Friday, December 4, 2020

CEMENT - Making Process,Chemical Composition, Types, Uses, Brands, IS Codes


Now a days in construction industry's cement concrete is widely used as a construction material. In cement  concrete cement is important ingredient in concrete cement is a binding material and it give the strength to concrete.
 Cement is very fine material having adhesive and cohesive property which provide the binding material for other ingredient. It is obtained by burning the materials together of argillaceous (mainly alumina) and calcareous (mainly calcium carbonate and lime) to partly fusion at a high temperature about 1400 to 1500 degrees celsius. Joseph Aspdin manufactured cement and called as portland cement because when it is hardened it produced a material stone from quarries near portland in England. 
The two calcareous and argillaceous materials used in manufacturing of cement. calcareous materials are lime, chalk, oyster shale and marl and argillaceous materials are clay, shale, slate, blast furnace slage.

Two process used in manufacturing of cement Dry and wet process. In dry process raw materials ground mixed and feed to rotary kiln in dry state. After grounted the material the gypsum is added 2 to 3% in rotary klin. The finished product of cement is finally baged in 50 kg per bag.
Chemical composition: 
The raw materials used in manufacturing of cement is mainly lime, silica, alumina, lron oxide. These materials present various property of cement. These material when subjected to high clinkering temperature combine with each other to form complex compound. The identification of the major complex compound is largely based on R.H.Bogues  work and hance  these are called Bogues  compound. 
Chemistry of cement: 
Portland cement consists of the following principal compound
(Figure: Represention of composition of portland cement)
Types of cements:
There are different types of cement as classified by Bureau of Indian standard (BIS) and it's IS Codes.

1. Ordinary portland cement
   A. 33 Grade- IS : 269- 1989
   B. 43 Grade- IS : 8112- 1989
   C. 53 Grade - IS : 12269- 1987

2. Rapid hardening cement
IS:8041- 1990

3. Fast Setting cement.

4. Low heat portland cement 
IS:12600- 1989.

5. Portland slag cement 

6. White portland cement.

7. Pozzolana portland cement

1. Ordinary Portland Cement
33 Grade : Using for PCC work, BBM and Plastering Work.
43 Grade : Useing for BBM & Plastering, Flooring, Waterproofing, Etc.
53 Grade : Using for RCC Concreting Work, Mass Concrete, Etc.

2. Rapid Hardening Cement
Using at under water construction.

3. Fast Setting Cement
Using for underground pile concreting.

4. Low Heat Portland Cement
Using for Mass Concreting, Machine Foundations, Furnace Foundation, etc.

5. Portland Slag Cement
Using for BBM  and plaster work at low cost housing projects. as well as using in mass housing project.

6. White Portland Cement
We are known this cement as white cement, which is commonly using for joint filling in flooring, skirting, using at sanitory fitting work, etc.

7. Pozzolana Portland Cement (PPC)
This type of Cement is widely use in construction field, most of use in brick masonry, plastering amd waterproofing, flooring, etc.

Famous Brands of Cement
1. Ultra Tech Cement
2. ACC Cement
3. Shree Cement
4. Dalmia Cement
5. Ambuja Cement
6. Bharti Cement
7. Birla Cement
8. JK Cement
9. Bangur Cement
10. Choromandal Cement

All above types only OPC and PPC coment are using at all the project's and this cement is easily available in the market. but from last 1 years the difference in rate of OPC cement and PPC cement is just ₹5.00 therefore lot of consultant are refer OPC cement insted of PPC. use is same but difference in strengths. as well as another challanges need to face on site about the stock of both types of cement need to keep seperately, otherwise there are chance to do concreting by PPC cement and this type of cases happened many times, and this is very dangerous to concrete structure. so using of OPC is always better.

Important : Every Cement bag have 90 days validity, that means we can use this within 3 months from the date of manufacturing. Every lot we need to check the manufacturing date on the coment bag and verity it. after expiry date don't use any cement bags for structural work. which is very dangerous. Expired cement bags can be use at Labour camp PCC work, PCC work at temporary site office, etc.
As well as we should know about its Initial Setting time and Final setting time. Initial setting time of Cement is 30min and final setting time is 600 min i.e 10 hours.
After concreting we should keep this structure atleast 10hrs to achieve the Compressive strength.
Mixing Proportion is also very important part while getti g the knowledge about cement. in our Material Constant blog we had discussed about all the cement constant which are required for our work.

CBEC India

(Article from Ms. Pranita)

Wednesday, December 2, 2020

Material Rates are increased, How can run Construction Industry?

Material rates are increased, Construction Sector in trouble

All we are known about construction industry is just step up to back to normal conditions after effect of COVID19 and Lockdown situations.

Before the yaer ago this sector is little affected due to Rera, GST and demonetization.
In May and June lockdown is over and all construction sector work is going to start. but during lockdown all are facing another big problem as all material rates are increased due to shortage of material.

Now another big problem is stand at front of construction industry is the Material rates of Steel and Cement are increased 20-22% more than existing rates.

From last few days, the row iron supply to steel industry is not sufficient this is affecting directly on the production. due to this rate of reinforcement steel is increased upto 20-22%. it is directly affecting on real estate and construction sector businessman.

In Jalna District of Maharashra, there is near about 25 nos of steel factories which are manufacturing 6mm to  40mm diameter steel bars. and annual production is  1.75 lakhs Metric Ton.
Two month ago steel rates are ₹. 38000 per Metric Ton now it is incresed upto ₹. 47500 per Metric Ton including GST. 

After unlock of all the sctors the real estate sector is started and it required materials but now due to shortage of material the rates are increased it is affecting on construction sector.

 From Jalna, Maharashtra, The steel is distribute and sold in Maharashtra, Karnataka, Andhra pradesh, Telangana, Madhya pradesh states. but currently this district can't full fill the requirements due to shortage of row material.

Also, The production of row iron metal from mine is decreased, due to that the rate of row material is increased. and another side demand is increased due unlock, but due to low manufacturing of reinforcement steel, the rates are incresed from ₹.38000-₹. 40000 to ₹.47000 - ₹. 47500 per metric ton within 2 months.

As per the statement of Polad manufacturer Association Mr. Sunil Goel, " Now production is going normal, the labour are return from other states and back to work after lockdown. but row material is still shortage, and situation is becomes critical. the income from iron and wastage is also decreased. now this situation is seems all over india, due to all this reasons the rates are going to increase."

As per Statement of CREDAI Member,
Not only Steel rates are increased but also Cement rate is also increased, two month ago cement bag rate is ₹. 240 per bag and now it is ₹.300 per bag. due this this the business calculations are collapsed. ALot of people are lost there jobs during the lockdown which is started by government to stop the Coronavirus. Increased unemployment affects sell of flats in apartments, and decreased in sell means loss of real estate. and other end the material rates are increased now it going to serious effect on the construction industry.
If you are Plan to 1,00,000 Sqft Built up area building. Then Steel is Supposed to 3.50kg Per Square Feet.

Required Steel = 1,00,000 Sqft X 3.50 Kg/Sqft = 3,50,000Kg i.e. : 350MT

Amount as per Existing Rates 
350MT X  ₹38,000 = ₹1,33,00,000

Amount as per New Rates
350MT  X ₹47,500 = ₹1,66,25,000

Difference in Amount = ₹ 33,25,000
Rate per Sqft = ₹33.25 per Sqft Extra amount required per Square feet.
(This is basic amount we have not included loading, unloading, labour, overheads, instrest, etc.)

(Source: News paper)