Merit and Demerits of concrete

 Context 

• Merits and Demerits of concrete.
• Strength of concrete 
• Durability of concrete 
• Workability of concrete 
• Consistency of concrete 

Merits of concrete 

1- Ingredients: ingredients of concrete are found everywhere and are cheap.

2 Simple production : the production of concrete is very simple compare to other building materials such as brick and steel 

3 Desire casting : it can be molded into any shape and size in the wet state . It can be delivered to any place by pumping. 

4-Desired Properties: Concrete is an artificial building material. In this the desired properties can be developed as required. 

5-Strength comparession strength of concrete is more than brick masonry and wood 

6- Safe concrete is much less affected by sun , rain dampness , fire , water etc 

7-Anti pest - it is safe from termites and pests 

8- Age It is a durable substance, its age is very much 60-100 years 

9- Maintenance  Maintenance expenditure on concrete structures is very less. 

10- Everlasting - The strength of concrete increases with lasting age while that of other construction materials decrease.

11- special use it is used in reinforced concrete and pre reinforced concrete in complex structures with long spans 

12- Low Cost - Concrete is cheaper than other construction materials like steel ,timber ,plastic etc 

13- Huge Structures : concrete structures are grand and huge which looks attractive 

 

Demerits of concrete  

1 Irreversible Once the concrete is molded it is difficult and skeptical to change its block.

2 Tensile Strength 

The tensile strength of concrete is very low ,to overcome this deffect ,steel is reinforced in concrete, which increase its cost.

3 Expansion joints : the heat shifts and shrinks the concrete , so it is necessary to add expansion joints to its composition.

4 Contraction The contraction occurs when the wet concrete dried ,due to which internal stresses are produced.

5 Vigilance there is a lot of vigilance in the production of concrete , the strength of the concrete is affected due to messing up of ingredients ratio or faulty concrete actions. 

6 Weight The concrete itself has a lot of weight. This increases the fixed weight of the structure 

7 Alkaline Water  

Cement concrete is not completely impermeable. It is affected when exposed to alkaline water 

8 expensive 

Form work Expensive form work is required to mold concrete components

9 Hard Repair 

Repair of concrete is difficult. Cracks and other defects are difficult to completely overcome 

10 Srcap Value 

The scrap value of concrete is Zero , while wood ,bricks, iron etc get some value even after the beneficial age  

Physical properties of concrete 

1 Strength 

2 Durability 

3 Workability 

4 Consistency 

 Strength of concrete

Cement concrete is mostly used in civil construction works and its compression strength is considered only , because the tensile strength of concrete is only 10% of the compression strength . Hence plain cement concrete is used only in structures on which only compression force is employed. 

The main factors affecting the strength of cement concrete are 

1- Variety and strength of concrete aggregate

2- water cement ratio 

3 proportioning of ingredients 

4 compaction of concrete 

5 curing of concrete 

Durability of concrete 

Cement concrete can be made endurable by using good quality cement and mixing and adopting suitable water cement ratios, mixing well compaction and curing 

Unsound cement and concrete made from weak aggregate are of low grade . Due to the entry of water , salts , gases , etc into the concrete pores and frequent change in the temperature , concrete decomposition begins 

Workability of concrete 

Workability is the quality of concrete that allows ready concrete to be used at the workplace without segregation or bleeding . In simple language ,it can be said that such fluid concrete ,which can easily reach all the corners in the form itself, and it can be compacted,is called workable concrete. 

Consistency of concrete 

The tendency of concrete to flow as a fluid is called consistency . The more water there is in the concrete , the lower its consistency will be . Consistency and workability are two related facts of concrete.