MATERIALS & CONSTRUCTION TECHNOLOGY

Chapter No. 1Chapter No. 1ConcreteConcrete

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PALESTINE UNIVERSITYFaculty of Applied Engineering and Urban

PlanningDept. of Architecture

Concrete : General definition 1 .CONCRETE

Concrete is a construction material obtained by mixing a cement material, coarse aggregate, fine aggregate, and in some cases admixtures. and water in a certain properties.( plain cement concrete)

If steel rods are embedded in the plain cement concrete

If instead of cement, lime is used as cementing material

in mix, the resulting mass in termed as

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Reinforced cement concrete (R.C.C)

Lime concrete

الخرسانة خصائصزمن هو والثالث النهائي الشك زمن والثاني االبتدائي الشك زمن هو االول

التصلد

عن - االبتدائى الشك اضافة 45من منذ يبدأ انه اي الخرسانه صب دقيقةبعدساعتين زمن الى الماء

عن - النهائى الشك زمن يزيد العادى 10وأال البورتالندى لألسمنت وذلك ساعاتالشك زمن هو وهو الحديدى واألسمنت التصلد سريع البورتالندى واألسمنت

النهائي من- يبدأ التصلد الى 10وزمن يوم 28ساعات

بدئ زمن من ساعات خمس او اربع عن الخرسانه صب تاخر اذا يحدث ماذاالخلط؟

فترة خالل تم الصب ان دام زالت 5او 4ما ما االسمنتوالحرارة فإن ساعاتاالسمنت ينحرق ولم فعالة

قوة خرسانة تكون ان فبدل الخرسانةالتصميمية قوة على أثر هذا ان 300صحيحانها ستجد فحصها بعد 250ربما

فيالمصانع الجاهزة الخرسانة حالة في لكن للخرسانة العادية الظروف في هذاالى تصل االبتدائي الشك فترة طول من تزيد مواد يضيفون .4فإنهم ساعات

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Architectural concrete masonry units are often integrally colored to enhance the appearance or achieve a particular effect. Concrete masonry units are colored by adding mineral oxide pigments to the concrete mix.

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Concrete in architectural design

Decorative Concrete

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Site Preparation• Uniformly grade, compact &

dampen the sub-grade• Use a 2”-3” layer of sand, gravel

or stone

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Classification of concrete:

1. Mud concrete.2. Lime concrete3. Cement concrete.

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Point of difference between cement and lime:1. Color of lime is always whitish. Color of cement is

generally grey, but it can be manufactured in other desired color also.

2. Cement when mixed with water, starts setting in a matter of 10-30 minutes and acquires strength in a day or two. Lime doesn’t start setting at such a small time and it takes quit a long period before hardening.

3. Cement is several time stronger binging material than lime.

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1. CEMENT concrete , mortars Cement is a very important binding material, used in the

construction industry. It may be natural cement or artificial cement.

Natural cement: is manufactured by burning and then crushing the natural cement stones. Natural cement stones are such stones which contain the following ingredient.

• 20-40% of argillaceous (clay)• Calcareous:(calcium carbonate-magnesium carbonate)• Siloca• Ammonia

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Artificial cement:This cement was first invented by Joseph Aspdin in 1824.

The burnt mixture of calcareous and argillaceous.

1. Alumina or clay(Al2O3):it is responsible for the setting action of the cement.

2. Silica (Sio2): it goes in to chemical combination with calcium and silicates which are responsible for imparting strength to the cement.

3. Lime( Cao):above 60%of the total contents, expansion disintegration والتفكيك التمدد

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4. Iron oxide: this mainly imparts color to the cement+ hardness

5. Sulphur Trioxide. الكبريت اكسيد Excess amount of it ثالثmay make cement unsound.

6. Calcium sulphate (CaSo4)or Gypsum. retard prolong the initial setting action of the cement.

7. Magnesium Oxide(MgO).in small amount it important strength and hardness to the cement.

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. األسمنت فحوصات و خواص

وللتأكد صفاته لتحديد الفحوصات من العديد االسمنت على يجرى: الفحوصات هذه أهم ومن للمواصفات، ومطابقته جودته من

األسمنت. 1 Fineness of Cementنعومة2. األسمنتية. للعجينة القياسي القوام فحصوالنهائي. 3 االبتدائي الشك Initial & Final setting timeزمن4. لالسمنت. الكيماوي التحليلاألسمنت. .5 ثبات6. المباشر. للضغط األسمنت مقاومة7. المباشر. للشد االسمنت مقاومةاالنثناء. 8 فحص

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CEMENT MANUFACTURE METHODS:

1.wet process (old)

2.Dry process ( modern)

ConcreteThe Rolary Klin :

A large metal cylinder its diameter near to 5m with total length 150m. rotate around its inclined axes under a temperature degree (1400-1500)OC .

All the involved materials are first of all broken in crushers in size of about 2.5 cm. separately. The crushed materials are then dried with a special drought .

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Wet , Dry Process At this method material crushed and dried then put in a rotating plate

A little amount of water added to the mixture to made a hard spheres 15mm diameter These spheres heated then be interred the Rolary Klin.

All remain steps completed as the wet method

Disadvantage of wet method Dry process of cement manufacturing is not advocated as this process is slow, more costly and -above all, the quality of cement produced is of inferior and non-

uniform quality So the dry method is more common than the wet method.

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Concrete TYPES OF CEMENTS

TYPES OF CEMENTS

Most commonly used cement in structures is the ordinary Portland cement. But for use under specific conditions, number of special types of cements have been developed. Following are some of the cements in most common us i, under ordinary, as well as specific conditions.

–Ordinary Portland cement .

–Air Entraining Ordinary Portland cement.

–White and colored cement

–Water repellent cement.

–Light cement

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Concrete TYPES OF CEMENTS

• Sulphate Resistant Portland cement.

• Air Entraining Sulphate Resistant Portland cement.

• High early strength Portland cement

• Air High early strength Portland cement

• Bacteria Resistant cement

• White and colored cement

• Water repellent cement.

• Light cement

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Concrete• Water repellent cement.

• Quick setting cement.

• Rapid hardening cement.

• Low heat cement.

• Blast furnace slag cement.

• High alumina cement.

• Pozzuolanic cement.

• Oil well cement.

• Expansive cement.

• Water proofing cement.

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT LABORATORY TESTS FOR PORTLAND CEMENTThe quality of cement is verified by conducting various exhaustive tests. Following are the standard tests for cement.

•Chemical composition test.

For this, detailed chemical analysis of cement is conducted. Chemical composition requirements of an ordinary and low heat Portland cements have been given earlier in this chapter, under heading chemical composition.

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT •Fineness test.The high fineness means more strength ,more workability ,and more interaction The exceeded fineness cause

– Increases in surface area and more released reaction heat – More cost of KLinker– Increase the cement volume decrees.

Fineness test. This test is done to verify the standard of grinding of cement. We know that rate of hydration and hydrolysis of cement, depend, upon its fineness and thus testing of the fineness of the cement is an essential feature. Fineness of cements can be determined either by sieve test or by air permeability test.

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT •Initial Setting time test

It is the time from the moment of mixing water with cement to consolidate the mixture

the vicat's needle

The interval between the addition of water to cement and the stage, when needle ceases to penetrate 5 mm layer of paste measured from the bottom, is known as initial setting time. of the cement .

Initial setting time. of the cement. Consider as 45 minutes .

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT •Final setting time.

The time interval between the moment water was added to cement and the moment, the stage is reached, when needle makes impression, but collar fails, is known was final setting time of the cement. This time is about 10 hours for ordinary cement.

Both initial and final setting time tests are used to detect the deterioration of cement due to storage.

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT •Compressive strength test:

This test is carried out to determine the compressive strength of the cement. For this test, cement and standard sand are taken in ratio of 1:3 and a paste is prepared by adding water at the rate P/4 + 2.5. Here P is the percentage of water required to produce a paste of standard consistency. The paste so prepared is filled in 76 mm. cube mould and vibrated on vibrating machine for 2 minutes. Twelve such cubes are molded. The freshly molded cubes are first keep in a damp cabin for 24 hrs.

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT •Compressive strength test:

and then shifted to water bath for curing. The cubes are then tested under a compression testing machine after 1, 3, 7 and 28 days of immersion. At each period interval three cubes should be tested and average compressive strength of the three should be taken as the compressive strength. The average compressive strength for ordinary, rapid hardening and low heat cements should be as given under physical properties.

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT •Tensile strength test.Tensile strength test. This test is carried out as followsPrepare a test cement mortar by taking cement and standard sand in ratio of 1:3 and then mixing water. The percentage of water to be mixed is determined by formula P/5 + 2.5, where P is the percentage of water required to produce a paste of standard consistency. Take a standard briquette and clean its internal surface properly. Small amount of grease or oil may also be applied to facilitate extrusion of the molded sample.

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Concrete LABORATORY TESTS FOR PORTLAND CEMENT

The mould is placed on a non-porous plate and filled with previously prepared mortar. After filling the mould some additional mortar is heaped on the mould and beaten with standard spatula, until it acquires the level of the mould and also water appears on the surface.

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Concrete WATER

•WATER

•Water used in mixing concrete must be clean and free of organic materials and similar materials which may react in an undesirable manner with cement or reinforcement bars as Oil ,Sault, alkaline, acids, and organic materials. On these bases, sea-water is not recommended for reinforced concrete construction. The water cement ratio is the most important single factor that affects the properties of concrete mix. Low W/C ratio results in higher strength but drier and hence less workable mix. Thus, the W\C ratio should be as low as permitted by the required workability and the available conveying and compaction means.

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Concrete WATER

•WATER

Values of W\C ratio in the range of 0.5 to 0.65 are in common use. Maximum permitted concentrations of various harmful elements as suggested by I.S.I. are given below.

To neutralize 200 ml of water sample it should not require more than 2 ml of 0.1 normal NaOH.

To neutralize 200 ml sample, it should not require more than 10 ml of 0.1 normal HC1.

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Concrete WATER

•WATERPercentage of solids should not exceed the following

percentages.Organic solids 0.02%Inorganic solids 0.30%Sulphate 0.05%Alkali chlorides 0.10%

In case of any doubt, the engineer in charge may actually conduct compressive strength test on concrete. Compressive strength exhibited by concrete should not be less than 90% of the strength expected from a concrete made with the distilled water.

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Concrete Aggregates

• Aggregates generally occupy about 70% to 80% of the volume of concrete and can therefore be expected to have an important influence on its properties; aggregates provide concrete with better stability and wear resistance. Aggregate may be classified as course or fine the characteristics of course affect the mechanical properties of the concrete by affecting the mechanical bond. According to ACI 318.83 code the nominal maximum size of course aggregate should not exceed 20% of the smallest dimension if the member, 33% of the thickness of the slab or 75% of the net spacing between bars. The shape and texture of the fine aggregate affects only workability.

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Concrete Aggregates

condition to be used for or the row material of cement.

aggregate , crushed or un crushed , are derived from natural

sources such as river terraces and river beds , glacial deposits ,

rocks, boulders and gravels, for use in the production of

concrete for structural purposes and mass concrete work.

Aggregate surface texture are ( soft or rough ,

porous). The best texture is the soft texture

Aggregate grade are (large ,medium, small, fine)

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Concrete Aggregates

Categories of aggregate used in concrete are two types:

Fine aggregate:

Fine aggregate is the aggregate most of which passes 4.75mm IS sieve and contains no more coarse material than permitted.

Natural sand is the fine aggregate which may results from natural disintegration of rock or deposited by rivers or glaciers, and there are another two types of aggregate named crushed stone sand and crushed gravel sand.

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Concrete Aggregates

Coarse aggregate:

Coarse aggregate is the aggregate most of which retained on 4.75mm IS sieve and contains no more finer material than permitted.

Uncrushed gravel is the coarse aggregate which results from natural disintegration of rock, and there are other types of coarse aggregate such as crushed gravel. Because aggregate occupy 70 to 80 % of the volume of concrete and can there for be expected to have an important influence on its properties .

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Concrete Aggregates

Coarse aggregate:

Coarse aggregate is the aggregate most of which retained on 4.75mm IS sieve and contains no more finer material than permitted.

Uncrushed gravel is the coarse aggregate which results from natural disintegration of rock, and there are other types of coarse aggregate such as crushed gravel. Because aggregate occupy 70 to 80 % of the volume of concrete and can there for be expected to have an important influence on its properties .

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Concrete TESTING OF Aggregates

TESTING OF AGGREGATE

Every times there are samples must be taken at various stages as :

– Sample at start of factory manufacture

– Sample when the sources change

– Sample when aggregate properties change.

After the samples be taken there are some tests carried out as :

– Unit weight

– Voids in Agg.

– Resistance to degradation of coarse Agg.

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Concrete MANUFACURE OF CONCRETE

•MANUFACURE OF CONCRETE:

After testing all raw material that concrete consist and

be approved ,concrete mixture designed

Design of concrete mixture mean to estimate the

amount of all concrete parts (water, cement, aggregate,

additives ).

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Concrete PROPARITES OF FRESH CONCRETE

•Workability

This test is conducted to find out the workability of the concrete. It is performed with the help of a vessel, shaped in form of a frustum of a cone open at both the ends. Diameter. of top end is 10 cm, while it is 20 cm at the bottom end. Height of the vessel is 30 cm. 16 mm diameter and 60 cm long steel rod having pointed end is used for temping purpose.

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Concrete PROPARITES OF FRESH CONCRETE

•workability

This test is conducted to find out the workability of the concrete. It is performed with the help of a vessel, shaped in form of a frustum of a cone open at both the ends. Diameter. of top end is 10 cm, while it is 20 cm at the bottom end. Height of the vessel is 30 cm. 16 mm diameter and 60 cm long steel rod having pointed end is used for temping purpose.

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Concrete

End

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