A freeze-thaw cycle test, nuclear magnetic resonance (NMR) T₂ spectrum test, uniaxial tensile test, and uniaxial compression test were designed to study the service conditions of engineered cementitious composites (ECC) in a freeze-thaw (FT) environment in cold areas. The degradation law of the mechanical properties and damage characteristics of the pore structure of ECC with three water-binder ratios (M1: W/B = 0.24, M2: W/B = 028, and M3: W/B = 0.32) are discussed. The results demonstrate that the number of micropores and mesopores in the ECC specimens increases with an increase in the number of freeze-thaw cycles (FTs), thus gradually increasing the porosity. The uniaxial tensile strength (UTS) and uniaxial compressive strength (UCS) decrease gradually with increasing number of FTs. After FTs300, the porosity of the three groups increases by 43.83%, 59.39%, and 59.16%; the loss ratios of UTS are 26.16%, 24.47%, and 19.63%; and the loss ratios of UCS are 31.52%, 27.98%, and 27.30%, respectively. Based on the mechanical properties and pore structure test results of ECC, relation models of the UTS and UCS of freeze-thaw damaged (FTD) ECC with porosity were constructed according to the simplified center hole model of ECC and the elastic mechanics theory. To further disclose the FT evolution laws of uniaxial tensile/compressive strengths (UT/CS), the relationship models of UT/CS and number of FTs with the degree of FTD were deduced. The constructed models and test results were compared with those of some classical porosity-strength models. It was found that the constructed models met the requirements of satisfactory reliability and applications.

设计了冻融循环试验、核磁共振（NMR）T ₂谱试验、单轴拉伸试验和单轴压缩试验，研究工程水泥复合材料（ECC）在冻融（FT）环境中的服役条件。寒冷地区。讨论了三种水胶比（M1：W/B=0.24，M2：W/B=028，M3：W/B=0.32）的ECC孔隙结构力学性能和损伤特征的退化规律. 结果表明，ECC试样中微孔和中孔的数量随着冻融循环（FTs）次数的增加而增加，从而逐渐增加孔隙率。单轴抗拉强度(UTS) 和单轴抗压强度 (UCS) 随着 FT 数量的增加而逐渐降低。FTs300后，三组孔隙率分别增加43.83%、59.39%、59.16%；UTS的损失率分别为26.16%、24.47%和19.63%；UCS的损失率分别为31.52%、27.98%和27.30%。基于ECC的力学性能和孔结构试验结果，根据ECC的简化中心孔模型和弹性力学理论，构建了冻融破坏（FTD）ECC的UTS和UCS与孔隙率的关系模型。为进一步揭示单轴抗拉/抗压强度（UT/CS）的FT演化规律，推导了UT/CS和FT个数与FTD程度的关系模型。将构建的模型和测试结果与一些经典的孔隙度-强度模型进行了比较。结果表明，所构建的模型满足了令人满意的可靠性和应用要求。