IMPROVEMENT OF FORCE-FEEDING PROPERTIES OF LIGHTWEIGHT AGGREGATE CONCRETE BY PUMP

摘要

PROBLEM TO BE SOLVED: To obtain a concrete good in force-feeding properties by a pump, and resistance to freezing and thawing by using a lightweight aggregate having specified bone dry specific gravity and water absorption, and formulating a biogum-based thickening agent therewith. ;SOLUTION: A lightweight aggregate having 0.8-1.5 bone dry specific gravity and ≤8% water absorption, and further having the surface subjected to a coating treatment with one or more kinds of iron compound of iron hydroxide, iron oxide and iron oxyhydroxide is used as the lightweight aggregate (e.g. expanded shale). The treatment is carried out by adding caustic soda to an aqueous solution of ferric chloride to provide a colloid solution or suspension of iron hydroxide, bringing the resultant liquid into contact with the lightweight aggregate, and simultaneously introducing air thereto to oxidize the iron hydroxide and to crystallize the iron oxyhydroxide, and also bringing the aggregate into contact with the obtained liquid. A high- performance AE water-reducing agent can be formulated therewith besides the biogum- based thickening agent (e.g. 0.01-0.10% welan gum based on water). The bulk density of the concrete in a hardened state is 1.6-1.9 t/m3, and 28-day compression strength is 40-60 N/mm2.;COPYRIGHT: (C)2000,JPO