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State-Of-The-Art Report on HSC and HSS in Japan ― Minehiro Nishiyama1

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State-Of-The-Art Report on HSC and HSS in Japan ― Minehiro Nishiyama1 Journal of Advanced Concrete Technology Vol. 7, No. 2, 157-182, June 2009 / Copyright © 2009 Japan Concrete Institute 157 Invited paper Mechanical Properties of Concrete and Reinforcement ― State-of-the-art Report on HSC and HSS in Japan ― Minehiro Nishiyama1 Received 25 May 2009, revised 12 June 2009 Abstract Sub-working group 1 of the Japan Concrete Institute (JCI) committee on Utilization of High-Strength Concrete (HSC) and High-Performance Concrete (HPC) (JCI-TC063A) has been working on collecting information from research on HSC and HPC as well as their practical use. The committee published a report in 2006 in Japanese. The objective of the report is to present state-of-the-art information on concrete with strengths in excess of about 60 MPa and high-strength steel reinforcement such as prestressing steel, excluding concrete made with atypical materials, such as fibers, or un- common techniques. It primarily addresses the mechanical properties of high-strength concrete and high-strength steel reinforcement. A concise digest of the report has already been published as a keynote paper in the proceedings of 8th International Symposium on Utilization of HSC and HPC in October 2008 in Tokyo. This paper is based on the keynote paper with additional information on High Strength Steel, HSS, reinforcing bars in Japan. 1. Introduction joints, structural walls, piles and structures constructed of HSC, including structural performance evaluation and Sub-working group 1 of the Japan Concrete Institute design of those structures. (JCI) committee on Utilization of HSC and HPC The committee published the 560-page state-of-art (JCI-TC063A) has collected and published report on HSC/HPC in 2006 in Japanese. The state-of-the-art information on concrete and steel rein- sub-working group of the committee is planning to pub- forcement with strengths in excess of 60 MPa and 500 lish an English version within a few years. This paper is a MPa, respectively. The report excludes concrete made concise digest of the report. with atypical materials, such as fibers, or uncommon This paper starts with mechanical properties of con- techniques. crete and reinforcement in the next chapter. The chapter In this report concrete strength in excess of 60 MPa in addresses compressive strength, fatigue strength, the field of building engineering and 80 MPa in the field modulus of elasticity, stress-strain behavior, shrinkage, of civil engineering is defined as high-strength concrete. creep, and fire resistance of concrete, which is followed Concrete up to 60 MPa and 80 MPa in design compres- by a chapter of classification, grades and use of rein- sive strength has been already incorporated in the codes forcing steel in Japan. Mechanical properties and fire of the Architectural Institute of Japan (AIJ) and the Japan resistance of reinforcing steel are also included in the Society of Civil Engineers (JSCE), respectively. chapter. In Chapter 4, structural performance of members In the building engineering field, super high-rise and frames is addressed in terms of uniaxial behavior of buildings, longer span beams, and reduction of member confined high-strength concrete, flexural and shear be- sections primarily induce the use of HSC. In the field of havior of beams and columns constructed of civil engineering longer span girders, reduction of girder high-strength materials. Beam-column joints and struc- sections and weight especially in bridges and tanks, as tural walls are also stated. As an application of well as construction of highly durable structures, are high-strength materials, design of super-high-rise build- motivations for the use of HSC. ings is addressed in the last chapter. The mission of the sub-working group 1 is to compile significant information on HSC not only as a material, 2. Mechanical properties of concrete but also its practical use for structures. The aims of the group are; This chapter summarizes HSC, reinforcement and bond 1) to collect information on state-of-the research and between concrete and reinforcement based on a literature practical use of HSC and, survey of past research. 2) to compile information on structural performance of In the first section compressive strength of HSC is members such as beams, girders, columns, beam-column described considering relations with water-binder ratio, admixtures, coarse aggregate, and age. There is a ceiling on compressive strength which can be reached with a 1 reduction of the water-binder ratio. The ceiling is con- Professor, Dept. of Architecture and Architectural sidered to be approximately 120 N/mm2. To obtain Engineering, Kyoto University, Kyoto, Japan. higher strength, enhancement of cementitious material E-mail:[email protected] 158 M. Nishiyama / Journal of Advanced Concrete Technology Vol. 7, No. 2, 157-182, 2009 and aggregate properties and curing conditions are essential. The above sections are followed by relationships be- ) tween compressive strength and splitting-tensile and 2 flexural strengths. Fatigue and elastic properties are m m discussed in relation to the stress-strain response. / N Shrinkage, creep, durability and fire resistance properties ( h are also summarized. Autogenous shrinkage and explo- t g sive spalling-off of cover concrete are important issues n e r that should be discussed for application of HSC to t s structural members. e v Summarized in the subsequent sections are classifica- i s tion, grades and use of high-strength reinforcement in s e 1 week r Japan. Mechanical properties, including those at elevated p 4 weeks temperatures, and connections for high-strength rein- m 13 weeks o forcing bars are presented. C Relationships between bond strength and concrete Binder-water ratio compressive strength as well as between bond stress and slip are described based on a literature survey. Experi- mental results and design equations for bond splitting Water-binder ratio (%) failure and lap splice strength are also summarized. Fig. 1 Relationship between water-binder ratio and com- pressive strength (Tomosawa et al. 1994). 2.1 Compressive strength 2.1.1 Relationship between water-cement ratio and compressive strength In the range of water-binder ratio larger than 25%, com- 140 Standard curing, W/C=0.45 ) pressive strength of concrete increases in proportion to 2 120 binder-water ratio. However, as shown in Fig. 1, in the m m range of water-binder ratio less than 25%, compressive / 100 High-belite cement (fine powder type) N strength peaks at about 120 N/mm2 (Tomosawa et al. ( High-belite cement (low heat type) h Ordinary portland cement t 80 1994). Moreover, even if their water-cement ratios are g n the same, compressive strength of concrete with large e 91-day r t 60 unit water content is smaller than that of concrete with s small water content. In Fig. 1, concrete was made from e v 28-day i 40 N: ordinary portland cement, SF: cement with silica s s e fume, and BS: cement with blast-furnace slag. r 20 7-day p m 2.1.2 Relationship between cement type and o 0 3-day compressive strength C 20 30 40 50 60 70 For concrete with water-cement ratio larger than 30%, C2S content (%) the strength-gain rate is different depending on the ce- ment type. However, with the decrease of water-cement 140 ) Standard curing, W/C=0.25 ratio to about 25%, the difference becomes smaller (To- 2 120 mosawa 1994). The relationship between the content of m 91-day m belite (C2S) and the compressive strength are shown in / N 100 Fig. 2. The results indicate that the compressive strength ( 28-day h at early ages (within 28-day) decreases as C S content t 2 g 80 increases. However, at an age of 91-days, the compres- n 7-day e r sive strength increases with a positive increment of C S t 60 2 s content (Uchida 1997). e 3-day v i 40 s s 2.1.3 Relationship between admixture type and e r compressive strength p 20 m Shown in Fig. 3 is the relationship between compressive o 0 strength and silica fume replacement ratio with regard to C 20 30 40 50 60 70 curing conditions (Nagataki 1988). It is revealed that C2S content (%) compressive strength peaks at a different ratio depending on the curing conditions. Fig. 2 Relationship between C2S content and compres- Shown in Fig. 4 is the case of fly ash, in which the sive strength at 3, 7, 28 and 91 days (Uchida 1997). M. Nishiyama / Journal of Advanced Concrete Technology Vol. 7, No. 2, 157-182, 2009 159 compressive strength obtained varies depending on the 2.1.6 Modulus of elasticity curing condition (Nagataki et al. 1988). In case of steam A formula that is able to estimate modulus of elasticity or 28-day water curing, compressive strength decreases applicable for both normal and high-strength concrete is as the replacement ratio increases. In autoclave curing, shown in Eq.3 (Noguchi and Tomosawa 1995b). the maximum compressive strength is obtained at the 2 1/3 replacement ratio of 40%. 4 ⎛ γ ⎞ ⎛ σ b ⎞ E = 3.35 ×10 ⋅ k1k2 ⎜ ⎟ ⎜ ⎟ (3) ⎝ 2.4 ⎠ ⎝ 60 ⎠ 2.1.4 Relationship between splitting tensile strength and compressive strength where, E: modulus of elasticity (N/mm2), γ: mass per unit 3 Relationship between splitting tensile strength and volume (t/m ), k1: coarse aggregate coefficient, 0.95: compressive strength is approximated by Eq.1 (Noguchi quartz schist crushed stone, crushed andesite stone, and Tomosawa 1995a). crushed cobblestone, crushed basalt stone, and crushed clay slate stone, 1.2: crushed limestone and calcination 0.637 σ t = 0.291σ b (1) bauxite, 1.0: other coarse aggregate, k2: admixture coeffi- 2 cient, 0.95: silica fume, blast-furnace slag powder, and micro where, σ t : splitting tensile strength (N/mm ), σ b : 2 powder made from fly ash, 1.1: fly ash, 1.0: no admixture.
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