Journal of Asian Concrete Federation Vol. 3, No. 2, pp. 105-114, December 2017 ISSN 2465-7964 / eISSN 2465-7972 https://doi.org/10.18702/acf.2017.12.3.2.105 Technical Paper Effects of different fine aggregates on the properties of ultra-high strength concrete Taku Matsuda* and Takafumi Noguchi (Received: July 27, 2017; Accepted: November 29, 2017; Published online: January 5, 2018) Abstract: When a coarse pore-structured fine aggregate with a large water absorption was used for concr- ete with a water-binder ratio of 0.12, unit water content of 135 kg/m 3 , and sand-aggregate ratio of 55%, the mobility, strength, and elastic modulus of concrete increased, with the autogenous shrinkage becoming extr- emely low. The authors attributed the reason for this phenomenon to the internal curing effect of fine aggre- gate based on tests using mortar samples and the properties of fine aggregate. The authors also considered that one reason for the increased strength of concrete is the reduction in the autogenous shrinkage of the mo- rtar phase, which reduces the risk of failure under local stress, based on the stress-strain relationship of con- crete and mortar under compressive deformation. Keywords: ultra-high-strength concrete, fine aggregate, internal curing, pore structure. 1. Introduction In their earlier study [1,2], the authors investi- gated the effect of using silica fume and fly ash in combination as supplementary cementitious materi- als (SCMs) for ultrahigh strength concrete with a water-binder ratio (W/B) of 0.20 or less. As a result, concrete made using both SCMs, silica fume and fly ash, led to a lower viscosity than with silica fume alone. Therefore, sufficient mobility was achieved even by reducing the unit water content (W) from 150 kg/m 3 to 135 kg/m 3 and increasing the sand-aggregate ratio (s/a) from 27% to 55%. The strength and elastic modulus thus increased and the autogenous shrinkage significantly decreased. (Figure 1 shows part of the results of the study [2]). However, these are results of tests conducted using specific materials (low-heat portland cement, silica fume, fly ash, ferronickel slag fine aggregate, and crushed hard sandstone). The purpose of the present study is to examine the applicability of the above- mentioned results to ultrahigh strength concrete made using different materials, while considering the reason why different materials lead to different properties of concrete (mobility, mechanical proper- ties, and autogenous shrinkage), thereby acquiring knowledge that contributes to the development of proportioning techniques. Fig. 1 – Part of the results of the early study [2] Table 1 gives the materials used in the present tests, which were conducted in two series. The binders are premixed cement (SFPC) made by re- placing a part of low-heat-type cement with silica fume, and fly ash (FA) conforming to Type I speci- fied in JIS A 6201; the fine aggregates are andesite (S1), hard sandstone (S2), and two types of ferro- nickel slags (S3 and S4); the coarse aggregates are andesite (G1) and two types of hard sandstone (G2 and G3). G2 and G3 from different sources are Corresponding author Taku Matsuda is the Chief of the Construction Material Group of the Technical Re- search Institute Technical & Engineering Service Divi- sion, Sumitomo Mitsui Construction Co., Ltd, Japan. Takafumi Noguchi is a Prof. of the Dept. of Architec- ture, Graduate School of Eng., The University of Tokyo, Japan. t :50cm flow time [s] E :elastic modulus (90℃)[kN/mm 2 ] σ：compressive strength (90℃)[N/mm 2 ] -500 -400 -300 -200 -100 0 100 0 4 8 12 16 20 24 28 Autogeneous shrinkage[×10 -6 ] Age[days] Black：W=150kg/m 3 Red ：W=135kg/m 3 11.8s 14.2s 8.4s t= 13.8s σ=247 σ=241 σ=236 σ=236 Broken line：s/a27% Solid line ：s/a% E=53.0 E=54.5 E=56.8 E=58.7 105