孔结构和含水量对水泥净浆矿化养护性能的影响

摘要/Abstract

摘要： 矿化养护水泥基材料在提高水泥制品性能的同时又能永久封存CO₂,被认为是一种非常有前景的减碳技术。水泥基材料孔结构对矿化反应的影响尤为显著,本文通过改变初始水灰比(w/c=0.35、w/c=0.40、w/c=0.45)和预处理时间(2、4、6、8、16、24、48和72 h)制备不同孔结构的水泥净浆,研究了孔结构及含水量对水泥净浆矿化反应的影响规律。结果表明,不同初始水灰比的水泥净浆均在预处理时间为8 h时固碳率达到最大值,并且固碳率随着初始水灰比的增加而增加。同时,对于早期水化(24 h标准养护+8 h预处理)的水泥净浆,初始水灰比对孔结构的影响远大于水化程度。初始水灰比为0.45的水泥净浆经8 h预处理后再进行8 h矿化养护,其固碳率、矿化深度、抗压强度分别达到20.35%(固碳率均为质量分数)、12.49 mm、61.99 MPa,与28 d标准养护试块强度(54.25 MPa)相比,经矿化养护后的试块抗压强度提高14.27%。矿化反应主要产物是CaCO₃和硅胶,CaCO₃的填充优化了水泥净浆的孔结构,孔径大于50 nm的孔显著减少,且产物CaCO₃的主要晶型为方解石、文石。

关键词: 水泥基材料, 矿化养护, 水灰比, 预处理, 孔结构

Abstract: Carbonation curing cement-based materials can improve the properties of cement products while permanently sequestering CO₂, which is considered to be a very promising carbon reduction technology. In this paper, cement pastes with different pore structures were prepared by changing the water-cement ratio (w/c=0.35, w/c=0.4, w/c=0.45) and pre-conditioning time (2, 4, 6, 8, 16, 24, 48 and 72 h), and the influences of pore structure and water content on the carbonation reaction of cement paste were studied. The results show that the carbon sequestration rate of cement paste with different water-cement ratios reaches the maximum when the pre-conditioning time is 8 h, and the carbon sequestration rate increases with the increase of water-cement ratio. At the same time, for cement paste with early hydration (24 h standard curing+8 h pre-conditioning), the influence of water-cement ratio on the pore structure is much greater than the degree of hydration. The cement paste with initial water-cement ratio of 0.45 undergoes 8 h pre-conditioning and then undergoes 8 h carbonization curing. Its carbon sequestration rate, carbonation depth and compressive strength reach 20.35% (mass fraction), 12.49 mm and 61.99 MPa, respectively, which increases the compressive strength by 14.27% compared with the strength of the 28 d standard curing test block (54.25 MPa). The main products of carbonation reaction are CaCO₃ and silica gel. The filling of CaCO₃ optimizes the pore structure of cement paste, significantly reduces the pores larger than 50 nm, and the main crystal forms of CaCO₃ are calcite and aragonite.

Key words: cement-based material, carbonation curing, water-cement ratio, pre-conditioning, pore structure

中图分类号:

TU528

石信超, 房晶瑞, 郅晓, 陈阁, 马腾坤, 张帅, 曲齐齐. 孔结构和含水量对水泥净浆矿化养护性能的影响[J]. 硅酸盐通报, 2023, 42(8): 2692-2702.

SHI Xinchao, FANG Jingrui, ZHI Xiao, CHEN Ge, MA Tengkun, ZHANG Shuai, QU Qiqi. Effects of Pore Structure and Water Content on Carbonation Curing Performance of Cement Paste[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(8): 2692-2702.

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