Concrete curing is a critical factor influencing its mechanical properties and durability. Traditional curing methods, such as water curing and plastic film curing, have significant limitations, including high water consumption and environmental pollution. This study introduces Microbial Induced Carbonate Precipitation (MICP) as an innovative, environmentally friendly curing method for ready-mixed concrete, addressing the urgent need for sustainable construction practices. The feasibility of MICP surface curing is investigated through comprehensive mechanical and durability tests, coupled with microscopic analyses to understand the underlying mechanisms. The results demonstrate that MICP curing substantially enhances concrete performance. Compared to traditional water curing, the samples cured using MICP have increased compressive strength and splitting tensile strength by up to 31.69% and 24.66%, respectively. Additionally, MICP surface curing significantly reduced capillary water absorption, electric flux, and chloride ion migration coefficient by 12.83%, 15.50%, and 17.36%, respectively. It is found that the optimal concentration of Ca2+ in the MICP solution initially improves concrete performance, which then diminishes at higher concentrations due to bacterial activity inhibition. Spraying the MICP solution at appropriate intervals and increasing the number of treatments further improved concrete properties by ensuring a more extensive and dense deposition of CaCO3. Microscopic analyses, including XRD, TG, and SEM-EDS, revealed that MICP surface curing leads to the formation of vaterite and calcite, which densely cover and fill microscopic cracks and pores, ensuring adequate hydration and simultaneously enhancing the concrete's mechanical and durability properties. This study concludes that MICP surface curing provides superior performance than traditional methods and offers a more sustainable and environmentally friendly curing method.

Fly ash (FA) and granulated blast furnace slag (GBFS) were used as a precursor for geopolymerization to develop a low-carbon pavement base construction material. Based on the orthogonal test method, three levels were set separately for the L9 (34) test considering the proportion of FA (raw fly ash to grained fly ash), ratio of sodium hydroxide to liquid alkaline activator (LAA), and proportion of GBFS mixed with FA and solid-liquid ratio [(FA + GBFS): LAA] as factors influencing the geopolymer. The influence of these factors on the unconfined compressive strength (UCS) of soil stabilized by geopolymer was studied. The optimal combinations of levels and factors were determined. The UCS with these ratios combined was 5.1 MPa. According to the above compositions, the mechanical (UCS, splitting tensile strength, and flexural tensile strength) and durability (drying shrinkage, water stability, freezing and thawing resistance, and wet-dry cycle) properties of soil samples stabilized using the aforementioned geopolymer were investigated. Moreover, scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis were performed to determine the effect of the change in hydration silicate gel in the UCS development. According to the SEM and XRD test results, hydrated silicate gels exist in the sample, filling the pores of the soil, making the soil more compact, bonding the soil particles, and enhancing the engineering performance of the soil. This study enables waste material utilization as a replacement and partially reactive material in pavement applications.

This study focuses on the development of eco and user-friendly mechanochemically-activated geopolymeric stabilizers, surpassing the limitations inherent in traditional geopolymerization methods. A comparative analysis was undertaken with conventionally activated geopolymer stabilizers to establish benchmarks for effectiveness in soil stabilization applications. Additionally, the research delves into the impact of granulated blast-furnace slag (GGBS) content on the mechanical and durability properties of stabilized soil samples. In addition, the investigation focuses on the influence of the activation method on soil effectiveness and strength post-exposure to sulfate attack. The durability performance is rigorously assessed through the immersion of specimens in a 1 % magnesium sulfate (MgSO4) solution for 60 and 120 days. The comprehensive evaluation includes visual appearance, mass changes, Ultrasonic Pulse Velocity (UPV), Unconfined Compressive Strength (UCS), and Fourier-Transform Infrared (FTIR) spectra of geopolymer-stabilized soil specimens. The results showed that before the exposure to the MgSO4 solution, the UCS of mechanochemically activated geopolymer (MAG) samples was higher (12-45 %) than that of conventionally activated geopolymer (CAG)-stabilized soil. Furthermore, the strength of the geopolymer-stabilized soil improved by 114 %, 247 %, and 361 %, at 50, 75, and 100 % GGBS content, respectively. On the other hand, after exposure to the MgSO4 solution, the results showed that the mechanochemically activated geopolymer-stabilized soil has better resistance to sulfate erosion than the conventionally activated geopolymer-stabilized soil. The residual UCS for MAG and CAG samples were 93 % and 89 % when exposed to 1 % magnesium sulfate solution for 60 days, whereas they declined to 70 % and 58 %, respectively, after 120 days of immersion.

In the context of sustainable building development, Compressed Earth Blocks (CEBs) have garnered increasing attention in recent years owing to their minimal environmental and economic impact. However, owing to the inherent diversity of raw soil and the production process's reliance on expertise, the properties of these blocks are subjected to multifaceted influences. Among these, the significance of soil particle size variation often remains overlooked, leaving its impact ambiguous. This study endeavours to address this gap in existing research by delving into this aspect. Two distinct batches of CEBs were produced by adjusting the grain size curve of a single type of sieved soil with different maximum mesh openings: 2 mm for R1 CEBs and 12.5 mm for R2 CEBs. Experimental results reveal significant differences in thermophysical characteristics: on average, R1 blocks show superior thermal performance, boasting a 23% reduction in thermal conductivity compared to R2 blocks, and are lighter, with an 8% decrease in dry bulk density. Although no significant changes in mechanical parameters were observed, finer-structured R1 blocks showed a 25% greater tendency to absorb water due to changes in their porous structure. This study sheds light on the sensitivity of thermal parameters to changes in soil particle size and shows that blocks with finer particles exhibit poorer heat conduction and heat diffusion. Besides providing new insights into the literature, this research also provides a strategic approach to optimise the thermophysical properties of CEBs. By understanding the influence of particle size, researchers and practitioners can now develop strategies to enhance these properties and improve the overall performance of CEBs.

This study investigates the impact of incorporating Juncus fibers (JF) into compressed earth blocks (CEBs) stabilized with varying Portland cement contents, aiming to enhance local construction materials' performance and reduce housing costs. CEB composites were produced with soil stabilized using different cement contents (4%, 8%, and 12% by weight) and JF reinforcement (0 to 0.2% by weight), compressed at 10 MPa with a hydraulic press. After 28 days of drying, the CEBs underwent diverse experimental characterizations to assess their physical, mechanical, thermal, and durability properties. The results revealed that incorporating JF led to a reduction in unit weight, ultrasonic pulse velocity (up to 36%), and dry compressive strength (approximately 17%). Higher fiber content correlated with increased water absorption and an increased capillarity coefficient. Thermal conductivity analysis indicated improved thermal performance, decreasing from 0.4350 W/m center dot K (12% cement without fibers) to 0.2465 W/m center dot K (4% cement with 0.2% JF). Despite the decrease in mechanical strength, CEBs with lower cement (4%) and higher fiber content (0.2%) demonstrated satisfactory durability (abrasion and erosion) and thermal insulation properties. This research suggests the potential of this material as a promising composite for the building materials industry. The findings contribute valuable insights into sustainable construction materials and have implications for cost-effective housing solutions.