A sustainable use of locally available wastes from agriculture as supplementary cementitious materials (SCMs) is an alternative solution for the prevention of excessive raw material usage, reduction of CO₂ emission and cost-effective concrete production. This paper studies the reactivity of non-traditional waste SCMs: Wheat straw ash (WSA), mixture of wheat and soybean straw ash (WSSA) and soybean straw ash (SSA), which are abundant as agricultural by-products in Serbia. The chemical evaluation using XRF technique, thermal analysis (TGA/DSC), XRD and FTIR methods were performed along with physical properties tests to investigate the feasibility of utilizing biomass ashes as cement substitutes. The obtained results demonstrate a high pozzolanic activity of WSA, which is attributed to a high reactive silica content of the ash and its satisfactory level of fineness. A wider hump in XRD pattern of WSA compared to WSSA and SSA confirmed that it abounds in amorphous (reactive) phase. The insufficient activity index of soybean-based biomass ashes, characterized with a low silica content, was improved by additional grinding and/or blending with amorphous silica-rich material. This points out the mechanical activation, i.e., grinding procedure, and chemical activation, i.e., modification of the chemical composition, as techniques efficient at producing pozzolanic materials from biomass wastes. Tested biomass ashes are characterized with negligible leaching values of heavy metals, thereby satisfying eco-friendly principles of SCM utilization. The application of biomass ashes as SCMs leads to substantial cost savings, as well as benefits to the environment, such as lower consumption of cement, reduction of CO₂ emissions during the production of cement and sustainable waste management.

As the cement industry is responsible for 7% of the global CO₂ emissions, locally and abundantly available materials are vastly valorized, and their use is assuming a significant role in this domain. Over the last few decades, significant research in the development of supplementary cementitious materials (SCMs) derived from industrial wastes, such as fly ash (FA), has been conducted. However, facing environmental pressures, coal power plants are closing across the planet. Hence there is an urgent need to identify sustainable SCMs that can replace FA in the concrete industry. Furthermore, the usage of FA in cement-based composites does not often produce satisfactory results from the aspect of certain properties, such as freeze–thaw durability. Therefore, the application of natural zeolites (NZs) for these purposes has emerged as an area of interest in the civil engineering practice. This paper presents the results of experimental research regarding the influence of NZ, as a mineral admixture, on the basic physical and mechanical properties of cement mortars, with a focus on frost resistance and drying shrinkage. The amount of NZ was varied from 10 to 30% in relation to cement mass. The findings indicate that NZ positively influences the drying shrinkage reduction regardless of the replacement level, while the best results concerning frost resistance can be achieved in cement blends with 10% NZ.

To combat environmental challenges—such as the depletion of natural resources and a high carbon footprint—and contribute to the effort of achieving zero-waste technology and sustainable development, the use of agricultural and industrial wastes in the cement industry has created a research interest. This study explores the potential of two types of harvest residue ash (HRA) and three types of ceramic waste (CP) as supplementary cementitious materials (SCMs) through: (1) the characterization of raw materials and (2) examining the physical properties and mechanical performance of cement-based mortar samples prepared with 10%, 30% and 50%wt of the selected SCMs ground into powder form as cement replacement. Two main variables were the water-to-binder ratio (w/b) and the effect of different grinding procedures. Experimental results demonstrated that flexural and compressive strengths were not significantly impaired by SCM additions of up to 50%, but higher replacement levels led to an increased permeability and higher capillary water absorption due to the dilution effect. Also, a lower w/b was shown to effectively reduce the porosity of mortar and increase its mechanical properties, allowing for higher shares of SCMs to be utilized. This study verifies the technical feasibility of cob corn ash and ceramic powder application as SCMs in mortar formulations, further promoting the practice of incorporating industrial and agricultural by-products in greener cementitious composites.

This paper presents results regarding the phase composition, microstructure and textural properties of two types of aggregates, which were prepared via crushing or pelletization of alkali-activated Class F fly ash and cured under different conditions. The alkali activator was the same for aggregate products, containing an alkaline solution consisting of 8 M NaOH and Na-silicate (8 M NaOH/Na-silicate = 1:2.5 mass ratio). The aforementioned properties were influenced by two different preparation procedures combined with varying curing regimes (under normal conditions at 20 °C, RH 40–60% for 28 and 120 days and under an accelerated regime, at 65 °C for 5 days). Aggregates were characterized using X-ray diffraction (XRD), Fourier-transform transmission infrared spectroscopy (FTIR), back scattered electron microscopy with energy dispersive spectrometer (BSE-EDS) analyses and mercury intrusion porosimetry (MIP). The results showed noteworthy structural and textural diversities between the two types of aggregate. The method of preparation and curing regime affected the formation of the N-A-S-H structure and the texture of the alkali-activated fly ash product, with the crushing method giving an advantage.

Due to greenhouse gas emissions, the production of cement clinker is considered unsustainable and many attempts are being made to replace cement with alternative materials sourced from agriculture, industry and other urban practices, such as construction and demolition works. The aim of this paper is to analyze the effects of cement substitution by locally available waste materials in Serbia, such as fly ash (FA), blast furnace granulated slag (BFGS) and wheat straw ash (WSA), up to the 50% replacement volume rate in cement–lime mortars. As the effective application of supplementary cementitious materials (SCMs) in cement-based materials requires a comprehensive insight into their properties, a characterization of materials involving all relevant physical, chemical and mechanical tests is conducted. Ten different mortar mixed with ingredients of a volume ratio 1:2:4 (cementitious powder/lime/sand) were designed and their consistency, bulk density, capillary water absorption, flexural strength, compressive strength and thermal analysis (TGA/DTA) results were examined to determine the influence of the abovementioned SCMs on mortar properties. Research findings highlight the possibility of replacing cement with slag (50%), fly ash (30%) or wheat straw ash (30%) while maintaining its performance and improving the economic and environmental impacts of masonry mortar production.

Implementing a circular approach through waste valorization in mortar production with environmentally efficient mix design is a viable pathway for relieving the ecological burden of greenhouse gas emissions, resource depletion and waste management. The main objective of this paper is to evaluate the feasibility of using fly ash (FA), corn cob ash (CCA), and ceramic waste powder (CWP) as supplementary cementitious materials (SCM) in cement–lime masonry mortars. As part of an extensive experimental study, twelve mortar mixtures were made: three reference and nine blended, with mixing ratios of 1:1:5, 1:0.7:4.2, and 1:1:4 ((cement + SCM)/lime/sand), by volume. The examined properties include workability, compressive and flexural strengths, dry bulk density, capillary water absorption, adhesive bond strength, and water vapor permeability. The compressive and flexural strengths of tested mortars were notably impaired, with reductions of up to 60%, while the capillary water absorption coefficient rose by 100% compared to the reference values. The adhesive bond strength of some blended mortars exceeded the strength of the reference mortars. Nevertheless, all blended mortars fulfilled the requirements for general-purpose mortars, while the majority met the criteria for structural masonry applications. In addition, a performance-based index and weighting triangle were used for the comparison and ranking of all analyzed mortar mixtures. The findings of this study may herald a novel use of FA, CCA, and CWP as more eco-friendly binding materials in contemporary construction leading to the reduction in the process’s carbon footprint, the improvement in cost efficiency, and the mitigation of the detrimental environmental impact of waste disposal.