Paper by SUZUKI YAHIRO TOKUDA from ISCR 9th 2004 Instanbul Turkey
The porous concrete surface and sub-base for pavements is required higher coefficient of permeability than 0.01cm/sec and higher bending strength than 3 or 4.5 N/mm2. In order to obtain workability and these qualities, suitable methods for testing consistency was investigated. It was possible to judge the consistency for quality control of porous concrete for pavements by using a vibrating compaction (VC) test machine. The settlement time for a fresh concrete sample to obtain a target void ratio (15%) was measured. From the viewpoint of bending strength and coefficient of permeability, the target settlement time was decided to be 20 to 40 seconds. On the basis of this consistency value, an appropriate mix proportion and unit fiber (network type) content was selected depending on the maximum size of coarse aggregate. It was shown that this mixture with small maximum size was more resistant to wearing and freezing and thawing ,and that one with large maximum size was higher sound absorption.