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A platform for research: civil engineering, architecture and urbanism
Freeze-deicing salt resistance and bond strength of PCC after freeze-thaw attack
The freeze-thaw resistance of a building material is an important parameter characterizing the durability. In publications we find the assumption that the amount of scaling may be reduced by polymer modification, but that the resulting interior damage is considerable. In many CDF and GIF tests made by the authors on mortars with different polymers this statement could not be fully confirmed. Although in some cases the capillary porosity was much higher, the capillary absorption of solutions of most PCC was lower than that of non-modified mixtures. It is highly probable that a certain hydrophobizing of the pore walls may be the reason for the usually good freezedeicing salt resistance. In tests with organic de-icing agents (potassium acetate, glycol) no evidence could be found that the process of damage might be influenced by such phenomena as the solution of the organic components from the mortar matrix. Only in tests on free polymer films a swelling effect could be detected, its intensity varied depending on the de-icing agent. It could, however, not be stated that the films had been affected by the agents used. A great problem in the use of PCC is their bond to concrete under freeze-thaw attack. The investigations show that after several cycles of the test regime according to RILI-SIB 2001 (cooling to -15 deg C, warming up to 60 deg C, tempering at 20 deg C in water after retention time) some PCC exhibit distinct net-like cracking and/or the bond partly or completely ceases to exist. Reasons may be different moduli of elasticity, changes in length and thermal expansion between PCC and base or properties of the base such as roughness and absorbing capacity.
Freeze-deicing salt resistance and bond strength of PCC after freeze-thaw attack
The freeze-thaw resistance of a building material is an important parameter characterizing the durability. In publications we find the assumption that the amount of scaling may be reduced by polymer modification, but that the resulting interior damage is considerable. In many CDF and GIF tests made by the authors on mortars with different polymers this statement could not be fully confirmed. Although in some cases the capillary porosity was much higher, the capillary absorption of solutions of most PCC was lower than that of non-modified mixtures. It is highly probable that a certain hydrophobizing of the pore walls may be the reason for the usually good freezedeicing salt resistance. In tests with organic de-icing agents (potassium acetate, glycol) no evidence could be found that the process of damage might be influenced by such phenomena as the solution of the organic components from the mortar matrix. Only in tests on free polymer films a swelling effect could be detected, its intensity varied depending on the de-icing agent. It could, however, not be stated that the films had been affected by the agents used. A great problem in the use of PCC is their bond to concrete under freeze-thaw attack. The investigations show that after several cycles of the test regime according to RILI-SIB 2001 (cooling to -15 deg C, warming up to 60 deg C, tempering at 20 deg C in water after retention time) some PCC exhibit distinct net-like cracking and/or the bond partly or completely ceases to exist. Reasons may be different moduli of elasticity, changes in length and thermal expansion between PCC and base or properties of the base such as roughness and absorbing capacity.
Freeze-deicing salt resistance and bond strength of PCC after freeze-thaw attack
Bode, K.A. (author) / Dimmig, A. (author)
2004
8 Seiten, 7 Bilder, 4 Quellen
Conference paper
English
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