Research On Frost Resistance And Acoustic Characteristics Of Basalt Fiber Reinforced Reactive Powder Concrete

The northern part of China belongs to the seasonal frozen area.The freeze-thaw effect is obvious.In order to ensure the smooth traffic of the road,the ice salt is usually melted to melt the ice and snow.Under such long-term chloride corrosion and freeze-thaw cycles,the corrosion and cracking of the concrete structure will occur,and the bearing capacity will decrease.This will seriously shorten the service life of the concrete structure.Reactive Powder Concrete(RPC),as a new type of cement based composite material with super high strength and high durability,is especially suitable for the design and protection of road and bridge structures in complex natural environment.Reactive powder concrete is usually blended with steel fibers to enhance its tensile,bending and shear capacity.As a metal fiber,steel fiber is easily corroded in acid base solution or even in air,and is unable to face complex natural environment.Basalt fiber,as a typical silicate fiber,has excellent mechanical properties,corrosion resistance and environmental protection.It is of great practical significance to study the frost resistance of Basalt Fiber Reinforced Reactive Powder Concrete.In this paper,based on Jilin province development and reform commission project "cold areas-basalt fiber reactive powder and application technology of preparation of high performance concrete",combining with the characteristics of season frozen area environment,using acoustic emission techniques,damage index and cracks on the frost resistance were studied.Clarify fiber types,dosage and freeze-thaw medium effect on the properties of reactive powder concrete frost resistance and failure mechanism,for the season in cold area and extremely harsh environments provide reference for engineering application data.This paper has carried out the following research contents:(1)The initial compressive and flexural strength of powder concrete,basalt fiber active powder concrete and steel fiber active powder concrete were tested,and the enhancement effect of basalt fiber content and fiber type on the mechanical properties of reactive powder concrete was discussed.(2)types of fiber,basalt fiber,steel fiber and freeze-thaw medium as the main parameters change,the indoor lab of reactive powder concrete fast freeze-thaw test,analyzes the different fiber in a single freeze-thaw cycle and chlorine salt-under the coupled action of freezing and thawing cycle,the mass loss rate,the changing rule of the relative dynamic elastic modulus.(3)considering the chlorine salt erosion,freeze-thaw factors together under the action of antifreeze performance of materials,selection of basalt fiber content for variables,chlorine salt-freezing and thawing cycle coupling experiment was carried out,and to explore the double factors,coupling under the action of basalt fiber-the durability of reactive powder concrete modified index(mass loss rate and relative dynamic elastic modulus,etc.),evaluate the specimen antifreeze performance and frost resistance improvement mechanism analysis.(4)of reactive powder concrete flexural experiment was carried out before and after freezing and thawing,test process record for mechanical and acoustic emission collection device inside the concrete acoustic emission signal collection,clear basalt fiber reactive powder concrete and steel fiber reactive powder concrete cracks during bending fracture.With the enhanced effect of reactive powder concrete comparative analysis,and evaluate basalt fiber content.