Effects Of Granite Composite Slag Powder On Cement Concrete Performance And Mechanism Study

At present,the contradiction between supply and demand of fly ash is increasing gradually in parts of our country.The exploration of new type of mineral admixture is imperative.At the same time,the granite mineral resources is abundant in our country,but large amounts of granite chips is wasted in the process of granite mining,which led to the granite resources wasted and the environment polluted.Thus it is a valuable research that the fine powder prepared by the waste granite chips is applied to concrete to serve as the replacement of fly ash.The article study the physical and chemical properties of granite powder via several material of modern testing methods,for example XRF、SEM、XRD etc.Study the effect regularity on working performance and mechanical performance of different strength grade concrete(C30,C40,C50 and C60)when the granite powder of different fineness mixed with slag powder according to the different dosage proportion replaces a part of the cement doped into concrete,and determine the ultimate mixture ratios of C30,C40,C50 and C60 concrete.Study the effect of granite composite slag powder on the carbonation resistance,resistance to dry shrinkage and sulfate attack resistance performance of concrete.Use modern test and analysis methods to analyze the impact of granite powder on the hydration products and micro morphology of cement concrete,and has carried on the preliminary discussion on its mechanism.(1)When the specific surface area of granite powder prepared by granite chips are 378,451,478m2/kg,the particle morphology of granite powder is the irregular multilateral particle,and has better grain size distribution.The chemical composition of granite powder is mainly SiO2,Al2O3,Na2 O,K2O,and the main mineral composition is quartz,albite,microcline,white mica.In alkaline condition,when the specific surface area of granite powder is the larger,it will have volcanic activity.The 28 d activity index of granite powder is lower than the fly ash,but is higher than 60%.And with the specific surface area of granite powder increasing,the 28 d activity index of granite powder is raise.The granite powder of 478m2/kg having the higher 28 d activity index than other two kinds of specific surface area is 68.6%.(2)With the dosage increasing of granite powder,the slumps of the concrete of each strength grade is raise.For the C30 concrete,451 m2/kg of the granite composite slag powder concrete has the higher slumps.For the C40,C50 and C60 concrete,478 m2/kg of the granite composite slag powder concrete has the higher slumps.C30 and C40 granite composie slag powder concrete have the same slump to fly ash concrete,and could meet the slump requirement of pump concrete.(3)The dosage proportion of granite powder and slag powder has a main effect on the strength of concrete.With the dosage increasing of granite powder,the strength of concrete is reduced on the whole.But the fineness of granite powder has a weaker influence with the strength of concrete.However,when granite powder has the same dosage with fly ash,appropriate fineness granite composite slag powder concrete has a higher strength than fly ash concrete in different strength grade concrete mix ratio.After a great deal of experiments and the adjustment experiment,the optimal dosage proportion of granite powder and slag powder and the appropriate fineness of granite powder are determined in every strength grade concrete,as follows:In C30 concrete,the appropriate specific surface area of granite powder is 478m2/kg,the optimal dosage proportion of granite powder and slag powder is 20 wt% of granite powder and 25 wt% of slag powder.In C40 concrete,the optimal dosage proportion of granite powder and slag powder and the appropriate fineness of granite powder are same to C30.In C50 concrete,the appropriate specific surface area of granite powder is 451m2/kg,the optimal dosage proportion of granite powder and slag powder is 20 wt% of granite powder and 20 wt% of slag powder.In C60 concrete,the appropriate specific surface area of granite powder is 478m2/kg,the optimal dosage proportion of granite powder and slag powder is 15 wt% of granite powder and 25 wt% of slag powder.(4)The granite composite slag powder concrete has a better carbonation resistance,resistance to dry shrinkage and sulfate attack resistance performance than fly ash concrete.The grain size distribution of the granite composite slag powder has a better effect on the compactness of the concrete than fly ash,and improves the durability of concrete is more.(5)Granite composite slag powder can take part in the hydration reaction of cement,and the well grain size distribution fills the holes inside the concrete to reduce the porosity.Thus the microstructure of concrete is more compact,and the compressive strength and durability of granite composite slag powder concrete is improved.