Browsing by Author "Santos, Pedro M.D."
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- Effect of surface preparation and bonding agent on the concrete-to-concrete interface strengthPublication . Santos, Dinis S.; Santos, Pedro M.D.; Dias-da-Costa, DanielConcrete-to-concrete interfaces are present both in new and existing structures. Two distinctive situations can be identified: (1) placing hardened concrete against hardened concrete parts, such as the case of precast members for viaducts and bridge decks; and (2) placing fresh concrete against hardened concrete parts, such as the rehabilitation and strengthening of existing structures by concrete jacketing or concrete overlay, among other techniques, as well as the use of precast members placed on site to later receive a cast-in-place concrete layer. The bond strength of the concrete-to-concrete interface is influenced by several parameters but mainly by: (1) the surface preparation; (2) the use of bonding agents; (3) the compressive strength of the weakest concrete; (4) the moisture content of the substrate; (5) the curing conditions; (6) the stress state at the interface; (7) the presence of cracking; and (8) the amount of steel reinforcement crossing the interface, among others. This paper presents an experimental study conducted to assess the influence of the surface preparation and bonding agent on the bond strength of the concrete-to-concrete interface. The contribution of the substrate moisture is also addressed. Experimental results are discussed and conclusions drawn.
- A state-of-the-art review on shear-frictionPublication . Santos, Pedro M.D.; Júlio, Eduardo N.B.S.Initially proposed in 1966, the ‘‘shear-friction theory’’ has been adopted in all design codes to analyse concrete-to-concrete interfaces. In the last decades, several improvements were suggested to take into account more influencing factors, to increase the accuracy and to enlarge the application field. The inclusion of the concrete strength and density and the consideration of the dowel action are examples of the proposed improvements. This paper presents a literature review on design expressions for shear-friction, chronologically ordered, describing proposals from the earliest research studies, precursors of the theory, until the most recent studies, incorporated in the newest fib Model Code. The most significant contributions are identified and a comparison between some of these design expressions is presented. Codes updates concerning shear-friction provisions are also identified in the literature review herein presented.