Water Influence on Mechanical Behaviour of Pavements: Experimental Investigation

Cane Cekerevac[24], Susanne Baltzer, Robert Charlier, Cyrille Chazallon, Sigur0ur Erlingsson, Beata Gajewska, Pierre Hornych, Cezary Kraszewski and Primoz Pavsic

Abstract This chapter presents laboratory and in-situ experimental techniques used to describe the mechanical behaviour of pavement material at different saturation stages. The use of repeated triaxial load testing to obtain stiffness characteristics as well as the ability of the material to withstand accumulation of permanent de­formation during cyclic loading is considered. For unsaturated soils, in addition to mechanical variables, it is shown that a moisture/suction control should be added. Several techniques are described to assist in this. A brief presentation of model pa­rameters and tests needed for model calibration are introduced. Evaluation of pave­ment structural capacity based on deflection measurements with non-destructive testing equipment are presented. Finally, some examples of laboratory and in-situ measurement are shown.

Keywords Laboratory testing ■ suction control ■ repeated triaxial test ■ CBR test ■ parameter calibration ■ field testing ■ laboratory and in-situ experimental results

10.1 Introduction

Besides proper construction design, the materials used in the construction of pave­ments should be such that the effects of excess moisture are minimized. To help achieve this purpose, several laboratory and in-situ methods can be used. For ag­gregates used within the unbound layer, performance, when subjected to traffic and moisture is mainly characterized by:

• the compaction properties;

• the amount of degradation;

• the composition (as determined by sieving analysis); and

• the evaluation of the quality of fines (in some cases).

All of these are index tests, which do not give us proper insight into the behaviour of the material under traffic loads and in different moisture conditions. A better under­standing of actual in-situ behaviour can be obtained with the cyclic load triaxial test and with the Falling Weight Deflectometer (FWD) and other in-situ tests. From June 2004 the manufacturers of aggregates in the EU are required to undertake the initial type test and Factory Production Control to ensure that their products conform with European Standard EN 13242 (CEN, 2002).