Title: Parameters Influencing the Performance of Shrinkage-Compensating Concrete
Author(s): Cataldo Matteo Corcella, Cristiano Cereda, Salvatore Tavano, Fulvio Canonico, and Daniela Gastaldi
Publication: Symposium Paper
Appears on pages(s): 1-15
Keywords: Expansive agent, Shrinkage compensating concrete, SRA, Superplasticizer
The performance of shrinkage-compensating concrete, in terms of reducing the risk of cracking, mainly depends on correct synchronisation between two different processes inside the concrete: the evolution of its early age mechanical strength which is controlled by cement hydration, and the expansion rate which is controlled by expansive agent hydration. Recently, the use of shrinkage reducing admixtures (SRA) has been recommended for the production of shrinkage-compensating concrete. Thanks to the synergy achieved by combining SRA and expansive agents there is an improvement in the performance of this kind of concrete even in the absence of prolonged wet curing. Some studies state that this positive combination is caused by retardation in the hydration rate of the expansive agent, which is able to induce a more efficient reinforcement tension. In this paper, the influence of the type of superplasticizer, SRA and temperature (10°-20°-30°C) on the hydration processes of the cement and the expansive agent have been tested in concrete and analysed with thermogravimetric analysis in cement paste. Compressive strength, workability loss, setting time and restrained expansion tests were carried out on concrete mixes. The results indicate that the type of superplasticizer used and/or the temperature have different effects on the hydration rate of the cement and the expansive agent. Some indications about the correct way to design a shrinkage-compensating concrete in different curing conditions are presented.