Effect of Addition Rate of Expansive Additive on Autogenous Shrinkage and Delayed Expansion of Ultra-High Strength Mortar
In this study, the effect of expansive additives on autogenous shrinkage and delayed expansion of ultra-high strength mortar was explored. The specimens made for the study were composed of ultra-high strength mortar, which was mixed with ettringite-lime composite type expansive additive. Two series of experiments were conducted with the specimens. The experimental results confirmed that the autogenous shrinkage of specimens was effectively decreased by increasing the proportion of the expansive additive. On the other hand, for the specimens, which had 7% expansive additive, and were cured for seven days at a constant temperature of 20°C, and then cured for a long time in either in an underwater, moist (Relative humidity: 100%) or dry air (Relative humidity: 60%) environment, excessively large expansion strain occurred. Specifically, typical turtle shell-like swelling expansion cracks were confirmed in the specimens that underwent long-term curing in an underwater and moist environment. According to the result of hydration analysis, the formation of expansive substances, calcium hydroxide and alumina, ferric oxide, tri-sulfate contribute to the occurrence of delayed expansion.
 Atsushi Teramoto, Kazuhiro Hott, Takaaki Okubo, Ippi Maruyama: Study on volume changes of silica fume cement paste with low water bonder ratio using expansive additive and shrinkage reducing admixture on early age, Annual Convention of Japan Concrete Institute, Vol.37, No.1, pp.439-444, 2015.7.
 Atsushi Teramoto, Yulu Zhang, Takaaki Okubo, Ippi Maruyama: Effect of the type of expansive additive on volume change of low water bonder silica fume cement paste on early age, Annual Convention of Japan Concrete Institute, Vol.1, pp.525-530, 2016.7.
 Architecture Institute of Japan: State-of-Art report on concrete with expansive additive/shrinkage reducing admixture, 2013.
 Masahiro Suzuki, Hiroki Nakase, Ippei Maruyama, Ryoichi Sato: Effect of temperature history on self-stress of ultra-strength concrete, Papers of Cement and Concrete, No. 59, pp. 375-382, 2005.
 Hiroshi Jinnai, Shuusuke Kuroiwa, Fold Namiki, Satoru Watanabe: Basic study on length change of ultra-high strength concrete, Summaries of technical papers of annual meeting Architectural Institute of Japan, pp.393-394, 2005.
 Kuo Takahashi, Mitsuru Tanimura, Shinya Satake, Shin-ichi Shibagaki: Reduction of shrinkage of ultra-high strength concrete by expansive additive, Annual Convention of Japan Concrete Institute, Vol. 30, No. 1, pp 471-476, 2008.
 Japan Concrete Institute: Report of Crack Control Guideline Revision Committee on mass concrete, 2014.
 Shunya Fukuda, Shunsuke Habara, Hisayuki Matsuo, Shinichi Miho: DEF expansion in mortar and concrete, Annual Convention of Japan Concrete Institute, Vol.30, No.1, pp.723-728, 2008.
 Gilles Escadeillas: Some factors affecting delayed ettringite formation in heat-cured motors, Cement and Concrete Research, 37(2007) 1445-1452.
 A. Pavoine, X. Biunetaud, L. Divet: The impact of cement parameters on delayed ettringite formation, Cement and Concrete Composite, 34(2012) 521-528.
 Shuzuhiro Habara, Shinya Fukuda, Tetsuya Oyamada, Tadashi Fujiwara: Sulfate expansion phenomenon due to DEF of concrete- Effect of materials, steam curing and storage conditions -, Papers of Cement and Concrete, No.60, pp.335-341, 2006.
 Shunkoshi Shinko, Masami Sato, Kojiro Koizumi, Yasuhiro Umemura: Fundamental studies on the temperature dependence of the fly ash pozzolanic reaction, Preliminary Paper on Science and Engineering in Nihon University School of Science and Technology, pp.489-490, 2015.
 Taku Matsuda, Koichi Hasuo: Study on ultra-high strength concrete using silica fume and fly ash, Mitsui Sumitomo Construction Technology Development Center Report (1884-1090), No.12, pp.109-115, 2014.
 Ping Xie, J.J. Beaudoin: Mechanism of Sulphate Expansion Ⅰ. Thermodynamic Principle of Crystallization Pressure, Cement and Concrete Research. Vol. 22, pp.631-640, 1992. Printed in the USA.
 George W. Scherer: Stress from crystallization of salt, Cement and Concrete Research 34 (2004) 1613-1624.
 Robert J. Flatt, George W. Scherer: Thermodynamics of crystallization stresses in DEF, Cement and Concrete Research 38 (2008) 325-336.
 Piyush Chaunsali, Paramita Mondal: Physico-chemical interaction between mineral admixtures and OPC-calcium sulfoaluminate (CSA) cements and its influence on early-age expansion, Cement and Concrete Research 80 (2016) 10-20.