Study of the Physico-Mechanical Properties of a Recycled Concrete Incorporating Admixtures by the Means of NDT Methods

During the last decades, the sector of construction has known a growing trend in construction and demolition (C&D) activities. The management of the collected debris and waste causes real problems at the environmental level, which can be seen in the decrease space in urban area and the agriculture land occupied by the waste of demolition. At the moment, researchers in civil engineering domain are called to propose new solutions to find substitutions of the natural aggregate such as, the recycled aggregates (RA) as an alternative for natural crushed aggregates (CA). This study here in focuses on the use the recycled aggregates coming from old concrete tested specimens from construction sites. The aim of this research is the formulation of a recycled aggregate concrete (RAC) within similar performances (resistance and durability) to conventional concrete (CAC). The superplastizier as admixture at dosages 0%, 0.5%, 1%, 1.5% and 2% was combined with a recycled aggregate at 100% replacement. The physico-mechanical properties at fresh and hard state were investigated, mainly the density, absorption, air content, elastic modulus and strengths. In addition the NDT test methods (ultrasonic and rebound hammer) were used to assess the compressive strength of the due concrete. The correlation study of strength (Rc) and the properties; such as elastic dynamic modulus (Ed), ultrasonic velocity (V), rebound hammer number (Is), absorption (A) and the density (γ) to predict the compressive strength in this particular case was considered.