# Teaching Characteristics of Wood Biomass Fly Ash Cement Composites
## 1 Introduction
On the other hand, authors [43] claimed that commercially available cement contains 20% substitute cement materials, including by-products from other industries (e.g., granulated blast furnace slag, fly ash from coal-fired thermal power plants, and silica fume), resulting in a cement-to-clinker ratio that is even higher. According to estimates given by [43], the use of substitute cement materials could reduce the CO\({}_{2}\) emissions from cement production by approximately 400 million tonne/year; therefore, applying WBA as a mineral admixture could contribute to the \"greening\" of the concrete industry, although there are current technical and commercial obstacles to its use [44]. When compared to the limit values according to EN 450-1 [45] for fly ash obtained from coal combustion, WBA has higher values of loss of ignition (LOI), CaO, MgO, alkali and sulphate components [6; 46]. The morphology of WBA particles is also different from coal fly ash: WBA particles have irregular shapes and are porous compared to the spherical glassified particles of coal fly ash. Therefore, WBA currently cannot be used in concrete using the recommendations given for coal fly ash [45; 46]. However, research has been further harnessed for the use of this potential supplementary cementitious materials (SCM) in the cement industry [47; 48; 49] as a tool and mitigation strategy for reducing carbon dioxide emissions associated with concrete production [50; 51; 52; 53]. Intensive studies of using WBA as a raw material in construction products have been performed [47; 54; 55], but minimal information exists in the literature regarding the ecological impact of WBA through its life cycle [22; 56]. [PERSON] et al. [22] examined the suitability of pH-dependent leaching; they performed long-term dynamic leaching tests on samples where three different WBAs were used in the cement mixture. They suggested the use of long-term dynamic leaching tests on monolithic specimens containing solid wastes in order to evaluate the environmental quality of construction materials. Using different leaching methods (EN 12457-3 and using Artificial Sweat and Gastric Fluids) research [56] showed that utilization of tested fly ashes in covered and paved structures is still possible, although an environmental permit would be required. The most extensive research where biomass fly ash was used in the cement composites was done by [57] with combination of different leaching tests (tank leaching test, parallel batch extraction test at different L/S ratios and the pH dependence leaching test) under different application scenarios (using mortar in an environment where release of substances is controlled by diffusion,evaluate a second life stage in which the material is used in a granular form and response of leaching to the change in surrounding environmental conditions). From available literature [6; 58] a large variation in the properties of local WBAs is observed depending on several factors such as the type of biomass used, the combustion technology, the temperature of the combustion and the location of the WBA collection. These variation also refer to heavy metals content in WBA samples that can present possible environmental risk [59]. Therefore, it is recommended to focus not only on a good technical performance but also on the release of contaminants in multiple life cycles of mortars that include biomass fly ash [57], which is addressed by this paper. When using WBA as a raw material in cement composites and in construction products, it is essential to determine its environmental impacts [30], which result from potentially enhanced contaminant leaching. The environmental acceptability of WBA as a potentially new raw material in the cement and concrete industry is related to the ability of the cement matrix to bind the contamination elements (in this case heavy metals) physically and chemically within the hydrate structure which should be analyzed.