Freezing-thawing durability

The recorded data on lignosulfonate water-reducing agents indicate that, as far as freeze-thaw durability is concerned, because of the low water-cement ratios possible, an enhancement to the durability will invariably be obtained. When the admixtures are used to effect a reduction in the cement content, there are strong indications that a considerable enhancement of durability is obtained, presumably due to a reduction in the cement matrix which is the part of the concrete susceptible to frost damage. The higher aggregate content would therefore allow easier dissipation of stresses. 

There is little information on the effect of this class of material on the freeze-thaw durability of concrete into which the admixture is incorporated. However, one set of data is shown in Table 1.24 [101]. 

The alkyl-aryl sulfonates find application in both the production of lightweight concrete and for enhancing the freeze-thaw durability of normal concrete. The usual raw material is orthododecylbenzene sulfonate, which is a basic surfactant used in a variety of industrial and domestic detergents. The formula is shown in Fig. 3.3. 

Table 3.23 The effect of spacing factor on freeze-thaw durability...

The presence of even small amounts of dampproofer improve the freeze-thaw durability of the concrete [16]. This is further indicated by... 

The reduction in porosity, decreased water content, and air entrainment that results when latexes are used in mortar and concrete mixes make them much more resistant to freezing and thawing conditions than conventional mortar and concrete. Figure 6.17 presents the freeze-thaw durability in water (-18 to 4°C) of combined water-and dry-cured SBR-, PAE- and EVA-modified mortars [98], The frost resistance of mortars made with these latexes is markedly improved even at polymer-cement ratios of 5%. However, an increase in the polymer-cement ratio does not necessarily produce further improvement in freeze-thaw resistance. EMM and EMC, when exposed to outdoor conditions involving freeze-thaw, UV radiation and carbonation show better weatherability when compared with conventional mortar and concrete. 

The use of superplasticizers in air-entrained concrete has caused much debate. Two main problems are associated with superplasticized air-entrained concrete (1) a decrease in air content by 1-3% when slump is increased from 75 mm to 220 mm after the addition of the superpiasticizer to create flowing concrete, and (2) a change in the air void system to less desirable values. However, most investigators [10-11, 12] have shown that, although the air-void spacing factor required for adequate frost resistance is altered, the change did not necessarily affect the freeze-thaw durability of... 

Table V shows the differences in the freeze-thaw durability of concrete-polymer specimens receiving radiation and thermal treatment. The data indicate that the thermally treated specimens have either the same or slightly better durability than the radiation treated material. The higher durability, however, may be related to the higher polymer loading present in the thermal samples for this series of tests.

The presence of even small amounts of dampproofer improve the freeze-thaw durability of the concrete [16]. This is further indicated by freeze-thaw testing of concrete specimens containing the wax emulsion type of dampproofer shown in Fig. 4.7. In this case, however, some air entrainment... 

Infiltration of the permeable concrete with molten sulfur yields a matrix which is almost impermeable to water. The freeze-thaw durability tests have indicated this is so, and immersion tests showed that fully infiltrated specimens absorbed less than 0.3% water by volume over several months, although methanol immersion and vacuum poro-simeter measurements revealed that a pososity of over 5% was available for filling. A total shrinkage of about 13% (Table I) occurs when liquid sulfur crystallizes to the stable low-temperature S< form, but much of the volume change appears to be accommodated in closed pores and intercrystal inversion fractures which affect the permeability little. 

Beaudoin, J. J., Sereda, P. J., The Freeze-Thaw Durability of Sulphur... 

Freeze-thaw durability factor Fly ash and aggregates 89.7% after 300 cycles Road-based and permafrost applications... 

Foy, C., Pigeon, M., Banthia, N. (1988) Freeze-Thaw Durability and Deicer Salt Scaling Resistance of a 0.25 Water-Cement Ratio Concrete, Cement and Concrete Research, Vol.18, pp. 604—614. 

The beams, fabricated in the material testing laboratory, having dimensions of 7.5 cm x 7.5 cm X 30 cm were tested for relative dynamic modulus in accordance with ASTM C 666-97. Three-inch cubes were sawn from each of the beams after the relative dynamic modulus test. The cubes were tested using procedures presented in ASTM C 116-90, Test Method for Compressive Strength of Concrete Using Portions of Beams Broken in Flexure. When the specimens were 28 days old, the freeze-thaw durability specimens were cured in lime-saturated water until testing was begun. 

Cramer SM, Carpenter AJ (1999) Influence of total aggregate gradation on freeze-thaw durability and other performance measures of paving concrete. Transp Res Rec 1668 1... 

The pore structure of latex-modified systems is influenced by the type of polymer in the latexes used and polymer-cement ratio as discussed in detail later. The total porosity or pore volume generally tends to decrease with an increase in the polymer-cement ratio. This contributes to improvements in the impermeability, resistance to carbonation, and freeze-thaw durability. 

Afridi, et al.l found that redispersible polymer powder-modified mortars provide a freeze-thaw durability similar to that of latex-modified mortars. Fig. 5,11 shows the polymer-cement ratio vs. freeze-thaw durability of redispersible polymer powder- and latex-modified mortars.I 1 Figure 5.12 sho % the weatherability of patching mortars using redispersible polymer powders. " ... 

Figure 5.11 Polymer-cement ratio vs. freeze-thaw durability of redispersible polymer powder-and latex-modified mortars.

The sodium abietate, the salt of abietic acid produced from natural pine tree resin, was used as the air entraining agent. The anionic admixtures, mainly alkylaiylsul-phonates, sodium oleate, as well as the non-ionic surfactants such as nonylphe-nolethoxylate are more and more frequently used. This surfactant is efficient air entrainer but does not perform well in freeze-thaw durability tests [358]. 

Effects on Freeze-Thaw Durability of Fibers in Concrete... 

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