The mechanical property characterization of dam concrete is a challenging task mainly due to the use of large aggregate sizes. The properties of dam concrete are often evaluated from wet-screened concrete tests using standard specimen sizes. A physically based relationship between dam concrete and wet-screened concrete strength properties is currently unavailable. A prediction methodology is proposed that can be used to obtain the compressive and the splitting tensile strength of dam concrete by taking into account the wet-screened strength results, the effect of the specimen dimensions, and the effect of the maximum size of aggregate. The predicted results are compared with test results available in the literature and with test results recently obtained during the construction of the Baixo Sabor dam. It is shown that the proposed prediction tool can be used to obtain accurate estimates of dam concrete strength.

This paper proposes a methodology for the prediction of the compressive creep strains of dam concrete based on wet-screened experimental results at constant elevated temperature conditions measured in situ. Due to its large aggregate dimensions, the experimental characterization of dam concrete has particular constraints. The wet-screened concrete, obtained by sieving the aggregates larger than a given dimension, after mixing, is used to cast standard specimens and to embed monitoring devices. An experimental in situ installation using creep cells was used to obtain the compressive creep strain development over time for the maturing conditions of the dam core. The study of the effect of wet-screening procedure on creep in compression considers three types of concrete, dam concrete and two wet-screened concretes tested at three loading ages, 28, 90 and 365 days. The comparison between different types of concrete at different maturing conditions requires the definition of a reference state given by the maturity method, using the equivalent age, and relies on the fit of compressive creep strains to the RILEM recommended model B3. To take into account the effect of the aggregate content on the deformability properties of dam concrete, an equivalent two-phase composite model was applied. The equivalent composite model considered the equivalent matrix as the wet-screened concrete and the inclusions as the larger aggregates that are removed during the wet-screening procedure. Predictions obtained with the composite model are close to the dam concrete experimental results, for the tested loading ages.

This paper aims at compiling the most relevant information concerning the use of cement-based mortars and concretes in the rehabilitation, retrofitting, and strengthening of hydraulic structures, namely concrete dams. The most important properties of cement-based mortars and concretes as repair materials are addressed, with a special focus on its compatibility with the concrete substrate. After a brief allusion to generic preparatory works, some of the most common practices are described. The main topics are mortar and concrete toppings, i.e., patches and overlays and thickening of the dam section. Among overlays, shotcrete and underwater works are addressed in detail. Littlerock, Oberems, and Storfinnforsen dam interventions are briefly described as successful rehabilitations involving the shotcrete method, whereas the Albbruck-Dogern dam intervention is given as an example of effective underwater repair works. As for dam section modifications, Kölnbrein, Olef, and Sasanagare dams are presented as conventional mass concrete placements within rehabilitation operations, while Les Toules, Gibraltar, Santa Cruz, and Littlerock dams are references for roller compacted concrete strengthening.

This paper proposes the use of the maturity method and a two-phase composite model for the prediction of dam concrete modulus of elasticity. The methodology was validated with test results obtained from experimental in situ setup using creep cells placed in the dam’s body, subjected to variable environmental conditions. It is shown that composite models can be used to predict the modulus of elasticity of in situ dam concrete based on the modulus of elasticity of the wet-screened concrete.