In the changing world, cement has become an indispensable item in the construction of every physical structure. Construction of physical structures cannot be thought of without the use of cement. After the Baisakh earthquake of 2072, the use of cement increased rapidly even in remote villages.
Cement is a 'chemical blinder'. Cement binds the sand, gravel and sand together. Generally there are two types of cement, brown and white. Today we are talking about the use of gray cement.
Various types of gray cement have been used in the world market. However, in the context of Nepal, three types of gray cement are being used namely OPC, PPC and PSC. The most commonly used cements are OPC and PPC. OPC is being used for pillars, beams and slopes while PPC is being used for applying plaster and mortar.
What is OPC?
Ordinary Portland Cement (OPC) is a cement made from ordinary limestone. Limestone is cooked at 1400 degrees centigrade and mixed with various substances to make clickers. The amount of clinker used in OPC is more. OPC is made by adding a maximum of five percent gypsum material to the clinker. As OPC has more clinker content, it sets quickly.
OPC is also of three types, 33 grade, 43 grade and 53 grade. These three types of cement have their own uses. It is 33 grade ordinary OPC. 43 grade cement is mostly being used while making the structure. 43 grade cement is used in building. Both 53 grade and 43 grade cement are used in building high-rise buildings, towers, and hydroelectric dams. It does not mean that 43 grade cement does not work in large constructions in Nepal, mostly 53 grade cement has started to be given more priority.
What is PPC?
Pozzolana Portland Cement (PPC) is made by mixing clinker with coal ash/dust (pozzolana). In making this cement, 70 percent clinker, 25 percent pozzolana and around 5 percent gypsum are used. As the amount of clinker is less, PPC takes some time to set.
This is not a bad cement in itself. However, in Nepal, PPC is mostly used for applying plaster and mud. It does not mean that the structure cannot be made using PPC cement. If the structure is designed in such a way that PPC can be sloped, it can be used.
What is PSC?
Portland slag cement (PSC) has only recently come into vogue. This cement is being used in both slopes, hard and plaster in Nepal.
What kind of cement to use in which structure?
All cements have their own characteristics. OPC sets up faster than PPC as the number of clickers is higher. In Nepal, OPC is mostly used to make slopes and pillars. OPC solution is used when working in places with gravel, sand and sand, PPC is used when working with sand only. PPC is mostly used for applying plaster and mud.
OPC is used if large and quick construction is to be completed. As OPC freezes quickly, it is considered appropriate to use it in large projects. PPC cement takes a little more time to set whereas OPC structure takes comparatively less time to set. OPC cement is also known as 'fast setting' cement.
It does not mean that PPC should not be sloped. Buildings are being sloped even by using PPC cement. Some have made slopes or pillars with PPC cement without knowing it, while some have made it with PPC cement after consulting the engineer.
All cements have their own characteristics. OPC sets up faster than PPC as the number of clickers is higher. In Nepal, OPC is mostly used to make slopes and pillars.
After making the slope and pillar by OPC, according to the engineer's advice, water should be added and soaked for some time so that the slope does not crack due to temperature mismatch. Where PPC is plastered or plastered, water is poured from time to time as per the advice of the engineer. In general, there is no significant difference in the capacity of OPC and quality PPC cement. The only difference in both the cements is the time it takes to set.
Different grades of cement can be used according to what kind of structure you want to make, how the engineer has designed the structure. The biggest thing should be the quality consistency of the cement you use. As if you buy any cement from any company, the quality should be the same.
The engineer has already decided which grade of cement to use while designing the structure. Generally 53 or 43 grade cement is sought for large buildings. However, when building a building, cement of this grade is not necessarily required, using the grade of cement according to the design of the building makes the structure stronger.
How much 'strength' is needed for the building you are going to build, what grade of cement should be used, what should be the ratio of ballast, sand, cement, chemicals and water to bring strength is already decided in the design of the building. This work is done by engineers and consultants.
Difference between grade and NS marks
Some consumers may also get confused between the grade of cement and the Nepal Quality (NS) mark.
The grade of cement is the load bearing capacity. This is the strength of cement. In Nepal OPC cement is available in 33 grade, 43 grade and 53 grade. Different grades of cement are used according to the design of the structure. Mostly 43 grade cement is being used for building houses. And this is appropriate. 53 grade cement is also being used in large buildings and infrastructure.
After studying and evaluating whether the cement produced by the industry is of good quality, the department awards the Nepal Quality (NS) mark. From time to time, the department brings cement samples from industry and market and tests them. If the quality standards are met, the NS mark is awarded. Consumers can rest assured when buying cement that has been given a quality mark by the department. Cement cannot be sold and distributed officially in Nepal without taking care of quality.
How long can it be used?
How cement is stored determines its useful life. Properly stored cement can be used up to three months from the production date.
Method of storage
Care should be taken while storing cement. Cement does not like dew at all. If the cement is kept in an open place or in a damp place, it will crumble. Lumpy cement does not work well. If kept in a damp place, cement can deteriorate even in one day.
However, if the cement is kept in a dry closed room, covered with Tripal so that water and air do not penetrate, it can be used for three months.
Things to consider while making the solution
This is the most important aspect. Cement is just a chemical blinder. You have to make a solution according to your structure. Water plays a very important role in making cement, gravel, sand solution. You should not use dirty water. Clean potable water should be used.
The engineer has already decided which grade of cement to use while designing the structure. Generally 53 or 43 grade cement is sought for large buildings. However, when building a building, cement of this grade is not necessarily required, using the grade of cement according to the design of the building makes the structure stronger.
An engineer or an experienced mason should prepare the solution by taking out the ratio of water and cement. If there is too much water in the solution, it will not work well, if there is less water, it will not work well.
When making the solution, the gravel, sand and water should be clean. And only the slope is strong. Use gravel and sand according to the standards. Sand should not be mixed with clay, cement cannot work properly. According to the design of the structure, if the ratio of gravel, sand, water and cement can be adjusted, the construction will be stronger.
You also bought good cement. Gravel and sand were also bought according to quality standards. However, no matter how good the cement, gravel and sand are, if the worker does not make the solution properly, it will not be strong. The person making the solution should be experienced. The advice of an engineer or consultant should be taken. Even after making the solution and putting it in the form, it should be dug well.
Common misconceptions about cement
Some consumers may have some misconceptions about cement. Now dozens of brands of cement are available in the market. We have to use cement according to the design of the structure according to the advice of the engineer or consultant. However, some consumers may have the illusion that 'cement is the same thing!' It should be understood that all cements may not be of the same quality. During the construction work, cement should be used as required.
Which cement is being used more in the market? Which cement users prefer? What kind of structure is being made with which cement? It can be seen from different angles. A brand is also your belief.
First of all, it should be checked whether the cement is made according to the quality standards. Engineers and contractors also know a lot about cement.
Some may think that if you put a little more cement, the house will be stronger. This is also just an illusion. Adding more cement will not make the house stronger. Do not add too much cement and do not add too little. Quality construction work can be done only with the right mixture of cement, water, gravel and sand. If the mixture is not good, no matter what brand and grade of cement is used, the structure will not be strong.
Cement and salt have the same characteristic, when they are less, they are rough and when they are more, they are loud.
If the design of the building is made to suit 43 grade cement, but using 53 grade cement does not mean that it will be stronger. The amount of cement in the solution should also be correct. Using more or less cement than the ratio does not strengthen the construction. Therefore, just as salt should be kept in order for vegetables to be tasty, in the same way, in construction work, the amount of cement should be used as specified by the technician.
Things that consumers should consider when buying cement
When was the first cement made when buying cement? You have to look at the production date. It should be checked whether there are lumps and cracks in the cement. It should also be checked whether the cement bag has got holes.
When buying cement, you should also check whether it has the Nepal Quality Mark. Cement whose production date is more than three months old should not be bought.
No comments:
Post a Comment