| Stone chips is regarded as waste in the quarry in morden times,which not only occupies land,pollutes the environment,but also causes a huge waste of natural resources.The physical properties of stone chips are similar to the sand and even more have the possibility to replace it.Studying the preparation of concrete with stone chips as fine aggregate will be an effective way to alleviate the supply-demand relationship of existing sand resources and solve the problems of land occupation and environmental pollution caused by stone chips.In this paper,we study the stone chips as the object which is the waste in the exploitation of rock debris,and the influence of the stone chips content in the stone debris on the working performance,mechanical properties,volume stability and durability of concrete is investigated and systematically studied.Based on the experimental study,the technical parameters of the application of stone chips in concrete are defined,and the results and technology obtained are demonstrated in a project in Kunming.The results are as follows:(1)When the content of stone powder in the chips is less than 20%,by the method of grinding and screeningthe,the activity index of the two kinds of stone powder are more than 70%;The main factor affecting the MB value of stone chips is mud content,but the influence of stone powder content on MB value is not significant.(2)When the slump and water consumption are basically the same,the dosage of concrete water reducer increases with the increase of stone powder content in stone chips,and increases continuously with the increase of stone powder content screened by stone chips compared with that of ground stone powder.(3)When the water consumption and slump of concrete are basically the same,the compressive strength of concrete can be improved to varying degrees when the content of stone powder is less than 30%,especially the early compressive strength of concrete can be increased 13%-25% on the first 3-days to 7-days.When the proportion of stone powder screened in the actual stone chips reacheed 30%,the 28-day strength of concrete begins to decline.(4)The 28-day electric flux of concrete with different stone powder content is between 2000 and 4000 C,and the chloride ion permeability resistance of concrete with different stone powder content are both on medium level.The performance of water permeability resistance is good when the sand chips in the concret,and all of them can reach the P12 level.With the increasing of stone powder content in stone chips,the frost resistance of concrete is better than that of stone chips with 9% stone powder content.The frost resistance grade can reached F425,and the frost resistance performance is the best.When the content of stone powder in stone chips is 16%.(5)It has very little influnce in the shrinkage and crack resistance of concrete when the content of stone powder in stone chips is less than 20%;However,when it is more than 20%,the dry shrinkage of concrete increase greatly in early times before 28-days,even more,the early crack resistance of concrete becomes much more worse.The anti-cracking performance is poor with different stone powder content,and it can only reach to grade I. |
