Lu Feng, Wang Haiyan, Wang Lichuan, Zhao Kai, Zhang Junru
School of Emergency Management, Xihua University, Chengdu 610039, China.
Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China.
Materials (Basel). 2022 Jun 23;15(13):4435. doi: 10.3390/ma15134435.
The present study explored the degradation law and service life prediction of tunnel lining concrete with different mineral admixtures under coupled actions of sulfate attack (SA) and drying−wetting (DW) cycles. The deterioration resistance coefficient (DRC) of compressive strength and influence coefficients of sulfate concentration, mineral admixture content, water/binder (w/b) ratio, and curing regime on DRC were studied. After that, a new service life prediction model based on damage mechanics was developed and analyzed. Results show that, by increasing the DW cycles, the DRC first increases and then decreases. DRCs of Ordinary Portland cement (OPC), fly ash (FA), and ground granulated blast-furnace slag (GGBS) concrete linearly decrease with the increase of sulfate concentration, while the silica fume (SF) concrete displays a two-stage process; by increasing the admixture content, the DRCs of FA and GGBS concrete exhibit two distinct stages, while the SF concrete depicts a three-stage process; increasing the w/b ratio linearly decreases the DRC; the DRC of curing regime was sequenced as standard curing (SC) > fog curing (FC) > water curing (WC) > same condition curing (SCC). Based on the experimental results, the service life prediction model is applied and validated. The validation results show that the proposed model can accurately predict the lifetime of concrete with different mix proportions. Furthermore, it is found that the mineral admixture can effectively improve the lifetime of concrete, and the composite mineral admixture is more effective than a single mineral admixture in improving the lifetime of concrete.
本研究探讨了在硫酸盐侵蚀（SA）和干湿（DW）循环耦合作用下，不同矿物掺合料的隧道衬砌混凝土的劣化规律及使用寿命预测。研究了抗压强度的抗劣化系数（DRC）以及硫酸盐浓度、矿物掺合料含量、水胶比（w/b）和养护制度对DRC的影响系数。在此基础上，建立并分析了基于损伤力学的新型使用寿命预测模型。结果表明，随着DW循环次数的增加，DRC先增大后减小。普通硅酸盐水泥（OPC）、粉煤灰（FA）和磨细粒化高炉矿渣（GGBS）混凝土的DRC随硫酸盐浓度的增加呈线性下降，而硅灰（SF）混凝土呈现两阶段过程；随着掺合料含量的增加，FA和GGBS混凝土的DRC呈现两个不同阶段，而SF混凝土呈现三阶段过程；增大w/b比会使DRC线性降低；养护制度的DRC排序为标准养护（SC）＞雾养护（FC）＞水养护（WC）＞同条件养护（SCC）。基于试验结果，对使用寿命预测模型进行了应用和验证。验证结果表明，所提出的模型能够准确预测不同配合比混凝土的使用寿命。此外，发现矿物掺合料可有效提高混凝土的使用寿命，且复合矿物掺合料在提高混凝土使用寿命方面比单一矿物掺合料更有效。
