Experimental Study On Mechanical Properties Of Alkali Activated Slag Grouting Material Under Freeze-thaw Condition

In the traditional construction process,Portland cement is a common material,until now,any project construction can not do without this material.However,with the development of society and the progress of technology,the disadvantages of traditional Portland cement also gradually appear.For example,in the manufacturing process,it will cause adverse effects on the environment,but also cause a waste of resources.Alkali activated slag cement,as a new and environmental friendly cementitious material,has attracted the attention of many scholars.At the application level,this material is gradually replacing Portland cement in some construction fields.In this paper,the mechanical properties and frost resistance of alkali activated slag cement were studied,and the hydration products and chemical groups in the products were analyzed by XRD and FTIR scanning.The specific work of this paper is as follows（1）The compressive strength and change curve of alkali activated slag itself and alkali activated slag test block mixed with fly ash were studied respectively.The compressive strength and change curve of alkali activated slag after adding early strength agent,polycarboxylate superplasticizer,polypropylene fiber and air entraining agent（SDS）were tested,and the optimum content of each material in the case of single mixing was obtained,At the same time,the influence of different substances on alkali activated slag and the reason of its compressive strength change are analyzed.（2）The mass loss rate and compressive strength loss rate of alkali activated slag cement were determined by freeze-thaw cycle test,and the frost resistance of alkali activated slag cement was explored as an index.Different admixtures and admixtures were added respectively,and the improvement of frost resistance of alkali activated slag cement and the effect of admixtures or Admixtures in test block were explored when they were used alone.Through the design of orthogonal experiment,the compounding of various admixtures and admixtures is completed,and a formula which can effectively improve the frost resistance of alkali activated slag test block is found out.The experiment shows that the formula can make the test block maintain more than 95%compressive strength and 99%mass after 20 freeze-thaw cycles,and its own compressive strength performance is also high,It can meet the test requirements.Through the comparison between the orthogonal experiment and other groups of experiments,it is determined that the formula can meet the requirements of frost resistance and has the best effect.（3）The hydration products and chemical groups in the products were analyzed by XRD and FTIR.Through scanning and analysis,it is confirmed that there are C-S-H,calcite（CaCO₃）and clinoptilolite(（Ca₂SiO₃）with poor crystallinity in the activated slag slurry obtained in this experiment.It is confirmed that the additives and admixtures used in this experiment strengthen the frost resistance of alkali activated slag material on the physical level,and there is not much change in the product.In addition,it is found that adding sodium silicate as a complex alkali activator can affect the polymerization degree of alkali activated slag slurry.