Study The Effect Of Aggregate Gradation On The Performance Of Porous Concrete

With the rapid development of construction,all types of building materials was used in excess which caused great burden on environment.Porous concrete belongs to framework-pore structure,which own variety of practical advantages in water seepage,noise absorption and plant hygiene etc.In recent years,it has gradually developed into ecological,green,diversified functional ecological concrete.However,porous concrete with framework-pore structure is still weak in strength and poor durability.In view of the deficiency of porous concrete,this paper studies the effect of aggregate gradation on the performance of porous concrete,which has a certain value.At first,the preparation of porous concrete in the laboratory was studied in this paper.After a preliminary inquiry,porous concrete with traditional mixing process,artificial shoot in plus vibration table with 4 to 5 seconds of molding process and sprinkle water coated curing process preparation method.This paper uses four factors and three levels of orthogonal test design.The aim is to give priority mix proportion of porous concrete.The main factors that affect the strength and water permeability of porous concrete are obtained,which are designing porosity value and aggregate size.According to the status of porous concrete workability studied,a comprehensive evaluation of the workability performance of porous concrete is proposed for the first time,which is a comprehensive evaluation of the excess slurry rate and the appearance of the new mixed porous concrete.According to the results of orthogonal test,the optimum proportion of porous concrete is determined.Secondly,this paper mainly aims at the current situation of the contradiction between the permeability coefficient and the strength of the porous concrete.Aggregate gradation as the research object,a large number of experimental studies with the porosity,permeability coefficient and cube compressive strength of the porous concrete on different gradation skeleton structure,Based on the theory of aggregate packing.At the same time,the statistics and analysis of plane porosity using Image-J graphics processing technology.The following conclusions are obtained:(1)The framework-pore structure of D-1~D-4 single size porous concrete strength decreases with the increase of particle size,effective porosity and permeability coefficient increases with the increase of particle size.(2)Sand ratio of single size porous concrete should be selected 6%~9%,coarse aggregate partial rate should be close to 9%,partial sand aggregate ratio should be close to 6%.(3)The strength value of porous concrete can be improved remarkably by the discontinuous gradation framework.In paper,AC-2,AC-3,ACD-11 grading has better cube strength and water seepage ability,which belongs to the better skeleton structure.(4)Plain porosity is able to reflecting the effective porosity,semi-connected and closed-gap distribution of concrete.The difference between plain film porosity and effective porosity measured is smaller,more favorable to improve the strength of concrete.Finally,the functional test of porous concrete is carried out in this paper which contains alkalinity property and anti-flying property.The results show that using water immersion measures in 30 days,the PH value of porous concrete decreased to 10.57~10.81,fall by about 16%.The greater porosity of porous concrete,pH dilution faster.PH value decreased gradually slow.Porous concrete scattering loss mainly concentrated in the first 30 seconds.The 30 s dispersion testing specimen quality accounted for the total loss of quality 50%~60%.The particle size of the single file anti-flying ability order is D-3>D-2>D-1>D-4.The greater sand ratio,the lower loss of flying quality.The discontinuous gradation can improve concrete anti-flying ability.