This paper investigates the freeze-thaw performance of engineered cementitious composites (ECC) reinforced with polyvinyl alcohol (PVA) fibers, by applying an innovative criterion for judging the specimen’s working state mutation. The ECC materials are prepared into 25 mixtures using the Taguchi method. Then, the fundamental transverse frequency, the flexural performance and the internal strain variation of ECC specimens subjected to freeze-thaw cycles are measured. Unlike the existing studies, this investigation focuses on the failure behavior of ECC materials in the process of freeze-thaw. The Mann-Kendall (M-K) criterion is introduced to detect the ECC specimen’s working state leap feature, leading to the updated definition of frost-induced failure concept. Furthermore, the three-level model for evaluating the freeze-thaw performance of ECC materials is established according to the revealed essential leap feature. Thus, the effect of each individual mix design factor on the frost-induced failure indices is perceived from the signal-to-noise (S/N) ratio analysis and the analysis of variance (ANOVA). Finally, a mix formulation estimated based on Taguchi method is recommended for its optimum resistance against frost-induced failure, which is verified by the confirmation experiment.

The working states of three types of engineered cementitious composites (ECC) link slabs subjected to vertical loads are investigated based on the structural working state theory. The scattered measured strains are firstly expanded into spatially continuous data using the response simulating interpolation method without loss of original information. The generalized strain energy density (GSED) is derived from these data and the sum of which are used to characterize the working states of ECC link slabs. Thereafter, the Mann-Kendall (M-K) criterion is introduced to detect the working state leaps during the whole loading procedure and two critical mutations are revealed: The yielding point and the initial structural failure point. Finally, the working state modes, the characteristics of strain fields and the development of internal forces are employed to verify the working state mutations around the revealed critical points. The GSED-based analysis of structural working state is an innovative method to discern some unseen working behavior characteristics which are ignored by traditional structural analysis theory. The work reported herein has a further effect in improving the structural design codes for ECC link slabs.

The engineered cementitious composite (ECC) mixtures were prepared with Portland cement, ground fly ash, silica sand, and polyvinyl alcohol (PVA) fibers. Accordingly, four mix design factors with five levels each were designed using the Taguchi method. The engineering properties of ECC (flow expansion, compressive strength, flexural strength, charge passed, and maximum freeze–thaw cycle) were evaluated, and the single-response optimizations were conducted separately. Unlike other studies assigning a relative weighting parameter to each response, the principal component analysis (PCA) was innovatively introduced to optimize the ECC’s multiple responses so that the single principal performance was obtained from the most objective perspective. Furthermore, the weighting parameters for utility concept were determined by the PCA. Thereafter, an optimum mix formulation was estimated using the PCA-based Taguchi method and the updated utility concept, which provided the most desired balance of these engineering properties. Finally, the contribution of each mix design factor to the principal performance of ECC was examined, and the estimated mix formulation was verified via an additional experiment.