Abstract:
A concrete composition for pavement repairing is provided to show excellent resistance to sulfate while reducing hydration heat and permeability and to suppress an alkali aggregate reaction. A concrete composition for pavement repairing comprises: 17-19wt% of binder containing 85-90wt% of ultra-rapid hardening cement and 10-15wt% of ultra-fine fly ash; and 5-15wt% of calcium hydroxide on a basis of the ultra-fine fly ash. A ratio of water to cement is 44-48% by weight. The content of fine aggregate is 32-37wt%. The content of coarse aggregate is 36-41wt%. The maximum size of the coarse aggregate is 19mm. The concrete composition for pavement repairing additionally contains 0.3-0.5wt% of multifunctional air-entaining agent and 0.2-0.5wt% of retarding agent on a basis of the binder.
Abstract:
A repair method for a concrete slope using a finish module is provided to bond the existing concrete with the poured concrete stably by driving a finish work module upward and downward and finishing the shotcrete poured surface. A repair method for a concrete slope using a finish module comprises the methods of; installing a crushing module(100) having crushing module supporters(110) for driving a pair of rails(10a,10b) and pressurized water injection devices(120) guided to the crushing module supporters; injecting the pressurized water to a degradation part of a concrete slope(1); installing a work module(300) having worktable supporters(310) for driving the rails and worktables(320) guided to the worktable supporters; pouring shotcrete on the cleaned concrete slope; mounting a finish work module(400) having finish device supporters(410) driven along the rails and finish devices(420) guided to the finish device supporters; and finishing the shotcrete poured surface.
Abstract:
A shrinkage measurement apparatus for a concrete specimen is provided to measure shrinkage of a pure concrete and to facilitate use thereof. A shrinkage measurement apparatus for a concrete specimen(1) includes a supporting unit(10), a slant forming unit(100), a propping unit(20), a measuring instrument mounting unit(30), and a shrinkage measuring instrument(40). The supporting unit supports the concrete specimen upward. The slant forming unit is formed in the upper part of the supporting unit so that the concrete specimen is mounted at a predetermined slant. The propping unit prevents separation due to sliding of the concrete specimen, which is formed on the end of a down slant side of the concrete specimen. The measuring instrument mounting unit is formed in the opposite side of the propping unit about the concrete specimen. The shrinkage measuring instrument measures the shrinkage of the concrete specimen, which is installed in the measuring instrument mounting unit.
Abstract:
PURPOSE: Provided is a method for preparing composition of extra rapid-hardening latex modified concrete expressing fluidity fit for installation and high early-stage strength, which improves a method for charging raw materials of the concrete composition and optimizes a function of a retardant. CONSTITUTION: The composition of extra rapid-hardening latex modified concrete includes extra rapid-hardening cement, latex, aggregate, and other additives. The composition of extra rapid-hardening latex modified concrete is prepared by a process comprising the steps of: moving the aggregate in a container to a inlet of a mixer, wherein the container has an open-and-close outlet(18) on its bottom to be placed onto an inlet of a mixer; and opening an outlet of the container to charge the aggregate into a mixer. 0.3-0.9wt% of a retardant based on the cement is added to water, diluted for 30-180 minutes, and used.