Study On The Performance Of Ordinary Portland Cement-Sulfoaluminate Cement Composite Cementing System Concrete

In order to save resources and protect the environment,it is necessary to ensure greening while developing the construction industry.As a special cement independently developed by my country,the characteristic of sulphoaluminate cement is that it has high strength at early stage and emits less carbon dioxide during use.However,due to the limitation of raw materials,the production cost is relatively high.At the same time,there are problems such as insufficient strength development in the later stage,which limits its large scale.Popularization of the area;while ordinary Portland cement has higher late strength,but there are problems such as slow early strength development and high carbon emissions.Because the advantages of two kinds of cement can complement each other,this paper will study the concrete of ordinary Portland cement-sulphoaluminate cement composite cementitious system on the basis of previous studies.Different proportions of ordinary portland cement were added to sulphoaluminate cement,and the effects of different quality of ordinary portland cement on the standard consistency water consumption and setting time of composite cementitious system were studied.The results show that adding ordinary Portland cement can promote the hydration reaction of sulphoaluminate cement to a certain extent,increase the water consumption of standard consistency and accelerate the initial and final setting time of cement.The sulphoaluminate cement concrete was mixed with ordinary Portland cement in different proportions to study the effect of different dosages of ordinary Portland cement on the compressive strength and split tensile strength of composite cementing system concrete.The research results show that the addition of ordinary Portland cement reduces the early compressive strength of composite cementing system concrete to a certain extent,but as the hydration reaction continues,the appropriate amount of composite cementing system concrete will be used in the later stage The compressive strength will be improved,which is higher than that of pure sulphoaluminate cement concrete;the splitting tensile strength of sulphoaluminate cement concrete will show strength inversion in the later stage,which will be improved by adding an appropriate amount of ordinary Portland cement.One phenomenon,the test splitting tensile strength recovery and increase again.Scanning electron microscope(SEM)is used to analyze the microscopic situation of hardened fragments of some concrete specimens.The test results show that the microscopic characteristics of hardened fragments are consistent with the results of concrete strength test.At the same time,it can be observed that in the later stage of hydration reaction of sulphoaluminate cement concrete,hardened fragments will produce tiny cracks due to structural deterioration.It is precisely because of these micro-cracks that the splitting tensile strength of the sulfoaluminate cement concrete will be reversed;adding a proper amount of ordinary Portland cement Later,due to the continuous hydration process of ordinary Portland cement,the generated hydration products will gradually fill and "repair" these micro-cracks,so that the cleavage tensile strength is restored and continues to grow.Figure[37]table[8]reference[54]...