Experimental Research On The Optimization Of Yunnan Highway C50 Prestressed Concrete Cement

Cement is the leading factor directly affecting the strength of concrete. The grade cement strength belonging to largely determines concrete’s. Now the strength grade of C50 concrete chosen for highway is increasingly high. This situation not only leads to the unnecessary waste, and also should responsible for cracks in prestressed concrete of T beam structure. Besides, more and more early age cracking has certain influence on development of concrete durability as well. Based on the above, it is necessary to study how the different strength grades of cement affect the integrated performance of concrete. All this study need to do is making appropriate choice about the strength grade of cement, and meeting requirements of both design strength and durability.How these two kinds of cement strength grade, called P.O42.5 and P.O52.5, impact on the concrete’s working performance, mechanical properties and durability were studied by experiments. The results showed that compared to P.052.5, P.O42.5 cement need relatively smaller workability admixture to reach the same working performance, and need lower cost under the same mix ratio condition.Although the strength of concrete made by P.042.5 is relatively low in the early phrase, its growth rate can catch up with cement P.O52.5 latter. Furthermore, based on concrete electric flux test data, its durability is better as well..The design of concrete mix ratio has an important influence on the strength of concrete. The reasonable selection of water cement ratio and cement sand ratio is not only economical, but also can meet the requirements of concrete mixture’s workability and concrete’s durability while guaranteeing strength.This experimental study focuses on the effect of water binder ratio and cement sand ratio on the compressive strength of mortar, and also comparative analysis about the reference mortar strength at the same time. The results show that in the design process, water cement ratio should be less than 0.33, and cement sand ratio should be not less than 0.65.Prestressed concrete is the main structural material of highway T beam. Now rebound method and ultrasonic rebound combined method are the most common and nondestructive testing methods for highway T beam intensity detection.But due to the different concrete raw materials, technology, geography and climate conditions from different places, the low accuracy of unified strength-measurement curve recommended by technical specification, poor local applicability,This experiment concentrates on the strength-measuring curve fitting specially for highway. By using raw material of highway, I independently completed experiments on the basis of 355 concrete specimens of resilience, ultrasound, compressive strength. Through the analysis of the effective data, this paper uses the least squares method and genetic algorithm to fit the rebound, ultrasonic rebound strength curve. The data error of the fitting rebound strength curve and ultrasonic rebound curve could meet the standard for special strength-measuring curve. And its presumed value is superior to the unified strength-measuring curve. The fitting strength-measuring curve improved the accuracy as ultrasonic rebound detected the concrete strength, which can be applicable to highway. Considering the genetic algorithm also has a high precision, as a result, it can be also applied to the curve fitting.