Most of dehydrated cake which was generated by turbid water treatment of the process for making crushed stone and crushed sand is subjected to landfill disposal. The effective use of dehydrated cake discharged from crushed stone quarry is required to relieve the tightness of the residual capacities of disposal sites and to secure limited natural resources. In this study, a dehydrated cake discharged from crushed stone quarry with excellent caking properties was examined to see if it can be used for soil materials, such as impermeable materials. In addition, physical and mechanical tests were conducted on the dehydrated cake, and then its properties were compared with those of commonly used cohesive soils. It was found that the dehydrated cake had significantly different properties from those of general cohesive soils, and it also did not match the mechanical properties of general compacted soils. Thus, it was concluded that the dehydrated cake cannot be handled based on the commonly used soil standards. In addition, it was found that reducing the water content and adjusting the particle size are effective in increasing the strength of dehydrated cake and that reducing the water content is particularly effective.
The objectives of this study are to evaluate the effects of freeze-thaw action on the abrasion resistance of a cementitious surface coating material. We prepared both air entrained (AE) and non-air entrained (nAE) Ordinary Portland Cement mortar beams with water-cement ratios of 40, 50 and 60%. After freezing and thawing tests were conducted on these specimens, they were subjected to the water jet abrasion test to investigate the effects of freeze-thaw action on their abrasion resistance. In the AE specimens after the freeze-thaw tests, the relative dynamic moduli of elasticity were over 90%, and the progress of degradation due to freeze-thaw was small. In the nAE specimens after the freeze-thaw tests, the relative dynamic moduli of elasticity were less than 40% at the maximum at the placement surface, 70-80% at the bottom surface, and 80-90% at the specimen center. Deterioration due to freeze-thaw progressed on the both surface layer. In addition, there was a difference in the progress of deterioration depending on the part of the specimen. The average wear depth of the mortar specimens after water jet abration test becomes smaller as the W/C is smaller and the surface quality is more dense in the initial state before being subjected to freeze-thaw action. The average wear depth of the mortar specimens after the freeze-thaw test increases as the relative elastic moduli of the specimens around surface layer decreases due to the freeze-thaw action. In this test, the abrasion resistance of the mortar containing after the freeze-thaw test was significantly improved by the addition of AE admixtures. This result suggests that the use and management of appropriate AE admixtures are important for securing frost damage resistance of mortar materials in frost damage environment.
Joint filling using single-component sealants is commonly employed in the repair of joints in irrigation channels, owing to its ease of use and economic efficiency. However, sometimes a single-component sealant becomes deformed soon after it is applied due to swelling, rupture, or leakage under the impact of back water pressure. This study focused on sealants for irrigation channels, and hardening confirmation tests and water pressure resistance tests were conducted, with evaluated the impact of deformation on the waterproofing of early-age sealants. The results show that at a low temperature of 0 ℃, each sealants manifested strength about 1 to 2 weeks later than at a temperature of 23 ℃. Additionally, when the acting water pressure exceeded 0.02MPa, balloon-shaped swelling and rupture of the single-component and two-component sealants occurred, reducing waterproofing. The results also revealed that the fast-hardening, three-component sealant is highly resistant to deformation caused by water pressure.