In order to evaluate the effect of steel fiber volume fraction on the anti-explosion performance of cellular concrete, this study analyzed four steel fiber contents of 0.5%, 1.0%, 1.5%, and 2.0%. On this basis, the effects of protective layer thickness and explosive amount on the anti-explosion performance of the structure were further explored. The results show that the protective layer with 1.5% steel fiber content can provide the best protective performance. The influence of explosion shock on the protected structure has been significantly attenuated. The peak pressure at the measuring point and the damage degree of the protected structure are significantly reduced compared with the unreinforced concrete slab. It is found that the SAP20S15 ratio protective layer can still maintain a high energy absorption effect by increasing the amount of explosives, and increasing the thickness of the protective layer can directly and effectively reduce the damage level of the protected structure. Fitting curves are meticulously provided to illustrate the damage degree of the safeguarded structure under the distinct influences of fiber content, explosive mass, and protective layer thickness. These curves enable a rapid evaluation of how these three factors influence the explosion resistance of the protective layer.

The clay attached to the inferior aggregate contaminates the concrete, which will have a serious negative impact on its workability and quality. The quaternary ammonium monocationic polymer (SP1) was synthesized from epichlorohydrin and dimethylamine by step-growth polymerization mechanism. Then, quaternary ammonium and quaternary phosphine dicationic polymer (SP2) was prepared via etherification reaction of SP1 with phosphorus tetrahydroxymethyl sulfate. This study attempts to improve the clay resistance of polycarboxylate superplasticizer (PCE) by combining SP1 or SP2 ionomers. The results of fluidity indicate that the fluidity increases with the addition of sacrificial agent, and the fluidity can reach 280 mm when the dosage of SP1 is 0.2%. Meanwhile, the presence of the sacrificial agent in PCE system can obviously improve the flow retention whole 120 min, showing the improvement in clay tolerance. The adsorption results suggest that the incorporation of sacrificial agent can affect the adsorption behavior, with a decline on MMT particles in total adsorption amount. XRD result demonstrate that the introduction of SP1 or SP2 into the PCE-MMT supernatant can compress the MMT layer spacing and avoid the interlayer adsorption for PCE. Specially, due to the synergistic action of double cations and hydroxyl groups, SP2 preferentially occupies the MMT surface, inhibits the spallation of clay and greatly reduces the surface area for adsorption, which is the main reason for improving the clay tolerance of PCE. This study provides promising solutions for PCE dispersion, with respect to cementitious systems contaminated by clay.

Cement production is associated with significant energy consumption and CO₂ emissions, whereas concrete waste from demolition and renovation has the potential for CO₂ absorption. This study investigated the effects of relative humidity and water-to-cement (w/c) ratio on the carbonation of hardened cement pastes with w/c ratios of 0.4, 0.5, and 0.6. Thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy were used to analyze the carbonated samples, which were exposed to five different constant humidity conditions and underwent five types of wet–dry cycles. The results indicated that higher w/c ratios increased the hydration degree and pore formation, facilitating CO₂ diffusion and promoting carbonation. Wet–dry cycles enhanced pore generation and calcium silicate hydrates (C-S-H) decomposition through shrinkage and deformation during the drying process. In addition, the minimum and maximum humidity of the wet–dry cycles influenced the formation of vaterite and amount of vaterite converted to calcite. The highest CO₂ uptake after 14 days for WC06-40100 with a w/c ratio of 0.6 exhibited twice that of RH40 and 22% higher than that of RH80 on day 14. Moreover, the amount of CO₂ uptake under RH40-100 for 28 days was approximately 17% of the annual CO₂ emissions from cement production.