Effects of Salinity on Structures and Construction Materials - Report Example

Salinity is usually measured and reported in terms of mg/L or ppm.  This is to mean that the amount expressed is milligrams of salt per liter of water or a kilogram of soil. Some soils have more content of salt than others and this is to means that salinity varies from one environment to the other. It has to be understood that salinity shows the Amount of salty in a given water body or a portion of the soil. (Smallwood 2002) This is the sum of the weights for different elements in a unit volume of the water. Various factors affect the concentration of salts in water or soil. For instance, the temperature is one of them that greatly affects the content of salts in a given amount of water. Commonly, seawater is known to contain a high number of salts. This is to say that the effects of salinity are highly portrayed on seawater and its environment. Such seawater with a certain amount of salt is said to be saline. Then again if the water in the ocean has salts, then it will be termed haline. Organisms that can dare withstand a range of the number of salts are called euryhaline. (Smallwood 2002) A plant that is adapted to saline conditions is called halophyte.

• Reinforced Concrete

As pointed out earlier, salinity has a great effect on the kind and the organism's number present in any water body which is being considered. The effect is extended to the soil thus affecting the building and construction of structures. Building materials are also affected by salinity. Buildings are significantly affected by the salinity either in water or a certain soil. (Smallwood 2002) The effects can be manifested in form of corrosion depending on the materials used in construction.  Other effects are in form reactions.  For instance, amorphous that is sometimes found in the aggregates together withhydroxyl ion from the cement pore solution leads to a reaction. The result of this reaction is to yield a very weak concrete that cannot be reliable in terms of strength. This is because the silica (which is crystalized poorly) undergoes dissolution and dissociation at a high rate in the alkaline water. This solution then dissociates to form the silicic acid which undergoes reactions in the pore water with calcium hydroxide that is found in the cement pastes. This forms a weakened concrete. 

These are just a mention of the main effects of the alkaline on building materials and the structures. The effects are more and are going to be discussed in stages and the type of structure or building material affected. (Smallwood 2002) Salinity has s great effect on the concrete. This is because some of the materials used to form concrete are reactive with the salts contained in water. The condition we did term as salinity. If then we have to consider the case of reinforced concrete, we will have to see how the salinity affects the nature and the strength of the concrete.

the concrete which has been reinforced is usually a very important constituent material in the concrete making process. Reinforced Concretes can easily be destroyed by the effects of the sea water, the fire, expanded aggregates, calcium leaching, physical damages, chemical damages (this is the carbonization, chlorides, sulphates and distilled water) and bacterial corrosion. The process has great and adverse effects on concretes mostly exposed to these damaging stimuli. (Bernstein 2009). Reinforcement concrete is made in a way to have low tensile strength and ductile which are the main inclusive features.

This reinforcement is strengthened by the addition of steel that acts as the reinforcing bars. This enables the reinforcement to resist the tensile stress of particular regions where it is thought that the concrete is not enough to offer resistance to stress during construction. (Bernstein 2009) In modern reinforcement, a strong reinforcement should at least have some common factors. Such factors include; high relative strength of the reinforcement. This is depends on the materials that are used.

It should also have high toleration of tensile strain to make it more firms to bring support. Irrespective of moisture, pH, and similar factors, it is also supposed to have good bond to the concrete. The reinforcement again should have thermal compatibility. This thermal compatibility should not cause any stress which is unacceptable when responding to the changes of temperatures. (Bernstein 2009) Also this durability in the concretes locality should not be altered by either continued stress or corrosion.

If such reinforcement has to be achieved, then relevant materials and conditions should be used to favor the construction of such a strong structure. (Smallwood 2002) Now the issue of effect of salinity comes in where the reinforcement is weakened by the salinity. This is through several ways that leads to construction of a very weak or a strong reinforcement that is later weakened. Since concrete is nothing but the mixture of some materials that are in a certain proportions to yield the coarse mixture.

Such materials are coarse bricks (stones) and fine aggregate (sand) mixed with a binding material (cement).n water is added to the above named mixture. Then it is mixed with small amount of water. . (Smallwood 2002) Now the problem begins when the mixture is added some amount of water since when water is added to the cement, the cement hydrates forming a microscopic crystal lattice that is encapsulating and that is locking the aggregate to form a rigid structure. The reinforcement is now made through pouring the mixture on a steel metal that is set to the place that is the target of reinforcement.

(Smallwood 2002) If now the water used happens to be salty, the condition we termed as salinity, then this may lead to reaction. This depends on the type of salt that is contained in the salty water. This is because different salts have different reactions with cement. Some are very severe to weaken the reinforcement in a few days after the reinforcement is set. Now, this is the reason as to why the reinforcement has to be a typical one and incase of the concrete has no reinforcement, it must have a good support so as to prevent the tension from developing.

At high Ph i.e. 11 and above, the reinforcement starts to corrode and below Ph 10 which is still a relatively high pH the corrosion is worsened.