Study On Early Autogenous Shrinkage Characteristics Of Glass Powder-Cement Composite Paste

In the rapid development of society,glass has become a material that cannot be ignored in construction and development.It has been used in all aspects of social production,and it has been accompanied by the generation of a large amount of waste glass.Since waste glass is a non-degradable material,if it is buried in place,it not only affects the sustainable development of the environment,but also causes great waste of resources.At present,all parties should actively follow the green development trend and pay attention to the recycling and utilization of waste glass,which is conducive to reducing production costs,saving resources and reducing the environmental burden.In the development of cement-based materials,there are many studies on the use of glass powder as auxiliary cementitious materials to replace cement in part,which mainly focus on the mechanical properties,durability and so on,and involve less research on the autogenous shrinkage of cement base materials by glass powder.According to the influence of glass powder on the autogenous shrinkage of cement paste,the paper designs the mix ratio of glass powder content,water-binder ratio and glass powder fineness as variables.By using compressive and flexural testing machine,corrugated tube autogenous shrinkage tester,X ray diffractometer,scanning electron microscope and nano-scarometer,the effects of glass powder on the mechanical properties,self-shrinkage properties,phase,hydration products,microstructure and nano-mechanical properties of cement paste are investigated from macroscopic and micro-nano-nano-view.The main conclusions obtained in this article are as follows:?1?The results of early mechanical properties show that the early strength development of glass powder-cement paste increases with age,increases with the decrease of water-cement ratio,but decreases with the increase of glass powder content.It is found that the early compressive strength reduction due to the use of glass powder can be compensated by reducing the water-cement ratio.?2?The autogenous shrinking results show that when the water-binder ratio is the same,the autogenous shrinkage gradually decreases with the increase of the amount of glass powder,and the addition of glass powder can significantly reduce the early autogenous shrinkage.The water-binder ratio has a greater influence on the autogenous shrinkage of the cement paste,and the autogenous shrinkage of the glass powder-cement paste increases with the decrease of the water-binder ratio.In addition,there is no significant difference in the autogenous shrinkage of the cement paste tested by the two different fineness glass powders used in this article.?3?The results of microscopic experiments show that the addition of glass powder increases the diffraction peak height of CH,the diffraction peak of CH increases gradually with the development of age,while the diffraction peak of C₂S decreases with the development of age,which indicates that the hydration degree inside the cement paste increases gradually,with the consumption of unhydrated cement particles C₂S,the hydration reaction produces more hydration products CH.In addition,the use of glass powder will degrade the early microstructure of cement paste,which has a certain effect on the change of autogenous shrinkage.?4?According to the analysis of the nano-indentation test results,the addition of glass powder changes the proportion of different types of C-S-H,resulting in the reduction of some hydration products,which affects the micro-phase distribution of the hydration products of the cement paste.Compared with the 7-day benchmark cement paste,the use of glass powder increases the volume fraction of pores and LD CSH,reduces the volume fraction of HD C-S-H,CH or UHD C-S-H and unhydrated particles.