Consulting

In concrete structures, deformation sometimes occurs due to other causes than external force, such as heat of hydration in cement, changes in temperature, and drying shrinkage. When such deformation is constrained, it can result in formation of cracks. Therefore, it is effective to make sectional-area voids at predetermined intervals and to provide crack-inducing joint to artificially generate cracks, so that formation of cracks can be concentrated within the predetermined area. Upon provision of crack-inducing joint, sufficient considerations are required to determine factors such as interval of crack-inducing joints, void rate, methods to prevent corrosion of rebars around joints, ways to retain necessary covering, and selection of filling material for joints. In general, interval of crack-inducing joints should be within 100 to 200% of the height of the concrete structure, and its void rate should be 20% or more. A usage example of a crack-inducing joint is introduced below.