00000nam 2200000zi 4500 9.907472 CaOODSP 20221107181410 m o d f cr |n||||||||| 211130s1993 onca o f000 0 eng d CaOODSP eng rda CaOODSP eng eng fre n-cn--- NH17-336/1993E-PDF Hooton, Robert Douglas, author. Sorptivity tests on carbonated concrete / prepared for: The Research Division, Canada Mortgage and Housing Corporation; submitted by: Professor R.D. Hooton and Mr. Wayne Silberman. Ottawa : Research Division, Canada Mortgage and Housing Corporation, [1993] 1 online resource (vii, 2 unnumbered pages, 18 pages) : illustrations text txt rdacontent computer c rdamedia online resource cr rdacarrier Title cover. Carbonation, a reaction between atmospheric carbon dioxide and the cement paste fraction of concrete, can reduce the alkalinity of concrete. If the depth of carbonation reaches the level of reinforcement, the steel will become depassivated and in the presence of moisture, can corrode. It would be useful to be able to predict the quality of concrete non-destructively in order to determine its susceptibility to carbonation. It is known that the rate of carbonation is diffusion related (ie.: related to the square root of time) and is influenced by concrete mix design (mainly the water to cement ratio, w/c) and the curing period provided at early ages. Both the w/c and the curing affect the porosity of concrete and hence the diffusion rate of carbon dioxide. If a low w/c concrete (eg. w/c = 0.4) is used and cured properly, carbonation after 50 years will likely only be a few mm. The rate of water absorption by a concrete surface is also a diffusion process which is related to the combined effects of w/c and curing, and is a relatively simple and inexpensive procedure. It can be done on cylindrical cores removed on a structure and also has possibilities as an in-situ, non-destructive test. In this study, a series of 28 concrete core segments, were tested for rate of aborption (sorptivity). Tests were done on the original surface, 2 mm below the surface, and approximately 50 mm below the surface in the uncarbonated zone. The purpose was to see a) if the sorptivity of the surface (affected by curing or lack of curing) would be higher than at depth, and b) if the concretes with high depths of carbonation were related to high sorptivity values. The results indicate that there was a rough relationship between depth of carbonation and the sorptivity of the outer surface of the concrete. It was concluded that the sorptivity test has potential for indicating the susceptibility of concrete surfaces to carbonation. However, the small size of the core pieces and their extended storage before test prevented obtaining a more precise relationship in this study. Therefore, this technique requires further development to be useful. Further work by the first author has resulted in a more precise test method using cores of at least 100mm diameter. This work as well as the subsequant has helped in the development of a draft ASTM standard test method for evaluating concrete quality. Includes abstract in English and French. Concrete Corrosion Testing. Concrete Moisture Measurement Testing. Béton Corrosion Mesure. Béton Humidité Mesure. Canada Mortgage and Housing Corporation. Research Division, issuing body. PDF 539 KB https://publications.gc.ca/collections/collection_2022/schl-cmhc/NH17-336-1993-eng.pdf