The construction industry is increasingly focusing on sustainability, creating a need for innovative materials. This comprehensive review examines the potential of calcined clays and nanoclays in enhancing construction materials and promoting resilient infrastructure. It emphasises their role in improving performance and supporting environmental conservation in sustainable development. The review discusses how varying proportions of calcined clays and nanoclays impact the performance of pavement materials, especially when combined with bitumen in asphalt mixtures. It highlights their benefits, including reduced chloride penetration, enhanced water resistance, and improved soil conductivity. Overall, the review suggests that the strategic integration of calcined clays and nanoclays into construction materials can enhance durability, optimise resource use, and support environmental sustainability.

Recently, natural and environmentally friendly materials have been highly considered for soil reinforcement and stabilization in road and geo-environment infrastructures and constructions. In the present research, laboratory experiments are conducted to evaluate the potential of combining barley fibers and nanoclay to enhance the mechanical properties of clay subgrade while maintaining its affordability and environmental sustainability. Also, it is aimed to explore the potential for extensive use of barley fiber waste, which ranks as the second most abundant agricultural product globally. The laboratory samples were produced by including nanoclay at concentrations of 0.5%, 1%, and 1.5% and barley fibers at concentrations of 0.3%, 0.6%, and 0.9% with fiber lengths of 5 mm, 10 mm, and 15 mm. The primary objective was to determine the optimal content of nanoclay and the most effective fiber length through the unconfined compressive strength (UCS) test. Afterward, the nanoclay was used at its optimal concentration along with different ratios of fibers to perform California bearing ratio (CBR), direct shear, indirect tensile strength, and freeze/thaw (F/T) tests. In addition, scanning electron microscopy (SEM) imaging was employed to examine the mechanism of soil reinforcement by incorporating fibers and the enhancement achieved by the nanoclay introduction into the prepared samples. The results revealed that adding nanoclay to clay caused the development of a cohesive gel between particles and fibers, resulting in improved interlocking and friction. The results also demonstrated a significant increase in the UCS by 142%, tensile strength by 178%, CBR by 120%, and shear strength characteristics. Furthermore, the samples containing an appropriate amount of nanoclay exhibited enhanced durability and greater strength when subjected to F/T cycles. This research determined the optimal fiber length and dose as 10 mm and 0.6%, respectively. Additionally, the highest UCS was achieved with a nanoclay concentration of 1%. Overall, the test results illustrate the effectiveness of these stabilizers in improving the mechanical properties of clay subgrades.

Puccinia striiformis f. sp. tritici causes the important disease, yellow rust of wheat (Triticum aestivum). Montmorillonite nanoclay (MNC) is naturally occurring and biodegradable. This study assessed in vitro anti-germination effects of MNC on P. striiformis uredospores. Application of MNC at 150 mg L-1 completely inhibited uredospore germination, and MNC at 100 mg L-1 reduced yellow rust severity in wheat plants by 89%. Expression of defense-related genes was increased after MNC treatment at 100 mg L-1, by 5.23-fold for jasmonate and ethylene-responsive factor 3 (JERF3), 4.89-fold for chitinase class II (CHI II), and 2.37-fold for pathogenesis-related protein 1 (PR1). Applying MNC at 100 mg L-1 also activated the antioxidant enzymes POD to 62.1 unit min(1) g(1 )fresh wt, PPO to 21.6 units min(1) g(-1) fresh wt, and CAT to 36.6 units min(-1) g(-1) fresh wt. MNC also enhanced phenolic content in wheat leaves (to 1489.53 mg 100 g(-1) f. wt), and reduced lipid oxidation levels (to 5.6 mu mol MDA g(-1) fresh wt). MNC at 100 mg L-1 also mitigated damaging effects of P. striiformis infections on host leaf cell ultrastructure, increased leaf photosynthetic pigments, and increased wheat plant growth. These results show that MNC has potential as a natural control agent for yellow rust of wheat, although field testing of MNC is necessary before this material can be recommended for wheat production.

Nanoclay, a processed clay, is utilized in numerous high-performance cement nanocomposites. This clay consists of minerals such as kaolinite, illite, chlorite, and smectite, which are the primary components of raw clay materials formed in the presence of water. In addition to silica, alumina, and water, it also contains various concentrations of inorganic ions like Mg2+, Na+, and Ca2+. These are categorized as hydrous phyllosilicates and can be located either in interlayer spaces or on the planetary surface. Clay minerals are distinguished by their two-dimensional sheets and tetrahedral (SiO4) and octahedral (Al2O3) crystal structures. Different clay minerals are classified based on the presence of tetrahedral and octahedral layers in their structure. These include kaolinite, which has a 1:1 ratio of tetrahedral to octahedral layers, the smectite group of clay minerals and chlorite with a 2:1 ratio. Clay minerals are unique due to their small size, distinct crystal structure, and properties such as high cation exchange capacity, adsorption capacity, specific surface area, and swelling behavior. These characteristics are discussed in this review. The use of nanoclays as nanocarriers for fertilizers boasts a diverse array of materials available in both anionic and cationic variations. Layered double hydroxides (LDH) possess a distinctive capacity for exchanging anions, making them suitable for facilitating the transport of borate, phosphate, and nitrate ions. Liquid nanoclays are used extensively in agriculture, specifically as fertilizers, insecticides, herbicides, and nutrients. These novel nanomaterials have numerous benefits, including improved nutrient use, controlled nutrient release, targeted nutrient delivery, and increased agricultural productivity. Arid regions face distinct challenges like limited water availability, poor soil quality, and reduced productivity. The addition of liquid nanoclay to sandy soil offers a range of benefits that contribute to improved soil quality and environmental sustainability. Liquid nanoclay is being proposed for water management in arid regions, which will necessitate a detailed examination of soil, water availability, and hydrological conditions. Small-scale trial initiatives, engagement with local governments, and regular monitoring are required to fully comprehend its benefits and drawbacks. These developments would increase the practicality and effectiveness of using liquid nanoclay in desert agriculture.

Marl clays with varying levels of calcite content often exhibit more erratic behavior compared to other problematic soils, especially when exposed to repetitive Freeze-Thaw (F-T) cycles. It is crucial to prioritize the mechanical properties and durability of this particular soil variety as neglecting such characteristics can result in irreversible harm to the superstructures. This research focused on examining the utilization of lime and Nanoclay (NC) as stabilizers and Glass Fiber (GF) as reinforcement for natural marl soil. The study involved preparing samples with 6% lime and up to 1.5% NC, combined with varying amounts of GF ranging from 0 to 1%. The samples were cured for 7 and 28 days and subjected to 0, 1, 4, and 8 F-T cycles. Several Unconfined Compressive Strength (UCS) and Indirect Tensile Strength (ITS) tests as well as microstructural analyses including Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) were performed on the samples before and after being exposed to F-T cycles. Results showed that the application of GF enhanced the UCS and ITS of lime-NC-stabilized marl soil by creating interlocking zones between the particles. The addition of lime and NC shifted the behavior of the soil sample from ductile to brittle, while the inclusion of GF caused the soil to revert to ductile behavior, resulting in a decrease in secant modulus (E50) and an increase in energy absorption capacity (Eu) compared to samples without GF. Furthermore, incorporating GF along with lime and NC into the marl soil improved the F-T durability even after 8 cycles and resulted in reduced strength deterioration compared to the control sample. The optimum mixture was found to be 6% lime, 1% NC, and 0.75% GF, resulting in a noteworthy improvement of 6.5 times in the ITS and a slight decrease of 6% after 8 F-T cycles compared to the untreated marl soil.