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CONCRETE TECHNOLOGY22 CPI %u2013 Concrete Plant International %u2013 4 | 2025 www.cpi-worldwide.commix, while the air content (as well as the density) in the M1 mix remained comparable to that of the M0 mix. After 28 days of curing, both WBA-containing mixes demonstrated compressive strengths approximately 30% lower than the reference mix. Despite the elevated water absorption of concrete with WBA, all mixes complied with the water absorption limit of 6% as specified in EN 1340:2004/AC:2007. Furthermore, all mixes passed the freeze-thaw and salt resistance tests %u2013 defined by an average peel value of 0.5 kg/m%u00b2 after 56 cycles %u2013 satisfying the requirements of exposure class XF4. Notably, the higher porosity of the M2 mix likely contributed to its improved freeze-thaw and salt resistance performance.Previous studies [12, 13] have demonstrated that the size and distribution of WBA particles, along with factors such as loss on ignition (LOI), sulphate content, magnesium oxide, free CaO, and the sum of pozzolanic oxides, can prominently alter the properties of concrete. These factors highlight the need for pre-treatment of the ash and guide its potential applications, such as its use as a partial replacement for cement or aggregates. Additionally, they influence the determination of the optimal proportions needed to achieve the desired concrete strength and exposure class. In some cases, simple methods such as sieving and grinding can effectively remove impurities from the ash, thereby enhancing its performance in concrete.In addition to serving as partial replacements for cement in concrete and blended cement formulations, the use of WBA and SSA as partial substitutes for fine aggregates is being systematically examined. Figure 3 presents samples of precast concrete pavement elements, where fly WBA has been utilized in the production of a novel WBA-blended cement (Figure 3(a)), and SSA has been used as a substitute for a portion of the fine aggregate (Figure 3(b)).ConclusionThe production of reduced-clinker cements is now within reach, as blended cements that comply with existing standards are already commercially available. However, the cement industry faces significant challenges, particularly in the availability of reliable clinker substitutes and the technical limitations tied to selecting cement types based on the specific conditions and exposure class requirements they must endure. Additionally, pre-treatment is often required for supplementary waste materials to improve their compatibility with intended applications. While technologies for pre-treatTable 1: Results of preliminary studies on the use of ash from wood biomass in concrete as a partial replacement of cement [11]Property Standard Mix IDM0 M1 M2Consistency %u2013 slump test (mm) EN 12350%u20132:2019 230 140 170Density (kg/m%u00b3) EN 12350%u20136:2019 2340 2310 2110Temperature (%u00b0C) EN 12350%u20131:2019 28.5 31.0 31.2Air content (%) EN 12350%u20137:2019 4.9 4.4 9.7Compressive strength after 1 day (MPa) EN 12390%u20133:2019 37.8 29.1 20.5Compressive strength after 28 days (MPa) EN 12390%u20133:2019 51.3 34.2 33.1Water absorption (%) EN 1340:2004/AC:2007 4.2 5.0 5.8Freeze-thaw resistance with de-icing salts (56 cycles) CEN/TS 12390%u20139:2016 0.03 0.37 0.05Fig. 3: Precast concrete pavement elements industrial production: (a) Pavers with WBA-blended cement; (b) Pavers with SSA as partial aggregate substitute.a) b)