Abstract:
PURPOSE: A hydration heat dissipation concrete composition using carbon nanotubes(CNT) is provided to reduce temperature cracks by increasing the tensile strength of concrete. CONSTITUTION: A hydration heat dissipation concrete composition includes a binding material, fine aggregates, coarse aggregates, and mixing water. The mixing water is consisting of 80-97 parts by water of general water and 3-20 parts by weight of CNT dispersed liquid. The CNT dispersed liquid consists of 96-98 parts by weight of a solvent and 2-4 parts by weight of CNT powder. The amount of CNT is 0.12-0.4 parts by weight based on 100 parts by weight of the mixing water. Magnesium oxide is coated on the surface of the CNT. 0.25-0.5 parts by weight of carbon fiber of 6-12mm length is added based on 100 parts by weight of the binding material.
Abstract:
PURPOSE: A variable hopper system is provided to increase the shipment amount of concrete by controlling the size of an outlet while the lower part of a concrete hopper slidingly moves according to the liquidity of the concrete. CONSTITUTION: A variable hopper system comprises an arrangement frame, a concrete hopper, hopper fixing frames(600), holding parts(200), horizontal rails(300), a driving cylinder(400), a control part, and a camera. The arrangement frame comprises multiple posts, girders, and beams. The concrete hopper comprises an upper hopper(110) and a lower hopper(120). The hopper fixing frames are installed in the upper part of the arrangement frame and are coupled to the upper hopper. The holding parts are coupled to both sides of the bottom of the lower hopper. Rollers(210) are arranged on the bottom of the holding parts. The horizontal rails are arranged on the beams of the arrangement frame. The rollers move on the horizontal rails. The driving cylinder is installed on the arrangement frame. The camera is installed to monitor vehicles entering a gap between the posts of the arrangement frame.
Abstract:
The present invention relates to a composition of in-site high early strength concrete expressing mold form removal strength without a change in the properties of cement, wherein a water-cement rate (W/C) is 25 to 40 parts by weight. The composition comprises: 130 to 220 parts by weight of fine aggregate based on the cement; 140 to 240 parts by weight of coarse aggregate based on the cement; 0.1 to 15 parts by weight of fly ash based on the cement; 0.1 to 15 parts by weight of blast furnace slag powder based on the cement; and a hardening promoting agent which is at least one of 1 to 5 parts by weight of powder-type hardening promoting agent based on the cement and 0.5 to 5 parts by weight of liquid-type hardening promoting agent based on the cement. The composition further comprises the hardening promoting agent of a normal amount. Accordingly, 14 MPa or more is satisfied for 12 hours which is a mold form removal standard so that the mold form removal standard is standardized so as to contribute to the civil engineering and construction industry.