• Fernández, Fernando
• Hernández, Miriam
• Parra, Carlos
• Gómez, Pablo
• Rodríguez, Carlos
• Sánchez, Isidro
• Sánchez, Marina
• Navarro, Rosa
• Rodríguez, Roberto

Abstract

<jats:p>Construction and Demolition Wastes (C&amp;DW) are one of the most produced solid wastes in society in terms of volume. Controlling the presence of gypsum in recycled aggregates is crucial for their use as recycled aggregates in concrete production, as their presence may cause expansive reactions due to the formation of secondary ettringite. This article presents the results of an experimental campaign in which the effect of the presence of recycled aggregates containing gypsum was evaluated using various types of Portland cements (CEM I, CEM IIIB, CEM IV) and alkali-activated slag (AAS). Four percentages of gypsum (2%, 5%, 10%, and 20%) were studied in replacement of natural aggregates. The properties were evaluated by means of compressive strength, flexural strength, ultrasonic, and dimensional stability tests. The behaviour obtained with 2% gypsum content are similar to those obtained with the reference samples in all types of cement studied (Portland cements and AAS). Once the 2% threshold is exceeded, the behaviour varies depending on the type of cement used. When CEM IIIB and CEM IV are used, the studied properties are minimally affected.</jats:p>

Topics

• impedance spectroscopy
• strength
• cement
• flexural strength
• ultrasonic
• atomic absorpion spectrometry
• gypsum