ローモンタイトの変質によるコンクリート劣化に関する研究

Abstract

Laumontite is a harmful mineral for concrete. Standard specifications for concrete structures described that laumontite and its dehydration material leonhardite would need care because there was volume change between laumontite and leonhardite due to drying and wetting. This action causes cracks in the concrete. However, no standards or conditions have been set for the use of laumontite -bearing aggregates. The purpose of this study is to considervt the effect on concrete and the formulation of deterioration countermeasures when using laumontite-bearing aggregates. First, qualitative and quantitative analysis using X-ray diffraction was performed on aggregates in New Caledonia and Japan. Next, cement paste containing single crystal of laumontite and mortar containing laumontite-bearing aggregates was prepared for deterioration reproduction and exposed in an environment where wetting and drying were repeated. Then, Density-enhanced mortar containing cement admixture was produced to prevent deterioration and exposed in a repeated dry and wet environment. From these results, deterioration was confirmed in the cement paste containing the single crystal of laumontite. On the one hand, no deterioration was confirmed in the mortar containing laumontite-bearing aggregates at the age of 196 days. Then, it was confirmed that the mortar containing the admixture tended to have higher strength than the mortar not containing the admixture.