This research addressed the recycling of cement kiln dust (CKD), a by-product of cement manufacturing. While significant quantities of CKD are generated every year, its utilization in construction has been to this day quite limited. Additionally, the issue of reusing already landfilled CKD has remained almost completely unexplored. The work made use of three fresh CKDs collected at different instances from the same U.S. plant, as well as CKD obtained from different locations in a 12 year old landfill adjacent to the plant. A comprehensive experimental study of the physio-chemical and engineering properties of the CKDs was performed, and the results compared to published data for other CKDs. Differences in the free lime content were observed between different batches of the fresh CKD and were ascribed to changes implemented to the cement plant. Tests performed on the landfilled CKD showed very consistent characteristics and the presence of only traces of free lime. A distinct characteristic of both CKDs is the small particle size (85--95% 10mum). There exist, however, marked differences in particle morphology between the fresh and the landfilled CKD, which have a significant impact on the engineering properties. Hence, the study highlights the potential impact of chemical alteration processes on the properties of reactive byproducts when exposed to the environment in a disposal site. Based on the results of the characterization study, several potential applications for the CKDs were identified. Two of these: soil improvement and controlled low strength materials (CLSM) were selected for additional work. In investigating the use of CKD for soil improvement, only one fresh CKD was found to be sufficiently reactive (thanks to presence of free lime). The results for the other fresh and the landfilled CKD suggest that these materials may be used in combination with limited amounts of Portland cement to treat wet subgrades or water-logged areas. The viability of using the low free lime fresh and landfilled CKDs was assessed through comparison of the fresh and hardened properties to those of fly-ash based mixtures. While all CKD mixtures displayed excellent flow properties, only those manufactured with the highest cement dosage considered (50 kg/m3) had setting times and strength compatible with their practical use in the field.
展开▼
机译：这项研究涉及水泥生产的副产品水泥窑粉尘（CKD）的回收。尽管每年都会产生大量的CKD，但迄今为止，其在建筑中的利用仍然非常有限。此外，重用已经填埋的CKD的问题几乎还没有被探索。该工作利用了从同一美国工厂在不同情况下收集的三个新鲜CKD，以及从该工厂附近具有12年历史的垃圾填埋场中不同地点获得的CKD。进行了CKD的理化和工程特性的综合实验研究，并将结果与其他CKD的公开数据进行了比较。在不同批次的新鲜CKD之间观察到游离石灰含量的差异，这归因于水泥厂实施的变更。在垃圾填埋场CKD上进行的测试显示出非常一致的特性，并且仅存在痕量的游离石灰。两种CKD的显着特征是粒径小（85--95％<10微米）。但是，新鲜和填埋的CKD在颗粒形态上存在明显差异，这对工程性能有重大影响。因此，这项研究强调了化学改造过程在处置场所暴露于环境时对反应性副产物的性质的潜在影响。根据表征研究的结果，确定了CKD的几种潜在应用。其中两项：土壤改良和受控低强度材料（CLSM）被选作其他工作。在研究使用CKD改良土壤时，仅发现一种新鲜的CKD具有足够的反应性（由于存在游离石灰）。其他新鲜和填埋的CKD的结果表明，这些材料可与有限量的波特兰水泥结合使用，以处理潮湿的路基或水淹地区。通过将新鲜和硬化性能与飞灰基混合物的性能进行比较，评估了使用低游离石灰新鲜和填埋的CKD的可行性。尽管所有CKD混合物均显示出优异的流动性，但只有那些考虑使用最高水泥用量（50 kg / m3）的混合物，其凝固时间和强度才能与它们在该领域的实际使用相兼容。
展开▼
