DEVELOPMENTS IN FIELD CONTROL OF EARTHWORKS COMPACTION

Laboratory and field tests with two comparatively new portable field instruments were carried out over the last two years in the UK to examine their potential for improving compaction control of highway earthwork materials. Both instruments produce quick results in the field. Data from the moisture condition apparatus has indicated that moisture suitability can be reliably measured for wet soils, but that calibration procedures for certain materials may have to make allowance for changes in material properties during the construction process. Slight modifications to the test procedure appear to give good results for materials in a dry condition. The clegg impact soil tester has demonstrated its ability to measure strength indirectly by comparison with California bearing ratio (CBR) values and by monitoring strength gain from "drying back". Although its use in a rapid method of predicting density gave consistently low results, these may well have been attributed to the moisture sensitivity of the material tested and a laboratory calibration technique not fully reproducing field conditions. The moisture condition apparatus may be suitable for quick moisture measurement in conjunction with the clegg impact soil tester (a). The number of the covering abstract of the conference is TRIS No. 368448. (TRRL)