In order to study the cement-industrial waste-based synergistic curing of silt soil, orthogonal design tests were used to prepare a new curing agent using cement, fly ash, blast furnace slag, and phosphogypsum as curing materials. In order to evaluate the cement-industrial waste-cured soils, unconfined compressive strength tests, fluidity tests, wet and dry cycle tests, and electron microscope scanning tests were carried out. The mechanical properties and microstructure of the cement-industrial slag were revealed and used to analyze the curing mechanism. The results showed that, among the cement-industrial wastes, cement and blast furnace slag had a significant effect on the unconfined compressive strength of the specimens, and the optimal ratio for early strength was cement-fly ash-slag-phosphogypsum = 1:0.11:0.44:0.06; the optimal ratio for late strength was cement-fly ash-slag-phosphogypsum = 1:0.44:0.44:0.06. In the case of a 140% water content, the 28d compressive strengths of curing agent Ratios I and II were 550.3 kPa and 586.5 kPa, respectively. When a polycarboxylic acid water-reducing agent was mixed at 6.4%, the mobilities of curing agent Ratios I and II increased by 32.1% and 35.8%, and the 28d compressive strengths were 504.1 kPa and 548.8 kPa, respectively. When calcium chloride was incorporated at 1.5%, the early strength of the cured soil increased by 33% and 29.1% compared to that of the unadulterated case year on year, and the mobility was almost unchanged. From microanalysis, it was found that the cement-industrial waste produced the expansion hydration products calcium alumina (AFt) and calcium silicate (C-S-H) during the hydration process. The results of this study provide a certain basis and reference value for the use of marine soft soil as a fluid filling material.

Structural colors are bright and possess a remarkable resistance to light exposure, humidity, and temperature such that they constitute an environmentally friendly alternative to chemical pigments. Unfortunately, upscaling the production of photonic structures obtained via conventional colloidal self-assembly is challenging because defects often occur during the assembly of larger structures. Moreover, the processing of materials exhibiting structural colors into intricate 3D structures remains challenging. To address these limitations, rigid photonic microparticles are formulated into an ink that can be 3D printed through direct ink writing (DIW) at room temperature to form intricate macroscopic structures possessing locally varying mechanical and optical properties. This is achieved by adding small amounts of soft microgels to the rigid photonic particles. To rigidify the granular structure, a percolating hydrogel network is formed that covalently connects the microgels. The mechanical properties of the resulting photonic granular materials can be adjusted with the composition and volume fraction of the microgels. The potential of this approach is demonstrated by 3D printing a centimeter-sized photonic butterfly and a temperature-responsive photonic material.

Integrating industrial wastes into soils to enhance their properties is a potential solution to current waste management challenges. Since the current literature lacks systematic studies on the mechanical performance of mixtures of soil, ladle furnace slag (LFS) and fly ash (FA), this research investigated the chemical stabilization of two different soils (clayey or sandy soil) using a concomitant mix of distinct types of industrial wastes: LFS and FA. A design of experiments (DoE) methodology was employed to systematically generate distinct mixtures for each soil sample, utilizing a simplex-centroid design. The mixtures were subjected to unconfined compressive strength (UCS), California Bearing Ratio (CBR) and resilient modulus (RM) tests. The industrial by-products improved the mechanical properties of the soils, providing UCS, CBR index and RM increases up to 130.5%, 324.4% and 132.6%, respectively. Synergistic and antagonistic effects related to the combination of different wastes were discussed, based on mathematical models with coefficients of determination ranging from 0.760 to 0.998, in addition to response surfaces generated for each response variable. The desirability function was applied to identify the optimal component proportions. The best mixture proportion was 80% soil, 20% LFS and 0% FA, which improved the formation of cemented compounds that contributed to the enhanced mechanical strength. The use of industrial waste for soil stabilization has therefore proven to be technically feasible and environmentally friendly.

The aim of this work is to develop a geopolymer-stabilized soil for civil engineering, especially in applications like curbs and crash barriers. Firstly, a central composite design was used to study the impact of the input factors on both compressive and flexural strengths. The input factors were the molar ratios SiO2/Al2O3 (X), Na2O/Al2O3 (Y) and H2O/Na2O (Z), which varied from 3 to 4, 0.9 to 1.1 and 20 to 26, respectively, while metakaolin/soil ratio remained constant at 0.33. Thanks to central composite design method, fifteen experiments were conducted to establish a second-order empirical model, linking the response function (mechanical strength) to the input factors (X, Y, Z) and their interactions. Secondly, the mass ratio of metakaolin to soil was decreased from 0.33 to 0.16, in order to minimize the environmental impact of the material. The physico-chemical and mechanical properties of mix-designs were investigated. The results revealed that the molar ratio H2O/Na2O (Z) was the most significant parameter, closely followed by SiO2/Al2O3 (X) and Na2O/Al2O3 (Y). Compressive strength values range from 3.4 to 23.0 MPa, while flexural strength values vary from 0.5 to 4.1 MPa. The highest mechanical strengths (23.0 and 4.1 MPa) are obtained for optimal molar ratios X, Y, and Z corresponding to 3.8, 0.9 and 20, respectively.