Showing papers by "Marc-André Bérubé published in 2004"

Evaluation of the expansion attained to date by concrete affected by alkali-silica reaction. Part I: Experimental study

Abstract: The expansion to date of the concrete from a structure affected by alkali–silica reaction (ASR) is a crucial parameter in the evaluation of the structural integrity of the structure. Three methods ...

Influence of Specimen Geometry, Orientation of Casting Plane, and Mode of Concrete Consolidation on Expansion Due To ASR

Abstract: Concrete specimens of different sizes and shapes were made with various reactive aggregates and stored under conditions favorable to the development of alkali-silica reactivity (ASR), with their expansion measured with time along the three directions. They have been cast vertically (cylinders and prisms) or horizontally (prisms and larger blocks), using a vibrating table, a vibrating needle, or rodding. The expansion due to ASR was always greater in the direction perpendicular to the casting plane. The higher the number of flat and elongated particles in the reactive aggregate, the higher the coefficient of anisotropy, defined as the ratio between the expansions perpendicular and parallel to the casting plane. This coefficient was constant through the course of the expansion. It was generally higher for the cylinders than for the prisms, and still less for larger blocks. Consolidation by rodding induced anisotropy coefficients distinctly smaller than consolidation using a vibrating table, while a vibrating needle induced intermediate values; however, all methods gave constant volumetric expansion at least up to an important expansion level. For prisms cast horizontally and measured axially in accordance with the concrete test CSA A23.2-14A or ASTM C 1293, consolidation using rodding induced long-term (axial) expansions greater by 71% compared with consolidation using a vibrating table. In order to reduce the experimental variability of the test, only one method of consolidation should be allowed. When evaluating field concrete affected by ASR, it appears important to consider the orientation with respect to the casting plane of the core samples subjected to mechanical or residual expansion tests.

Evaluation of the expansion attained to date by concrete affected by alkalisilica reaction. Part II: Application to nonreinforced concrete specimens exposed outside

Abstract: In part I, relationships were obtained in the laboratory between the expansion due to alkali-silica reaction (ASR) and (i) the "stiffness damage test" (SDT), (ii) the "damage rating index" (DRI), and (iii) the surface cracking of the concrete. These tests were conducted on nonreinforced concrete blocks and cylinders made with various reactive aggregates and stored at 38 °C and >95% relative humidity. The objective of part II was to verify the validity of the relationships from part I for concrete elements made in the laboratory but exposed outside. On average for the 51 blocks and 14 slabs tested, the surface cracking increased with ASR expansion and approached the measured expansion in the case of the most severely exposed sections of the specimens tested. The ratio between the expansion estimated from the surface cracking and the measured expansion varied greatly from one specimen to another (between 0 and 4.3), however. Taking into account the type of reactive aggregate involved did not explain the sit...