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The rising demand for ultra-high-performance concrete (UHPC) necessitates innovations in sustainable materials. This study explores the substitution of ordinary Portland cement (OPC) with thermally and mechanically activated nano-kaolin in varying proportions from 0.5 to 0.25%. A uniform quantity of double-hooked end steel fibers was added to all the mixes. Activated nano-kaolin variants showed significant enhancement in UHPC properties. Specifically, UHPC with 0.20% thermally activated kaolin (B3-TAK-20) exhibited a 21.6% increase in compressive strength and a 25.5% increase in modulus of elasticity at 90 days, with the modulus of rupture doubling compared to the reference mix. These improvements are attributed to the amorphous nature of thermally activated nano-kaolin, resulting in a denser concrete matrix and reduced porosity. Beyond the optimal 0.20% kaolin replacement, an increase to 0.25% diminished compressive strength. Durability tests showed enhanced acid resistance, with only a 6.7% mass loss for the thermally activated nano-kaolin mix and a consistent reduction in water absorption by 14.4% as kaolin proportions increased from 0.5 to 0.25%. The study also noted a decrease in water absorption by 22.9 and 12.3% at 56 and 90 days, respectively, indicating the thermally activated nano-kaolin’s enhanced performance. This research underscores the potential of activated kaolin as a viable alternative to OPC, paving the way for more sustainable UHPC production.

Foam concrete or foamcrete is a lightweight, porous material with a wide range of applications in the construction domain. This article focused on reviewing porosity, thermal conductivity, acoustic properties, compressive strength (f c′), elastic modulus (E), flexural strength (f y), stability, resistance to hostile environments, density, and fire resistance of foam concrete. A systematic literature analysis was conducted to identify relevant research trends on foam concrete. The challenges and limitations of foam concrete research were highlighted, including the lack of standardized testing methods and the need for more research on the long-term durability and structural performance of foam concrete. The analysis of the literature data revealed that there had been a growing interest in foamcrete research over the past decade. Foam concrete may be utilized in several construction applications due to its adaptability and wide range of uses. Its potential uses can be increased by developing new manufacturing methods and the inclusion of certain admixtures. The present research has the potential to be advantageous for scholars interested in collaborative advancement and the exchange of novel tactics and concepts, owing to the visual and statistical representation of the regions/countries and researchers that have contributed.

Utilizing waste materials to produce sustainable concrete has substantial environmental implications. Furthermore, understanding the exceptional durability performance of ultra-high-performance concrete can minimize environmental impacts and retrofitting costs associated with structures. This study presents a systematic experimental investigation of eco-friendly ultra-high-performance self-compacting basalt fiber (BF)-reinforced concrete by incorporating waste nanomaterials, namely nano-wheat straw ash (NWSA), nano-sesame stalk ash (NSSA), and nano-cotton stalk ash (NCSA), as partial substitutes for Portland cement. The research evaluates the effects of varying dosages of nanomaterials (ranging from 5 to 15% as cement replacements) in the presence of BFs. Rheological properties were analyzed, including flow diameter, L-box, and V-funnel tests. Additionally, the study investigated compressive, splitting tensile, and flexural strengths, load-displacement behavior, ultrasonic pulse velocity, and durability performance of the ultra-high-performance self-compacting basalt fiber (BF)-reinforced concrete (UHPSCFRC) samples subjected to sulfate attack, freeze-thaw cycles, autogenous shrinkage, and exposure to temperatures of 150, 300, 450, and 600°C. Microstructural characteristics of the mixtures were examined using X-ray diffraction (XRD) analysis. The findings reveal that self-compacting properties can be achieved in the UHPSCFRC by incorporating NWSA, NSSA, and NCSA. The presence of 10% NWSA significantly improved the mechanical properties of the UHPSCFRC, exhibiting more than 27.55% increase in compressive strength, 17.36% increase in splitting tensile strength, and 21.5% increase in flexural strength compared to the control sample. The UHPSCFRC sample with 10% NWSA demonstrated superior performance across all extreme durability tests, surpassing both the control and other modified samples. XRD analysis revealed the development of microcracking at temperatures of 450 and 600°C due to the evaporation of absorbed and capillary water and the decomposition of ettringites.

Concrete is the most frequently employed man-made material in modern building construction. Nevertheless, the serviceability of concrete structures has been significantly reduced owing to a variety of durability issues, especially when serving in a non-ideal environment and exposed to internal/external attacks such as chloride penetration, carbonation, sulfate, and so on. Several scholars have performed numerous studies on the strength and microstructure features of volcanic ash (VA) concrete and have discovered encouraging findings. However, since the information is spread, readers find it difficult to evaluate the benefits of VA-based concrete, limiting its applicability. As a result, a detailed study is required that offers the reader an easy approach and highlights all essential facts. The goal of this article (Part Ц) is to conduct a compressive review of the physical and chemical aspects of VA and its impact on concrete durability and microstructure properties. The findings demonstrate that VA considerably improves concrete durability owing to pozzolanic reaction and micro-filling voids in concrete materials. Cost–benefit analysis shows that 10% utilization of VA as cement decreased the overall cost by 30%. The assessment also notes a research gap that must be filled before VA may be utilized in practice.

This study thoroughly reviews the recent design methods for ultra-high-performance concrete (UHPC) with agricultural waste. The goal is to identify UHPC composites that meets environmental sustainability requirements while fulfilling workability, durability, and mechanical properties. The capacity of typical review studies is limited in bridging the various literature aspects systematically. The article includes comparative analyses identifying these methods’ intrinsic connections and current trends. The analysis indicates that 71% of documents on incorporating agricultural waste into UHPC are in the “Engineering” and “Materials Science” disciplines, with 69% being journal articles, and 27% conference documents. Significant research keywords involve “Ultra-High-Performance Concrete,” “Cements,” “Sustainable Development,” and “Agricultural Wastes,” highlighting the extensive exploration of agricultural waste in UHPC. It has been discovered that agricultural waste can replace silica fume in UHPC, improving strength and durability by reducing pore volume and enhancing microstructure. Substituting 5–30% of cement with rice husk ash significantly boosts compressive strength, enhancing cement hydration, pore structure, and pozzolanic reaction, offering substantial environmental benefits and supporting the construction industry’s contribution to low-carbon sustainable development. This article provides guidance and recommendations for developing sustainable UHPC to meet diverse design specifications, promoting environmentally friendly construction practices.

The construction sector has been under growing public attention recently as one of the leading causes of climate change and its detrimental effects on local communities. In this regard, geopolymer concrete (GPC) has been proposed as a replacement for conventional concrete. Predicting the concrete’s strength before pouring is, therefore, quite useful. The mechanical strength of slag and corncob ash (SCA–GPC), a GPC made from slag and corncob ash, was predicted utilizing multi-expression programming (MEP). Modeling parameters’ relative importance was determined using sensitivity analysis. When estimating the compressive, flexural, and split tensile strengths of SCA–GPC with MEP, 0.95, 0.93, and 0.92 R 2-values were noted between the target and predicted results. The developed models were validated using statistical tests for error and efficiency. The sensitivity analysis revealed that within the mix proportions, the slag quantity (65%), curing age (25%), and fine aggregate (3.30%) quantity significantly influenced the mechanical strength of SCA–GPC. The MEP models result in distinct empirical equations for the strength characteristics of SCA–GPC, unlike Python-based models, which might aid industry and researchers worldwide in determining optimal mix design proportions, thus eliminating unneeded test repetitions in the laboratory.

The paper industry is one of the biggest sources of trash and stands out for its effects on both human health and ecological harmony. However, these waste could also help the building sector become more ecologically friendly. Beyond ecological considerations, modern construction often requires materials to make concrete durable, resisting heavy loads and less harmful environmental influences. This creates opportunities for waste management and practical application. This review provides a detail overview of eco-friendly construction ideas that deal with the practical use of materials that are often discarded (paper pulp ash). The impact they had on the characteristics of the construction material, the best mixture composition, and a discussion of the benefits and drawbacks of the “green” addition received the majority of the attention (paper pulp ash). The essential concrete properties such as consistency, setting time, flowability, compressive strength, flexural strength, tensile strength, and impact strength are reviewed. Furthermore, the cost benefits and environmental benefits of paper pulp ash as construction materials are also discussed. The study concludes by suggesting a line of inquiry for the creation of an environmentally friendly structural material for a sustainable future.