The creep, or extension with time, that takes place in geosynthetics under load is an essential parameter to consider in the design of reinforced soil walls. The report describes the phenomenon of creep, how it is measured and how it is presented for use by a civil engineer. Creep data are presented for five geosynthetics: both heavy and lightweight plain weave polypropylene fabrics, a woven polyester/polyamide fabric, a coated polyester strip, and a high density polyethylene grid. Data are provided for test durations up to about 50,000 hours, ie more than five years. Some tests were undertaken at elevated temperatures and the use of the technique of time-temperature superposition to predict long term behaviour is examined. The phenomenon of stress relaxation is also described and the results of some short term stress relaxation tests are presented and compared to the data obtained from creep tests. The application of the test data to design is illustrated by example. (A)

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