| As glass is widely used in construction engineering,medical products,daily life,electronic parts,automotive components and other fields,the amount of waste glass has also increased dramatically.The treatment of waste glass particles to partially replace nature sand will affect the fluidity,strength and alkali-silica reaction.The use of mineral admixture will not only improve the utilization rate of solid waste,but also affect the mechanical and working properties of waste glass cement mortar to a certain extent.In this article,we mainly explore the effect of compound mineral admixtures on the strength of specimens,the reaction of alkali aggregates and the expansion inhibition mechanism when waste glass sand partially replaces natural sand.The research content and relevant conclusions of this article are as follows:1.Carried out the test of the best content of waste glass sand,with the consistency,segregation degree,strength and expansion rate as the evaluation index.The test results showed that when replacement rate of the waste glass is 30%,the waste glass cement mortar demonstrated good water retention and fluidity,and reached the strength peak.Waste glass partially replacing natural sand could reduce the expension of mortar alkali-silica reaction.2.Fixed the content of waste glass sand being 30%,the fluidity,strength and alkali-silica reaction tests of mortar were carried out with the content of fly ash and slag powder as variates.The results show that both fly ash and slag micropowder could inhibit the alkali-silica reaction of the waste glass mortal,and the inhibition effect of fly ash is more obvious at the same dosage.Considering comprehensively the strength and the inhibition effect of alkali-silica reaction,it is recommended that the optimal dosage of fly ash is about 10%-30%,and the optimal dosage of slag powder is about20%-40%.3.Fixed the total mineral admixture is 30%,the best mix proportion test is carried out on composite fly ash and slag powder.The research showed that the expansion rate of the compound mineral admixture waste glass mortar was significantly reduced.When the fly ash:slag powder=3∶2,the effect of inhibiting alkali-silica reaction is the best,and the expansion rate is only 0.107%in 28d.According to the ratio of fly ash and slag powder,the inhibition effect of different ratio of compound admixtures on alkali-silica reaction displays the following relationship:3∶2>3∶1>2∶3>1∶1>1∶3.4.Using X-ray diffraction(XRD)and scanning electron microscope(SEM),test analysis of composite admixture waste glass mortar and microscopic mechanism was carried out.The research showed that the main mechanism of slag and fly ash inhibiting the expansion effect of alkali-silica reaction was as follows:1)Pozzolanic reaction between mineral and with calcium hydroxide,the hydration product of cement,produces C-S-H gel with a low calcium-to-silicon ratio,which causes the alkali metal ions in the system to be"cured";2)The occurrence of pozzolanic reaction reducing and consuming the alkali content in the system,greatly reduce the formation of alkali-silicic acid gel;3)Mineral admixtures and secondary pozzolan reactants fill the pores of the slurry,making the structure more dense and preventing the diffusion of metal ions such as Na~+、K~+. |
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