• Title/Summary/Keyword: concrete durability.

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Improvement of Durability and Change of Pore Structure for Concrete Surface by the Penetrative Surface Protection Agent (함침계 표면보호제에 의한 콘크리트 표면의 세공구조 변화 및 내구성 향상)

  • Kang, Suk-Pyo;Kim, Jung-Hwan
    • Journal of the Korea Concrete Institute
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    • v.18 no.1 s.91
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    • pp.125-132
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    • 2006
  • Recently, surface finishing and protection materials were developed to restore performance of the deteriorated concrete and inhibiting corrosion of the reinforcing-bar. For this purpose, surface protection agent as well as coatings are used. Coatings have the advantage of low Permeability of $CO_2,\;SO_2$ and water. However, for coatings such as epoxy, urethane and acryl, long-term adhesive strength is reduced and the formed membrane of those is blistered by various causes. Also when organic coatings are applied to the wet surface of concrete, those have a problem with adhesion. On the other hand, surface protection agent penetrates into pore structure in concrete through capillary and cm make a dense micro structure in concrete as a result of filling effect. Furthermore, the chemical reaction between silicate from surface protection agent and cement hydrates can also make a additional hydration product which is ideally compatible with concrete body. The aim of this study is to examine the effect of penetrative surface protection agent(SPA) by evaluating several concrete durability characteristics. The results show that the concrete penetrated surface protection agent exhibited higher durability characteristics for instance, carbonation velocity coefficient, resistance to chemical attack and chloride ion penetration than the plain concrete. These results due to formation of a discontinuous macro-pore system which inhibits deterioration factors of concrete by changed the pore structure(porosity and pore size distributions) of the concrete penetrated surface protection agent.

Mechanical and durability properties of self-compacting concrete with blended binders

  • Xie, T.Y.;Elchalakani, M.;Mohamed Ali, M.S.;Dong, M.H.;Karrech, A.;Li, G.
    • Computers and Concrete
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    • v.22 no.4
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    • pp.407-417
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    • 2018
  • Over the past three decades, self-compacting concrete (SCC), which is characterized by its superior rheological properties, has been gradually used in construction industry. It is now recognized that the application of SCC using supplementary cementitious materials (SCM) is highly attractive and promising technology reducing the environmental impact of the construction industry and reducing the higher materials costs. This paper presents an experimental study that investigated the mechanical and durability properties of SCCs manufactured with blended binders including fly ash, slag, and micro-silica. A total of 8 batches of SCCs were manufactured. As series of tests were conducted to establish the rheological properties, compressive strength, and durability properties including the water absorption, water permeability, rapid chloride permeability and initial surface absorption of the SCCs. The influences of the SCC strength grade, blended types and content on the properties of the SCCs are investigated. Unified reactive indices are proposed based on the mix proportion and the chemical composition of the corresponding binders are used to assess the compressive strength and strength development of the SCCs. The results also indicate the differences in the underlying mechanisms to drive the durability properties of the SCC at the different strength grades.

A Study on the Concrete Durability by Fly Ash Replacement Ratio (플라이애쉬 치환율을 고려한 콘크리트의 내구성에 관한 연구)

  • Kim, Dongbaek;Lee, Kwangjae
    • Journal of the Society of Disaster Information
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    • v.10 no.4
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    • pp.566-571
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    • 2014
  • Recently, with concentrated social and engineering interests on durability, diversified subsequent researches have been progressed. The Chloride-induced corrosion, carbonation, freeze-thaw etc, deterioration factors of concrete act to concrete not privately but complexly, Fly ash is most frequently used admixture which is using a reduction method of deterioration. And the fly ash effects on improvement of durability with enhancement of fluidity, decrease of crack with reduction of hydration heat, promotion of long-age strength and have a economic advantage which replaces cement as a binding material. But, fly ash have different qualities and occasionally reduce the durability and strength by adhesion of AE admixture with unburned carbon powder etc. In this study, the experiments will take about various replacement ratio of fly ash concrete, and will analyze, consider the results, after these will verify applicability and validity as admixture and binding material.