Reusability and in-situ strength measurement of CLSM

Effective recycling technology for by-product materials is one of the main issues in this new millennium. Recently, the recycling technology was successively applied to CLSM (Controlled Low-Strength Materials) constructions. CLSM is defined by ACI Cement and Concrete Technology (ACI 116R) as "material the result in a compressive strength of 8.3MPa (1200psi) or less at the age of 28 days". The purpose of this research is to evaluate the physical properties of re-used CLSM and propose the simple method for in-situ strength measurement. As for the re-usability evaluation, physical properties of CLSM with excavated CLSM being re-used as an aggregate were examined. Test result showed that the compressive strength and the bleeding rate of re-used CLSM were able to be controlled by the f/a (filler aggregate ratio) and cement content. Up to second recycling of excavated CLSM was found to be possible and very effective for sustainable development. In-situ strength measurement was proposed in this study with applying very simple test method. Yamanaka cone penetration method, which is already used for soil engineering, was applied for estimating the in-situ strength of CLSM. Test result should a good relationship between in-situ compressive strength and the penetration depth.