Granular Subbase Research Articles

An experimental comparison of the filtration characteristics of construction fabrics under dynamic loading

The article describes laboratory tests carried out to assess the filtration characteristics of various fabrics when placed between a granular sub-base and a cohesive soil. An apparatus similar to that used by Snaith and Bell was used to test Terram 1000, Fibretex f2-b, G100 and Lotrak 45/45, all of which, except Lotrak 45/45, were non-woven. A loading period of 24 h was used for four types of cohesive soil in the first series of tests. Type 1 soil only was used in the second series with separate loading periods ranging from 12 h to 96 h. Results show that repeated loading without a fabric resulted in considerable migration of the subgrade into the sub-base. Introducing a fabric reduces the movement of the subgrade particles, the degree of reduction depending upon the properties of the fabric. The presence of a sand layer beneath the fabric assists in the formation of a filter. There was some evidence that the period of repetitive loading is more significant in subgrade migration than the number of load repetitions. (TRRL)

Construction Materials Control for the AASHO Road Test

A brief description of some of the test methods and statistical quality control procedures used during construction of the American Association of state Highway Officials (AASHO) Road Test in Ottawa, Ill. is given. Control of compaction of the earth embankment and the granular subbase and base courses have been emphasized.

Construction Materials Control–AASHO Road Test

A brief description of some of the test methods and statistical quality control procedures used during construction of the AASHO Test Road is given. Emphasis has been placed on control of compaction of the earth embankment and the granular subbase and base courses.

Tests to Evaluate Concrete Pavement Subbases

Tests conducted to develop performance criteria for evaluating strength contributions made by subbases to pavement structure; static load tests were made on isolated rectangular uncurled concrete panels 6 in. thick supported by dense graded, well compacted granular subbases of different thicknesses over clay subgrade with modulus of subgrade reaction (k) of 100; results reported.

Tests to Evaluate Concrete Pavement Subbases

Tests conducted to develop performance criteria for evaluating strength contributions made by subbases to pavement structure; static load tests were made on isolated rectangular uncurled concrete panels 6 in. thick supported by dense graded, well compacted granular subbases of different thicknesses over clay subgrade with modulus of subgrade reaction (k) of 100; results reported.