An attempt to shed light on the use of agro-industrial-based wastes as supplementary cementitious material (SCM) or as alkali-activated binder (AAB) material is mainly focused in this review paper. The SCM or AAB acts as a suitable replacement for cement, as the cement manufacturing tends to contribute to 8–10% of global CO₂ emissions. To gain acceptability in the construction industry, diverse agro-industrial-based wastes must demonstrate their potential as precursors in AAB or as SCM. The binder materials discussed among the agricultural wastes are rice husk ash, olive waste ash, and coconut-based waste ash, and the industrial wastes are ground granulated blast furnace slag, fly ash, and ultra-fine steel slag. The paper also analyses the effects of calcined and uncalcined agro-industrial-based wastes on pozzolanic properties of binder system. It is clear from the studies that the calcined wastes tend to provide greater reactivity compared to the uncalcined wastes, that helps in early strength development in the binder system. The review findings indicate that the agro-industrial-based wastes provide pozzolanic and hydraulic properties, thereby making them suitable as an AAB or as a SCM.

Self-healing concrete is an innovative solution to improve durability issues in traditional concrete structures. The review focuses on a novel approach in self-healing concrete technology by partially replacing cement with agro-industrial waste, which has received less attention in existing literature. The use of agro-industrial waste aims at increasing the environmental sustainability of concrete production, it also introduces unique properties that contribute to the self-healing process. The literature of various agro-industrial waste materials like coffee husk ash (CHA), rice husk ash (RHA), sugarcane bagasse ash (SCBA), fly ash, and ground granulated blast furnace slag (GGBS), as a potential replacement for cement. The waste materials that act as supplementary cementitious materials and possess inherent healing properties due to their chemical composition. To evaluate the processes governing this precipitation, this paper discusses the impact of incorporating agro-industrial waste on bacterial concrete's mechanical, durability, and self-healing performance. The present work sheds a light on various factors of bacterial concrete such as types of bacteria and dosage, mix proportion and the outcome of mechanical and durability tests. Furthermore, the study emphasizes the need for comprehensive investigations on self-healing concrete's long-term performance and scalability with agro-industrial waste. The limited availability of studies on use for future research to explore deeper into the connection between agro-industrial waste and self-healing concrete, opening the door to more durable and sustainable building materials. Graphical abstract

The task of turning agricultural waste into practical construction and building materials has been placed before civil engineers. Coffee husk is produced in vast amounts due to the global commerce of coffee beans, which are incinerated into ash when used as fuel, producing coffee husk ash (CHA). Even though many researchers have worked on the utilization of CHA in concrete, they have been used as partial cement replacement but not as a replacement of aggregates. The experimental study of the performance of concrete on fine aggregate replaced partially with CHA is represented in this paper. The fine aggregate is replaced by 0%, 2%, 4%, 6%, and 8% by weight of CHA. The performance of the partially replaced fine aggregate with CHA is reviewed by considering the compressive strength and workability of fresh concrete and the splitting tensile strength, flexural strength, durability under acid and alkaline media, thermal conductivity, and rapid chloride permeability test of hardened concrete. The results indicate that the partial replacement of fine aggregate with 4% of CHA (CHA04) in concrete provides a positive impact to all the selected performance parameters. The compressive strength, flexural strength, and splitting tensile of the CHA04 mix were 43.4 MPa, 3.7 MPa, and 2.44 MPa, respectively, which were 28.4%, 19.35%, and 1.66%, respectively, greater than normal concrete mix (CHA00). Even the study of acid and alkaline attack on the CHA04 mix showed lesser strength reduction as compared to other mixes. The RCPT showed less chloride permeability, and the thermal conductivity is higher for CHA04, indicating lesser voids compared to other mixes. With the help of this investigation, it can be said that fine aggregate replacement with 4% CHA has the best strength and durability properties compared to regular concrete.

Present research involves determining the effects of a proposed novel nano-silica prioritized-steam-treated recycled concrete aggregate (RCA) on microstructural, mechanical, and durability aspects of concrete incorporated with waste ceramic powder (WCP). The study on novel nano-silica prioritized-steam-treated recycled concrete aggregate revealed that 3% nano-silica induction with 3-h steam treatment for 50% adhered mortar bonded RCA performed optimally. The physical characterization of treated RCA showed improvement compared to untreated RCA, which was confirmed by microstructure study indicating the formation of additional calcium silicate hydrates in the bonded adhered mortar of treated RCA. Furthermore, as WCP has significant contents of alumina and silica, an optimum ternary binder mix was developed with cement, fly ash, and WCP. Later, a study was performed to analyse the performance of treated RCA incorporated in WCP prioritized concrete mix. The mechanical performance of WCP prioritized concrete with treated RCA was investigated through compressive strength, flexural strength, split tensile strength, and modulus of elasticity. The quality was ensured through ultrasonic pulse velocity, water absorption, and density characterization. The durability of concrete was studied with 5% concentrated hydrochloric acid attack and sea water (pH = 8.3 to 8.7) exposure conditions for a duration of 148 days (including 28 days of portable water curing period). Overall, 30% of the ternary mixture based on WCP prioritization, 50% adhere mortar-based RCA, and 3% of nano-silica prioritization steam treatment (3 h) demonstrated the best performance in terms of both mechanical and durability aspects. The study concluded that due to its improved performance, the innovative nano-silica priority steam treatment approach could replace 100% of RCA in concrete. Furthermore, treated RCA being advantageous because of easy adoptable technique for real-time practices as well as maintaining consistency regards RCA characteristics throughout concrete mixture be the challenge.