Hydration-strength-durability-workability of biochar-cement binary blends
Hydration-strength-durability-workability of biochar-cement binary blends
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DOI：
10.1016/j.jobe.2021.103064
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发表时间：
2021-10
影响因子：
6.4
通讯作者：
Xu Yang;Xiao-Yong Wang
中科院分区：
文献类型：
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作者：
Xu Yang;Xiao-Yong Wang
研究了不同生物炭掺量（水泥掺量为2%和5%）下生物炭混合试样的和易性、力学性能、超声脉冲速度（UPV）、水化热、水化程度、水化产物、耐久性（氯离子扩散和电阻率）、细观结构和微观结构。综合各项试验结果，我们发现：(1)可加工性随着生物炭替代比的增加而降低。(2)生物炭的加入降低了抗压强度，且与龄期早期相比，后期强度降低不明显。(3)生物炭的加入降低了UPV。对于不同龄期的所有试件，抗压强度均可回归为UPV的指数函数。(4)随着生物炭含量的增加，累积热量减小。与稀释效应相比，生物炭的成核效应微乎其微。(5) x射线衍射（XRD）和热重分析（TGA）表明，随着生物炭含量的增加，Ca(OH)2含量降低。此外，TGA结果表明，随着生物炭含量的增加，水泥水化程度降低。(6)随着生物炭含量的增加，氯离子扩散系数增大。此外，由于生物炭不导电，电阻率随生物炭含量的增加而增加。(7)光学显微图显示，随着生物炭含量的增加，介孔空隙也增加。此外，扫描电镜（SEM）分析表明，生物炭颗粒的内部孔隙可以为水化产物的形成提供空间。
This study presents the workability, mechanical properties, ultrasonic pulse velocity (UPV), heat of hydration, degree of hydration, hydration products, durability (chloride ion diffusion and electrical resistivity), mesostructure, and microstructure of biochar blended specimens with various biochar contents (2% and 5% of cement). Based on the various test results, we found that (1) the workability decreases with an increase in the biochar replacement ratio. (2) The addition of biochar reduces the compressive strength, and compared with the early age, the reduction in strength at later ages is less obvious. (3) The addition of biochar reduces the UPV. For all specimens at various ages, the compressive strength can be regressed as an exponential function of the UPV. (4) With the increase in biochar content, the cumulative heat decreases. Compared with the dilution effect, the nucleation effect of biochar is marginal. (5) X-ray diffraction (XRD) and thermogravimetric analysis (TGA) showed that as the biochar content increases, the Ca(OH)2content decreases. Moreover, the TGA results showed that as the biochar content increases, the degree of cement hydration decreases. (6) As the biochar content increases, the chloride diffusivity increases. Moreover, because biochar is non-conductive, the electrical resistivity increases with increasing biochar content. (7) Optical micrographs showed that as the biochar content increases, the meso air voids also increase. Moreover, scanning electron microscopy (SEM) analysis revealed that the internal pores of biochar particles can provide space for the formation of hydration products.