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The influencing mechanism of dry-wet cycling on the NOxdegradation and sterilization properties of photocatalytic cement mortar (PCM) with g-C3N4/CoAl-LDH was investigated through the optical properties, mineral composition of cement hydration products, pore characteristics and nitrogen (N) content. The results indicate that as the cycle number increases, the N content, band gap, Urbach energy, NOxdegradation rate and sterilization rate exhibit periodic variations, while the peak intensity of CH (a cement hydration product) decreases gradually. After 10 cycles, PCM demonstrates the maximum Urbach energy, N content, NOxdegradation and sterilization rate, as well as the minimum band gap. At this stage, the Urbach energy, N content, NOxdegradation and sterilization rate of PCM with 1.0 % g-C3N4/CoAl-LDH increase by 16.2 %, 24.9 %, 15.4 % and 40.8 %, while the band gap and the CH peak intensity decrease by 5.4 % and 23.4 %, respectively. Although the NOxdegradation and sterilization rates of PCM exhibit periodic fluctuations during the dry-wet cycling, both of them surpass those before the cycles, which shows the excellent photocatalytic durability of PCM. It is expected that this study not only presents a new perspective on evaluating the durability of PCM’s photocatalytic property, but also provides an alternative approach for the design of new multifunctional nanocomposites in cementitious materials for environmental pollution control.

In this paper, an advanced photocatalyst, B-TiO2/MgAl-CLDH, was synthesized and applied in cement mortar. The photocatalytic NOxdegradation ability of cement mortar containing B-TiO2/MgAl-CLDH under different initial NOxconcentrations and flow rates was investigated. The results show that B-TiO2/MgAl-CLDH has stronger visible light absorption, lower recombination rate of electron-hole pairs and narrower optical band gap than commercial nano-TiO2(P25), resulting in enhanced NOxremoval efficiency. Specifically, the maximum NOxdegradation ratio of B-TiO2/MgAl-CLDH is 23.4% within 30min, which is about 5 times that of P25. For photocatalytic mortar, the initial NOxconcentration (from 1.0 ppm to 2.0 ppm) and flow rate (from 1L/min to 3L/min) were positively correlated with NOxremoval amount, while negatively correlated with NOxremoval ratio. Based on the internal molecular diffusion properties of NOx, Langmuir-Hinshelwood and the power law kinetic models were used to predict the NOxdegradation ability of photocatalytic mortar. The modeling of NOxdegradation process presents a reliable prediction of the NOxremoval ability of photocatalytic mortar, serving as a valuable tool for assessing the mortar’s NOxremoval effectiveness for policymakers and engineers.

This paper presents work in the laboratory assessment of a new family of self-healing materials that hold promise for "crack-free" concrete or other cementitious composites. This innovative system features the design of passive smart microcapsules (PSMs) with oil core and silica gel shell, prepared through an interfacial self-assembly process and sol-gel reaction. Methylmethacrylate monomer and triethylborane were chosen as the healing agent and the catalyst for use in the system and were microencapsulated. The microcapsules were subsequently dispersed in fresh cement mortar along with carbon microfibers. The morphology of the microcapsules was examined by using a field emission scanning electron microscope. Mechanical tests and electrochemical impedance spectroscopy measurements were carried out to evaluate the self-healing effect of PSMs and the possible physicochemical changes or interactions in the carbon microfiber-reinforced mortar matrix.

This paper presents work in the laboratory assessment of a new family of self-healing materials that hold promise for “crack-free” concrete or other cementitious composites. This innovative system features the design of passive smart microcapsules (PSMs) with oil core and silica gel shell, prepared through an interfacial self-assembly process and sol–gel reaction. Methylmethacrylate monomer and triethylborane were chosen as the healing agent and the catalyst for use in the system and were microencapsulated. The microcapsules were subsequently dispersed in fresh cement mortar along with carbon microfibers. The morphology of the microcapsules was examined by using a field emission scanning electron microscope. Mechanical tests and electrochemical impedance spectroscopy measurements were carried out to evaluate the self-healing effect of PSMs and the possible physicochemical changes or interactions in the carbon microfiber–reinforced mortar matrix.