Environmental effects of concretes produced from partial replacement of cement and sand with coal ash were investigated. Oxide composition of coal ash and cement was determined with X-ray fluorescence spectrometer, while particle size and shape were determined using scanning electron microscope. Concrete mixtures were produced by replacing cement and sand with coal ash at 10, 20, 30 and 40%. Their workability, setting times and compressive strengths were obtained using iron cube mold, Vicat apparatus and compression testing machine, respectively. Biochemical oxygen demand (BOD) and pH of curing water were analyzed. Pollution potential of the cement and concretes produced by partially replacing cement with coal ash was evaluated using CO₂ emission simulation. Concretes in which sand was replaced with coal ash (CAS) had better slumps and compressive strengths than those in which cement was replaced with coal ash (CAC). Setting times increased as more coal ash was added but were lower for CAS. BOD analysis of curing water showed it was safe for livestock consumption and body contact during recreational use. CO₂ emissions and concrete carbonation analysis showed blending of cement with coal ash reduced emissions which ranged from 0.22 to 0.33 kg but was 0.37 kg in conventional concrete. CAC-40:60 had the lowest emission of CO₂ from cement. CO₂ uptake after 50-year service life showed that CAC-30:70 had the highest absorption-to-emission ratio of 38.5%. Secondary application of coal ash in concrete production should be encouraged as concretes of similar strengths were obtained with reduction in environmental pollution.

中文翻译：

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用煤灰部分代替水泥和砂子生产的混凝土对环境的影响

研究了用煤灰部分替代水泥和沙子所产生的混凝土的环境影响。用X射线荧光光谱仪测定煤灰和水泥的氧化物组成，而用扫描电子显微镜测定粒径和形状。通过用10％，20％，30％和40％的煤灰代替水泥和沙子来生产混凝土混合物。它们的可加工性，凝固时间和抗压强度分别是使用铁立方模具，Vicat仪器和压缩试验机获得的。分析了生化需氧量（BOD）和固化水的pH值。使用CO ₂评价了用煤灰部分代替水泥生产的水泥和混凝土的污染潜力排放模拟。用煤灰（CAS）代替沙子的混凝土比用煤灰（CAC）代替水泥的混凝土具有更好的坍落度和抗压强度。凝结时间随着加入更多的煤灰而增加，但对于CAS则更短。生化需氧量的BOD分析表明，它在牲畜娱乐活动中食用和接触身体都是安全的。CO ₂排放量和混凝土碳化分析表明，水泥与煤灰的掺混减少了排放量，范围为0.22至0.33 kg，但在常规混凝土中为0.37 kg。CAC-40：60的水泥中CO ₂排放最低。一氧化碳₂50年使用寿命后的吸收表明，CAC-30：70的最高吸收/发射比为38.5％。应鼓励粉煤灰在混凝土生产中的二次应用，因为获得了具有类似强度的混凝土，同时减少了环境污染。