Marc-André Bérubé

Bio: Marc-André Bérubé is an academic researcher from Laval University. The author has contributed to research in topics: Alkali–silica reaction & Alkali–aggregate reaction. The author has an hindex of 25, co-authored 54 publications receiving 2011 citations.

The mineralogical and petrographic analysis of concrete aggregates

Abstract: The aggregates used in concrete have to meet a number of specifications relating to mechanical performance, durability, chemical stability, alkali reactivity, gradation, shape, surface texture, and the presence of harmful substances. Numerous standard tests are used to ensure aggregates meet those specifications. However, petrographic examination, despite being qualitative in nature, remains the most valuable test for predicting the overall performance of concrete aggregates in any control test, and in service, as well.

Evaluation of surface sealers for concrete hydraulic structures exposed to low temperatures

Abstract: Many hydraulic structures exhibit downstream cracks and surface degradation due to porous and non air-entrained concrete cast only a few decades ago, wetting–drying and freezing–thawing cycles. These degradations could be prevented by minimizing surface saturation and water infiltration by sealing the concrete surface. Many different types of sealers, such as silanes, siloxanes, boiled linseed oil, epoxies, urethanes and cement-based products, are presently available on the market. However, despite their ready availability, very few or no laboratory or field evaluations have ever been undertaken to evaluate their effectiveness, specifically for hydraulic structures exposed to extremely low temperatures. Consequently, 60 different surface sealers were selected for laboratory evaluation, aimed at minimizing water or moisture infiltration, and to extend the service life of hydraulic structures, besides reducing the harmful effects associated with concrete surface deterioration. The tests carried out on these sealers comprised reduction of absorption and evaporation capacity, durability under freezing–thawing and wetting–drying cycles, acid rain, UV radiation, effect of various parameters, such as concrete water:cement ratio (W/C), sealers application temperature, pH variation, presence of hydrostatic pressure, etc. Preliminary data showed that silanes and siloxanes exhibited satisfactory results, however, products from the same family yielded variable results. This paper summarizes a part of a large study on concrete sealers for hydraulic structures in cold climates.

Recent applications of a modified gel pat test to determine the potential alkali-silica reactivity of carbonate aggregates

Abstract: A modified gel pat test was developed in which polished concrete slices, 75 mm × 75 mm × 25 mm in size, were immersed in a 1 N NaOH solution at 38°C for 56 days. A rating system, called the gel pat test rating (GPTr), was then developed to quantify the amount of gel formed on the polished concrete sections. The basic parameters used are (1) the proportion of particles showing gel deposits on their surface, and (2) the average amount of gel formed at the surface of the particles. The method was applied to 65 samples of carbonate aggregates from the St Lawrence Lowlands of Quebec (Canada). Fairly good correlations were obtained between the GPTr and the results of various test methods currently used to evaluate the potential alkali-reactivity of concrete aggregates in Canada. The microstructure and the composition of the reaction products formed at the surface of the reactive particles in the gel pat test were evaluated using a scanning electron microscope equipped with an energy-dispersive X-ray analyser. The results obtained were compared with those of similar work performed on concrete cores taken from deteriorated concrete structures from various parts of the St Lawrence Lowlands.

Le barrage Sartigan dans la Beauce (Québec), Canada : un cas-type de détérioration du béton par des réactions alcalis–granulats

Abstract: The Sartigan dam, a concrete ice-retention dam built in 1967 along the Chaudiere River, near Saint-Georges de Beauce, Quebec, Canada, shows numerous megascopic and microscopic signs of alkali–aggregate reactivity of the alkali–silica type (expansion, polygonal map cracking, silico-alkaline gels, looseness of cement paste – aggregate bonds, characteristic rims on fracture surfaces through coarse reactive aggregate particles, etc.). Besides, the three conditions considered as essential to promote these reactions in concrete have been satisfied in this case: the use of a high-alkali cement, conditions of high humidity reinforced by frequent wetting–drying cycles, and aggregates considered as potentially alkali-reactive in concrete (rhyolitic tuffs with a devitrified matrix rich in microcrystalline quartz).

Study of the structure of a sensitive Champlain clay and of its evolution during consolidation

Abstract: Scanning electron microscopy and mercury intrusion porosimetry are used in parallel to identify the structure of a medium sensitivity Champlain clay. The clay structure is observed firstly on intac...

Physicochemical and engineering behavior of cement treated clays

Abstract: This paper examines the relationship between the microstructure and engineering properties of cement-treated marine clay. The microstructure was investigated using x-ray diffraction, scanning electron microscopy, pH measurement, mercury intrusion porosimetry, and laser diffractometric measurement of the particle size distribution. The engineering properties that were measured include the water content, void ratio, Atterberg limit, permeability, and unconfined compressive strength. The results indicate that the multitude of changes in the properties and behavior of cement-treated marine clay can be explained by interaction of four underlying microstructural mechanisms. These mechanisms are the production of hydrated lime by the hydration reaction which causes flocculation of the illite clay particles, preferential attack of the calcium ions on kaolinite rather than on illite in the pozzolanic reaction, surface deposition and shallow infilling by cementitious products on clay clusters, as well as the presence of water trapped within the clay clusters.