PhD : "Investigation of the self-cementing properties and mechanical behaviour of recycled concrete aggregates"

PhD defense : Chong WANG

Team : GCE

Title : "Investigation of the self-cementing properties and mechanical behaviour of recycled concrete aggregates"

His thesis defense that will take place on April, 13th at 14h in the Amphithéâtre Jean Arp at INSA Strasbourg. The defense will be in English, followed by a reception. 

Summary:

The reuse of recycled concrete aggregates (RCA) as a substitution to natural aggregates (NA) in pavement base and subbase layers has become more popular in recent years. Occasionally, a growth of stiffness and strength in unbound base and subbase layers built with RCA can be observed, which is known as self-cementing properties of RCA. However, the self-cementing properties and mechanical behaviour of RCA still lack the support of test data. This dissertation presents an investigation on self-cementing properties, microstructure and mechanical behaviour of 3 RCA materials (NRCA, ORCA and RCAP) under monotonic and repeated load triaxial tests. Results show that NRCA exhibits strong self-cementing properties while those of ORCA and RCAP are negligible. The hydration products not only form bonds between bonds, but also fill the small macro-pores between particles (radius above 1 μm and less than 20 μm). The permanent deformation of NRCA, with strong self-cementing properties, decreases quickly after curing 180 days, then reaches a constant and very low value. As for the resilient deformation behaviour, the resilient modulus of NRCA increases with increasing curing time. After curing 720 days, the ranking of NRCA can be improved from C2 to C1, which can be used in high-level pavement. 

Keywords: recycled concrete aggregates, unbound granular materials, self-cementing properties, repeated load triaxial test, permanent deformation, resilient deformation, monotonic triaxial test, microstructure.

The jury will be composed of:

• Mme. HATTAB Mahdia : Rapporteur (Professeur, Université de Lorraine)
• M. CUI YuJun : Rapporteur (Professeur, École des Ponts ParisTech)
• M. TORRENTI Jean-Michel : Examinateur (Professeur, École des Ponts ParisTech, Université Gustave Eiffel)
• Mme. BRAYMAND Sandrine : Examinateur (Maître de conférences, Université de Strasbourg)
• M. CHAZALLON Cyrille : Directeur de thèse (Professeur, INSA Strasbourg)
• M. HORNYCH Pierre : Co-directeur de thèse (Chargé de recherche (HDR), Université Gustave Eiffel)