Research On Chanism Sand Characteristics Based On Mother Rock And Rheological Properities Of Cement Slurry

With the rapid development of the construction industry,the demand for concrete is growing,and high-quality natural sand resources will become increasingly scarce,meanwhile,in many places,the abuse and indiscriminate excavation has caused serious environmental damage,so do that the development of new sand source is imperative.Mechanism sand is the particle with size smaller than 4.75 mm after mining from mother rock,mechanical crushing and screening,excluding the soft and weathered rock.Its characteristics is closely related to that of mother rock.As a concrete fine aggregate,it also has an important impact on the performance of fresh concrete which is mainly affected by its rheological properties.However,the rheological properties of concrete are difficult to evaluate accurately because of the existence of coarse aggregates.A lot of studies have shown that the rheological properties of concrete can be evaluated indirectly by rheological properties of cement paste and mortar.This paper systematically studied the compressive strength,flexural strength,surface hardness,chemical composition,mineral composition and other parameters of mother rocks based on the representative ones of granite,limestone,diabase and basalt at Fujian province.The V7-10 sand-making machine of Fujian south road machinery co.,LTD is used to make sand under the same parameters and production process.The gradation,fineness modulus,particle shape,angularity and specific surface area properties of four kinds of mechanism sand were systematically measured.After the analysis of the data,it find that the flexural strength of four mother rocks rank as basalt > diabase > limestone > granite.The greater the flexural strength and the flexural compression ratio of the mother rock,the greater deviation of the modulus at the mechanism sand,the larger fineness modulus and smaller specific surface area,the stronger of the angularity.In the process of sand making,it should be based on the flexural strength,e flexural compression ratio of mother rock to adjust the sand parametersIn order to reveal how the characters of four kinds of material mechanism sand,stone powder,clay powder influence the cement paste,cement mortar added polycarboxylate superplasticizer and the rheological properties.Experimental research was carried out on the condition with stable content of polycarboxylate superplasticizer solid content,water cement ratio(0.35)of cement paste,cement mortar,changing the type of polycarboxylate superplasticizer mixed with the mother liquor M.By testing the fluidity of cement paste mixed with different polycarboxylate superplasticizer,screening out the superior polycarboxylate superplasticizer: low sensitive VO4,slump-loss resistable S10 C,water conservative SO8 D.In addition,through adding stone powder with the ratio of 0%,3%,5%,7%,9% or clay powder with that of 0%,1%,2%,3% respectively on the basis of the same cement paste and mortar mix ratio,the experiment result showed the influence degree of four kinds of mechanism sand,four kinds of stone powder,two kinds of clay powder on rheological properties of cement slurry mixed with optimized composite polycarboxylate superplasticizer,and compared with the mixed with M.By the results of experimental,conclusions are showed as follows:The relationship between the mechanism sand characteristics and the cement mortar rheological parameters is: the correlation degree of mortar rheological parameters ranks as basalt > diabase > limestone > granite,the fineness modulus,angularity and particle morphology and methylene blue value(MB value)are ranked same with mortar rheological parameters,the relationship between stone powder characteristics and cement paste rheological parameters and influence degree between both is basalt > diabase > limestone > granite.It also shows that when the total amount of granite,limestone and diabase powder is 3%,the amount of basalt is about 5%,the additional stone powder will improve the rheological properties of cement paste,so,including the powder content in mechanism sand,the total powder content controlled at about 10% will be better.In addition,fineness and granule morphology will also influent the rheological parameters of cement paste by the effect of water absorption,granule shape and filling effect.The influence rank of clay powder characteristics is bentonite > ordinary clay,keep content of clay powder within 2% will be better.The weaker of the clay powder interlayer force is,the larger variation of the interval is;the stronger water absorption,the adsorption of the molecular functional groups of polycarboxylate superplasticizer is;the worse of rheological property of cement paste is.Combined with the influence of mixed powder on the cement paste,mortar rheological properties,the microscopic characterization analysis like Zeta potential,Total organic carbon(TOC),XRD small angle diffraction,Infrared Spectroscopy,and the experiment research on Zeta potential,adsorption capacity,adsorption mode,etc.of polycarboxylate superplasticizer and clay particles,it can be included that the slump-loss resistable polycondensate polycarboxylate has strong anti-clay performance,and it should be developed the size of branch chain of its functional structure in the molecular structure belong to is larger than 2nm.