The increasing demand for high-strength lightweight concrete (HSLWC) with excellent mechanical properties has inspired the development of nanomaterials in fundamentally solving brittleness and cracking. This work investigated the effects of graphene oxide (GO) on the mechanical properties and microstructure of HSLWC, including the workability, density, compressive strength in different curing regimes, splitting tensile strength, flexural strength, modulus of elasticity and scanning electron microscopy (SEM). Six groups of mixtures were mixed with GO aqueous solution at a dosage of 0.00%, 0.02%, 0.04%, 0.05%, 0.06%, and 0.08% by weight of cement, respectively, and dispersed by ultrasound for 30 min. The test results showed that adding a low volume of GO to the specimens could slightly increase the density, rationally reduce the slump, and significantly improve the mechanical properties. The maximum increase in compressive strength, splitting tensile strength, modulus of elasticity and flexural strength of HSLWC with GO at 28 days was by 24%, 17%, 15%, 20%, respectively, as compared with HSLWC without GO. Simultaneously, the SEM results showed that GO could not only fill nano-scale pores, but also regulate the formation and growth of flower-like crystals, which was an important factor for the further improvement of properties. The research results provided a potential new pathway to improve the mechanical properties of HSLWC.

An effective pathway to achieve the sustainable development of resources and environmental protection is to utilize shale ceramsite (SC), which is processed from shale spoil to produce high-strength lightweight concrete (HSLWC). Furthermore, the urgent demand for better performance of HSLWC has stimulated active research on graphene oxide (GO) in strengthening mechanical properties and durability. This study was an effort to investigate the effect of different contents of GO on HSLWC manufactured from SC. For this purpose, six mixtures containing GO in the range of 0–0.08% (by weight of cement) were systematically designed to test the mechanical properties (compressive strength, flexural strength, and splitting tensile strength), durability (chloride penetration resistance, freezing–thawing resistance, and sulfate attack resistance), and microstructure. The experimental results showed that the optimum amount of 0.05% GO can maximize the compressive strength, flexural strength, and splitting tensile strength by 20.1%, 34.3%, and 24.2%, respectively, and exhibited excellent chloride penetration resistance, freezing–thawing resistance, and sulfate attack resistance. Note that when the addition of GO was relatively high, the performance improvement in HSLWC as attenuated instead. Therefore, based on the comprehensive analysis of microstructure, the optimal addition level of GO to achieve the best mechanical properties and durability of HSLWC is considered to be 0.05%. These findings can provide a new method for the use of SC in engineering.

This study investigated the effects of incorporating carbon nanotubes (CNTs) into rice husk ash (RHA) sustainable concrete on its mechanical properties, permeability and microstructure characterisation. Mechanical test results suggested that the addition of 0.10 % multiwalled CNTs (MWCNTs) yielded optimal results, with increases in the compressive strength, splitting tensile strength, flexural strength, and elastic modulus of the RHA concrete at 28 days of 7 %, 23.81 %, 17.5 %, and 1.0 %, respectively. However, with further addition of MWCNTs, the mechanical properties ultimately deteriorated. Further, the incorporation of CNTs enhanced the long-term performance of RHA sustainable concrete. The addition of 0.1 % MWCNTs and 15 % RHA yielded a 20 %, 14 %, and 66 % decrease in water absorption, porosity, and chloride diffusion coefficient compared to the mixture solely containing 15 % RHA. Scanning electron microscopy of this mixture revealed the filling and bridging effects of MWCNTs between the hydration products have enhanced the performance of RHA sustainable concrete.

The environmental issues in the construction industry have garnered considerable attention in numerous studies. Ecologically sustainable green concrete addresses environmental challenges in the construction industry. This study investigates the impact of multi-walled carbon nanotubes (0–0.20%) in rice husk ash (15%) concrete to replace Portland cement. The mechanical and durability properties of four concrete mixtures were analysed. Adding 0.1% multi-walled carbon nanotubes and 15% rice husk ash yielded satisfactory results, significantly improving durability compared to concrete without multi-walled carbon nanotubes. With the addition of 0.1–0.2% multi-walled carbon nanotubes, the density and elastic modulus increased, the 28-d sorptivity decreased by 4.64–28.76%. The resistance ability of 111-d mass loss and compressive strength loss increased by 50.93–61.71% and 25.28–48.47% under sulphate attack, respectively. The resistance ability of mass loss increased by 3.7–35.97% under acid attack. And 120-d drying shrinkage resistance improved by 3.08–9.23%. The predicted and experimental results were compared using the Sakata, GL 2000, B3, ACI 209, and CEB-FIP models. Sakata and B3 provided the most accurate early-stage and long-term drying shrinkages with variation coefficients of 0.13–0.33 and 0–0.05, respectively. Moreover, the sustainability of rice husk ash concrete containing multi-walled carbon nanotubes was evaluated, and its environmental friendliness was confirmed. Thus, the viability of multi-walled carbon nanotubes in rice husk ash sustainable concrete significantly contributes to sustainable construction.

The direct CO₂ emissions of the cement production industry have increased significantly, accounting for approximately 7% of the CO₂ emissions. Rice husk ash (RHA), an agricultural byproduct, has gained substantial interest as a commonly used supplementary cementitious materials (SCMs) and shows potential application in concrete. This study comprehensively examines existing literature on ternary and quaternary cementitious composites mixed with RHA, providing a detailed overview of their mechanical properties, durability, and CO₂ emissions. Analysis shows that the use of combinations of RHA and other materials as SCMs improves the mechanical and durability properties of cementitious composites and reduces CO₂ emissions during concrete production when compared with that of replacing aggregates. Specifically, the synergistic use of RHA and olive waste ash increases compressive strength by 58.7%, and the synergistic use of RHA and steel fiber increases flexural strength by 78.4%. The combination of RHA, steel fiber, and waste marble powder increases splitting tensile strength by 96.5%, and the synergistic use of RHA and bacteria increases water absorption resistance by 69% and chloride resistance by 83%. The combination of RHA and bacteria increases permeability resistance by 83%. Furthermore, the synergistic use of RHA and nano-CuO also increases permeability resistance by 51.88%. Finally, the synergistic use of RHA and fly ash achieves the optimal reduction in CO₂ emissions. Consequently, considering the challenges of global warming and climate change, this comprehensive review can be a reference for further exploring the utilization of RHA in building materials.