In this study, a series of suspensions were fabricated by dispersing calcium carbonate (CaCO₃), cement and silica fume into a polycarboxylate-ether plasticizer (PCE)/water solution. The PCE used was a comb-like copolymer containing a sodium polymethacrylate (PMA) backbone partially esterified with polyethyleneglycol (PEG) side chains. Sedimentation and optical microscopy tests indicated that both CaCO₃ and cement could form homogeneous suspensions. The crystallization behavior of the PEG side chains revealed that PEG had stronger interactions with CaCO₃ than with cement and silica fume particles, which was further confirmed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). A detailed time-of-flight secondary ion mass spectrometry (ToF-SIMS) examination suggested that PEG was mainly located on the surfaces of the CaCO₃, and the PMA backbones were mainly located on the surfaces of the cement and silica fume, respectively. The different interactions between copolymer and inorganic particles were associated with their interfacial tensions, and had a remarkable influence on the paste fluidity.

Concrete structures have to withstand the combined effects of external load and environmental factors. Therefore, it is meaningful to study the durability of concrete under compression and carbonation. The air permeability coefficient (k_Au) and pore structure of concrete under uniaxial compression and carbonation were measured by the Autoclam method and mercury intrusion porosimetry (MIP). The Autoclam test results showed that the concrete k_Au changed in a concave parabolic manner with the compressive stress level, and the inflection point of the stress level was 45%. The MIP results showed that the characteristic pore structural parameters (porosity, average pore diameter, median pore diameter by area, and median pore diameter by volume) first decreased and then increased with the stress level change. The change in concrete microstructure was a result of the combined effect of pore filling, decalcification, and densification, as well as the split effect. The key pore structural parameters affecting k_Au were confirmed using gray relational analysis (GRA). The top three parameters with the highest correlation with the carbonated concrete k_Au were porosity (gray relational grade γ_i = 0.789), median pore diameter by volume (γ_i = 0.763), and proportion of transition pore volume (γ_i = 0.827). Furthermore, the regression analysis showed a good linear relation between k_Au and the important pore structural parameters.