Freeze-thaw testing

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... 

Feldberg plot 23, 24, 35 Franck-Condon principle 5, 6, 10 Franck-Condon factor 10, 53, 54 FRASTA 160 Freeze-thaw test 244 Friction factor 135 Fullerene 107, 347... 

DNA contamination Stability tests Freeze-thaw tests... 

Wet-dry and freeze-thaw tests performed under laboratory conditions yield data difficult to extrapolate for field use. This is because laboratory tests represent the worst conditions (also those most readily controlled) such as complete drying followed by complete saturation. Under field conditions, it is more probable that both wet-dry and freeze-thaw conditions are partial rather than complete. This consideration must be taken into account when interpreting manufacturers data such as shown in Tables 11.3 and 11.4, which compare acrylamide with acrylate. 

As between 6 and 9 days of underwater submerging, the weight gain was less than 1% for all boards, all of them were considered as having reached the equilibrium in water in terms of readiness for freeze-thaw test. The freeze-thaw test was conducted as described above. Data are shown in Table 12.17. 

Freeze-Thaw Test. A limited number of mixes were subjected to a series of freeze-thaw cycles in a chest-type freezer at a rate of 6-10 cycles/day. The fundamental transverse frequency at zero cycles, rj, was measured at the beginning of each test. Additional values, rjC, were also measured at 50, 70, 110, and 150 cycles. The fundamental transverse frequency-squared vs. the number of freeze—thaw cycles is plotted in... 

Freeze-thaw test (3 cycles) Pass Blending Procedure ... 

Portions of these paints were oven aged for 10 days at 60 °C, as an indication of long-term stability. Freeze-thaw tests were also run that consisted of five cycles at -25 °C. 

Table IV. Viscosity Stability of Zinc Ammonium Complex-Modified Paints After Heat and Freeze-Thaw Testing ...

A work targeted specifically to civil infrastructure application has reported mechanical data on freeze-thaw tests conducted on isophthalic polyester and vinyl ester pultruded/glass fiber RPs (Chapter 3). Specimens were aged in accordance with ASTM C666 (namely, 40F to OF followed by a hold at OF and a ramp up to 40F followed by a hold) while submerged in 2% sodium chloride and water. Specimens were removed after every 50 cycles and tested in ASTM 3-point flexure mode. The results clearly indicated a reduction in flexure strength and modulus after 300 cycles. 

Freeze-thaw tests in the concrete series were conducted according to ASTM C 666 (Procedure B rapid freeze-thaw under air conditions). It was applied on standard prismatic specimens at the dimensions of 80x80x360 mm. The experiment was conducted after the specimens had been cured for 28 days. Heat transfer calculations were made in order to determine how long the heat in the specimens would take to reach the optimal heat required for the experiment so that the freeze-thaw test could be made in the deep frost according to ASTM C 666. Therefore, the central heat of the specimens (20 °C) was lowered to -20 °C. The central heat of the specimens left in the water was increased to 5.4 °C. 30 cycles were made altogether, with the central heat adjusted in such a way that it would vary between -20 °C (2 hours and 40 minutes) and 5.4 °C (36 minutes). 

Freeze-thaw testing 10 cycles with 18 hours immersion in water at 20°C, followed by 3 hours at -30°C, followed by 50°C. 

Figure 11.17. Scanning electron photomicrographs of near-end sections of steel reinforcing rods in salt-contaminated concrete slabs after freeze-thaw testing (A) polymer-impregnated core (B) unimpregnated core. (Mehta et ai, 1975.)...

Standardized accelerated tests are useful for carrying out comparative tests of different composite materials. It is easier to determine which material is better than to forecast its effective durability. For example, it is believed that freeze-thaw tests as imposed by ASTM (2003) or other standardization institutions could ensure acceptable durability of cement-based materials in natural conditions during their lifetime in the climate of Northern America and Central Europe, even if the validity of simulation of natural conditions is doubtful. The possibility of using accelerated tests for glass-fibre-reinforced composites are discussed in Chapter 4. 

Cho et al. (2003) were the first to report on freeze-thaw testing. They investigated fuel cell performance under thermal cycling between 80 °C and -10 °C using H2/O2 as fuel and oxidant respectively. After four thermal cycles, the cell performance decreased by about 100 mV and impedance measmements revealed an increase in ohmic and charge transfer resistance. Ohmic resistance was increased from -0.3 to 0.7 Q cm at 0.7 V and 0.9 Q cm at 0.8 V applied potentials, while charge transfer resistance was increased from -0.2 to 0.3 2 cm at 0.7 V and -0.6 to 0.9 Q cm at 0.8 V. Since membrane proton conductivity remained constant throughout the experiment, it was concluded that the increase in ohmic resistance was due to the enhancement of contact resistance between the electrodes, the membrane and the flow fields. 

Freeze-thaw test A sample of ink is placed in a freezer at -15 °C for 4 h. Changes in viscosity, homogeneity, and seeding tendency are observed. 

European Norm EN 1348 addresses this issue in a heat test as well as in a freeze/ thaw test. Shear stress between substrate and tile normally concentrates in the peripheral zones of a tile. That means, the bigger the tile the higher the flexibiHty of the adhesive has to be in order to avoid cracking or delaminating of the tile. The flexibility (deformation capabihty) of a ceramic tile adhesive depends on the polymer/ce-ment ratio. It is one of the two most important ratios to be determined in a ceramic... 

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