Bétons à haute performance pour fabriquer des panneaux destinés à réparer des structures submergées

Abstract

The field of repair of submerged hydraulic structures (dams, stilling basins, lock chambers, and so forth) is becoming more and more important given the economic worth of such structures. Damage caused by abrasion can make it difficult to maintain such structures in service. The purpose of the study described in this paper was to develop durable high-performance concretes that can be used for manufacture of board for repair of abrasion-damaged surfaces. The board might also be placed on surfaces already repaired with colloidal concrete poured underwater. Two types of cement (Type 30 and Type 10) and two high-performance coarse aggregates (granite and dolomitic limestone) were used. The eight concrete mixes developed included a variety of additives and admixtures such as silica fume, steel fibre, latex, and superplasticizer. For precise characterization of the mixes, hydraulic abrasion tests, compressive strength tests, and freeze–thaw cycle resistance tests were performed. In addition, shrinkage, thermal expansion coefficient, and permeability of the concretes were measured; in some cases, the board might be subject to freeze–thaw cycles in structures partially emptied for repair or maintenance. Results show that high-performance concretes with very low water: cement ratio, good workability, and improved freeze–thaw cycle resistance can be manufactured. Concretes made with Type-30 cement, silica fume, and granite or limestone aggregate offer excellent hydraulic abrasion resistance (depth of erosion on the order of 1 mm after 72 h), compressive strength greater than 115 MPa after 91 days, and a freeze–thaw durability factor of more than 100%. Key words: abrasion, concrete, durability, steel fibre, silica fume, freeze–thaw cycle, latex, board, underwater repair.