Complementary testing techniques applied to obtain the freeze-thaw resistance of concrete

Abstract

Most of the standards that evaluate the resistance of concrete against freeze-thaw cycles (FTC) are based on the loss of weight due to scaling. Such procedures are useful but do not provide information about the microstructural deterioration of the concrete. The test procedure needs to be stopped after several FTCs for weighing the loss of material by scaling. This paper proposes the use of mercury-intrusion-porosimetry and thermogravimetric analysis for assessing the microstructural damage of concrete during FTCs. Continuous strain measurement can be performed without stopping the FTCs. The combination of the above techniques with the freeze-thaw resistance standards provides better and more precise information about concrete damage. The proposed procedure is applied to an ordinary concrete, a concrete with silica fume addition and one with an air-entraining agent. The test results showed that the three techniques used are suitable and useful to be employed as complementary to the standards. RESUMEN: Resistencia del hormigón frente a ciclos hielo deshielo medida con técnicas complementarias.Las normas para evaluar la resistencia del hormigón a los ciclos hielo-deshielo (CHD) se basan habitualmente en la pérdida de peso por descascarillamiento. Son útiles, pero no proporcionan información sobre el deterioro microestructural del hormigón. Además, exigen detener el ensayo para pesar el material desprendido. Se propone el uso complementario de la porosimetría por intrusión de mercurio y el análisis termogravimétrico para evaluar el daño microestructural del hormigón durante los CHDs. La medida continua de las deformaciones puede hacerse sin detener los CHDs. La combinación de las técnicas enumeradas con las normas de ensayo proporciona información más completa sobre el daño del hormigón. El procedimiento propuesto se aplica a un hormigón convencional, a un hormigón con adición de humo de sílice y a otro con aireante. Los resultados de los ensayos mostraron que las tres técnicas usadas son útiles y adecuadas como complemento a las establecidas en las normas.

Experimental determination of the influence of fresh concrete’s composition on its resistance to water and de-icing chemicals by means of two methods

“…), which is confirmed by the conclusions published, e.g., in 37,42,43,45,47 . The results of the experi- Dependence of the D5 coefficient according to method C 20 on cement and plasticiser content at an average w/c ratio Slika 7: Odvisnost koeficienta D5 po metodi C 20 od vsebnosti cementa in plastifikatorja pri povpre~nem razmerju w/c ment described in this paper suggest that the composition of fresh concrete has a demonstrable influence on the resistance of the concrete surface layer to the action of de-icing chemicals.…”

“…Compared with the concretes containing additives, the de-icing-chemical resistance of the concrete with no plasticiser was lower by several orders of magnitude. The article 37 describes the same tendency in the behaviour of concretes with a different content of additives in relation to their resistance to water and de-icing chemicals. The results in 37 during the CDF test.…”

“…The article 37 describes the same tendency in the behaviour of concretes with a different content of additives in relation to their resistance to water and de-icing chemicals. The results in 37 during the CDF test. The issue of the resistance of concrete to water and de-icing chemicals is also discussed in 38 , where the matter being tested is the de-icing-chemical resistance of concretes with a different plasticiser content (as well as silica fume and an air-entraining additive).…”