Title : REPAIR OF CONCRETE DAMS DAMAGED BY FROST AND INTERNAL SULFATE ATTACK: EVALUATION OF THE EFFICIENCY OF DIFFERENT TREATMENTS
Authors : E. Menéndez and B. Aldea
Publication : 13th – 16th February 2013
Volume :
Pages : 14-Jan
Price : 250
Abstract : The hydraulic structures like dams are exposed to water. The saturation of concrete tends to raise the risk of appearance of different types of alterations in function of the characteristics of the concrete components and environmental factors. The inclusions of pyrites or pyrrhotites in aggregates can induce ettringite crystallization and formation of internal cracks. And the exposition to successive freeze-thawing cycles produces cracks formation and loss of material mainly at superficial level. Also, the combination of both processes increase the speed in the deterioration of the concrete. To do an adequate repair of damaged concrete, it is necessary remove the affected concrete from the surface, regenerate the surface, avoid access of the water and protect it to the direct action of temperature. In hydraulic structures, the surface to be treated is large and with difficult access, and due to this it is necessary to use repair products cheap and easily applied. In the present work, different repair products have been tested to identify the suitable one to be applied in a concrete dam with internal sulphate attack and frost damage. Seven repair products were applied on concrete cores without frost damage extracted from the interior of the dam and with a moderate micro-cracking due to ettringite formation. Also, concrete cores without treatment are tested as reference to observe the evolution of damage. The test samples were exposed to successive cycles of freeze and thawing until 56 cycles. During test the visual aspect was observed and monitored internal damage by non-destructive techniques. Also, the compressive strength was determined at the end of the frost test has been corroborating that the use of non-destructive techniques permits to evaluate alterations undetectable only with the visual inspection. Finally, elastic cement modified with latex is identified as the most adequate product to be use in the reparation