Effect Of Glass Powder/Glass Sand Synergy On ASR Performance Of Cement-based Composites And Its Economic Analysis

Concrete and mortar are important building materials,but concrete and mortar consume a lot of energy and produce greenhouse gases in production.As an important industrial material,glass is extremely difficult to dispose after being discarded,and a large amount of waste glass occupies valuable land resources.At present,the application of waste glass in cement-based materials is mainly used as auxiliary cementite or fine aggregate alone.The main problem is that waste glass cannot be used as auxiliary cementite and fine aggregate at the same time,and glass sand will produce Alkali aggregate reaction(ASR).Based on the above reasons,waste glass was used as a substitute for cement and fine aggregate at the same time in this paper to explore the influence of glass powder/glass sand synergy on ASR performance and its economic analysis.The experiment was divided into two types,the first type of glass sand group,glass sand replacement rate of 10%,20%,30%respectively;The replacement rate of glass sand in the second mixture ratio was the same as that in the first group,and glass powder was used to replace 20%cement in each group.The main conclusions are as follows:(1)The addition of glass sand increases the pore volume of mortar after 14 days of curing;after 24 days,tehe effect of glass sand on the pore volume of mortar is weak;the addition of glass powder reduces the pore volume of glass sand at 14 days.(2)During the curing period,the glass powder consumes calcium hydroxide,and the thermograv imetric results indicate that the pozzolanic reaction occurs during the curing period.(3)Scanning electron microscope was used to observe the morphology of glass powder and glass sand,and it was found that the expansion gel generated by ASR of glass sand caused cracks in mortar.(4)Glass sand will produce a considerable number of microcracks,leading to a large expansion rate of specimens,and the higher the replacement rate of glass sand,the larger the expansion rate.The addition of glass powder significantly reduces the number of microcracks,inhibits the ASR reaction of glass sand,and enhances the specimen's resistance to the entry of external harmful substances.(5)Due to the occurrence of ASR reaction and expansion cracks in glass sand,the compressive strength of test pieces would be seriously reduced,However,the addition of glass powder successfully suppressed ASR and reduced the number of cracks,making the compressive strength of test pieces exceed that of the control group.(6)Through the economic analysis of concrete and mortar with different mix ratios,glass sand is not suitable for separate application of concrete and mortar,but the joint use of glass powder and glass sand can improve the value coefficient of concrete and mortar.To sum up,this paper studied the influence of glass powder and glass sand on ASR of cement matrix composite materials.The experiment found that glass sand alone would reduce the compressive strength of specimens due to ASR.However,although the early strength was reduced after the use of glass powder and glass sand together,the strength exceeded that of the control group in the long run.In this experiment,20%glass powder and 30%glass sand,whether concrete or mortar,are evaluated based on their compressive properties,ASR and economic analysis to obtain the optimal mix ratio.