Issue 43

S. Jing et alii, Frattura ed Integrità Strutturale, 43 (2018) 33-42; DOI: 10.3221/IGF-ESIS.43.02 41 C ONCLUSION n this paper, the orthogonal experiment was carried out to study the compressive property and tensile property of high toughness cementitious composite, and the preliminary conclusions are as follows: 1) The failure pattern of high toughness cementitious composite is significantly different from ordinary concrete. There is no phenomenon of sudden collapse when it is damaged by compression, and all the specimens can maintain a good integrity without the phenomenon of peeling. There are a large number of fine cracks that appeared in almost the entire area of the specimen during the process of tension, showing the characteristic of significant quasi-strain hardening. Finally, it is proved that the ultimate tensile strain of high toughness cementitious composites is much larger than that of ordinary concrete. 2) No matter whether for compressive strength or ultimate tensile strain, the primary and secondary order of the influence of the four factors is: water-binder ratio, fly ash content, plasticizer content and sand-binder ratio. In terms of compressive strength, the smaller the water-binder ratio, the higher the strength; and the compressive strength increases first and then decreases with the addition of fly ash or plasticizer content. However, the effect of sand-binder ratio on the compressive strength is relatively small. For the toughness of the material, the ultimate tensile strain improves with the increase of the water-binder ratio or fly ash content; the influence of sand-binder ratio and plasticizer content is not obvious. 3) Considering both compressive strength and toughness, the water-binder ratio is the key factor, because the influence of it on both is far greater than that of other factors. Yet it should be noted that the influence of water-binder ratio on compressive strength and toughness is diametrically opposed. Taking into account the main feature of ECC, namely its superior toughness, the water-binder ratio should be increased as much as possible while ensuring the compressive strength will not be too low. A CKNOWLEDGMENTS he authors are grateful to the finical support from the Key Projects of College Outstanding Achievements Transformation (KJZH14220). R EFERENCES [1] Zhang, J., Li., V. C., Effect of inclination angle on fiber rupture load in fiber reinforced cementitious composites, Composites Science & Technology, 62 (2002) 775–781. [2] Li, V. C., Large volume, High-performance applications of fibers in civil engineering, Journal of Applied Polymer Science, 83 (2010) 660-686. [3] Li, V. C., Leung, C. K. Y., Theory of steady state and multiple cracking of random discontinuous fiber reinforced brittle matrix composites, ASCE Journal of Engineering Mechanics, 118 (1992) 2246―2264. [4] Wang, S., Li, V. C., Engineered cementitious composites with high-volume fly ash, Aci Materials Journal, 104 (2007) 233-241. [5] Mirandola, A., Lorenzini, E., Energy, environment and climate: from the past to the future, International Journal of Heat and Technology, 34 (2016) 159-164. [6] Redon, C., Li, V. C., Wu, C., et al. Measuring and modifying interface properties of PVA fibers in ECC matrix, Journal of Materials in Civil Engineering, 13 (2001) 399-406. [7] Chi, Y., Xu, L., Zhang, Y., Experimental study on hybrid fiber–reinforced concrete subjected to uniaxial compression, Journal of Materials in Civil Engineering, 26 (2014) 211-218. [8] Li, V. C., Mishra, D. K., Wu, H. C., Matrix design for pseudo strain-hardening fiber reinforced cementitious composites, Material and Structures, 28 (1995) 586-L595. [9] Xu, S. L., Cai, X. R., Zhang, Y. H., Uniaxial compressive stress-strain full curves and measurement of ultrahigh toughness fiber reinforced cement matrix composites, China Civil Engineering Journal, 42 (2009) 79-85. [10] Hu, C. H., Gao, Y. E., Ding, W. C., Experimental on compression properties of ultrahigh toughness cementitious composite properties, Journal of Building Structures, 34 (2013) 128-132. I T