effect,conserve urban water resources,improve urban green rate,achieve building energy conservation,and protect the ecology.This paper firstly uses the range and variance methods to determine the order of influencing factors of water-binder ratio,target porosity,and reinforcing agent on permeable concrete,and draws up the benchmark mix ratio;secondly,it analyzes the influence of slag powder,basalt fiber,polypropylene fiber,and polymer.Single factor test analysis of acrylonitrile fiber and micro-silica powder determines the range of slag micro-powder,the most suitable fiber-basalt fiber,and micro-silica powder;then the orthogonal test is used to determine the best mix ratio of the water-permeable concrete mixed with mineral admixtures;Finally,through the anti-freezing performance test to analyze the index change law.The results showed that:(1)The influencing factors of 28 d compressive strength of permeable concrete are: water-binder ratio>reinforcer>target porosity,and the influencing factors of water-permeability coefficient are: water-binder ratio>reinforcing agent>target porosity.The water-binder ratio of the permeable concrete is 0.30,the target porosity is 20%,and the amount of reinforcing agent is 5.5%.The standard mixing ratio is cement: water: stone: water reducing agent: reinforcing agent = 427: 128: 1630: 3.42:23.49.(2)Single factor test shows that the mixing amount of slag powder is 10%～20%,the most suitable fiber for permeable concrete is basalt fiber,and the mixing amount is 0.05%～0.15%,and the mixing amount of microsilica powder is in the range of0.05%～0.15%.It is 4%～8%.(3)Orthogonal test shows that: slag powder is mixed with 10% of the same mass to replace cement,basalt fiber is added with 0.15% by volume,and microsilica fume is mixed with 8% of the same mass to replace cement.It is the best mix ratio of permeable concrete with mineral admixture.Compared with the OR group of the benchmark group,it can be seen that the compressive strength of the permeable concrete specimens with the best mix ratio is 33.5% higher than that of the benchmark group,the flexural strength is increased by 37.5%,the compression ratio is increased by 5.8%,and the water permeability coefficient is increased by 3.34mm/s.(4)After the freeze-thaw cycle test,the mass loss rate of the benchmark group OR permeable concrete reached 4.869%,which was close to the 5% failure edge,and the relative dynamic elastic modulus was 47.6%,which was lower than the initial relative dynamic elastic modulus 60% The test piece is easily damaged by freezing;while the mass loss rate of the M3 group permeable concrete mixed with 10% slag powder,0.15% basalt fiber,and 8% microsilica fume is 3.136%,which does not reach3.5%,and the relative dynamic elastic modulus is 68.38%,greater than 60%,the correlation coefficients are all greater than 0.97,it is more difficult to be damaged by frost,and the frost resistance performance is significantly improved,meeting the requirements of frost resistance index.