The aim of the research is analyzing the feasibility of rapid quality evaluation method for fly ash(FA) fineness using hydrometer and mass cylinder considering the FA acceptance investigation at ready mixed concrete plant. Furthermore, in this research, depending on various qualities of FA, the influence on engineering properties of cement mortar are evaluated and the results can be summarized as follow.
1) Regarding the evaluation method, it is known that the optimum capacity of mass cylinder is 1 000 cc with the FA quantity of 100 g, and the number of required shaking is 15 times. According to the influence factors evaluation results, the temperature of water and sample should be 20℃ for the highest reliability. From the feasibility analysis of rapid evaluation test method depending on FA fineness with different degrees of refining, the possibility of FA quality evaluation is proved with a high correlation between FA fineness and density of suspension. At this time, the measuring timing of the density is at 3 minutes for optimum.
2) As a reliability evaluation of FA specification, the density, fineness, and loss on ignition values are related with density of the suspension, among them, the fineness shows the most desirable relationship with suspension density. Additionally, based on the verification study with the former research, the actual FA supplied ready mixed concrete plant showed similar fineness results with raw coal ash due to the Blaine test differences or missed refining process.
3) Depending on various qualities of coal ash, for fresh state mortar, refined fly ash(Rf) showed higher flow result than raw coal ash(Ra), and the degree of difference showed the highest at 1:1 mortar mix design. In the case of air content, for all mortar mix conditions, similar trend is shown, and only Rf and reject coal ash(Rj) showed satisfied results of air content. Regarding the compressive strength result, as well as the flow results, at 1:1 mortar mix design, a clear trend was shown. At early age, the mortar mixture incorporated FA showed late strength development rather than OPC, after 28 days, the mortar mixture including Rf showed similar or higher compressive strength than OPC is shown. As a durability performance, because of air entrainer absorption, the mortar mixture with Ra showed low freeze-thawing resistance performance with low air content.
In summary, using a simple apparatuses of hydrometer and mass cylinder, the quality evaluation of FA is possible. Furthermore, it is considered that this method can be applicable for actual ready mixed concrete plant as an acceptance investigation.