Experimental Study On Properties Of Modified Cement Mortar Backfilled With Snow Melting And Ice

Snow removal methods in winter are mainly divided into two categories:removal method and thawing method,of which thawing method is further divided into chemical thawing method and thermal thawing method.In practice,there is a thermal thawing method that can be applied to an existing road.The asphalt layer on the surface is first removed,then the underlying layer is grooved to bury the carbon fiber starter wire,and finally the grooved joints are backfilled and a new asphalt layer is laid.The purpose of this paper is to study the backfilling materials used in the process of grooving and pointing backfilling in this technology,in order to obtain the backfilling materials with suitable properties for practical projects.Cement mortar is a kind of traditional backfill material,widely used,through adding different adding material will make its physical properties change and so on the basis of the actual engineering needs,on the basis of(cement mortar mixed with iron powder,mineral powder and rubber particles,compared with reference mortar,the modified mortar strength,frost resistance,thermal conductivity,and to study the influence of seepage resistance,The thermal conductivity is the most important property of the material in this paper.The design control group is the basic mortar with mixing ratio of cement:standard sand:water=1:3:0.5,and the iron powder is mixed with the dosage of1%,2%,3%,4%,5%(each dosage is mixed with three types of ultra-fine,medium and super-coarse iron powder).Ore powder in accordance with 5%,10%,15%,20%,25%volume fraction of cement replacement volume;Rubber particles are replaced with sand by volume fraction of 5%,10%,15%,20% and 25%.The main work of this paper is as follows:(1)Basic mechanical tests were carried out,including cube compressive strength test,flexural strength test and freeze-thaw cycle test.The results show that the iron powder can improve the compressive strength,flexural strength and freezing resistance of the material to a certain extent,and meet the requirements of the basic engineering.Although ore powder has better improvement effect on these three aspects,the improvement degree is not significantly superior to that of iron powder.Rubber particles can improve the freezing resistance of the material and have a negative effect on the strength of the material.(2)Physical tests were carried out,including thermal conductivity tests and impermeability tests.The results show that the iron powder,especially the coarse iron powder,can improve the thermal conductivity of the material obviously,and meet the basic engineering requirements in the aspect of impermeability.The mineral powder can improve the thermal conductivity and impermeability of the material,but there is an obvious gap with iron powder in improving the thermal conductivity of the material.Rubber particles can improve the impermeability of the material and have a negative effect on the thermal conductivity of the material.(3)Adding coarse iron powder into cement mortar has a great influence on the thermal conductivity of mortar.In order to explore the transmission mode of heat flow in mortar,cement mortar series thermal conductivity model and parallel thermal conductivity model are established.According to the thermal conductivity test results,a series and parallel mixed thermal conductivity model of mortar mixed with coarse iron powder is proposed.The results show that the theoretical values calculated by this model are highly consistent with the experimental values.