Microstructure, permeability and mechanical properties of accelerated shotcrete at different curing age
Microstructure, permeability and mechanical properties of accelerated shotcrete at different curing age
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不同养护龄期加速喷射混凝土的微观结构、渗透性及力学性能
DOI：
10.1016/j.conbuildmat.2014.12.111
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发表时间：
2015-03
影响因子：
7.4
通讯作者：
Sha Ding
中科院分区：
文献类型：
--
作者：
Jiabin Wang;DitaoNiu;Sha Ding
由于普通混凝土的水化过程不同，低碱速凝剂喷射混凝土不仅终凝时间短、早期力学性能高，而且水化产物也不同。采用X射线衍射、热重-差示扫描量热法和扫描电镜等方法研究了不同养护龄期下喷射混凝土的微观结构，探讨了其水化过程。并对喷射混凝土的孔结构和渗透性能进行了测试。研究了喷射混凝土的力学性能。结果表明，在速凝剂的作用下，石膏在水泥-速凝剂-水体系中的缓凝作用消失。C3 A快速水化形成水化铝酸钙（CAH）晶体，并且由钙矾石、钠长石和CAH形成网状结构。大量的水化热提高了水泥熟料矿物的水化速度和密度，从而导致早期养护阶段的高力学性能。浆体凝结时间随水胶比和粉煤灰掺量的增加而增加。因此，水化过程和水化产物的微观结构和形态发生了变化。过量的水和粉煤灰会增加喷射混凝土的孔隙率，直接导致渗透性变差。当FA掺量为30%时，其渗透性和抗压强度较20%时差。研究表明，混合料S2的抗压强度与劈裂抗拉强度之间存在简单的0.5次幂关系，其力学性能分别与渗透率和孔隙率之间存在指数关系。
Given the different hydration processes of ordinary concrete, shotcrete with low-alkali accelerator not only has short final setting time and high early age mechanical properties but also different hydration products. Shotcrete microstructure was studied at different curing ages by X-ray diffraction, thermogravimetry–differential scanning calorimetry, and scanning electron microscopy to investigate its hydration process. The pore structure and permeability of shotcrete were also tested. The mechanical properties of shotcrete were then studied. Results showed that under the effect of accelerator, the retarded action of gypsum disappeared in the cement–accelerator–water system. C3A hydrated quickly to form calcium aluminate hydrate (CAH) crystals, and a mesh structure was formed by ettringite, albite, and CAH. A large amount of hydration heat improved the hydration rate of the cement clinker mineral and the density, thus leading to high mechanical properties at the early curing age. The setting time of pastes increased with increasing water–binder ratio and fly ash (FA) dosage. Thus, the hydration process and the microstructure and morphology of the hydration products changed. Excessive water and FA increased the percentage of pores in shotcrete, which directly caused poor permeability. The permeability and compressive strength were poor when the FA dosage was 30% compared with that of 20%. Based on the investigation, a simple 0.5 power relationship between compressive strength and splitting tensile strength of mixture S2, meanwhile, there was an exponential relationship between mechanical performance and permeability or porosity, respectively.
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影响因子：
11.4
作者：
Deschner, Florian;Winnefeld, Frank;Neubauer, Juergen
通讯作者：
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11.4
作者：
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J. Bullard;H. Jennings;R. Livingston;A. Nonat;G. Scherer;J. Schweitzer;K. Scrivener;Jeffrey J. Thomas
影响因子：
11.4
作者：
Jennings, HM
通讯作者：
Jennings, HM
影响因子：
11.4
作者：
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通讯作者：
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