| The application of waste glass powder in concrete as a cementitious material has become a feasible method to solve the waste glass solid waste at present,achieving the dual benefit of environment and economy,especially in some developed countries,such as Europe and America,etc.Its theory and technology application has been improved.However,the formal technical specification of waste glass powder as mineral admixture has not yet been formed in China,and its practical application in projects is rare.The restricting the of basic theory shortage for waste glass powder as cementing material has not been solved well.Starting with the hydration reaction products and pore structure,this paper reveals the physical / chemical nature and mechanism of the hydration process of waste glass powder cement paste,which provide a practical and reliable theoretical basis for solving the key technical problems that restrict the development of waste glass powder cement paste.In this paper,waste glass powder is used as mineral admixture and Ca(OH)2 and Na2SO4 are used as activators adding to the cement.By means of physical mechanical property testing,XRD,TG-DSCcomprehensive thermal analysis,SEM,MIP characterization,etc.,the influence of waste glass powder on cement paste hydration products and cemented sand pore structure is studied.The results show that:(1)The formation of the hydrated product ettringite was retarded and inhibited by waste glass powder,and the smaller the particle size of waste glass powder was,the more obvious the inhibition effect was.The effect of different color waste glass powder on the delay and inhibition of ettringite did not show a very specific rule,but the brown waste glass powder had the weakest effect on the formation of ettringite.(2)Waste Glass Powder reduced Ca(OH)2 content,and with the increase of waste glass powder particle size,the content of Ca(OH)2increased.Meanwhile,the endothermic peaks of Ca(OH)2 showed an increasing trend with the prolongation of age,indicating a higher crystallization degree of Ca(OH)2 hydration products.Such results indicated the waste glass powder reduced the thermal decomposition temperature of Ca(OH)2 to some extent.(3)The content of C-S-H gel in cement paste was increased by waste glass powder.At 0~7 days,the content of C-S-H gel decreased with the increase of waste glass particle size,;when hydrated to 28 days,the content of C-S-H gel was almost equal.The content of C-S-H gel was affected by different colors of waste glass powder,but it did not show some certain regularity.(4)Waste glass powder reduced the flexural strength of cement sand,and the flexural strength increased with the particle size of waste glass powder decreasing.The color of waste glass powder did not show a certain rule on the flexural strength of cement sand,but the specific influence rule was still need further studied.(5)The early compressive strength of cement mortar was decreased and the late strength was increased by waste glass powder and the color of waste glass powder had a certain influence on the compressive strength of cement sand,that was the strength of brown waste glass powder cement sand was the highest in the early stage of hydration,the green one was the second,and the white one was the lowest.In the late period of hydration,the strength of white,brown and green glass-cement sand was almost equal.(6)Waste glass powder could reduce the total porosity of cement paste to some extent,but the effect of different waste glass powder color on the slurry porosity was not significant.According to the distribution of pore size,waste glass powder could increase the less harmful and harmless holes,and reduce the harmful holes and more harmful holes in cement mortar. |
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