Compressive Strength of Repaired Road by Recycling Technique of Pavement Materials

The Department of Highways, Thailand, has used the pavement recycling technique to restore damaged pavement since 1965. This technique is economical because cement is readily available at reasonable cost in Thailand. From this study, it is found that the field roller-compacted strength, qufr is lower than the laboratory strength, qul under the same dry unit weight, soil-water/cement ratio and curing time due to several field factors. The ratio qufr/qul varies from 50 to 100%. Non-uniformity in mixing soil with cement is realized by the ratio of field hand-compacted strength to laboratory strength, qufh/qul ranging from 0.75 to 1.2. For most data, the field roller-compacted strength is 55 to 100% the field hand-compacted strength. This might be caused by the difference in compaction method and curing condition between laboratory and field stabilization. From this field observation and the proposed model, a practical procedure for repairing damaged roads using the pavement recycling technique is introduced. The procedure consists of the determination of cement content, the execution of the field stabilization and the examination of the field strength. It can save on sampling and laboratory testing and hence cost