Dynamic modulus and fatigue testing of lightly cementitiously stabilized granular pavement materials

This paper examines the characterization of a granular material lightly stabilized with slag-lime cementitious binder particularly utilizing the monotonic and cyclic load IDT testing method. An extensive laboratory investigation was carried out to determine the mechanical properties of the lightly stabilized granular material and to establish fatigue life relationships by IDT testing and typical results obtained from this ongoing research are presented in this paper. This study shows that the static stiffness modulus and dynamic stiffness modulus of the stabilized material increases with binder content and showed little change with moisture content variation around the optimum moisture content. Fatigue life relationships were established using two methods, namely the approach of determining the number of cycles for 50% reduction in the stiffness compared to the initial stiffness and the energy ratio method, and they both showed similar linear relationships. It is therefore concluded that cyclic load IDT testing can be used reliably to characterize lightly stabilized granular materials with slag-lime in terms of their strength, stiffness modulus and fatigue life relationships

Fatigue characterization of lightly cementitiously stabilized granular base materials using flexural testing

The fatigue characteristics of a lightly stabilized granular material under traffic loading are important considerations for the design of a pavement containing such material. This paper examines the use of flexural testing with on-sample midspan deflection measurement for determining fatigue characteristics of lightly stabilized granular base materials. The experimental program included cyclic load flexural testing to determine the stiffness modulus, fatigue life, and damage characteristics of a granular material stabilized lightly with 1-3% cement-fly ash and to establish relationships for predicting the fatigue life. Fatigue life was estimated using the energy ratio approach and compared with the number of load cycles required to break the specimen. Empirical relationships are proposed to relate the fatigue life with tensile strain and stress ratio similar to those proposed in the literature. Progressive damage due to fatigue and permanent deformation accumulation with increases in the load cycles is also presented in this study. 2016 American Society of Civil Engineers.Scopu

Backcalculation of resilient modulus of lightly stabilised granular base materials from a cyclic load testing facility

Resilient moduli of pavement layers are the basic input parameters for the design of pavements with multilayers in the current mechanistic-empirical pavement design guides. Field measurements are generally believed to provide accurate values to backcalculate pavement layer moduli, but the tests to measure the relevant parameters are difficult to perform, expensive and causes disturbance to the public. Therefore, backcalculation of pavement layer moduli from laboratory scale model testing has been a focus of recent pavement research. This paper presents a backcalculation analysis to evaluate pavement layer moduli using a 3D numerical model developed using the FLAC3D finite difference software. The pertinent measurements that are required for the backcalculation analysis were collected from a cyclic load testing facility under traffic type cyclic loading conditions with a typical pavement structure consisting of a granular road base lightly stabilised with cement-flyash over an expansive soft clay subgrade. This study indicates that the stabilised base material had cross-anisotropic resilient properties with an average vertical resilient modulus of 2875 MPa and an average horizontal resilient modulus of 1598 MPa. From this investigation, the resilient moduli of the stabilized granular base layer and subgrade clay were backcalculated reliably from the analysis using FLAC3D numerical model

Settlement analysis of foundation soil over long time and comparison with field performance

This paper models the consolidation of the foundation soil of a wide geogrid reinforced embankment close to its centre-line. An elastic viscoplastic model has been used for the analysis. A creep function that takes into account of the non-linear nature of creep has also been incorporated in this model. The predicted results are compared with the field measurement data and with the analysis results obtained using two other models (i.e. Kutter and Sathialingham, 1992 and modified Cam-Clay)

Permanent deformation study of pavement layers using a laboratory pavement model testing

Lightly stabilized granular materials with slow-setting cementitious binders are widely used in the construction of new pavements and rehabilitation of old pavements in Australia and other countries. Higher strength and durability of these materials combined with relatively low cost are reasons they are widely used. The mechanistic-empirical design of pavements with lightly stabilized materials requires key parameters, such as permanent deformation of these materials. A cyclic load-testing facility was developed for studying the permanent deformation characteristics of pavement materials. In particular, a typical pavement structure consisting of a lightly stabilized granular road base material over an expansive soft clay subgrade material was studied using a pavement model testing (PMT) facility. In the PMT facility, the model pavement structure was constructed in a 1.0 × 1.1 × 0.6-m steel tank, and the wheel loading from the vehicle was simulated using a circular steel plate subjected to sinusoidal-type axial loading through an actuator assembly. The results of this study indicate that the permanent deformations of the pavement structure and the subgrade increased with the number of load cycles and were greatly affected by the moisture movement from the subgrade to the stabilized base layer