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

Abstract

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.

Sustainable Masonry Mortars with Fly Ash, Blast Furnace Granulated Slag and Wheat Straw Ash

“…Although biomass makes up 61% of the total potential of RES in Serbia, its usage rate for energy purposes is still not more than two percent. However, growing amounts of biomass ash are created as waste products during its combustion, estimated at five thousand tons per year [5,6]. They are most commonly disposed of in landfills or recycled on agricultural fields.…”

Biomass Bottom Ash as Supplementary Cementitious Material: The Effect of Mechanochemical Pre-Treatment and Mineral Carbonation

“…Similar results have been reported by [ 23 ], who found that mechanochemical activation improved the reactivity of the biomass fly ash, resulting in strength comparable to that of the reference for 5–15% cement replacement. The combination of mechanochemical activation with other treatments that have been reported to enhance the performance of biomass ash in cement-based materials, such as the removal of lightweight particles by floatation [ 29 ] and the addition of silica fume during the milling process [ 38 ], is worthy of further investigation for obtaining higher strength composites.…”

“…At these levels of substitution, the filling effect of the biomass ash, as well as its potential hydraulic and/or pozzolanic activity, has been found to counteract the dilution effect, resulting in adequate or enhanced strength performances. Pre-treatment of the biomass ash—including water washing [ 24 , 34 ], mechanical and chemical activation [ 23 , 38 ], heating, and removal of organic matter [ 29 ]—has been proven effective for improving the reactivity of the ash and thus the mechanical performance of biomass-ash-modified cementitious composites. It should be noted that the majority of the abovementioned studies concerned the utilization of BFA [ 18 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 31 , 33 , 34 , 35 ] in cement composites, and only a few focused on BBA [ 18 , 20 , 29 , 30 , 39 ].…”

Characterization of harvest residues ashes and ceramic waste powders originating from Vojvodina as potential supplementary cementitious materials

“…Several researchers have introduced agricultural wastes, in form of ash, as a partial replacement of cement or as an alkaline activator including rice husk ash (RHA) [1], olive waste ash (OWA) [2], sugar cane bagasse ash (SCBA) [3], corn cob ash (CCA) [4], palm oil fuel ash (POFA) [5], wheat straw ash (WSA) [6], soya straw ash (SSA) [7], almond shell ash (ASA) [8], cornstalk ash (CSA) [9], barley straw ash (BSA) [10], etc.…”