Experimental Research On Mixing Ratio Optimization Of C50 High Performance Segmental Concrete

With the acceleration of urbanization,the pressure of urban traffic continues to increase and the scale of underground rail transit in China has been expanded.During the process of subway shield construction,the segment is one of its main support components.The performance of the segment directly affects the working performance and service life of the subway tunnel.At present,most of the segments are mainly reinforced concrete.In order to ensure the strength of the concrete,the cement consumption in actual production tends to be conservative.How to reasonably and effectively reduce the amount of cement in the concrete mix ratio has important practical significance for improving the competitiveness of the enterprise..This article relies on the Wuhan Metro Line 29 project to reduce the amount of cement for the main purpose,according to the site used raw materials and production requirements,on the basis of the production of concrete mix,the system of the optimal test study.(1)The performance indexes of various raw materials were studied and determined.Compatibility tests were conducted on two types of cement and two types of water-reducing agents,which are commonly used in production,and a group with better compatibility was selected for testing.The results of the study show that AWB-Z water-reducing agent is compatible with Huaxin Cement.(2)Two sets of orthogonal tests were designed by consulting the literature and combining production mix ratios.Among them,one set adopted the speci-fied calculation method of concrete mix ratio based on the Borrome formula,and the other set was based on close packing theory.The concrete mix design method.When assessing the test results,the control index is mainly compressive strength,and the workability of the mix is ??ensured.From each set of orthogonal tests,a set of concrete mix proportions with a smaller cement content is selected.(3)A comparison was made between the design methods for the mixing ratios of the two segment concretes.The results showed that when the gravel grade used was poor,the concrete mix ratio was adjusted based on the close-packed theory concrete mix design method.The intensity is relatively high.(4)Incorporating cement powder and fly ash in different proportions and other qualities instead of cement in the mix proportion of the reference concrete,and comparing the influence of different proportions of mineral admixtures on compressive strength of the concrete,and determine its resistance.The performance indicators such as permeability,resistance to chloride ion permeability,etc.,from which a set of optimal concrete mix ratios are selected,(5)The performance ratios of concrete obtained from the experiment were compared with the production mix ratios,and the leak test of the segments was performed on the test mix ratio.The results of the study show that,compared with the mix ratio used by the current manufacturer,on the basis of meeting the strength requirements,the mix ratio obtained from the test has better impermeability,resistance to chloride ion permeation,and higher early steaming strength.In the uni-concrete,the total amount of cementitious material and the amount of cement used were reduced to different degrees,with values of 27 kg and 65 kg,respectively.