Vastu is considered the interplay of various forces of nature involving the five elements of earth, water, wind, fire and ether and strives to maintain equilibrium as these elements influence, guide and change the living styles of not only human beings but every living being on earth. Thus they influence our deeds, luck, behavior and other basics of life.

Vastu Shastra is the sublime elucidation of your surrounding and their influence on your life. Vastu literally means " house" or Dwelling Place and its principles establish to create a harmony between the fine elements viz. Earth, Sky, Fire, Water and Air in the environment.
Vastu Shastra unifies the science, art, astronomy and astrology, it can also be said as an ancient mystic science for designing and building. Vastu Shastra helps us to make our lives better and will secure from things going wrong.

Vastushastra is an ancient building science which covers the philosophy and theory of Architectural works to construct any building and as well as living style of people. Vastushastra is based on various natural energies, which are available free cost in atmosphere like:
•    Solar Energy from Sun. Lunar Energy from Moon
•    Earth Energy
•    Sky Energy
•    Electric Energy
•    Magnetic Energy
•    Thermal Energy
•    Wind Energy
•    Light Energy
Cosmic Energy

Utilization of such energies gives us pleasure peace, prosperity and money etc in our life. Now a days we are having National Building code, which gives us certain regulations to construct building, whereas in past our ancestors were having Vastu Shastra as a religious & rigourics code. As per shastra Vastu Purush is god of building science, hence let us pray. Thus Vastu is rational, as it is scientific, it is permanent as it is based on directions and directions are unchangeable. It is beneficial as it is a bridge between man, material and nature and above all it is practical, as it is very simple to follow. Build your house according to the guidelines provided by vastu and lead a healthy and happy life.
Vastu can be used for every room, every house, every temple, every shop industry, town planning, tour, cities and even for earth. Vastu can be used for micro as well as for macro level.
Every creature on earth starts its life with sunrise as it performs day & night. Hence there is much importance of sun in every one life. It gives ultra violet rays in morning and infra red rays in evening which one basic need to reduce / generate bio-chemical germs, N2/ Oxygen / CO2 on earth.
Sun indicates light (illumination) will power, generosity, solar system, luck or fate, mobility and in body. It rules over bone, eye, heart, spinalcord, blood circulation and soul etc. Hence east direction is auspicious; it belongs to lord Indra. North is considered auspicious since magnetic lines of forced moves from North to South, thus origin of all the life.
There are three forces in action to create harmony. Wind, water and fire or, vaayu, jal and Agni. If these forces are kept in their appropriate places, then there will be no disturbance. But if water is put in place of fire and wind in place of water or in any other combination, the forces will start acting accordingly and create disharmony and unpeacefulness.

 

Authenticity Of Vastu
The biggest Proof of vastushastra can be found during the time of Ramayan and Mahabharat. Even in the cities of Mohanjodaro and Harappa the application of vastushastra can be seen. Since the science goes far back to the times of Lord Rama and Lord Krishna there are many interesting mythological stories concerning the origin of Vastupurush (the deity).

If you consider it a mythological fact then here are the most unbelievable examples that Vastu is a science and one must follow it wholeheartedly.

Geographical situation of an area affects the nature thus the vastu for every place changes. We see that some countries are much advanced, developed and prosperous while others are much backward.

Apart from the geographical conditions and different nations, if we take examples within our country, you will be surprised to see. Have you ever thought that why tajmahal is so famous that it has become the 7th wonder of the earth and why exactly similar structure called"chandbibi ka makbara" situated in Aurangabad is not yet known to the people. Why is so that the Tirupati balaji is world famous and other temples situated in the same regions are still waiting for the pilgrims to come…. This is all vastu , they are famous because they are made according to vastu.

Thus to achieve the happiness, peace and prosperity, one must follow the principles of vastu.

Vastu is an empirical science. Over the years, based on the knowledge in the Vedas, repeated studies on a number of buildings, offices, temples, houses, apartments have shown a positive correlation between the application of Vastu principles and success. It can be extensively applied to various edifices natural and man made land masses, temples, factories, homes, office buildings and corporate headquarters.

Water in the Northeast is considered most auspicious and Japan has the largest water body in this direction, a reason for its being one of the most prosperous countries in the world. Mumbai again has water in the North East and the Atomic Power Plant (Agni) in the South East thus according to Vaasthu principles and the most powerful, prosperous place in India.

The location and construction of the famous Balaji Temple, the most prosperous in India, are all according to Vastu: Water tank in the Northeast, Kitchen in Southeast, and the Lord in Southwest facing East and so on. Studies conducted on cities like New York, London, Singapore, Hong Kong etc have shown they are according Vastu principles.

The most famous prosperous industrial houses have also been studied; The Tata head quarters in Mumbai, Akbarallys the most successful retail store in India, factories of FACOR a highly successful industry in A.P. and many others have been found to be according to Vastu.

 

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Vastu is a science of direction that combines the five elements of nature and cosmos, ultimately balancing with man and the material. This mysterious science unifying the five elements called ‘Panchbhootas’- earth, fire, water, sky and space and paving a way for enlightenment, happiness and prosperity. 

Five elements
According to Vastu, the cosmos is full of beneficial energies which we must learn to tack as well as keep in balance if we wish to experience a state of well-being. Energy is essentially emanated by two forces- the five elements and the electro-magnetic energy generated by the rotation of earth. Earth is a third planet among the nine planets and the only place where life exist due to the presence of panchbhootas. Sun, air and space are universally available and can be moulded in accordance with human needs by the act of design. To thoroughly understand the act of design with these five elements we need to discuss all these elements briefly in a separate manner: 

Earth-The first and foremost element of nature which exerts maximum energy. It is necessary to consult the land you are purchasing, as plot’s soil, area everything matters in Vastu. The selection of site is considered very important in Vastu element. A detailed inspection of soil, plot, site, shape and size has to be done before commencing the construction. Earth (prithvi) is the most important element in Vastu and influence human lives in every way. 

Water-Water (jal) is present on earth in the form of rain, ocean, sea and rivers. It is the second foremost element considered in Vastu. Vastu provides proper directions for the placement of water sources. Water is an element of north-east. As far as the flow of domestic water is concerned, it should be drained out of north-east only. The water bodies such as swimming pool and aquarium etc need to be made in north-east, this direction is auspicious and suitable for water

Fire-Fire (Agni) is considered as an element of south-east. In a house kitchen fire or electrical gadgets shall be place in south-east. Light is the essence of life, and sun is the natural light giver. Fire is the basis of all sources of energy including thermal power and atomic power. There should be proper ventilation for sunlight being necessary and natural source of light for human beings.

Air-Air (vayu) is a necessary thing for all of us living on this earth. In Vastu air is another important element which is considered before applying it. Air is an element of north-east. Air consists of various gases on earth like oxygen, nitrogen, helium, carbon dioxide etc. A balanced percentage of different gases, atmospheric pressure and humidity level are important for living beings on this earth. There are important directions for windows and doors in Vastu so as to receive a good amount of air.

Space-Sky is never ending and our space is full of constellations, galaxies, star, moon, sun and all the nine planets. It is also called universe which is known as ‘Brahamand’- the place of god. Space has a very important place in our lives and Vastu gives different directions for better space. Indian houses used to have open space in the centre of the house. Akash is a brahmasthan which should be an open place, any disturbance related to space in house would lead to detrimental results.

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Generally there are two types of steel bars available in the market.
 

1.Mild steel bars

2.Deformed steel bars

Mild steel bars

Mild steel bars are used for tensile stress of RCC (Reinforced cement concrete) slab beams etc. in reinforced cement concrete work. These steel bars are plain in surface and are round sections of diameter from 6 to 50 mm. These rods are manufactured in long lengths and can be cut quickly and be bent easily without damage.

Deformed steel bars

As deformed bars are rods of steels provided with lugs, ribs or deformation on the surface of bar, these bars minimize slippage in concrete and increases the bond between the two materials. Deformed bars have more tensile stresses than that of mild steel plain bars. These bars can be used without end hooks. The deformation should be spaced along the bar at substantially uniform distances. 

 

Physical Requirement:

S.No	Types of nominal size of bars	Ultimate Tensile Stress N/mm2 minimum	Yield Stress N/mm2	Elongation Percent minimum
1.	Mild Steel Grade I or Grade 60
	For bars up to 20mm	410	250	23
	For bars above 20mm upto 50 mm	410	240	23
2.	Mild Steel Grade-II or Grade 40
	For bar up to 20mm	370	225	23
	For bars above 20mm upto 50 mm	370	215	23
3.	Medium Tensile Steel Grade-75
	for bars up to 16mm	540	350	20
	for bars above 16 mm up to 32 mm	540	340	20
	for bars above 32 mm up to 50 mm	510	330	20

Various Grades of Mild Steel Bars

Reinforcement bars in accordance with standard IS No. 432 part-I can be classified into following types.   

1) Mild Steel Bars: Mild steel bars can be supplied in two grades 

     a)Mild steel bars grade-I designated as Fe 410-S or Grade 60 
     b) Mild steel bars grade-II designated as Fe-410-o or Grade 40

2) Medium Tensile Steel Bars designated as Fe- 540-w-ht or Grade 75

Grade II Mild steel bar are not recommended for use in structures located in earth quake zones subject to severe damage and for structures subject to dynamic loading (other than wind loading) such as railways and highways bridges.

Every lot or consignment of mild steel bars brought at the site of work should be tested in laboratory before use in the work. However for small work one can use mild steel bars on the basis of verifying tests results made by manufacturer in his own laboratory; which are available with supplier. 
Some of manufacturers stamped MS bars grade with their make /name and also give certification of test and grade. On the basis of the above information you can store mild steel bars grade-wise at the site of work.

Steel Bars for RCC Work 

All finished steel bars for reinforced work should be neatly rolled to the dimension and weights as specified. They should be sound, free from cracks, surface flaws, laminations, rough, jagged and imperfect edges and other defects. It should be finished in a work manlike manner. 

General precautions for steel bars in reinforcement

• Steel bars should not be clean by oily substance to remove the rust.
• Steel bars should be stored in such a way as to avoid distortion and to prevent deterioration and corrosion.   
• Overlapping bars do not touch each other and these should be kept apart with concrete.
• The bar is bent correctly and accurately to the size and shape as shown in drawings.
• Steel bars are clear, free from loose mil scales, dust and loose rust coats of paints, oil or other coatings which may destroy or reduce bond strength. No over lap is given in the bar having a diameter more than 3.6CM, if required, the bar should be welded.
• The steel bars should not be disturbed while lying cements concrete.
• If possible, the bar of full length is used.
• The overlap if given should be staggered.
• The cranks in the bar at the end should be kept in position by using spots.
• Required cover under steel bars should be given before laying the cement concrete.  

 

Weight of Different Steel Bars

When we want to purchase Mild steel members from the market, the shopkeeper quotes the price of steel members in weight.  
When any type of steel members for use in house construction is required, we calculate the length of steel member in feet or meter but we are ignorant about the weight of steel.  

Here are details of weight per meter for various types of steel members:-

This will help us for estimated weight and cost. It will also help at the time of purchase to avoid pilferage in weight.

M S Steel round & square Bar
Sr.No.	Dia of steel bar	Weight per meter
		Round Bar	Square Bar
a	6 mm	0.22 Kg.	0.28 Kg
b	8 mm	0.39 Kg	0.50 Kg
c	10 mm	0.62 Kg	0.78 Kg
d	12 mm	0.89 Kg	1.13 Kg
e	16 mm	1.58 Kg	2.01 Kg
f	20 mm	2.46 Kg	3.14 Kg
g	25 mm	3.85 Kg	4.91 Kg
h	28 mm	4.83 Kg	6.15 Kg
i	32 mm	6.31 Kg	8.04 Kg
j	36 mm	7.99 Kg	10.17 Kg
k	40 mm	9.86 Kg	12.56 Kg
l	45 mm	12.49 Kg	15.90 Kg
m	50 mm	15.41 Kg	19.62 Kg

 

 

 

Specification of Steel

Types of Steel

 Generally the steel is of two types mentioned below.  

• Structural steel
• Mild steel and medium tensile steel bars for concrete reinforcement.

Structural Steel:

This specification covers steel sections, plates and bars of the following categories for use in structural work:- 

Quality of Finished Structural steel

All finished steel subject to tolerances should be fine and rolled cleanly to the dimension, sections and weights specified. The finished material should be free from cracks, surface flaw lamination rough, jagged and imperfect edges and all other defects. The material should comply in all respects with the test and requirements mentioned in INDIAN standard 226, applicable to the material (Members, sections, plates and bars.) specified or required.

The following varieties of steel should be used for structural purposes.

• S.T 42-S: The standard quality steel designated as ST-42, confirming to IS: 226 should be used for all types of structures (riveted or bolted) including those subject to dynamic loading and where fatigue, wide fluctuation of stress and reversal of stress are involved, as for example: - Girders, Crane Gantry, road and railway bridges etc. It is also suitable for welding up to 200 mm thick material.
• S.T 42-W: The fusion welding quality steel designated as ST 42 W confirming to IS: 2062 is used for the structures subject to dynamic loading.           
• S.T 42-O: The ordinary quality steel designated as ST 42-O confirming to IS: 1977 is used for the structures not subject to dynamic loading, other than wind load where welding is not used.
• S.T 32-O: This ordinary quality of steel designated as ST 32-O confirming to IS: 1977 is used for door window frames, grills, steel gates, building hardware fencing etc.

Mild steel and medium tensile steel bars for concrete reinforcement

 The specification covers requirement and methods of the test for rolled mild steel and medium tensile steel bars in round and square sections.

Tolerance of medium tensile steel for Construction Work

The bars should be rolled up to following tolerances.

S. No.	Diameter of Bar(mm)	Total Tolerances(mm)
1.	19 and below	0.4
2.	20 and 21	0.45
3.	22,23 and 24	0.5
4.	25 and over	2% of dia.

Quality of Finished medium tensile steel:

The following points ensure the quality of finished steel for construction work.

• All finished steel should be fine and rolled cleanly to the dimension and should have weight as specified by BIS subject to permissible tolerance.  
• The finished material should be free from cracks, surface flaws laminations, rough and imperfect edges and other harmful defects. 
•  Steel section should be free from excessive rust, scaling and tilting and be well protected.

Precautions while purchasing steel window grills

Steel is the most important element and basic raw material for construction of a building. Well finished and good quality steel is required for any strong construction. So you need to have a careful eye while purchasing steel. The steel must be free from rust, cracks and surface flaws. Let’s know some steel purchasing guidelines.  

Remember while purchasing steel

1. Accurate Rates

The house owner should verify rates from different shops in the market. He should also ensure about the quality of steel.

2. Quality Workmanship

Observe workmanship of already finished material at shop/workshop of manufacture before giving order.     

3. Accurate Size Measurement 

Ask manufacturer to measure the sizes of door and windows from the site of your house. If the sizes are taken by manufacturer, he can not make any excuse at the time of fittings.

4. Quality Material

Check whether the material i.e. mild steel angle flat T channel etc. used in windows/grills has a surface free from cracks, surface flaws having uniform width and thickness. The material is free from rust.  Steel member should bear stamp on the surface from reputed manufacturer. 

5. No Joint in Steel Member  

Any individual member used in structure should be in one piece without having any joint. 

6. Finished Exposed Edges

All exposed edges are finished square and smooth by filing, milling or planning. The welding is equal to the length of joint, not in touch form and be smooth. Any welding material’s chip is not left on the surface of any member. The holes are drilled in spite of punched and be according to the requirement.

7. Grills’ Quality

The grills should be cleaned of all sides, rust and foreign matter and be painted with priming coat after fabrication works. Fix grills in windows properly leaving no space with required screws or welding as the case is.

8.Proper Weight

Take weight in your presence carefully at the time of weighing.

Note down: To prevent pilferages in weight and know more about the weight and length of steel members, you can take help from the article “Weight of different Steel Members”.

 

TMT Bars (Thermo Mechanically Treated Bars)

TMT Bars,Thermo mechanically treated bars are high strength deformed steel bars used in reinforced cement concrete (RCC) work manufactured with the help of advancement of technology. TMT bars are latest production in MS steel bars and have superior propertiessuch as strength, ductility, welding ability, bending ability and highest quality standards at international level.

What is thermo mechanically treatment process?

By adopting thermo mechanically treatment process higher strength of TMT bars is obtained. In this process, steel bars get intensive cooling immediately after rolling. When the temperature is suddenly reduced to make surface layer hard, the internal core is hot at the same time.  Due to further cooling in atmosphere and heat from the core, the tempering takes place. This process is expected to improve properties such as yield strength, ductility and toughness of TMT bars. With above properties, TMT steel is highly economical and safe for use. TMT steel bars are more corrosion resistant than Tor steel.

How to get higher strength of TMT bars?

Generally, higher strength of TMT bars can be obtained by increasing carbon content, micro alloying, and thermo mechanically treatment or cold twisting. So far in India, cold twisting of bars is extensively used for the production of high strength bars. The two main ribs become helical when cold twisting process is done whereas these ribs in hot rolled bars are straight. The excess of carbon content threatens its property of welding ability.   

In TMT bars, this problem has been eliminated. In these bars, carbon content has also been brought down leading to improved ductility and can be restricted to 0.2% to attain welding ability and at the same time no strength is lost. The joints can be welded by ordinary electrodes without any extra precautions.  

Caution

• While purchasing TMT bars, notice identification mark on these bars from manufacturing firm. 
• For big projects it is advised to check that only one type/grade of bars is brought to the site and is used in the project after conducting test for each lot. Do not use mixed, 2 or 3 types/grades bars in RCC work at one work.  

HSD Steel Bars (High Strength Deformed Bars)

High strength deformed bars IS: 1786-1985 are steel bars which are provided with lugs, ribs, projection or deformation on the surface and are produced in form of cold twisted deformed bars. These bars are extensively used for reinforcement purposes in a construction. Due to ribs or projections on the surface, these steel bars minimize slippage in concrete and increase the bond between two materials i.e. between cement concrete and steel bars.

The deformed bars have more compressive and tensile stress than that of mild steel plain bars. High strength deformed bars have improved anchorage; therefore they can be used without end hooks or bent up ends of bars. This reduces labor for fabrication of steel reinforcement.  The deformation is spaced on bar at uniform distances. These bars are produced in sizes or sections from 4 mm to 50 mm in diameter.  
  
Generally cracks develop in reinforced concrete around mild steel bars due to stretching of bars, loss of bond under the load. To minimize this problem, deformed bars having projecting ribs or twisted surface which improves the bond with the concrete should be used in RCC work.   

Features of HSD Bars

• Low carbon value: HSD Bars have lower carbon level, resulting in good ductility, strength and welding ability.
• Superior bonding strength: HSD bars are well known for their excellent bonding strength when used with concrete. 
• Welding capability: Since these bars have lower carbon content, they have 100% welding capability than conventional bars.
• High tensile strength: HSD bars feature high tensile strength. They offer great asset in construction process, where a lot of bending and re bending is required. 
• Wide application range: These bars have wide application range like in building residential, commercial and industrial structures, bridges, etc. 
• Satisfactorily malleability, minimum weight and maximum strength and suitable for both compression and tension reinforcement.

Process of production of bars

The main process for production of bars is hot rolling followed by cold twisting. Latest technological advances in the field of micro-alloying of steel and thermo-mechanical treatment process have resulted in the production of deformed bars as reinforcement for use in cement concrete in three grades namely Fe 415, Fe 500 and Fe 550.       
 

The strength of bonds of deformed bars

In addition, the calculated strength of bonds of deformed bars should be 40 to 80 % higher than that of plain round bars of same nominal size. Tor steel possesses the strength of 1.5 to 2.0 times of mild steel in compression as well as in tension, whereas it costs only 10% more than mild steel.

Deformed steel bars have minimum 0.2% proof stress or yield stress in N/mm square. Proof stress is the stress at which non proportional elongation equal to 0.2% of the original gauge length takes place. Hence deformed steel bars are very economical to use in RCC work. Structural Engineer recommends cold twisted deformed (Ribbed or Tor Steel Bars) bars as they are best quality steel bars for construction work.

Mechanical properties of high strength deformed (HSD) steel bars for concrete reinforcement

Property	Grade of Steel
	Fe415        Fe500           Fe550
0.2% proof stress/ yield stress minimum N/mm square	415.0         500.0            550.0
Elongation, percent minimum on Gauge length 5.65 VA where A is the cross sectional area of the test piece	14.5           12.0               8.0
Tensile strength, minimum, N/ mm square	10% more than proof stress but not less than 485, 8% more than proof stress but not less, than 545, 6% more than proof stress but not less than 585

 

How to ensure weight of steel members?

While purchasing mild steel members from the market, the shopkeeper quotes prices of steel

members in weight. But we are ignorant of the fact (the weight of steel members) used in house construction and calculate the length of steel members in feet or meter. The following tables/details are useful for estimated weight and cost and help in purchasing of steel members to avoid pilferage in the weight. 

M S Steel Round & Square Bar

S. No.	Dia. of Steel Bar (mm)	Weight per meter Round Bar                             Square per meter Kg.                                           Kg.
1.	6	0.22                                          0.28
2.	8	0.39                                          0.50
3.	10	0.62                                          0.78
4.	12	0.89                                          1.13
5.	16	1.58                                          2.01
6.	20	2.46                                          3.14
7.	25	3.85                                          4.91

 

M S Angles

S. No	Size of Angle mm.	Weight per meter Kg.
1.	20x20x3	0.9
2.	25x25x3	1.1
3.	30x30x3 30x30x4	1.4 1.8
4.	35x35x3	1.6
5.	35x35x4	2.1
6.	40x40x6	3
7.	40x40x3	1.8
8.	40x40x4	2.4
9.	40x40x5	3
10.	40x40x6	3.5
11.	50x50x3	2.3
12.	50x50x4	3
13.	50x50x5	3.8
14.	50x50x6	4.5

 

 

S. No.	Size of Girder	Weight per meter Kg.
1.	150x50	7.1
2.	150x80	14.2
3.	175x50	8.1
4.	175x90	16.7
5.	200x60	9.9
6.	200x100	19.8
7.	225x80	12.28
8.	225x100	23.5
9.	250x200	40.9
10.	300x150	37.7
11.	300x200	48.1

T- IRON

S. No.	Size of T-Iron	Weight per meter Kg.
1.	75x150	15.3
2.	100x200	20
3.	125x250	27
4.	150x250	29.42
5.	100x50	8.1
6.	75x80	7.1
7.	100x100	12.7
8.	75x50	3.5

 

What is binding wire

Binding wires are made from high quality carbon steel making them highly resistant to corrosion and abrasion. In RCC work where we use MS steel bars either plain or ribbed  or tor, binding wires are used to bind the steel bars  to each other at appropriate place according to design at a spacing defined by the drawing.  The steel bars should not be disturbed while lying cements concrete in any of member such as column, beam, slab wall etc.

If the bars are disturbed than it will reduced the strength of RCC. So proper binding is necessary to intact the steel bars. Binding is usually done by hand with the help of hand tool but in heavy work big diameter steel bars some time bind with the help of welding.

Binding or fabrication of reinforcement shall be as per drawing and Bending shall be cold bending done either mechanically or with hand but to a correct radius with tools meant for the above work conform to IS 2502. Steel bars should be clear, free from loose mil scales, dust and loose rust coats of paints, oil or other coatings which may destroy or reduce bond strength. The bar is bent correctly and accurately to the size and shape as shown in drawings. The bar is bent correctly and accurately to the size and shape as shown in drawings. If possible, the bar of full length is used.   Overlapping bars do not touch each other and these should be kept apart with concrete.    The overlap if given should be staggered. The cranks in the bar at the end should be kept in position by using spots.

 
Quality / Specification

The binding wire should be 16 or 18 gauge annealed wire conforming to IS 280. It shall be free from rust, oil, paint, grease, loose mill scale or any type.

 

It shall be free from corrosion and abrasion and should be abrasion
Highly stringent.
Its tensile strength is half hard i.e. the Tensile Strength: 250-430 N/mm2.
and  Elongation: 40 % @ measuring length of 5.0 x dia.

Precaution while binding

 The binding wire should be cut in to pieces from coil for binding.
Care should be taken that the length of wire should not be less than 4’’. Take 2 numbers wire and bind diagonally at joint tightly. Do not leave any joint, bind all the joints. At some places, there is a practice to bind alternately joints which is wrong practice and reinforcement may loose during laying RCC slab.

 

 

...

Gray Cement

In general ‘Cement’ means Gray Ordinary Portland Cement which is used for general purposes in construction. The cement is one of the most important raw materials used in building as the strength of any construction work depends on the quality cement. The gray cement should be factory-manufactured from a reputed manufacturer. It must not be from local plant manufacturer. It is properly packed from factory, not be hand packed locally. While taking supply of gray cement, manufacturing date, grade and type should be checked. The cement should not be more than six weeks old from the date of manufacturing. 

Types of gray cement

According to chemical properties gray cement can be classified as follows.

• Ordinary Portland cement (for general use)
• Rapid-hardening Portland cement (where high early strength is required)
• Low heat Portland cement (in mass concrete for dam etc.)

Manufacturing of gray cement

All types of cement like Ordinary Portland Cement, Rapid-hardening Portland cement or Low heat Portland cement are manufactured by intimately mixing Calcareous, Argillaceous and Silica, Alumina or Iron Oxide bearing materials, which are burnt at clinkering temperature and are ground to produce gray cement, complying with specifications. No material except Gypsum or Water or both should be added after burning.   

Specifications of gray cement

Fineness

There are following two methods to check fineness of Portland cement.

• Method 1:  After sieving, the cement on IS test Sieve No.9 (B.S. Sieve No 170) should not      exceed 10% in case of Ordinary Portland Cement. 
• Method 2:  Specific surface by Air Permeability Method should not be less than 2150 sq. cm/  kg in case of Ordinary Portland Cement

Soundness

Alternatively autoclave expansion should not be more than 0.5% when tested according to IS 269 of 1989.

Setting time

Setting time of any type or any grade of cement when tested by Vicat apparatus method described in IS: 4031 should confirm following requirement.

• Initial setting time    Not less than 30 minutes
• Final setting time:    Not more than 600 minutes i.e. 10 hours

Compressive Strength

After 28 days compressive strength of cement concrete mix for various types of cement concrete mix is following.  

Compressive strength of cement concrete mix

S. NO.	Type of Mix	Ratio of Mix	Compressive strength
1.	M 10	1:3:6	100 kg. Per cm square
2.	M 15	1:2:4	150 kg. Per cm square
3.	M 20	1:1.5:3	200 kg. Per cm square

Note: Cement concrete cubes filled in above mentioned cement ratios should be tested after curing for 7 days and the strength of cement concrete should not be less than 70%.  

General guidelines for gray cement

Cement is the most important raw material used in construction of a building. You can ensure the quality of ‘Cement’ with following guidelines.

• Cement bag bears date of manufacturing 
• One cement bag has 50 Kg. weights
• Cement bags are not hand stitched
• Consignment must have identification mark on the package
• Cement is packed in bags of synthetic jute or polypropylene bags
• Factory manufactured instead of plant manufactured
• Bears manufacturer's name or his trade mark , grade and type of cement
• Not older than six weeks from the date of manufacturing
• Not partially set due to moisture or have small lumps in bags
• Not pressed or have lumps due to high pressure of stack, having more than 10 to 12 bags
• The bags are not torn by side and stitched in later

Precautions while transporting cement

• Carry bags in clean vehicle which is not dustier or on earth etc. as it reduces the strength of cement.
• Take cement bags under covered Polythene or ‘Tarpaulin’ during monsoon season. 
• Labor should not tear bags while loading and unloading cement bags.   

Precautions while stacking/storing gray cement

• Store cement in moist proof area otherwise quality of cement will be affected
• Stack cement bags in dry, leak proof and moisture proof shed/fumes
• Place cement bags on dry brick floors, wooden crates or planks
• Don’t place cement bags on the earth in any case
• Don’t make stack of bags higher than 10 bags to avoid lumps under pressure 
• Don’t stack up cement bags with outer walls to protect it from dampness
• Pile up cement bags from different manufacturer separately
• Make use of cement on first come first serve basis 
• Cover cement bags with polythene during monsoon season
• Keep cement bags close to each other to reduce air circulation  

Caution for storage/stacking

• When construction work is assigned to a contractor, make sure he takes proper care of cement. Many times contractors do not take care for proper storage of cement at site as it costs them labor and money.  This results in reduction in strength of cement as shown in the table below. 
• In some cases, it is observed that after laying RCC slab on some parts of building, the contractor dismantles his temporary store at site and places cement bags on ground floor of building which is under construction. It is not good as cement bags may draw moisture from floor and walls of new building and results in reduction of strength in cement because new building is wet due to construction work in progress.

Reduction in cement strength due to storage

S. No	Storage Period	Reduction in Strength
1.	Fresh cement	Nil
2.	Three months old	20%
3.	Six months old	30%
4.	12 Months old	40%
5.	24 Months old	50%

                                                           

Caution for cement strength

• Cement retards in hardening and reduces strength due to absorption of moisture during storage.
• It is okay for cement to absorb up to 1.2% moisture as this level of moisture is acceptable but if absorption exceeds 5%, the cement is destroyed for all practical purposes. 
• Different types of cements should not be mixed while using them for constructional purposes. 

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Most people do not realize the many choices they have for staircases. May be they do not know about some mistakes in stairs design, it may be width of staircase, size of treads or height of risers. These all mistakes can easily be customized if the home owner knows about the common mistakes in stairs designs. The maximum numbers of steps should not be more than 15 in one flight if so landing should be provided after 15 steps for comfort while moving up and down the stairs. Avoid water tap near the entry of stairs on terrace if so there are chances of water flow in the stairs that will make the stairs slippery.

1.Improper width of stair case

The minimum width of staircase should be 125cm for two or three apartments where the number of users is more than 10. 

2. Steep slope of stair

 30-degree slope is ideal for stairs, due to lack of space slope should not exceed 45 degree.  

3. Improper width of tread

Tread width less than 200 mm may be dangerous and cause accident. Keep minimum width of tread 250mm for residential and 300 mm for non-residential buildings. To increase the width of tread step nosing should be provided.

4. Improper height of risers

Make sure riser’s maximum height is 190 mm and minimum height is 150 mm. Risers of height more than 190 mm are very uncomfortable. It causes difficulty for old age and ill people; children also do not feel comfortable. Riser’s maximum height for residential building should be 190 mm and for commercial building should be 170mm. If the available space is very less than riser height can be 200 mm. Riser of heights less than 150mm are also too much uncomfortable.

5. Unequal size of steps

Make sure that the all risers are of consistent height from the top to bottom otherwise it may cause accident. Risers of different height will throw the cadence of foot that may cause fall in stairs.

6. Slippery floor

Non slippery material should be used for stairs floor.Marble floor is best suitable for residence; avoid polishing of marble that will make the marble slippery.

7. Provision of Hand Rail at proper height

Make sure that hand rails are easily seen in day or night time. Where both end of stair is open provide the handrail on both sides of stairs. In case where stair has walls on both sides then handrail should be provided on walls. The height of handrail should not be less than 800mm and not more than 900mm. The space between the supports of handrail in houses should not more than 250mm and horizontal/ cross support should be 150 mm from top of stair steps to avoid any accidental fall especially for kids.

8. Improper light

 2-way electric switches should be used for stairs for easy access of switch from top and bottom of the stairs. Provision of natural light and ventilation is necessary in the stair to save energy bill during day time and stair can be used at the time of electricity failure.

9. Provision of gates

Some times it has been seen that baby / kids climb on the steps and are not able to return then they either cry for help or fell in the steps. To avoid such situation proper gates/ doors must be provide at the top and bottom of stair with locking arrangements. It is also necessary for security to avoid the entry of intruders.

10. Improper Headroom

The clear height above stair steps is called headroom. If headroom is less than 170 cm, than there is a chances of accident, the minimum clear headroom in stairs should be 2.00 meters.

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