Micro-stress analysis and identification of lightweight aggregate’s failure strength by micromechanical modeling

• Distributions of micro-stresses in leightweight aggregate concretes are presented.
• LWA’s failure strength is deduced through a micromechanical modeling approach.
• Localization scheme allows analyzing local stress fields and failure behaviors.
• The distributions of micro-stresses at the interface depend on LWAs’ natures.
• LWA failure strength identification allows predicting LWAC compressive strength.

This work is based on a dual approach of experiments and micromechanical modeling in order to characterize the failure behaviors of lightweight aggregate concretes (LWAC). Many classes of LWAC were tested, based on five families of lightweight aggregates (LWA) and three types of mortar matrices: normal, high performance (HP) and very high performance (VHP). Micromechanical modeling is based on an iterative homogenization approach and associated localization: local stress distributions during the uniaxial compression tests can be predicted in LWAC’s components and at their interface. Experimental compressive strengths were measured on manufactured 16 × 32 cm cylindrical specimens. The confrontations between micromechanical modeling and experiments were used to identify LWA’s failure strengths which are difficult to measure, and to quantify the inaccuracies related to conventional methods. These corrected values of LWA’s failure strength were introduced into a failure criterion modeling: associated predictions of LWAC’s compressive strength are in good agreement with the experimental measurements.