Types of concrete

FAQ ON CEMENT & Concrete Types

FAQ
1 What is the Raw Material used for manufacture of cement?
Calicareous (Limestone Obtained from mines) ,argillaceous materials (Clay, Bauxite) and Iron are the commonly used raw materials in the manufacture of cement.
2 How is cement manufactured?
Manufacture of cement comprises of four stages viz.
1. Extraction of lime stone from mines.
2.Blending of ground limestone,Clay or Bauxite and iron ore or Laterite in right proportion and cintering in rotary kilns at a high temperature of 1400oC to 1500oC form Clinker.
3. Grinding of clinker with Gypsum to form cement.
4. Storing in silos, testing and despatch form the final process of manufacture.
3 What is the chemical composition of cement and the contribution of each chemical compound?

Chemical Compounds Range in *OPC% Reaction Rate Strength Attained Liberation of Heat
Tri-Calcium-silicate (C3S) 40-55 Fast
High High

Di-Calcium silicate(C2S)
25-40 Slow Lowfirst high later Low
Tri-calcium Aluminate(C3A) 8-11 Fast Low Very High
Tetracalcium Alumino ferite 13-17 Moderate Low Moderate

4 What is the role of Gypsum in cement?
Gypsum is added to control the 'setting of cement'
5 What is 'Setting of Cement'?
Setting is the stiffening of the cement paste.Broadly it refers to change of fluid to rigid state.
6 What do you mean by hardening of cement?
Hardening is the gain of strength in cement. This process of gain of strength continuous up to one year rapidly approximately and gradually after one year and up to 5 years.
7 Why should cement be 'fine'?
The rate of hydration of cement depends on the fineness of cement and for a rapid development of strength high fineness is necessary
8 What is meant by 'Soundness of Cement'?
Cements may sometimes contain free lime, which may cause expansion. Hence soundness test is conducted to see that even if uncombined lime is present in cement whether it is in prescribed limits. If it is within the prescribed limits then it is said to be sound.
9 What does, 53 grade, 43 grade and 33 grade cement indicate?
Grades 53 , 43 and 33 indicate the compressive strength of cements in Newtons for one mm2 area. i.e. 53 grade means a compressive strength of 53 N.per mm2 attained after a curing period of 28 days. Similarly 43 and 33 grades may be defined.
10 Does the colour of the cement affect it's strength?
The colour of the cement depends on the raw mateirals used. If the raw materials contain more iron resulting cements will be darker. Colour has no significance on any properties of cement. The strength of the cement is dependent on the correct proportion of raw material mix
11 What are the reasons for slow setting and quick setting of cement?
Slow setting in cement is due to Salts and chemicals in water, sand and aggregate. Cold Weather, Less cements , High % of impurities, adultrated cement, improper water cement ratio. Quick setting of Cement is due to : addition of low quantity of Gypsum, hot weather condition, high cement fineness.
12 How to store cement ?
Proper storage of cement shall permit easy access for inspection and identification.Cement shall be stored in suitable weather tight structures, to protect the cement from dampness.It shall not be piled more thah ten bags in a stack and shall be arranged in header and stretcher fashion as far as possible.while removing the bags for use,"FIRST IN FIRST OUT" rule shall be applied.
13 What is Mortar ?
Mortar is a mixture of sand, cement and water.
14 Why is concrete the most widely used construction material?
Concrete is the most versatile mouldable construction material ever known to mankind.It bears excellent fire and weather resistant properties. Most intricate shapes can be achieved with concrete . It is very good in compression though weak in tension.It is supplimented by steel to achieve tensile strength. Centuries old monuments bear testimony for its life.
15 What should be the quality of aggregate for a good concrete?
Aggregate for concrete should be inert, dense, hard durable ,structurally sound, capable of developing good bond with the cement paste, weather resistant and unaffected by water.
16 What is the sources of aggregate?
Natural sand, gravel, pebbles, rocks crushed to required size and manufactured aggregates like blast furnace slag are sources of aggregate. IS 456-2000 stipulates that the aggregates should conform to IS 383-1970.
17 What is the function of water in 'concrete'?
It is with water that the cement undergoes the process of hydration to form a gel with binding property covering the aggregates uniformly on mixing. However water for mixing shall be limited to achieve a required consistency as excess water is deterrent to concrete.
18 Can any water be used in concreting?
It is important that water used in concrete should be free from impurities Generally it should be of potable quality. Bore water would need checking before using because it often contains impurities which affect setting times and reduce the strength of concrete. Sea water is not suitable for reinforced concrete as it causes corrosion. IS456-1978 gives the maximum possible limits of solids in water.
19 What is an admixture?
An admixture is a chemical formulation generally added to concrete while mixing to induce certain desirable properties to it like better workability with water reducing admixture, delayed setting the retarders, improve the rate of hardening with accelerating admixtures, and air entertainment for better flow and lubrication.
20 What is meant by 'Reinforced Cement Concrete' (RCC)?
Concrete is strong in compression and weak in tension. A plain concrete beam when it is subjected to bending fails at the bottom side due to tension. Hence to make concrete strong in tension, steel is embedded so that it becomes strong both in tension and compression. The concrete embedded with steel is called `Reinforced Cement Concrete'
21 What are the factors affecting the workability of concrete?
The factors that are affecting the workability of concrete are water content, aggregate type and grading, aggregate/cement ratio, presence of admixtures and fineness of cement.
22 What is meant by batching?
Measurement of various ingredients of concrete like sand, metal and cement for each batch of concrete per design is called batching. Volume batching and weigh batching are the two types of batching in vogue
23 What is the process of mixing of concrete?
The different stages of `mixing of concrete' are : To locate a correct spot on a firm ground close to the concrete site, positioning the mixture machine conveniently oriented to feed the hopper , emptying the drum of concrete on the platform prepared. To stack metal,sand and cement per design mix work out per batch.to feed the drum with required quantity of water.To feed the drum with the contents of hopper and allow the mix in the rotating drum for 1 &1/2 to 2 minutes till a homogeneous mix is obtained .To empty the drum of concrete on the platform and leading it to the concreting spot.
24 What are the factors affecting the strength of concrete?
The factors that are affecting strength of concrete are : Water cement ratio Shape and size of aggregate Aggregate cement ratio ,Degree of compaction ,Age of concrete and Air entrainment and moisture in aggregate.
25 What is meant by seggregation of concrete?
Seggregation of concrete can occur in two form. In the first the coarser particles tend to separate out while concrete being conveyed along a slope(for e.g.sloped roof and staircase waist slab)or,not being homogeneous coarse aggregate settle below leaving the slurry with fine aggregate below.The second form of seggregation occurs in wet mixes by separation of grout from the mix.This happens due to over vibration of concrete and dropping of concrete from a height .
26 Why is a 'crack' developed?
A crack is developed whenever stresses in the structural component exceeds its strength .This may be due to external forces, foundation settlement, thermal changes, chemical action etc.
27 Why do 'plastering cracks' occur?
Plastering cracks appear because of evaporation of water, increased thickness, very fine sand, low quality bricks, non uniform plastering, improper seasoning of walls, use of different mix proportion , improper filling of joints, insufficient curing, more free lime/MgO.
28 Why do RCC cracks?
RCC cracks due to insufficient reinforcement and cover, corroded steel, high slump, improper vibration, volume changes, excessive coarse aggregates, expansion of concrete, lack of sufficient quantity of cement, electrical conduits not placed at sufficient depth in concrete.
29 What do you mean by M20, M30, M40 concrete?
M20, M30, M40 Grades of concrete indicates compressive strength of concrete in Newtons for one mm2 area which is called the characteristic strength of concrete after 28 days. M20 mean 20 N/mm2 similarly M30 is 30 N/mm2.
30 What is meant by water cement ratio?
The quantity of water used for mixing of concrete per unit volume related to the quantity of cement is called water cement ratio and is expressed as the ratio of the weight of water to the weight of cement used in a unit volume of concrete.
31 What is curing?
Maintenance of a favourable environment for the continuation of chemical reaction that are responsible for hardening of cement is called curing.
32 What methods are commonly employed to ensure sufficient moisture for curing?
Ponding, continuous sprinkling, covering with wet cloth, polyethylene sheets, sealing coat applied as a liquid commonly known as "Curing compounds" are some of the methods commonly employed for curing
33 What are the common mistakes which affect the quality of concrete?
Use of too much or too little water for mixing.
Incomplete mixing of aggregate with cement.
Improper grading of aggregates resulting in seggregation or blending of concrete.
Inadequate compaction of concrete.
Using concrete which has already begun to set.
Placing of concrete on a dry foundation without properly wetting it with water.
Use of aggregate containing foreign materials such as earthy matters, clay or lime. Use of water containing solids, chemicals etc
Too much trowelling of the concrete surface.
Leaving the finished concrete surface exposed to sun and wind during the first ten days after placing without curing.

Source : http://www.indiacements.co.in/asktheconcreteman.htm#

Classification
Grade
Applications

Ordinary
M10
PCC (Plain Cement Concrete) e.g. Levelling course, bedding for footing, concrete roads, etc.

M15
PCC e.g. Levelling course, bedding for footing, concrete roads, etc.

M20
RCC (Reinforced Cement Concrete) e.g. Slabs, beams, columns, footings, etc. (for mild exposure)

Standard
M25
RCC (Reinforced Cement Concrete) e.g. Slabs, beams, columns, footings, etc.

M30
RCC e.g. Slabs, beams, columns, footings, etc.

M35
RCC e.g. Slabs, beams, columns, footings, etc.

M40
RCC e.g. Pre-stressed concrete, slabs, beams, columns, footings, etc.

M45
RCC e.g. Runways,Concrete Roads (PQC), Prestressed Concrete Girders, RCC Columns, Prestressed beams

M50
RCC e.g. Runways,Concrete Roads (PQC), Prestressed Concrete Girders, RCC Columns, Prestressed beams

M55
RCC e.g..Prestressed Concrete Girders and Piers

High Strength
M60 - M80
RCC work Where high compressive strength is required such as high rise buildings, long span bridges, ultra-thin white topping etc and constructions in aggressive environment e.g. Spillways of dams, coastal construction


In addition to producing normal grade concrete ranging from M10 to M80, we produce customized special types of concrete for different applications.

Types of Special Concrete Application

High Volume Fly Ash Concrete
Mass concrete, raft foundations, roads, pavements etc.

Silica fume concrete
All high strength concrete applications in extreme environmental exposure condition like marine structure etc.

GGBS, Slag based concrete
All underground RCC application requiring high chemical resistance and enhanced durability

Ternary blend concrete
All RCC application directly in contact with aggressive soil / chemicals in marine environment and in sewage / effluent treatment plants

Light weight concrete
Repair and rehabilitation work, for thermal insulation, light weight structural fill, and light weight pre - cast panel etc

Corrosion resistant concrete
All types of RCC applications in high water table area including work near coastal areas, water tanks, etc

Polymer concrete
Repair and rehabilitation work for floorings and buildings where high early strength is required

Self Compacting Concrete
Thin sections and elements with congested reinforcements. Recently IS 456 has also included SCC with specifications in its codal provision.

Coloured Concrete
For architectural and aesthetic use

Fibre-reinforced Concrete
For concrete with higher ductility and abrasion/erosion resistance

Pervious Concrete
Concrete for parking areas, pavements, drive-ways to ensure drainage or rain-water harvesting

Water-proof Concrete
Terraces, basements, water contact structures

Temperature Controlled Concrete
Mass concrete, hot-weather concrete etc

Source
http://www.ultratechconcrete.com/concrete_smartusage.html
Hyderabad
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How to Have a More Energy Efficient Home

The energy efficient home is one of the biggest concerns of the future. Whether it's summer, winter, or anywhere in between, you may be constantly throwing money out the window. How does this happen? Through wasting energy. Not only can you save money by implementing a few quick tips, you can also help the environment by consuming less resources, and emitting less toxins into the environment.

Instructions

1. Save the lights. All homes need to be lit. However, you can make your house and energy efficient home by reducing the amount of electricity used to light your home. You can do this by implementing a few quick tips. Number one is to turn off unneeded lights. This sounds simple, and it is, but having just one unneeded light on can quickly add up to a lot of wasted money each year. Be sure to turn off the light anytime you leave a room. You can also reduce the amount of electricity you use by investing in energy efficient light bulbs. These bulbs come in a variety of light types ranging from the yellow glow you may be used to, to bulbs that mimic the look of sunlight. These bulbs use significantly less electricity and last longer than your typical light bulb as well.

2. Block the Drafts. Drafts are one of major concerns when it comes to keeping the heat or air conditioning in an energy efficient home. Draft can occur because of gaps underneath doors or around windows. For windows use caulk to seal ups any openings between inside your home and the outside. For doors use a towel to block the drafts. You can also sew up a long fabric bag the length of the door and fill it with rice. This will add weight to the fabric and help better block the drafts. Updating your doors and windows can also save you a significant amount of money in the long run towards your energy efficient home.


3. Replace the Thermostat. Investing in a self regulating thermostat for your energy efficient home may also help you save a significant amount of electricity. These thermostats will keep your home at a constant temperature allowing you to stay comfortable while not using more heat or air conditioning than you need. Turn these thermostats down in the winter time and up in the summer time while you are sleeping to help you save more energy.

4. Check the water heater. Water heaters are one of the largest culprits when it comes to wasted energy. For an energy efficient home Turn your water heater down even five degrees. That can save you a significant amount of money. Even when you are not using your hot water, the water heater still has to keep the water at the set temperature. If you have an older water heater, consider replacing it for one that is better insulated and more efficient. This will prevent heat energy from escaping the unit.

5. Replace the furnace filter. Regardless of whether you use oil, gas, or electricity to power your furnace, dirty filters make your furnace have to work harder and in turn waste more energy. You should check your filters at least every other month to see if they need to be replaced.

6. Research your appliances. Appliances have come a long ways in helping you save energy while still not sacrificing their ability to work properly. Look for appliances that have great energy efficiency rating (EER). The better the EER, the less energy the appliance will consume. Even better, newer models will make your home feel updated while creating an energy efficient home in the process.

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Project Mgmt versus Const Mgmt

Project Management versus Construction Management
Each project is unique and needs to be evaluated as to which method will be the best fit for the Owner.
In today's marketplace, the choices regarding construction are becoming more and more varied. Not so many years ago, an Owner's decisions were limited to choosing a designer, a contractor, and a manufacturer. These choices, however, have broadened drastically. Not only have means, methods and procedures for construction expanded, but the administration process alternatives for construction have become virtually limitless. There are, however, two main options which are prevalent in the industry, Project Management and Construction Management.

Project Management is the conventional method of construction administration. The Owner has direct contracts with both the Consultant and the Contractor.
The Owner is able to retain direct control over all aspects and the quality of the project. This process allows the Owner more flexibility in decisionmaking. The Owner ultimately makes the final decisions. In addition, the Owner may realize the benefit
of competitive bidding. Construction Management is a progressive, more "convenient" method of construction project administration. The Owner has only one direct contract, with the Construction Manager. The Contractor becomes a subcontractor to the Construction Manager (Consultant). The Owner is not bothered by having to make every decision and may realize a time reduction in the completion of the job. Finally, the Owner's accounts payable department only has to deal with one company.

Similarities Project Management and Construction Management are the same in many ways. First, they both involve the same three parties: the Owner, the Consultant, and the Contractor. The Consultant represents the Owner under both contracts. All communication between the Owner and the Contractor flows through the Consultant. The Contractor, along with any subcontractors, still performs all of the construction work. The Consultant will still be responsible for developing and interpreting the Construction Documents, observing the work, performing inspections,and reviewing submittals.

Differences
The first difference between the two methods deals with the relationships between
the parties. In Project Management,the Consultant and the Contractor have no formal contract between them. They do have a third party relationship which stipulates how they are to work together. They rely on each other to perform certain duties which affect each other's work, but their contracts are only with the Owner. In Construction Management, the Contractor has a direct contract with the Consultant and does not have any direct agreement with the Owner. The Contractor now has a third party relationship with the Owner and is paid by the Consultant, not directly by the Owner.
A second major difference arises in contractor selection. Under a Project Management agreement, the Owner selects the Contractor. The Owner can use competitive bidding or negotiate a price with a specific Contractor. This, however, is the Owner's decision to make. The Consultant can advise, but has no direct responsibility for this decision. Under a Construction Management agreement,the Consultant has greater responsibility for selecting the Contractor. The Consultant and Owner make the decision about competitive bidding or negotiating a price once the project budget
has been established. The Owner may not realize the most competitive price with this process. The Owner has delegated that responsibility to the Consultant under the framework of the Contract Budget. The third difference falls in the matter of liability. Under Project Management, the Consultant has liability only for the design. The Contractor has liability for the actual work and its conformance to the Construction Documents. Under this agreement, for any decision which the Owner makes without the Consultant's approval, the Owner assumes responsibility and liability. Under Construction Management, the Consultant assumes responsibility for the design and also for the work. If an issue were to arise, the Owner only has one entity with whom to deal. The Consultant is responsible to the Owner for any part of their Contract which is not met. The Contractor is responsible to the Consultant for their work. The final liability will be shared by the Consultant and the Contractor if the Contractor fails to perform. The Owner's direct liability under this management system is less than under Project Management.
The Conclusion
Both Project Management and Construction Management have advantages and disadvantages associated with them. Each project is unique and needs to be evaluated as to which method will be the best fit for the Owner to achieve company objectives and realize the greatest return on investment.

Value engineering Definition and Concept

Concept
The concept evolved from the work of Lawrence Miles who, in the 1940's was a purchase engineer with the General Electric Company (G. E. C). At that time, manufacturing industry in the United States was running at a maximum capacity to supply the allies with arms. There were shortages in steel, copper, bronze, nickel, bearings electrical resistors, and many other materials and components. G. E. C wished to expand its production of turbo supercharger for B24 bombers from 50 to 1000 per week.

Miles was assigned the task of purchasing the materials to permit this. Often he was unable to obtain the specific material or component specified by the designer, so Miles reasoned, "if I can not obtain the product, I must obtain an alternative which performs the same function". Where alternatives were found they were tested and approved by the designer.
Miles observed that many of the substitutes were providing equal or better performance at a lower cost and from this evolved the first definition of value engineering.

. Definition
It is an organized approach to providing the necessary functions at the lowest cost
From the beginning the concept of value engineering was seen to be cost validation exercise, which did not affect the quality of the product. The straight omission of an enhancement or finish would not be considered value engineering. This led to the second definition :

It is an organized approach to the identification and elimination of unnecessary cost
Unnecessary cost is Cost which provides neither use, nor life, nor quality, nor appearance, nor customer features.

. How different it is from Quantity surveying
The following tasks are undertaken by quantity surveying practitioners and are not considered to form any part of value engineering
- Producing contract documents including the bill of quantities
- Analyzing complex projects into manageable work packages
- Planning and controlling cost
- Valuing work in progress and exercising cost control during construction
- Evaluating tender bids and contractual arrangements
- Preparing valuations for insurance purposes and advising on insurance claims
- Sub contract documentation
- Settlement of final accounts
- Advice and settlement of contractual disputes and claims
- Advising on taxation grant and financial matters
- Schedule resources
- Planning and programming design and construction work
- Use of network analysis techniques
- Project and construction management


The following tasks are undertaken by Quantity Surveyors, and are involved in value engineering practice:

- Preparing and administering maintenance programs.
- Forecasting expenditure flows.
- Advising on cost limits and preparing budgets.
- Advising on Cash Flow Forecasting.
- Advising on Life Cycle Costing.
- Cost Analysis.
- Cost benefit Analysis.
- Estimating
- Evaluating alternative designs.
- Undertaking feasibility Studies.
- Investment Appraisal
- Measuring and describing construction work but only in terms of cost planning.

Energy Efficiency in Electrical Utilities

01 Electrical system
02 Electric motors
03 Compressed air system
04 HVAC and refrigeration system
05 Fans and blowers
06 Pump and pumping system
07 Cooling tower
08 Lighting system
09 DG Set system
10 Energy efficient technologies in electrical systems

Annexure

General Aspect of Energy Management and Energy Audit

01 Energy Scenario
02 Basics of energy and it's various forms
03 Energy management and audit
04 Material and Energy Balance
05 Energy action planning
06 Financial management
07 Project management
08 Energy Monitoring and Targeting
09 Global Environmental Concerns

Simple ways to learn about Earthquakes Design

1: What Causes Earthquakes?
2 : How the Ground Shakes?
3 : What are Magnitude and Intensity?
4 : Where are Seismic Zones in India?
5 : What are the Seismic Effects on Structures?
6 : How Architectural Features Affect Buildings During Earthquakes?
7 : How Buildings Twist During Earthquakes?
8 : What is the Seismic Design Philosophy for Buildings?
9 : How to Make Buildings Ductile for Good Seismic Performance?
10 : How Flexibility of Buildings Affects their Earthquake Response?
11 : What are the Indian Seismic Codes?
12 : How Do Brick Masonry Houses Behave During Earthquakes?
13 : Why should Masonry Buildings have Simple Structural Configuration?
14 : Why are Horizontal Bands Necessary in Masonry Buildings?
15 : Why is Vertical Reinforcement Required in Masonry Buildings?
16 : How to Make Stone Masonry Buildings Earthquake Resistant?
17 : How do Earthquakes Affect Reinforced Concrete Buildings?
18 : How do Beams in RC Buildings Resist Earthquakes?
19 : How do Columns in RC Buildings Resist Earthquakes?
20: How do Beam-Column Joints in RC Buildings Resist Earthquakes?
21 : Why are Open-Ground Storey Buildings Vulnerable in Earthquakes?
22 : Why are Short Columns more Damaged During Earthquakes?
23 : Why are Buildings with Shear Walls Preferred in Seismic Regions?
24 : How to Reduce Earthquake Effects on Buildings?

How to Improve your Decision-Making

This may surprise you, but most great leaders use the same 5 steps for making decisions. So read the 5 steps below and use them to improve your decision-making on projects:

Investigate the problem

When a problem is presented to you, take the first step by spending the time needed to identify its root cause and make sure it's not just a symptom of another underlying problem. Project problems are usually related to people, processes, equipment or materials. Find out when, why and how it occurred and its impact on the project.

Prioritize it

On projects, problems occur all the time. You need to determine whether each problem needs your urgent attention or not, based on its impact on the project. If it's high impact (e.g. it's preventing your team from working) then it's "high priority" and you need to stop work and get it resolved quickly.

Identify the solutions

With a clear understanding of the problem and its priority level, you need to identify solutions to address it. Then review each alternative to determine whether it actually:

Solves the root cause of the problem
Is easy and practical to implement
Will prevent the problem from re-occurring
Make your decision

Now you have all of the information you need to make your decision. Don't make your decisions too hastily. Take time out of your day to carefully consider all of the pros and cons. Go for a walk, or if it's really important sleep on it so you have a clear head when deciding. Make non-important decisions quickly, but take a little more time when making decisions which are critical to the success of the project.

Act on it

Once you have thought it through and made your decision, you need to be fully committed to implementing it. Act on it immediately by telling your team about it and then scheduling the tasks needed to make it happen. Remember, every problem affects your project in some way, so you need to act quickly once you've decided on what to do.

If you follow these steps for every decision you have to make, then you'll make better decisions, faster. And you'll feel good about it.

One way to reduce the number of decisions you have to make on projects, is to use a Project Methodology. It will guide your entire team through a proven step-by-step process, so that everyone knows what has to be done. So you don't have to decide how you want to run your projects. You simply follow the methodology to do it.