Porous concrete (POC, no-fines concrete or pervious concrete), an environmentally friendly material, has received much attention in recent years due to its applications, such as permeable pavement, water purification site, being a vegetation base, or functioning as a habitat for organisms. POC is a special concrete consisting of a cementing matrix (paste or mortar), coarse aggregate, little or no fine aggregate, admixture, water, and continuous voids which are intentionally incorporated to produce various kinds of special characteristics. It has great potential to be used widely in both civil engineering and architecture in the future. Void ratio (percentage of voids), one of the most important properties, impacts various characteristics, such as strength, permeability, water retention, and water wicking. In addition, void ratio is easily changed and the void ratio of each part is likely to be different from that designed when constructed on site because of the variation of the degree of compaction and the wall effect of the mold where used. Therefore, the quality evaluation that directly evaluates the variation of the void ratio of each part of POC at post-construction is extremely important. According to previous researches, the ultrasonic wave velocity method is one of the simplest testing methods for POC. This is non-destructive and probably applicable to POC because there is a strong correlation between ultrasonic wave velocity and void ratio. Therefore, it is also considered possible to predict the void ratio of POC with ultrasonic wave velocity, if the relationship is expressed in advance by mathematical functions. Furthermore, it is possible to express and predict various characteristics of POC, such as strength, permeability, water retention, and water wicking, with the predicted void ratio. In this paper, relationships between void ratio and ultrasonic wave velocity of POC were examined. According to test results, it was confirmed that the relationship between void ratio and ultrasonic wave velocity can be fitted by a quadratic function. In addition, so as to clarify the main factor affecting relationships between void ratio and ultrasonic wave velocity of POC, cross-sections of POC specimens were analyzed. As a result of the analysis, it was confirmed that the minimum cost path through which ultrasonic waves propagate in POC is the dominant factor in the relationships between void ratio and ultrasonic wave velocity of POC.
|ジャーナル||Journal of Structural and Construction Engineering|
|出版物ステータス||Published - 7 2018|