The Study Of The Influence Of High Temperature For The Properties Of Lining Concrete

This thesis topic researches the hazard controlling and pivotal building techniques of extra long tunnel which buried under the high geothermal area. According to the national test specification and operation specification, simulates concrete maintaining in high geothermal environment. The main purpose of this paper is to investigate4aspects which influenced by high geothermal environment, they includes the selection of raw materials of lining concrete, the selection of configuration parameters and mix design of lining concrete, the basic mechanical properties and the durability of lining concrete.(1)This paper analyzes the influence of raw materials of concrete and the requirements of raw materials under high temperature environment. It also selects the raw materials of lining concrete under high temperature environment, designs the mix design according to the code requirement, and considers the performance of the concrete which mixed for the test.(2)It detailed studies the basic mechanical properties of the lining concrete with this mix design, including the compressive strength, splitting tensile strength and elastic modulus. Analysis the influence of the concrete’s mechanical properties under high temperature maintenance condition. Investigation the influence effects of mechanical properties by mixing fly ash and slag powders to the concrete. The experiment proved that high temperature maintenance condition can improve the compressive strength of concrete, but it makes a lower strength than normal temperature curing of the later stage. It can reduce this influence by mixing fly ash and slag powders, especially the fly ash will be a good compensation to the concrete’s later stage strength. The concrete’s splitting tensile strength and elastic modulus under high temperature maintenance have a similar influence to the compressive strength of concrete under high temperature maintenance, but there isn’t any compensation effects be found after mixing fly ash and slag powders, instead, some still can produce negative effects.(3)Researching concrete durability with JJF (mixed with water reducer and20%fly ash). Through experiment investigates the concrete’s resistant ability of sulfate erosion and carbonation under high temperature maintenance condition and normal temperature maintenance condition. The test data show that the concrete which under high temperature maintenance has more resistant sulfate erosion ability than those under normal temperature maintenance (30times,60times cycle); High temperature maintenance accelerates the concrete carbonation, it has an adverse effect to resistant carbonization ability.(4)Through the study of mechanism, analysis the effects reasons with mechanical properties and durability of lining concrete which has admixtures and high temperature maintenance.