foundation system of burj al arab

Concrete Corrosion in Relation to Ice Removal Agent

From the past, when people became used to apply deicers, it becomes common that these salts (deicers) results disintegration of surface. These salts are:

a. Sodium chloride

b. Calcium chloride

c. Sometimes both are applied

But this guidelines concluded some results that are based on laboratory and practical experiences with

Concrete corrosion due to ice removal agent
a. Sodium chloride

b. Calcium chloride

c. Ethyl alcohol

d. Urea

It is also observed that these salts can accelerate reinforcement corrosion leading failure called concrete spalling.

Here we will address deicers as ice removal agents. Many performances of concrete have not yet been understood clearly. In this case also we have a fairly well understanding. However, it is ascertained that the mechanism of disintegration is primarily due to physical causes rather than the chemical causes. Dear reader in the next part of this topic we will learn about mechanism involved in disintegration of concrete under application of ice removal agents.
Two types of pressures are developed there which do the harm to concrete member. These pressures are:

A. Disruptive osmotic pressure

B. Hydraulic pressure

The pressures are developed mainly in paste, just like ordinary frost disintegration, but the degree of pressure is more severe.

Dicers clear concrete pavement from snow and ice
These formations of pressures in the paste, is greatly influenced by concentration of ice removal agents. Here we are providing some observations concluded in the guide: ACI 201.2R; Guide to Durable Concrete.

Klieger and Verbeck in 1957 showed that when a concentration of moderate intensity is used in ponding concrete mass, a most severe scaling of concrete is observed. The moderate concentration means (3-4)%.

The above observations were conducted over four ice removal agents namely

a. Sodium chloride

b. Calcium chloride

c. Ethyl alcohol

d. Urea
Chloride captures steel reinforcement: deicing salt

Cady and Brown (1975) also found similar results as discussed in previous posts, i.e. intermediate concentration results most severe disintegration of surface.
Liquid calcium chloride for removing ice on concrete pavement
Litvan in 1975 and 1976 also sought results consistent with other two observations. But he had added some extra conclusion which is ice removal agent results high degree of saturation in concrete. He furnished that this is the main cause of detrimental effect.

At a particular temperature of concrete , salt solution in ice removal agents produce a vapor pressure than that of water i.e. little or almost no drying is observed between wetting and cooling cycles. ASTM C672 provides determination procedure to assess resistance of a particular mix against scaling under application of ice removal agents. 

No comments:

Post a Comment