Akademik Veri Yönetim Sistemi
2nd International Eurasian Conference on Science, Engineering and Technology (EurasianSciEnTech 2020), Gaziantep, Türkiye, 7 - 10 Ekim 2020, ss.2
The state of Qatar has been reported as one of the countries which have the highest cement consumption per capita due to rapid growth in construction and infrastructure works. The sustainable construction industry has been looking for alternative supplementary cementitious materials to reduce the cement consumption. In this study, a detailed chemical, physical and mineralogical characterization of the solid residues, i.e. boiler ash (BA) and residue ash (RA), from the Qatar’s domestic waste incinerator is examined. Three different batches of mortar are manufactured: one is the control without ash, second is the mortar with BA, and third is the mortar with RA. Cement replacement by ash in the second and third batches is kept at 10, 20 and 30% by cement weight. The influence of these ashes on workability, setting time, strength, and durability is investigated.
The observations by SEM clearly showed that both ashes are inhomogeneous, non-spherical, porous and vesicular. Boiler ash contains more coarse particles than RA. Chemical composition, also in line with the particle size distribution, indicates higher unburned carbon content in BA. Moreover, both ashes are found to be enriched in calcium. However XRD analyses indicates that most of the calcium is present in the crystalline phase and not available for hydration. The amount of silicates, aluminates, and iron oxide is very low in RA, and is found to decrease its pozzolanic reactivity. Higher amounts of silicates, aluminates, and iron oxide in BA resulted in higher pozzolanic activity and improved the strength gain of PC-BA mortars with curing. In terms of compressive strength and permeability properties, the optimum mixing ratios for BA and RA is 20% and 10%, respectively. These mortars can be suitable for many nonstructural applications such as basement, floor and low force structures.