Influence Of Water-binder Ratio On Pervious Recycled Aggregate Concrete

According to relevant regulations and existing research results,pervious concrete was prepared from waste precast concrete beam members as a source of recycled coarse aggregate.Based on the water-cement ratio of 0.3 and the sand rate of 10%,the change of single cementitious material to the regenerated bone was studied.Permeable concrete permeability,permeability and strength properties.Five types of pervious concrete were designed: 1)pervious natural concrete(PNC);2 previous recycled concrete(PRC);3 using fly ash equivalent to replace 20% of cement;4 using silica powder equivalent to replace 6% of cement;5 Add naphthalene water reducer,water reducer to take 1% of cement quality.The results show that the porosity and water permeability coefficients range from 17.8% to 21.8%,0.27 to 0.48 cm/s,and the compressive strength is 4.0 to 9.63 MPa,respectively.The basic properties can meet the requirements,and the fly ash can significantly increase its resistance.The compressive strength increased by about 44%,and the effect of incorporating a naphthalene-based superplasticizer and silicon powder was not significant.Preparation of pervious concrete with waste concrete pavement as the source of recycled aggregates.By changing the water-binder ratio and mixing admixtures,the effect of water-binder ratio on the strength,water permeability and wear resistance of recycled aggregate permeable concrete was studied.Research on Capillary Water Absorption Process of Recycled Aggregate Pervious Concrete.Four types of mix ratios were designed: 1 natural aggregate permeable concrete with a water-solubility ratio of 0.3 as the benchmark;2 water-cement ratios of 0.24,0.27,0.30,0.33,and 0.36 recycled aggregate permeable concrete;3 with a water-binder ratio of 0.3.Based on the benchmarks,fly ash,silicon powder,recycled fine powder and other quality recycled concrete permeable cements were selected,among which fly ash content was 5%,10%,15%,20%,and 25%.For 2%,4%,recycled fines were 5%,10%,15%,20%.The results are shown as follows:(1)The density and compressive strength of permeable concrete with recycled aggregates tend to decrease with increasing water-binder ratio(0.24~0.36),and the porosity and water permeability increase.The wear loss rate increases with the increase of porosity and decreases with the increase of compressive strength,both of which meet the exponential trend.When the water-binder ratio is 0.30,the average density is higher than that of other conditions,and the porosity and permeability coefficient are the lowest.The compressive strength and splitting tensile strength are 9.1 and 1.7 MPa,respectively,which are higher than natural aggregate permeable concrete(6.9,1.6 MPa).(2)Replacing equal amounts of cement with recycled fines or fly ash can result in a decrease in the density of the concrete mix.With the increase of fly ash content(5-20%),the average density of the mixture showed an upward trend,compared with the porosity from 27.5% to 20.9%.When the fly ash parameters reach 25%,the density begins to drop.The porosity is highest when the fly ash parameter is 5%,so the water permeability is best at this time.When the content of regenerated fine powder was 15%,the density value was the highest(1735 kg/m3)and the corresponding porosity was the lowest(23.1%).The compressive strength of recycled concrete permeable concrete ranges from 3.0 to 9.1 MPa,splitting tensile strength ranges from 1.0 to 1.7 MPa,and the wear loss rate ranges from 22.9 to 45.1%.As the compressive strength increases,the wear resistance increases.In addition,as the silicon powder content increases(2 to 4%),the strength and water permeability increase.(3)The process of capillary water absorption in the damage-free state of recycled aggregate permeable concrete is as follows: the front curve shows a linear trend of growth.With the continuation of the water absorption time,the rate of cumulative water absorption increases slowly.The cumulative water absorption of the unit cross-sectional area from the start of water uptake to 6 h and from 1 to 8 d was analyzed,and the linear relationship between the cumulative water absorption and the square root of the water absorption time was fitted.The water absorption rate of this test is higher than the recommended water absorption rate of ASTM C 1585-04,and the less the amount of regenerated fine powder(10~20%),the higher the cumulative water absorption value.