The incorporation of PCMs in energy piles holds significant potential for revolutionising thermal management in construction, making them a crucial component in the development of next-generation systems. The existing literature on PCM-integrated energy piles largely consists of isolated case studies and experimental investigations, often focusing on specific aspects without providing a comprehensive synthesis to guide future research or practical applications. To date, no review has been conducted to consolidate and evaluate the existing knowledge on PCMs in energy piles, making this review the first of its kind in this field. Up until now, this gap in research has limited our understanding of how PCM configurations, thermal properties, and integration methods impact the thermal and mechanical performance of these systems. Through thoroughly analysing the current research landscape, this review discovers key trends, methodologies, and insights. The methodology used here involved a systematic search of the existing SCI/SCIE-indexed literature to ensure a structured review. Based on the SLR findings, it is evident that current research on PCMs in energy piles is focused on improving thermal efficiency, heat transfer, and compressive strength. Furthermore, precise adjustments in melting temperature significantly impact efficiency, with PCM integration boosting thermal energy extraction by up to 70 % in some cases, such as heating cycles, and saving up to 30 % in operational costs. PCMs also reduce soil temperature fluctuations, improving structural integrity through minimising axial load forces. However, challenges remain, including reduced mechanical strength due to voids and weak bonding, high costs, and complexities such as micro-encapsulation. We acknowledge that there are gaps in addressing certain key factors, including thermal diffusivity; volume change during phase transitions; thermal response time; compatibility with construction materials; interaction with soil, creep, and fatigue; material compatibility and durability; and the long-term energy savings associated with PCM-GEP systems.

The lunar base establishing is crucial for the long-term deep space exploration. Given the high costs associated with Earth-Moon transportation, in-situ resource utilization (ISRU) has become the most viable approach for lunar construction. This study investigates the sintering behavior of BH-1 lunar regolith simulant (LRS) in a vacuum environment across various temperatures. The sintered samples were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), along with nanoindentation, uniaxial compression, and thermal property tests to evaluate the microstructural, mechanical, and thermal properties. The results show that the sintering temperature significantly affects both the microstructure and mechanical strength of the samples. At a sintering temperature of 1100 degrees C, the compressive strength reached a maximum of 90 MPa. The mineral composition of the sintered samples remains largely unchanged at different sintering temperatures, with the primary differences observed in the XRD peak intensities of the phases. The plagioclase melting first and filling the intergranular pores as a molten liquid phase. The BH-1 LRS exhibited a low coefficient of thermal expansion (CTE) within the temperature range of - 150 degrees C to 150 degrees C, indicating its potential for resisting fatigue damage caused by temperature fluctuations. These findings provide technical support for the in-situ consolidation of lunar regolith and the construction of lunar bases using local resources.

Using local materials with low environmental impact is essential in building living spaces, combining energy efficiency, environmental respect, and user well-being. However, despite advances in using natural materials, few studies have focused on integrating spathe fibers into earth bricks to optimize their thermal, mechanical, and hydric performance. The study aims to develop an innovative approach to using spathe fibers as natural reinforcement in manufacturing soil bricks while analyzing their impact on thermal, mechanical, and hydric properties. Several soil bricks reinforced with spathe fibers at different concentrations (0%, 1%, 2%, 3%, 4%, and 5%) were developed. Thermal performance was assessed using the hot disk method, while mechanical strength was measured in compression and flexure with capillary absorption tests. Based on fiber content, the brick density ranged from 1719.75 to 1247.6 kg/m3. The thermal conductivity of the materials ranges from 0.621 to 0.327 W/m. K, indicating good insulating performance. Maximum capillary water absorption values range from 170 to 287%, revealing a difference in water permeability depending on fiber content. Compressive strengths range from 1.4 to 3.6 MPa, and flexural strengths range from 1.6 to 1.91 MPa, suggesting potential for structural applications. Physico-chemical and geotechnical analyses confirm the suitability of the soil for the production of spathe fiber-stabilized bricks. This study offers an alternative to conventional bricks, contributing to the promotion of ecological and sustainable building materials suitable for arid and semi-arid climates.

This study contributes to the understanding of the vernacular raw-earth heritage of the Champagne region in France, where such structures are currently being documented. The research investigates the mineral composition, grain size distribution, and physico-chemical, mechanical, thermal, and hydric properties of seven adobe types derived from soils with varying compositions (predominantly silicate or limestone-based soils). In particular, the influence of calcite content, which spans a wide range from 0 % to 84.9 %, was examined. The results indicate a strong dependency of peak compressive strength on calcite content: higher CaCO3 levels correspond to lower peak compressive strength. Additionally, the study reveals that the metal oxide content of soils is a critical factor directly associated with mechanical performance. Interestingly, it was observed that historical builders often used weaker adobes for load-bearing purposes and stronger ones for filling, likely without adherence to formal construction standards. Rather than compressive strength, wall design appears to have played a more critical role in structural stability. Regarding thermal properties, calcite content showed minimal influence on diffusivity, specific heat capacity, and thermal conductivity across all adobe samples. Furthermore, all adobes demonstrated excellent to very good moisture regulation performance, with corresponding Moisture Buffer Values varying from 1.65 to 3.09 g/(m2.%RH). The findings of this study underscore the potential of traditional raw-earth techniques in rediscovering and evaluating earthen architecture, with implications for promoting sustainable and environmentally friendly contemporary earthen construction and renovation practices.

The current paper aims to experimentally investigate the thermal performance of geo-energy piles and walls fabricated with Phase Change heat exchangers. Four prototype concrete geo-energy structures (i.e., piles and walls) were tested using two distinct types of heat exchangers, including standard heat exchangers and PCM heat exchangers. The PCM heat exchangers utilized in the current study were filled up with two different types of Phase Change Materials (PCM) with melting points of 26 degrees C and 42 degrees C for geo-energy piles and walls, respectively. The thermal efficiency of the geo-energy piles/walls was experimentally assessed over 100 h of continuous operation under cycles of cooling and heating. The findings illustrated that using PCM heat exchangers led to enhancing the heat transfer efficiency of geo-energy piles by 75 % and 43 % in heating and cooling operations, respectively, compared to those achieved using a standard heat exchanger. Furthermore, the heat transfer performance of geo-energy walls with a PCM heat exchanger was enhanced by 43 % and 32 % in heating and cooling tests, respectively, compared to those achieved using a standard heat exchanger. Moreover, the findings indicated that the inclusion of PCM heat exchangers in geo-energy structures contributed to reducing: the impact on soil temperature and thermal interference radius as well as the potential structural damage due to thermal stress.

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.

Climate change, soil consumption and waste management are among the major challenges that current and future generations will have to afford. New opportunities and challenges for the building sector take advantages of sustainable materials where waste is used in place of raw matter. This paper presents results of an experimental study in which different combinations of straw fibers with lime putty have been investigated to develop innovative materials. Both lime and straw are natural, renewable resources, contributing to sustainable building practices. The use of lime putty, which can be produced locally, together with straw, an agricultural by-product, contributes to reduce the carbon footprint associated with building materials. Decreasing heat exchange through buildings allow to achieve a better indoor comfort. Insulating properties of lime putty-straw materials have been tested to characterize and compare the experimental materials with traditional and existing one. Furthermore, mechanical properties under compressions were investigated evidencing how these materials have enough strength to be conveniently employed as base floor. The study finally aims at responding to current challenges in the transition towards low environmental impact processes, showing a potential way to produce low carbon emission buildings.