Environmentally Friendly Masonry Mortar Blended with Fly Ash, Corn Cob Ash or Ceramic Waste Powder.

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.

Effects of Grinding Methods and Water-to-Binder Ratio on the Properties of Cement Mortars Blended with Biomass Ash and Ceramic Powder.

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.

Reactivity and Pozzolanic Properties of Biomass Ashes Generated by Wheat and Soybean Straw Combustion.

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.

Aggregates Obtained by Alkali Activation of Fly Ash: The Effect of Granulation, Pelletization Methods and Curing Regimes.

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.

Monitoring of water content in building materials using a wireless passive sensor.

This paper describes an innovative design of a wireless, passive LC sensor and its application for monitoring of water content in building materials. The sensor was embedded in test material samples so that the internal water content of the samples could be measured with an antenna by tracking the changes in the sensor's resonant frequency. Since the dielectric constant of water was much higher compared with that of the test samples, the presence of water in the samples increased the capacitance of the LC circuit, thus decreasing the sensor's resonant frequency. The sensor is made up of a printed circuit board in one metal layer and water content has been determined for clay brick and autoclaved aerated concrete block, both widely used construction materials. Measurements were conducted at room temperature using a HP-4194A Impedance/Gain-Phase Analyzer instrument.