Effect Of Granite Powder On Low-strength Hydraulic Concrete Properties And Micro-pore Structure

With the rapid economic development,the demand for stone materials has increased rapidly.In 2015,granite stone production was 669 million m~3,a year-on-year increase of16.8%,showing a sustained growth momentum.Granite power produced from stone production exceeds 10 million tons/year.At present,At present,the annual consumption of granite stone powder is less,and the utilization rate is low.Stone powder invades large amounts of land and pollutes water and air.More than 80%of China’s irrigated area depends on channel water for irrigation.At present,there is a high cost of anti-seepage in the seepage prevention channel,which can not reach the anti-seepage effect.The study found that the replacement of part of the cement with granite stone powder within a certain range of content can improve the crack resistance,impermeability and frost resistance of the hydraulic concrete.At the same time,the strength also meets the engineering requirements,and the granite stone powder can be recycled to save natural resources and improve economic efficiency.In this test,the impact of granite stone powder on the macroscopic properties of concrete,such as compressive strength,impermeability and frost resistance,was studied.The concrete pore structure was quantitatively and qualitatively analyzed by means of mercury injection test and electron microscope scanning.Through the comprehensive analysis of macroscopic and microscopic aspects,the mechanism of stone powder impact on concrete was explained.At the same time,the concrete pore structure was quantitatively and qualitatively analyzed by the MIP and SEM.Through a comprehensive macro and micro analysis,the mechanism of stone powder impact on concrete was explained.Finally,the relationship between the content of granite stone powder and the strength of micro pore structure parameters was studied.The test results show that:When the granite powder content is 5%,the compressive strength and frost-resistance of the concrete slightly increase or remain unchanged.When the content exceeds 10%,the compressive strength and frost resistance of concrete gradually decrease with the increase of the content.Granite powder promotes the impermeability of concrete.The relative permeability coefficient of concrete is higher than the pure cement group when the content is less than 20%,and the impermeability of concrete is the strongest when the content is 5%.When the content is 25%~30%,it can meet the requirements of the specification for the use of channel concrete in small channels in moderate areas.When the content is 15%to 20%,it meets the requirements for the use of all channels in temperate regions,small and medium channels in cold regions,and small channels in severe cold regions.When the content is less than 10%,it meets the requirements for the use of other channels except for the large-scale channels in cold regions and cold regions.The effect of granite powder on the concrete pore size was determined.Scanning electron microscopy indicated the existence of a throat and the influence of granite powder on the throat.The mechanism of the influence of the throat and pore size on the macroscopic properties(compressive strength,impermeability,and frost resistance)of the concrete were revealed.At less than 10%,stone powder could reduce the pore and throat diameter and increase the number of throats.When the content was between 10%and 20%,stone powder could increase the pore diameter and number of throats and reduce the throat diameter.Throats increased the impermeability with a stronger influence than the increase in pore diameter.When the content exceeded 20%,the effect of the throats on the concrete impermeability was weaker than that of the increase in pore diameter.The relationship between granite powder content,micropore structure parameters(porosity,20~200nm pore volume,fractal dimension),and strength were established.The relationship can be used to predict the strength of low-strength concrete for different granite dosages.This information is highly relevant to engineering practices.