Concrete freezing-thawing cycles

Building durability, by preventing decay of wood-based materials, corrosion of metals, and spalling of masonry and concrete caused by freeze-thaw cycles... 

It can be concluded from the assessment of the data in this section that inclusion into a concrete mix of a water-reducing admixture of the lignosulfonate, hydroxycarboxylic acid and air-entraining type should not lead to any deterioration in the durability of that concrete to freeze-thaw cycling. Indeed there are strong indications that, when used either as a means of reducing the water-cement ratio or, alternatively, of reducing the cement content, more durable concrete may result. 

In the early days of the use of superplasticized concrete, some concerns were aired regarding the resistance of air-entrained concrete containing superplasticizers to freeze-thaw cycling. However, more recent research has indicated the following ... 

The effect of the entrainment of a minor amount (4-6% by volume) of air on the ability of concrete to withstand freeze-thaw cycling is remarkable [3] and is illustrated in Fig. 3.1. 

Fig. 3.1 The effect of 300 freeze-thaw cycles (according to ASTM C666 Procedure B) on air-entrained (right) and plain concrete (left).

Concrete containing calcium chloride develops strength more rapidly and, therefore, has a greater resistance to damage by freezing at an early age, as shown in Fig. 5.30. There is some indication, however, that at later ages, the more mature concrete is less resistant to freeze-thaw cycling [22, 33]. 

Vacuum saturating and freeze-thaw cycling has a much greater detrimental effect on the ordinary asphalt concrete than on the sulfur-asphalt concrete. Indeed after soaking, the sulfur-asphalt concrete shows a slight increase in stiffness, and the freeze-thaw cycling causes only a slight decrease in stiffness. The sulfur-asphalt concrete thus appears more durable than its ordinary asphalt counterpart. 

Figure 5. Variation of resilient modulus with temperature, soaking, and freeze-thaw cycling for a sulfur-modified asphaltic concrete and a concrete in which the asphalt is unmodified (46)...

Concrete structures often show cracks. There are several reasons for the formation of these cracks, including physical effects, drying shrinkage, crazing, thermal effects due to seasonal variations in external temperature, early thermal contraction, freeze-thaw cycles and structural effects such as overloading and impact (Concrete Society, 1982). 

This test followed ASTM C 1152-90 Standard Test Method for Acid-Soluble Chloride in Mortar and Concrete. The chloride content was investigated for the samples subjected to the deicing scaling test. Chloride measurements were taken after 25 freeze-thaw cycles. With an electric rotary-hammer powder samples were taken from concrete at four different depths 0 to 12mm, 12 to 25mm, 25 to 38mm, and 38 to 50mm. 

For the 25 freeze-thaw cycles, it was found that plastic fillers did not change the chloride penetration profile of concrete. More cycles are needed to confirm this result and to explore effects with a larger number of cycles. 

In addition to the forms of attack already discussed, cracking and spalling of concrete due to acid-induced corrosion can also lead to and accelerate other forms of attack having other causes, most notably freeze-thaw deterioration. Prudil (30) found that concrete which normally withstood attack due to freeze-thaw cycling was subject to attack after exposure to acid solutions. 

While most concrete defects occur as the result of flaws in design and installation, even good designs sometimes experience defects, earthquakes or similar events, freeze/thaw cycles, vapor/moisture permeability or overloading which lead to a need for repair. The floor should be checked periodically for cracks, spalling, bug holes, honeycombs, or other flaws. Where such flaws appear, they should be repaired and sealed. 

ABSTRACT This research project aims to use reactive powder concrete, RPC. as a new repair material and evaluate its bond strength and bond durability to existing concrete. One accelerated aging environment, namely a freeze-thaw cycle acceleration deterioration test, was selected for the evaluation of bond durability of the repair materials. Before and after aging, the samples were evaluated by the compressive strength, bond strength (slant shear test), steel pull out strength, and relative dynamic modulus NDT tests. 

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