Study On The Design And Construction Technology Of Volcanic Ash Cement Concrete Pavement

Volcanic ash material Distributes in many provinces and regions northeast and northwest of our country. Because of excellent exclusion of temperature performance, high chemical activity, convenient exploitation, low-cost, wide distribution and abundant storage, volcanic ash has a huge potential as road construction material. Traditional road construction materials are deficient where volcanic ash distributes, which restricts the local road construction and economic development to a certain degree. Therefore, according to local conditions and materials, using mountain rich volcanic ash to construct roads, not only can save cost, increase total length of road with limited funds, but also improve the quality of pavement.According to the physical, chemical character and particle composition, combined with road construction material technique index requirements, feasibility analysis of application of volcanic ash material is conducted. Applied researches of volcanic slag cement replace some of the concrete coarse aggregate and size reduction volcanic ash as concrete admixture to improve the performance of cement concrete are carried out. There six chapters in this paper. The preface of the first chapter illustrates distribution of volcanic ash in the world and different physical and chemical characters test. Reference to indoor test results, application possibility analysis of the material to road, applied scope of volcanic ash to road projects.The second chapter mainly introduces that as the additive, fine volcanic ash can not only improve hydration degree of cement, but also react with Ca(OH)2 ,which is called secondary hydration reaction. And the secondary hydration products can fill the harmful pores in hardened cement paste and improve the interface performance between hardened cement paste and the aggregate, which will have a positive iMPact on cement paste and concrete microstructure. Consequently, it will have a beneficial effect on macroscopic mechanical properties, especially the durability. The volcanic slag crushing value and Los Angeles abrasion loss and other physical indicators are tested to further testify feasibility of application of volcanic slag. Mixing tests of volcanic slag and crushed stone are carried out to obtain composite gradation.The third chapter introduces different volcanic slag substitution ratio of coarse aggregate cement concrete. The proper ratio is determined based on the performance of cement concrete and economic factor. Test results show: the best ratio of volcanic slag to replace coarse aggregate is 80 percent. 28-day flexural tensile strength of volcanic slag concrete and cement concrete is approximate and both meet regulatory requirements. Because the volcanic slag material used as coarse aggregate of cement concrete can satisfy regulatory requirements and reduce the cost, which proved the practical value of the design. At different ratio of size reduction volcanic ash in concrete, the workability, mechanical property and durability are studied. Results show that properties of concrete are best at ratio of 15%. According to mix proportion design and test results, design index of volcanic ash cement concrete are proposed.The fourth chapter mainly describes the program, key construction control and test detection of testing road. And the test results prove the correctness of study results. Volcanic ash construction process has differences coMPared with ordinary cement pavement because volcanic ash has the characteristics of light weight, large absorption and so on; therefore, it is rapid to coagulate. And the galling time have been an appropriate time ahead. Through the observation, the application effect is checked for volcanic ash in cement concrete pavement. The paper makes an emphasis analysis on key technology of properties of lower sensitivity to temperature and smaller shrinkage coefficient to temperature which can effectively reduce shrinkage cracking. and summarizes the construction technology, which provides reliable technical support for success application and generalization of volcanic ash in cement concrete pavement in cold area. In the fifth chapter, benefits of volcanic ash material used in pavement engineering are analyzed combined with engineering entity quality and research achievement extension. Meanwhile, application of volcanic material can reduce the waste soil of the road construction, which protects the environment. The increase in mileage of highway construction can improve the quality of transport and the level of regional economic development and social benefits.Chapter six summarizes the results of this article and proposes recommendations of next step study.