습윤상태의 피복두께와 물-시멘트비를 고려한 반전위와 철근 부식량의 상관성
Relationship between Half Cell Potential and Corrosion Amount Considering Saturated Cover depth and W/C ratios in Cement Mortar
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초록
콘크리트는 다공성 건설재료이며, 매립된 철근의 부식은 내구성 및 안전성에 큰 영향을 미친다. 본 연구는 비파괴 검사인 반전위측정값과 생성된 부식량과의 상관성을 피복두께, 물-시멘트비를 고려하여 도출하는 것이다. 이를 위해, 3가지 수준의 물-시멘트비와 4가지 수준의 피복두께를 가진 시멘트 모르타르 시편이 제조되었으며, 3가지 수준의 촉진부식기간을 고려하여 부식량 및 반전위를 측정하였다. 습윤상태에서는 반전위가 크게 증가하였으며, 부식량과 촉진기간은 선형적인 관계를 가지고 있었다. 부식량이 증가할수록, 피복두께가 감소할수록, 물-시멘트비가 증가할수록 반전위는 증가하였다. 전체의 반전위 측정값을 부식량과 비교할 경우 0.67의 낮은 결정계수를 가지고 있었으나 부식량(촉진기간)을 고려하여 3가지 수준을 고려할 경우 0.90이상의 높은 결정계수를 가지고 있었다. 실내조건과 같이 온도가 일정하고 포화상태일 경우, 측정된 반전위는 부식량과 선형적인 상관성을 가지고 있었으며, 피복두께, 물-시멘트비, 철근직경, HCP의 측정범위를 알 수 있다면,매립된 철근의 부식량을 예측할 수 있다고 판단된다.
Abstract
Concrete is a construction material with porous media and corroded steel inside affects negatively to durability and structural safety. Thisstudy aims a derivation of quantitative relationship between measured HCP (Half Cell Potential) and corrosion amount considering cover depth andW/C (water to cement) ratio. For the work, cement mortar specimens with 3 different W/C ratios and 4 different cover depths are prepared, HCPsare measured with 3 different corrosion level. HCP measurement significantly increases in the saturated condition and linear relationship is observedbetween corrosion level and acceleration period. With increasing corrosion level and W/C ratio, and decreasing cover depth, HCP measurementincreases. Considering total corrosion level and HCP measurements, relatively low COV(Coefficient of Variation) of 0.67 is evaluated throughmulti-linear regression analysis, however higher COVs over 0.90 can be obtained considering level of HCP measurement. In the room condition,corrosion level can be evaluated through measured HCP in the given conditions of cover depth, W/C ratio. diameter of steel inside.
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