concrete _full report

8/7/2019 concrete _FULL REPORT

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CONCRETE TECHNOLOGY (BEC 201) 2010

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CONTENT PAGE

INTRODUCTION

FACTORS CAUSING VARIATIONS IN

THE QUALITY OF CONCRETE

1) Personnel

2) Material, Equipment and Workmanship

STATISTICAL QUALITY CONTROL

FIELD CONTROL

ADVANTAGES OF QUALITY CONTROL


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INTRODUCTION

Concrete is generally produced in batches at the site with the locally available materials

of variable characteristics. Therefore, it is likely to vary from one batch to another. The

magnitude of this variation depends upon several factors, such as, variation in the quality of

constituent materials; variation in mix proportions due to batching process; variation in the

quality of batching and mixing equipment available; the quality of overall workmanship and

supervision at the site. Moreover, concrete undergoes a number of operations, such as

transportation, placing, compacting, and curing. During this operations, considerable variations

occur partly due to quality of plant available and partly due to differences in the efficiency of

techniques used. Thus there are no unique attributes to define the quality of concrete in its

entirety. Concrete is generally referred to as being of good, fair or poor quality. This

interpretation is subjective. Therefore, it is necessary to define the quality in terms of desired

performance characteristics, economics, aesthetics, safety and other factors. However it should

be appreciated that concrete has mainly to serve the dual needs of safety (under ultimate loads)

and serviceability (under working loads) including durability. These needs vary from one

situation and type of construction to another. Therefore, uniform standards valid for general

application to all the works may not be practical.

The aim of Quality Control is to reduce the above variations and produce uniform

material providing the characteristics desirable for the job envisaged. Thus quality control is a

corporate, dynamic programme to assure that all aspects of materials, equipment and

workmanship are well looked after. The tasks and goals on these areas are properly set and

defined in the specifications and control requirements. The specifications have to state clearly

and explicitly the steps and requirements, adherence to which would result in a construction of

acceptable quality. Each step in construction procedure is therefore to be specified. The

probability based specifications containing allowable tolerances on its attributes is more rational


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and is preferred. Quality control is thus conformity to the specifications, no more no less. The

most practical method of effective quality control is to check what is done on totality to comfort

to the specifications.

In view of different processes involved in the manufacture of the concrete, the problems

of quality control are diversified and their solution elaborated. The factors involved are the

personnel, the materials and equipment, the workmanship in all stages of concreting. Therefore,

it is necessary to analyze the different factors causing variations in the quality and the manner in

which they can be controlled.

The Quality of an industrial product does not mean the best or excellence. It is defined

as the fitness of the product to do the job required of it by the user. It may also be said to be the

ability of the product to meet the design specifications that are usually set, keeping in view theintended purpose of the product. As stated earlier it would be better to set or define an optimum

quality level for a product rather than trying to make it of best possible quality. This approach

will unnecessarily make the product more expensive, which may not be acceptable to the

customer.

Quality control can be defined as the controls applied at each manufacturing stage to

consistently produce a quality product. It can also be expressed as the application of the

operational techniques and activities, which sustain the quality of a product or service to

satisfy given needs.

FACTORS CAUSING VARIATIONS IN THE QUALITY OF CONCRETE

1) PersonnelThe basic of experienced for the success of any quality control plan is the availability of

experienced, knowledgeable and trained personnel at all levels. The designer and the

specificationwriter should have the knowledge of construction operations as well. The site

engineer should be able to comprehend the specification stipulations. Everything in quality

control cannot be codified or specified and much depends upon the attitude and orientation of

people involved. In fact, quality must be a discipline imbibed in the mind and there should be

strong motivation to do everything right the first time.

2) Material, Equipment and Workmanship


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For uniform quality of concrete, the ingredients (particularly the cement) should preferably be

used from a single source. When ingredients from different sources are used, the strength and

other characteristics of the materials are likely to change and, therefore, they should only be used

after proper evaluation and testing. The same type of cement from different sources and atdifferent times from the same source exhibit variations in properties, especially in compressive

strength. This variation in the strength of cement is related to the composition of raw materials as

well as variations in the manufacturing process. The cement should be initially once from each

source of supply and, subsequently, once every two months. Adequate storage under cover is

necessary for protection from moisture. Set cement with hard lumps is to be rejected.

Grading, maximum size, shape, and moisture content of the aggregate are the major

sources of variability. Aggregate should be separately stock piled in single sizes. The gradedaggregate should not be allowed to segregate. The simple rule of grading is that:

i. For fine aggregate, long continuous gradings are preferred and there should be minimummaterial passing through 300 micron and 150 micron sieves,

ii. For fine aggregate, the gradings that are at the coarser end of the range are more suitablefor rich mixes and those at the fine end of range should be suitable for lean mixes,

iii. A coarser aggregate consistent with the size of the member and the spacing ofreinforcement is more suitable, and

iv. The aggregate sizes should be so selected that one size fits into the voids left by the nexthigher size.

The aggregate should be free from impurities and deleterious materials; since for every 1 per

cent of clay in sand, there could be as much as 5 per cent reduction in the strength of the

concrete. The moisture content of aggregates should be taken into account while arriving at the

quantity of mixing water. The aggregates are required to be tested once initially for the approval

of each sources of supply. Subsequently, tests should be conducted daily at the site for grading

and moisture content.

The water used for mixing concrete should be free from silt, organic matter, alkali, and

suspended impurities. Sulphates and chlorides in water should not exceed the permissible limits.

Generally, water fit for drinking may be used for mixing concrete.


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The equipment used for batching, mixing and vibration should be of the right capacity. Weight-

batchers should be frequently checked for their accuracy. Weightbatching, of materials is

always preferred to volume batching. When weight-batching is not possible and the aggregate

are batched by volume, such volume measures should be frequently checked for the weight-volume ratio. Mixers performance should be checked for conformity to the requirements of the

relevant standards. Concrete should be mixed for the required time, both under mixing and over

mixing should be avoided. The vibrators should have the required frequency and amplitude of

vibration.

The green concrete should be handled, transported and placed in such a manner that it does not

get segregated. The time interval between mixing and placing the concrete should be reduces to

the minimum possible. Anticipated targets of strength impermeability and durability of concrete

of concrete can be achieved only by thorough and adequate compaction. One per cent of the air

voids left in concrete due to incomplete compaction can lower the compressive strength by

nearly 5 per cent. Adequate curing is essential for handling and development of strength of

concrete. The curing period depends upon the shape and size of member, ambient temperature

and humidity conditions, type of cement, and the mix proportions. Nevertheless, the first week or

ten days are the most critical, as any drying out during this young age can cause irreparable loss

in the quality of concrete.

STATISTICAL QUALITY CONTROL

Probabilitybased guidelines or specifications are usually laid down to ensure that the

concrete attains its desired properties with the minimum expenditure. The specifications allow a

certain limits of variability between individual samples. There is little gain in narrowing down

the tolerance limits unless the process is capable of operating within these limits. The process of

ensuring compliance to specifications which take into account the actual variability of concrete is

termed quality control. The statistical quality control procedures are used to ascertain the range

of values that can be expected under the existing conditions.


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In the production of concrete the compliance to specifications required that the mix

ingredients, size of aggregate, watercement ratio, cement content, workability as well as

methods of mixing, compaction and curing to be adopted for a particular work are specified such

that they are easy to follow. It should be noted that the usual 28 days cube tests are not qualitycontrol measure in the strict sense, they are, in fact, acceptance tests. In situations of site

production and placing, the quality of the concrete is to be controlled way ahead of the stage of

testing cubes at 28 days. Moreover, the compressive strength, although taken as an index of the

quality of concrete, does not satisfy the requirements of durability where impermeability and

homogeneity are more important parameters. However, the acceptance criteria of the quality of

the finished product can be based on the compressive strength of a number of 150 mm-cube

specimens after 28-day moist-curing.

FIELD CONTROL

The field control, in other words, inspection and testing, play a vital role in the overall

quality control plan. Inspection could be of two types, quality control inspection and acceptance

inspection. For repeated operations early inspection is vital, and once the plant has stabilized,

occasional checks may be sufficient to ensure continued satisfactory results. The operations

which are not of repetitive type would require, on the other hand, more constant scrutiny.

Apart from the tests on concrete materials, concrete can be tested both in the fresh and

hardened stages. Of these two, the tests on fresh concrete offer some opportunity for necessary

corrective actions to be taken before it is too late. These include test on workability, unit weight

or air content (where air-trained concrete is used), etc. Accelerated strength tests by which a

reliable idea about the potential 28 days strength can be obtained within few hours, are effective

quality control tools. In contrast to this, the usual 28 days strength test is, in fact, a post mortem

of concrete which has become history by then. Therefore, it is only acceptance tests, which help

the decision-maker decide whether to accept or reject the concrete.


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ADVANTAGES OF QUALITY CONTROL

Some of the advantages of quality concrete are the following :

i.

Quality control means a rational use of the available resources after testing theircharacteristics and reduction in the material costs.

ii. In the absence of quality control there is no guarantee that over-spending in one-area willcompensate for the weakness in another.

iii. In the absence of quality control at the site, the designer is tempted to overdesign, so as tominimize the risks. This adds to overall cost.

iv. Checks at every stage of the production of concrete and rectification of the faults at the righttime expedites completion and reduces delay.

v. Quality control reduces the maintenance control.It should be realized that if the good quality concrete is made with cement, aggregates, and

water, the ingredients of bad concrete are exactly the same. The difference lies in the few

essential steps collectively known as quality control.

QUALITY MANAGEMENT IN CONCRETE CONSTRUCTION

The quality is thus a philosophy rather than a mere attribute. It is from the philosophy the

distinctive culture emanates, guiding the society to attain targets set by it. The presence or

absence of this culture makes all the difference which determines the level of acceptability.

Every piece of equipment or product is subjected to quality management in the industrial

production as a matter of a routine. The quality management ensures that every piece of product

keeps on performing over a period of time without heavy maintenance and upkeep. Fortunately

in concrete construction even if rigid quality management measures are not followed, it

performs, at least for reasonable period of time. On account of this co-operative property of the

material, the concrete construction industry has been operating under the misconception that

rigid quality management measures which are essential for an industrial product or not that

essential for concrete. Thus in concrete industry of most of the developing countries, in spite of


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best efforts a great deal is yet to be achieved to derive maximum benefit out of this culture.

Measures have been devised to enhance serviceable, maintenance and rehabilitation free life of

the material and minimize, if not completely eliminate the possibilities of failure. The measures

thought of are all related to Quality Management. Due to well co-ordinated efforts, a quantumjump has taken place in the design of the reinforced concrete. The present day design methods

are no longer limited to the earlier deterministic approaches such as working stress methods, but

the limit state methods based on semi-probabilistic approaches are now being extensively

practised.

The word characteristic has now come to stay in the codes of practice. The characteristic

value approach gives insight the underlines the importance of quality assurance.

Apart from the strength of concrete, the other important area of concern is the durability

of concrete. A great deal of attention has been focussed on this and concrete technologists have

come up with many effective suggestions. Some of them are :

i. Use of minimum quantities of cementii. Drastic reduction in water-cement ratio maintaining the workability by use plasticizersiii. Use of pozzolanasiv. Use of low-heat cementv. A good quality control in design testing and production of concrete (most important)

The ever-increasing use of concrete in engineering structures, has made a demand of very high

order to fulfil the targets or engineering excellence. In some structures the design is not limited

to ensure structural integrity, but is based on the axiom that the probability of failure of such

structures must be as low as possible and lower than a predetermined value of extremely small

order.


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Management of Uncertainties

i. Primary UncertaintiesAll the structures have probabilities of failure in spite of being designed to carry the loads

safely because in the probabilistic design approach, the design variables such as loads

material strength, etc. are considered as random variables. Hence the probability of

occurrence of a very large or a very small value of variable is never zero; the probability of

such occurrence may, however, be very small. Thus whenever, the load variable exceeds the

strength variable a failure situation occurs. If by applying a better quality control the

standard deviation of mix is reduced, than the probability of failure will be reduced.

ii. Secondary uncertaintiesThe secondary uncertainties are introduced during both the design and construction phases.

Selection of inappropriate design conditions, use of inapplicable site data, injudicious

assumptions regarding boundary conditions and other data in design introduces secondary

uncertainties. During construction more secondary uncertainties are introduced, e.g. use of

appropriate materials, violation of design conditions and incorrect interpretation of

designers requirements, etc. Thus the level of confidence which may be viewed as a

measure of closeness of the behaviour of the actual constructed structure to that of analytical

model influences the probability of failure.

Although the odds of primary uncertainties can be taken care of by allowing for the randomness

of the design variables, no proven analytical approach is available within the present state-of-the-

art to increase the level of confidence against the effect of secondary uncertainties. Therefore, it

is imperative that a systematic implementation of quality management system in design,

manufacture and construction is a must as to produce a safe and reliable structure.

QUALITY MANAGEMENT SYSTEM (QMS)

QMS is the management and control system document having three elements: Quality Assurance

(QA) plans, implementation of Quality Control (QC) process and Quality Audit (QA) system of

tracking and documentation of quality assurance and quality control programmes. QMS ensures


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that the intended degree of excellence is attained. The owner or his representative formulates the

policy, determines the scope of quality planning and quality management, establishes the

relationship between the various participating agencies, and delegates responsibilities and

authorities to them so that the quality objectives as set by owner or achieved. It must beunderstood that QMS cannot be developed in totality at the inception. QMS has to undergo

stages of development as various project phases such as design, procurement of materials,

construction, inspection, erection and commissioning are entered into with more and more

agencies being involved and interfaces take place.

Various Stages of Development of QMS

Planting : Owner formulates QA policy and develops QA plans

Engineering : The consultant develops his own design QA programme and that of prospective

vendors and contractors

Procurement : Suppliers develop and submit their own QA programmes and QC methods

Construction : Contractors develop and submit their QA programmes and QC methods

Inspection : The testing agencies develop their QA programmes

The stage-wise development of QA programme based on owners QA plan are required

to be reviewed and approved by the owner or by his consultant as the case may be.

Quality Assurance (QA)

It is planned and systematic pattern of all actions necessary to provide adequate confidence that a

product will conform to established requirement. It is a system of procedures for selecting the

levels of quality required for a project or a portion thereof to perform the functions intended and

assuring that those levels are obtained. QA is thus the responsibilities of the owner/user to ensure

that consultants follow codes and sound engineering practices and that contractors and suppliers

of materials comply with the contract requirements. QA programme developed by each agency

responsible to the extent of its contractual obligation must contain the policies, practices,


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procedures and method to be followed such that the quality objectives laid down by the owner in

his QA plan are fully met. The QA programme must be addressed fully (to the extent applicable)

to the following aspects.

i. Organization set-upii. Responsibilities and authorities of various personnel involvediii. Identification of co-ordinating personneliv. Quality control measures in design including field changesv. Establish of control norms, acceptance and rejection criteria for materialsvi. Inspection programme for verification of contractual compliance including

acceptance and rejection criteria

vii. Sampling, testing, documentation and material qualificationsviii. Corrective measures during non-complying conditions and non-conformanceix. Resolution of technical differences/disputesx. Preparation, submission and maintenance of records at all stages

The quality assurance activity has to start right at the planning and design stage. Development of

a QA programme for design activities is an art by itself and is beyond the scope of this book.

Apart from organizational and administrative aspects, it has to cover procedures of design,

conformance to codes, proper detailing and attention to durability and constructability. One

important part of quality assurance id Peer Review. It is review of the project including its

design, drawings and specifications by an Independent Professional or an agency, with equal or

more experience and qualifications than of the professionals engaged for the design of the

project.

Quality Control (QC)

It implements the quality plan by those actions necessary for conformance to the established

requirements. It is the system of procedure and standards by which a contractor, product

manufacturer, material processor or the like, monitors the properties of finished work.


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QC is the responsibility of the contracting organization. The contracting organization is also

responsible for QC activities related to its sub-contractors. Quality control starts with the

construction. The constructing organization prepares the QA programme manual describing and

establishing the QA and control system to be used by it in performing design, purchasing,fabrication, production of concrete and other construction activities for the contractual

responsibilities assigned to it. Application area, identification of agencies and personnel

responsible for implementing, managing and documenting the QC programmes, their

responsibilities and authorities must be well established in the document. The detailed steps in

these procedures depend upon the scope and type of work and owners policy decision.

Quality Audit (QA)

This is a system of tracking and documentation of Quality Assurance and Quality Control

programmes. Quality Audit is the responsibility of the owner, and has to be performed at regular

intervals through the tenure of the project. Quality Audit covers both the design as well as the

construction phases. Thus the concept of Quality Management encompasses a total project and

each element of that project. The systems on methodology of implementing concept of Quality

Management depend on the available materials and construction technology. As the concrete

technology changes, these systems also change. As such the systems of implementing concepts

of Quality Management are not universal but regional and not static but dynamic, and ever

changing.

An integrated systematic implementation of QMS is extremely beneficial, but any attempt to

make its piecemeal use will defeat the very purpose for which it is intended. In other words in

order to produce a safe, reliable and durable structure, Quality Culture must begin at the

beginning and be carried through all the stages of design, procurement, construction and be

continued further into the in-service regime. It is only a matter of systematic cultivation and a

desire towards increased perfection that can make a complete metamorphosis of a developing

construction industry.

COST EFFECTIVENESS OF QUALITY MANAGEMENT


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It has been the general experience that whether it is the owner who has to cover the cost of

Quality Assurance, Quality Audit and Peer Review or the contractor who has to cover the cost of

Quality Control, the expenditure is met out of savings which accrue from the project due to

implementation of Quality Management Systems (QMS). On the part of owner the QualityManagement ensures a product of assured quality, strength, reliability and maintenance free

durable life cycle. This is achieved by eliminating chances of mistakes on planning, overdesign

or underdesign and ensures proper detailing and constructability. Any of these items if

overlooked can later cost heavily to the owner. It is universally accepted that every project has a

Quality Cost Component. Every contractor has a choice as to when he will pay the cost. He can

pay the controlled cost of Quality Control during construction, or he can pay the uncontrolled

cost of correcting the defective workmanship and materials later. Patched up work, dismantling

and re-doing unacceptable work, maintenance and up-keep during performance guarantee period

may cost a contractor up to 20 to 25 per cent of his gross income. The unwilling contractors may

be motivated to introduce Quality Control within their organizations, by fixing the criteria of

acceptability of concrete based on statistical control of strength which has a small range with a

provision of a bonus for a better quality control than stipulated. An intensive dialogue between

consultants and contractors on concrete specifications, acceptability criteria, testing procedures,

field controls, inspection systems, etc. with the common objective of updating these documents

and procedures for definitely attaining the desired quality may be extremely helpful.

Since the development of concrete technology is closely linked to general construction industry,

the passing away period of shortage and variance have forced the construction industry to change

and modernize. The changed situation is bound to give an impetus to concrete technology to

update itself. Alternate criteria for acceptance of concrete based in its durability instead of its

load-carrying ability which helps in prolonging the serviceability life of concrete may be

designed. The latter is based on passivity of concrete which can be evaluated by its minimum

strength 28 days. The former is based on active concrete that functions under changing

conditions and respond to varying environments and abuses. Its performance mainly based on

water-cement ratio. Thus the design must not be linked just to the strength of concrete of

concrete but also to the durability of concrete.


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The introduction and implementation of Quality Management systems can be successful if the

concrete industry directs its efforts towards increasing reliability, durability, economy, energy

efficiency, versatility, capability, adaptability and aesthetics, as well as towards improvements in

materials, material handling, quality control, education users, construction methods, codes andspecifications, disposal and recycling of waste and extension of the environment under which

concrete can be used and placed. In addition, efforts should be directed to the development of

accurate non-destructive testing procedures, continuous batching and new placing methods,

immediate quality control tests, simplified forming methods, simplified reinforcing procedures,

simplified methods of joining structural members, new design concepts, performance codes and

improved cold and hot weather construction practices. The QMS need be update to keep pace

with advancement in concrete technology.

Quality control tests

1) Slump testThis is a site test to determine the workability of the ready mixed concrete just before its placing

to final position inside the formwork, and is always conducted by the supervisor on site. The

mould for the slump test has the shape of frustum of a cone, 300mm high. The diameter at the

base is 200mm and at the top is 100mm. The mould is placed on a smooth surface and filled with

concrete in four equal layers.

Each layer is tamped 25 times with a standard 16mm diameter rod, rounded at the end, and the

top surface is struck off by means of a trowel. Then the mould is lifted vertically upwards

without disturbing the concrete inside the mould. This allows the concrete to subside. This

subsidence is referred as Slump of the concrete. Generally, a concrete having slump less than


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25mm is considered as concrete of very low workability and a slump value greater than 150mm

is designated as concrete with very high workability.

Limitations of slump test

The test must be conducted by a trained personnel. Otherwise large variations can occur. This

test is not very accurate for very stiff and very lean mixes. The slump can vary from 0 for dry

(stiff) mixes to complete collapse for very wet and lean mixes. The slump test must be conducted

as soon as possible after mixing.


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Slump values for various concrete works

SI.No Placing conditions Degree of workability Slump (mm)

1 Mass concrete, lightly reinforced

sections, pavements, canal linings

Low 25-77

2 Heavily reinforced sections,

pumped concrete

Medium 50-100

3 Insitu piling, trench fill High 100-150

The value of the Slump is measured at a site. Slump is the distance from the horizontal bar (rod)

and the top of the subside concrete.

2) Compression test


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Compression test determines the strength of concrete under standard conditions.

Concrete cylinders or concrete cubes are used for the compression test depending on the national

standard or contract requirements.

Compression test method

The concrete test samples, whether cylinders or cubes, are made on site and tested in a laboratorywith a compression test machine. Moulding the test sample should be completed within 20

minutes of obtaining the sample. The compressive strength of the test samples determines the

acceptability of the concrete represented.

Assuming test cylinders have to be tested, the tools required are:

a) three-cylinder moulds (100 mm 200 mm or 150 mm 300 mm),

b) small scoop,

c) bullet-nosed tamping rod (600 mm 16 mm),

d) steel float,

e) steel slump plate (500 mm 500 mm), and

f) rubber mallet.


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First clean the cylinder mould and slump plate and coat the inside of the mould and plate with a

thin film of mineral oil to prevent adhesion of the concrete. For the 100 mm 200 mm cylinders

the mould is then filled to one-half and the concrete compacted by rodding with the tamping rod

25 times. The strokes should be uniformly distributed over the cross sectional area. The mould isthen overfilled and compacted by rodding 25 times into the top of the first layer. If after

compaction the top is not completely filled, add more concrete and work into the concrete

surface. Each mould is tapped all around with a rubber mallet to remove air bubbles and assist

compaction of the concrete. If the 150 mm 300 mm cylinder mould are used the concrete is

compacted in three equal layers instead of two.

Then

(a) the top of the concrete is leveled off with the tamping rod and any concrete around the mould

is cleaned,

(b) the surface of the concrete is smoothed with a wooden float,

(c) the cylinders are capped,

(d) the moulds identified with a code number and left in a cool dry place to set undisturbed for at

least 24 h. The mould is then removed and the concrete cylinder marked and sent to the

laboratory where it is cured for a specified period prior to testing in compression. All moulds are

cleaned and oiled after use to prevent rusting. The curing period depends on the specification,

although seven days and 28 days are commonly used. The capping carried out on the test

specimen before testing is to make the top surface of the specimen as smooth and plain as

possible. If the specimen surface, which is in contact with the platen of the compression test

machine, is rough and not plain, stress concentrations are introduced and the apparent strength of

the concrete is greatly reduced. Suitable capping materials are aluminous cement, high strength

dental plaster and a molten sulphur mixture. However, other capping materials have been used.

The main requirement is that the capping compound should not be weaker than the concrete, or

appreciably stronger.


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QUALITY CONTROL APPLICATION IN CONCRETE CONSTRUCTION

The quality control of a concrete construction can involve many requirements, such as

determining the:

y mechanical properties of the reinforcement to be usedy dimensions of the reinforcementy location of the reinforcement in the construction before concrete is pouredy location of pre-stressing ductsy properties of the cement used in the concretey properties of the concrete mix designed for use in the structurey control of the aggregates and sand going into the concretey control of water additionsy mixing of the concretey transport of the concrete to the construction sitey slump of the concretey pouring of the concretey vibration/compaction of the concretey preparation of areas where different concrete pours are doney control of compression test samplesy control of formwork removal.

In fact one could even begin with the preliminary work before construction begins that may

involve geotechnical investigations necessary to assess foundation conditions, etc. The quality

control department, at all times, needs to compare the results of inspections and/or tests with the

requirements defined in the contract documents and with the relevant construction standards

called up in the contract.

CONCLUSION

Quality control can be expressed as the application of the operational techniques and

activities, which sustain the quality of a product or service to satisfy given needs. In brief the

objective of quality control is to provide the customer with the best product at minimum cost.

Improvements in product design, consistency in manufacture, reduction in costs and improvedemployee morale can achieve this objective.

We have two types of tests to determine the quality of concrete. The first one is slump

test. Slump test is about to determine the workability of the ready mixed concrete just before its

placing to final position inside the formwork, and is always conducted by the supervisor on site.

The second test is compressive strength which is test samples determines the acceptability of the

concrete represented.


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concrete _full report

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