抄録
This report made a test study by aiming to get basic data concerning the choice and mixing proportions for aggregate of ultra high-strength concrete (about 90-130 MPa). The results are shown as follows, Compressive strength (of ultra high-strength concrete) is influenced by compressive strength of rock and volume of 400 kN crushing values for coarse aggregate when fixing strength of mortar to low water-to-cementitious ratio. When 400 kN crushing value of aggregate is 11-23 % and water-to-cementitious ratio is less than 0.25, this strength is concluded for material and mixing proportions of ultra high-strength concrete. Compressive strength of concrete increase with decrease in maximum size of coarse aggregate, but optimum maximum size varies in kinds of coarse aggregate. The slopes of the curves in the region subsequent to maximum stress increase with decrease in compressive strength of rock and increase in grading of coarse aggregate and we can see sudden brittle stress fracture developed in concrete. In order to get compressive strength of ultra high-strength concrete, it is effective to raise compressive strength of rock and crushing strength and grading (maximum size) of coarse aggregate and bonding between coarse aggregate and mortar and at the same time to bring strength and deformation of aggregate close to strength of aggregate and deformation of matrix mortar or increase it.
