凍結融解를 받은 斷面修復 콘크리트의 鹽化物 浸透 特性에 관한 硏究

Abstract

Recently, reduction of service life is reported caused by effect of the various deterioration factors. Mostly the deterioration of the concrete structure does the chloride effect. These factors penetrated from the concrete surface and diffused into internal of concrete. Specially, concrete is porous material, these porosity of concrete inside exert negative impact in durability as acts deterioration factor's transfer path. In the meantime, in the case of concrete construction, it is trend that using of repairing materials to repair concrete that was deteriorated. It is used polymer type that polymer in mortar, epoxy type that contain epoxy resin and grouting type by section restoration material. Each section restoration material is having high durability than normal concrete. Therefore, because resistivity for deterioration is changing by construction section restoration material, it is very important that research deterioration resistivity by the finish and repairing. But researches about freezing thawing and chloride ion penetration resistivity of repair materials are very fewer than normal concrete. In this study, calculated chloride diffusion coefficient into concrete and section restoration materials by rapid chloride penetration test after a freezing and thawing experiment. Using this, could get following conclusion as result that reproduce chloride ion diffusion by finite element analysis. the conclusions follow :

(1) In a freezing and thawing experiment, dynamic modulus of elasticity reduced by freezing and thawing cycle increases. Specially, displayed sudden reduction of dynamic modulus of elasticity in between 0 cycles and 100 cycles, and section of the next looked stabilized tendency.

(2) In case of specimen that construct section restoration materials to concrete than only section restoration material specimen, freezing and thawing resistivity observed high. This is considered by supplement section restoration material of dense structure as that concrete comparative big porosity eases freezing and thawing action.

(3) In case of specimens those do not receive freezing and thawing action, when compared with concrete specimen, normal-strength Polymer-Type, high-strength Polymer-Type, Grouting-Type's section restoration material is constructed specimens those are 64%, 26%, 6.7% in calculating chloride ion diffusion coefficient. Could know that each section restoration material is valid in chloride ion permeation resistance.

(4) All specimens can be observed that chloride ion diffusion coefficient grows by increasing of freezing and thawing. In case of concrete and normal strength Polymer-Type specimens, chloride ion diffusion coefficient are bigger than other specimens, and showing amount of increase is big according to increasing of freezing and thawing cycle. Section restoration materials of high-strength Polymer-Type and Grouting-Type observed that increase of diffusion coefficient by dense structure is slight.

(5) In estimate result of chloride service life by freezing and thawing, concrete case could know that service life decreases changelessly according as freezing and thawing cycle increases. Normal strength Polymer-Type section restoration material observed that service life is fallen sharply after 200 cycles while show slow reduction until 200 cycles, and high strength Polymer-Type section restoration material shows sudden decline until 100 cycles and displayed slow reduction ever since. Also, Grouting-Type's section restoration material observed that chloride service life decreases most sharply than another specimens.

(6) Expectation service life estimated concrete case is 12 years, 20 years in case Polymer-Type section restoration material (RA) is constructed, 70 years in case high-strength Polymer-Type section restoration material (RB) is constructed, when Grouting-Type's section restoration material is constructed, it predicted by more than 200 years. Thus Could prove by estimate service life that it uses FEM analysis that restrain transfusion of chloride ion by constructing section restoration material.

This research carried out prediction service life using chloride ion diffusion coefficient of concrete and section restoration material that is measured according to freezing and thawing within limited extent. Hereafter, with many room experiments and research under environment similar to actuality environment, specially it need to be considered that there is necessity to investigate direct cause about fluctuation of chloride ion diffusion coefficient by freezing and thawing through micro-analysis.