Study On The Road Performance And Technology Of Manufactured Sand Cement Concrete

Natural sand is a kind of non renewable resources,with the decrease of natural sand production,people began to explore the use of manufactured sand instead of natural sand for highway engineering construction.The Guangxi area is rich in limestone,Therefore,the limestone manufactured sand is gradually used in the cement concrete pavement.Because of the high content of powder and mother rock is not wear-resistant,it is difficult for concrete pavement which is fully used in the limestone mechanism to meet the standard requirements.Therefore,it is very important to study the wear resistance of manufactured sand cement concrete pavement for its popularization and application.In this paper,the wear resistance of sand mortar and concrete is studied as the major research object.Based on experimental research,combined with microscopic mechanism analysis technique,studied the Influence of manufactured sand methylene blue value,stone powder content and particles morphology of limestone manufactured sand to mortar and concrete strength,dry shrinkage and abrasion resistance.The effect of particle shape,particle size and surface characteristics on the wear resistance of the mortar and concrete and the mechanism of methylene blue value and stone powder content on the wear resistance mechanism of sand mortar and concrete are mainly analyzed.At the same time,a new design method of cement concrete mix proportion based on full calculation method,cement paste filling theory and surplus coefficient is put forward.The results of this study show that: the influence of the content of stone powder and methylene blue value to dry mortar shrinkage and abrasion resistance are better than the concrete.The more the content of powder the larger the dry shrinkage of mortar,but the concrete shrinkage rate first increased and then decreased with the increase of the content of stone powder.The dry shrinkage ratio of manufactured sand mortar and concrete is bigger with the increase of methylene blue value,with the increase of the content of stone powder,the influence of methylene blue value to the changes on the dry shrinkage of mortar and concrete is decrease.The wear resistance of mortar and concrete decreased with the increase of sand powder or methylene blue value.Summarize the specimens of dry shrinkage and the wear value found that the bigger shrinkage of the manufactured sand mortar and concrete the worse the wear resistance.Let natural river sand as a reference,may use specific surface ratio of manufactured sand and natural river sand to characterize manufactured sand.Tests show that this ratio is constant over 1,the more close to the ratio of 1,the better the wear resistance of mortar and concrete,the greater the ratio,the worse the wear resistance of mortar and concrete.The XRD results show that the cement hydration degree maximum when the content of manufactured sand powder is about 10%.This is probably the reason that concrete has the biggest strength when the content of stone powder is about 10%.With the help of electron microscope scanning we found the clay adsorption on aggregate surface,there are a series of interconnected small cracks in interfacial transition zone between aggregate and cement paste when the water disappeared,and the size and width of crack increased with the increase of methylene blue value.This may be the reason for the decrease of the strength and wear resistance of concrete with the increase of methylene blue value.This paper is supported by the Guangxi traffic science and technology project(No.20152615).