The University of Jordan Faculty of Engineering and Technology Department of Civil Engineering ______

Concrete technology 0941351

Summarization for: Dr. Basel Hanaenah

By: Qusai Waleed AL-Qudah

By: Qusai Waleed AL-Qudah ------1

 Introduction:  World production of concrete equal 11 billion yearly.  The deference between steel & concrete is: Steel: from factory. Concrete: we produce it.

 The types of concrete: 1- Lite weight concrete. 2- Normal concrete. 3- Heavy concrete. 4- Precast concrete.

 Components of concrete: 1- Paste: cement + water. 2- Mortar: paste + sand. 3- Aggregate: coarse + fine. Then concrete consists of paste + aggregate.

 Non-Air entrained concrete:

1- Rich mix:

Cement 15%

Water 20% Aggregate 62%

Entrapped air 3%

 In rich mix: 40% Paste & 60% Aggregate.

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2- Lean mix: Cement 7%

Water 16% Entrapped air 0.5%

Aggregate 76.5%

 In lean mix: 20% Paste & 80% Aggregate.  Lean mix Min cement Min cost Good concrete

 From it: o The ratio of aggregate in cement range between 60% - 80%.

o .

 Air entrained: it use when concrete is subjected for force attack. )يتم إضافته عشوائيا و يستخدم لتقليل الشد في الخرسانه(  Air entrained volume more than Air entrapped volume.

 Good concrete: 1- Acceptable materials. 2- Fresh concrete. 3- Hardened concrete: (strength & durability). 4- Cost.

 Notes: 1- Brittle material: is very weak material. 2- Ductile material: is very strong material. 3- The concrete is brittle material because the concrete can’t bear high tension.

.)قوة الشد التي تتحملها الخرسانه من قوة التقلص تساوي عشرة أضعاف القوه التي تتحملها من قوة الشد( 4-

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 Fresh concrete:  Fresh concrete basically on workability.  The workability depend on: 1- Section will be concreted. 2- Method of compacting.  Over compacting on concrete lead to segregation (risk of segregation).  Incomplete compacting on concrete lead to honeycombed.  Type of mixture of concrete: 1- Soft mixture: using for pour the columns. 2- Hard mixture: using for Airport Street.

Cement

 Cement was patented by Joseph Aspdin (Leeds builder) in 1824 that the modern cement.  The cement is called is hydraulic binder.  سمي اإلسمنت بالرابطه المائيه ألنه ال يرتبط ببعضه اإل بوجود الماء.  الخاصيه اإلسمنتيه: أن يقاوم اإلسمنت الماء بعد تصلبه.

 Portland cement:  The modern cement called Portland cement relative to Portland city.  To produce the Portland cement: 1- Mixing calcareous and argillaceous intimately in predetermined proportion, the mixing is called slurry mixing. o Calcareous: for example limestone or chalk. o Argillaceous: for example silica and alumina. o Are mixed in one of following conditions: A- Dry proses. B- Wet proses. 2- Burning this mixing in a large rotary kiln temperature of a bout 1400C. o If the mixture has been in wet proses the temperature in rotary kiln is 1500C to dry water lead to more cost. 3- The production of burning is small balls called Clinkers. o The diameter of clinkers range between 3-25mm. 4- Cooling the clinkers (cooling rate).

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5- Grinding the clinkers (surface area, specific area) 6- Add Gypsum (CaSO4, 2H2O).  We add Gypsum to cement to prevent the hardening of the concrete mixing quickly.  The temperature in rotary kiln is called clinkers temperature.  We don’t add gypsum to clinkers with cooling step because the water in gypsum will evaporate lead to gypsum losing effective.

 Slurry mixing:

Approximate composition limits of Portland cement:

Oxide Symbol Content, per cent CaO C 60-67 SiO2 S 17-25 Al2O3 A 3-8 Fe2O3 F .5-6.0 MgO M 0.1-4.0 Alkalis A 0.2-1.3 SO3 Ṡ 1-3

 The important components in cement are (C & S).  Iron oxide (Fe2O3) is used to determine the cement color.  Alkalis is two types: 1- Na2O. 2- K2O.  Alkalis (in cement) + reactive silica (in aggregate) lead to increase in volume (crack) this is called Alkali Aggregate reaction (AAR) or Alkali Silica reaction (ASR).  The upper reaction is internal attack in concrete.

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Main compounds in Portland cement:

Name of compound Oxide composition Abbreviation Tricalcium silicate 3CaO , SiO2 C3S

Dicalcium silicate 2CaO , SiO2 C2S Tricalcium aluminate 3CaO , Al2O3 C3A Tetracalcium aluminoferite 4CaO , Al2O3 , Fe2O3 C4AF

 The calculation of the potential composition of Portland cement is based on the work of R, H. Bogus equation others, and is often referred to as “Bogus composition”.  Bogus equation for the percentage of main compound in cement, the terms in brackets represents the percentage of the given oxide in the total mass of cement.  Bogus equation is impure equation.  C3S is called A-lite.  C2S is called Be-lite.  C3A is called Ce-lite II.  C4AF is called Ce-lite I.  Hydration: chemical reaction between cement & water.  The hydration is exothermic reaction.

C3S & C2S  C3S: fast hydration / responsible early strength.  C2S: slow hydration / responsible late strength.  C3S & C2S are the most important compounds.  The silicate in cement are not pure compounds, but contain minor oxides in solid solution, these oxides have a significant effects on the atomic arrangement, crystal form, and hydraulic properties of the silicates.  When C3S & C2S hydrated lead to produce C-S-H gel.  CSH: calcium silicate hydrated.  C3S show effects on strength in period less than one week.  C2S show effects on strength in period less than four weeks.

C3A  The presence of calcium aluminate (C3A) is undesirable.  C3A is continuous little or nothing to the strength of cement except at early age.  C3A is minimum contribution in strength of hydrated cement.

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 C3A is extreme rapid with water.  When C3A reacts with water producing (CAH).  CAH: calcium aluminate hydrated.  When gypsum reacts with C3A producing calcium sulfa-aluminate.  When C3A or CAH reacts with external sulfate which producing calcium sulfa- aluminate lead to increase in volume (cracks).  The increasing in volume with C3A reacts with gypsum is 124%.  The increasing in volume with CAH reacts with gypsum is 227%.

C4AF  C4AF is minimum contribution than C3A in strength of hydrated cement.

 Hydration:  Hydration: chemical reaction between water & cement.  The hydration prose is exothermic proses.  Speed of hydration depends on: 1- Temperature (heat of hydration). 2- Fineness of grains.  When temperature is increase, the rate of hydration will increase.  When the fineness of grains is increase, the rate of hydration will increase.  The rate of hydration is high in concrete mixing leads to minimum strength in next time.  The productions of hydration proses is: 1- C-S-H gel. 2- Ca(OH)2 (Portland lite).  C3S produce more than twice as much Ca(OH)2 as is formed by the hydration of C2S.

 Heat of hydration & strength:  The temperature at which hydration occurs greatly affects the rate of heat development, which for practical purpose is more important than the total heat of hydration.  The same total heat produced over a longer period can be dissipated to a greater degree with a consequent smaller rise in temperature.

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 For the usual range of Portland cement, about one half of the total heat liberated between 1 & 3 days, about three quarters in 7 days and nearly 90 percent in 6 months in fact.  Low strength in start concrete but more strength in future.  The amount of heat of hydration is constant.  The rate of heat out of concrete is difference.  Half the energy coming out of concrete in one to three days.  One quarter coming out of concrete in other four days (three quarters coming out of concrete in seven days).  Finally, 90% of energy coming out in six months.

 Test on cement: 1- Fineness of cement:  Depend on surface area or specific surface.

 The unit of specific surface is ( ).

 The methods to determine specific surface: 1- Wagner method. 2- Lea and Narse method. 3- Nitrogen adsorption method.  الحبيبات األنعم تغطي مساحه أكبر من كرات الكلنكرز لذلك يتم طحن هذه الكرات كما أنها تساعد في زيادة سرعة التفاعل مع الماء.

2- Consistence of standard paste: .القوام المناسب للخلطه اإلسمنتيه : Consistence

 Consistence measured by water cement ratio (vicat apparatus).

 The standard consistence of between 26 & 33mm.

3- Setting:  Setting: hardening proses of concrete.  Type of setting: 1- Flash setting. 2- Natural setting. 3- False setting.

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 Setting time: 1- Initial setting: increasing temperature. 2- Final setting: reducing temperature. 

Flash setting:  Case: do not add gypsum.  Responsible on flash setting: C3A.

Natural setting:  Natural harden proses of concrete.

False setting:  False setting: take apparatus or texture + no heat produced.  Case: semi hydrated gypsum from the cooling proses.  Solution: remix the concrete mixture (restore the initial workability).

4- Soundness:  Soundness: it is an essential that the cement pastes.  Once it has set, does not undergo a larger change in volume, one restriction is that there must be no appreciable expansion, which under conditions of restraint could result in distribution of the hardened cement paste.  Such expansion may occur due to reaction of free lime (Magnesia and calcium sulfate, and cements exhibiting this type of expansion are classified as unsound.  To measure the soundness we can use Le Chatelier.

5- Strength:  Strength tests are not made on neat cement paste because of difficulties in obtaining good specimens and in testing with a consequent large variability of test result.  The test on cement strength can apply by cement-sand mortar.

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 Types of Portland cement: 1- Type I: Ordinary Portland cement:  It is most common cement.  We can use this cement in normal concrete.

 The specific gravity of general cement is ranging between (3.10-3.17 ), usually

3.15 .

 We use this type of cement when there is no exposure to sulfates in the soil or water ground.  Modern Ordinary Portland cement is contains more C3S so that it is more strength.

2- Type III: Rapid- hardening Portland cement:  It is a similar to type I but there a difference in little chemicals composition.

 It has contain a higher C3S & higher fineness (325 ) so that more strength.

 We can’t use these types of cement in large structural or in mass concrete construction because of it’s higher of heat development.  We can use this types of cement at this conditions: 1- Cold weather. 2- Precast concrete. 3- Repair concrete.  The setting time if ordinary Portland cement & Rapid Portland cement is same.  The rapid Portland cement is only marginally greater than then ordinary Portland cement. Specific rapid-hardening strength:  This cement is ultra-high early strength Portland cement.

 This cement contains higher fineness (700-900 ) & higher gypsum contents, this

doesn’t affect long-term soundness.

3- Type IV: Low heat Portland cement:  We can use this cement in large dams.  This cement is low heat of hydration.  We can use this cement at this conditions: 1- Hot weather. 2- Mass concrete.

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 The limit of heat of hydration to 250 at the age of seven days and 290 at the age

of twenty days.  This cement contains a lower C3S & C3A, there is a slower development of strength than with ordinary Portland cement, but the ultimate strength is unaffected.

 The fineness must not be less than 320 to ensure a sufficient rate of gain of

strength.

4- Type II: Modified Portland cement:  This cement is very low strength may be a disadvantage.  This cement has a higher rate of heat development than that of low heat cement.  The rate of gain of strength is similar to that of ordinary cement.  We use this type of cement in this conditions: 1- Low heat. 2- External sulfate attack may occur.

5- Type V: sulfate-resisting Portland cement:  This cement has a low of C3A content so as to avoid sulfate attack from outside the concrete.  The formation of calcium sulfa-aluminate and gypsum would case distribution of the concrete due to increase in volume of the resultant compounds.  The heat developed by sulfate-resisting cement is not much higher than that low heat cement, which is advantage, but the cost of the former is higher due to the special composition of the raw materials.

6- Type IS: Portland blast- furnace cement.

7- Slag: super sulfated cement.

8- White and colored Portland cement.

9- Type IP, P AND I(PM): Portland-pozzolan cement:  Pozzolan: siliceous and aluminous materials which in itself possesses little or no cementitious value.

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 Type IP: for general construction.  Type P: when high strength at early age are not required.  Type I(PM): is pozzolan-modified Portland cement for use in general concentration  The pozzolan cement is limited to between 15%-40% of the total mass of cementation materials for type IP & type P, while type I(PM) requires less than115% pozzolan.  The types of pozzolan cement is: 1- Silica fume. 2- Fly ash.  Pozzolan may often be cheaper than a Portland cement that they replaced but their chief advantage lies in slow hydration and therefore low rate of heat development.  Portland-pozzolan cement or a partial replacement of Portland by the pozzolan is used in mass concrete concentration.

 The specific gravity of pozzolan cement is ranging between (1.9-2.4 ).

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Aggregate

 The type of aggregate: 1- Normal aggregate. 2- Artificial aggregate: up normal aggregate.

 Aggregate isn’t inert because in physical, thermal & sometime chemical properties influence the performance of concrete such as improving the volume stability and durability.

 Size classification:  The range of size up to a maximum size which usually lies between 10mm to 50mm, 20mm is typical.  Grading: particle size distribution (size classification).  Low grade concrete may be made with aggregate from deposits containing a whole range of size (from the largest to the smallest size).  The sieve that separates between coarse aggregate & fine aggregate is 5mm (No.4 AASTM sieves).  The term Aggregate is sometimes used to mean coarse Aggregate in contradistinction to sand, a particle which is not correct.  Fine aggregate (sand) considered to have a lower size limit of about 0.007mm or a little less.  The silt size is ranging between 0.06mm to 0.0008mm and smaller particles are termed clay.  Loam is soft deposit consisting of sand.

 In order to be able to proportion concrete mixes the following aggregate, properties are needs: 1- Shape & texture. 2- Specific gravity. 3- Absorption capacity and condition. 4- Bulk density. 5- Grading: (effect on fresh state).

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Shape & texture:  It very important to determine the properties of fresh concrete & hardened concrete but fresh state properties more than hardened state properties.  Shape and surface texture of aggregate is influence the strength of concrete, especially so far high strength concrete.  Roundness: the angularity of edge of aggregate.  Roundness measures the relative sharpness or angularity of edges of corners of particle.  The actual of roundness is the consequence of the strength and abrasion resistance of the parent rock and the amount of wear to which the particle has been subjected.  The shape of aggregate depends on the nature of parent material and the type of crashers and its reduction ratio, for example the ratio of initial size to that of the crashed product.  The types of aggregate depends on shape is: 1- Rounded. 2- Irregular. 3- Flaky. 4- Angular. 5- Elongated. 6- Flaky and elongated.  Surface texture depends on hardness, grain size and pore characteristics of the parent material (hard, dense and fine grained rock generally having smooth fracture surface).  The types of aggregate depends on surface texture: 1- Glassy. 2- Smooth. 3- Grander. 4- Rough. 5- Crystalline. 6- Honeycombed.  We use more water in concrete mixture when: 1- Use fine aggregate more than coarse aggregate in concrete mixture. 2- More voids in concrete mixture.  Shape & surface texture will affect on workability through paste requirements: 1- Coating. 2- Reduce the attritions between the aggregate.

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 The workability decreasing with an increasing in the angularity number (when we use coarse aggregate (more angularity) the workability of concrete is mini.  From it we use more paste for flaky & elongated aggregate and honeycombed aggregate because both have many voids.

 Mechanical properties of aggregate: 1- Bonds:  Flexural strength is more affected than compressive strength.  Rough aggregate is more Correlation than smooth aggregate. الروابط بين الحبيبات الخشنه أقوى من الروابط بين الحبيبات الناعمه.  Angular aggregate is more Correlation than non-angular aggregate. الروابط بين الحبيبات زاوية الشكل أكثر ترابطا من الحبيبات قليلة الزاويه )دائريه(.  Honeycombed and flaky & elongated aggregate particle are linking with each in strong links.  To determine the quality of bonds is rather difficult and no accepted test exists. Generally, when bond is good, a crashed concrete specimen should contain some aggregate particles broken right through, in addition to the numerous ones separated from the paste matrix. However, an excess of fractural particles suggests that the aggregate is too weak.  All separated aggregate weak bonds.  All broken aggregate weak aggregate.  Mechanical bonds between rough surface aggregate.  Physical bonds between smooth surface aggregate.  From last two sentence mechanical bonds is stronger than physical bonds.

2- Strength:  The compressive strength of concrete cannot significantly exceed that of the major part of the aggregate contained therein.  Voids between aggregates can be viewed as aggregate particles of zero strength.  Indirect test compressive load on concrete.  Direct test tension load on concrete.  The good strength of the normal aggregate is ranging between 80MPa to 200MPa.  The aggregate crashing value (ACV) test used to determine the strength of aggregate.

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Aggregate crushing value:  Aggregate crushing value: the ratio of the mass of material passing the sieve to the total mass of the sample.

 .

 To make Aggregate crashing value test: 1- Material to be test should be pass 14mm test sieve and be required a 10mm sieve. 2- The sample should be dried in an oven at 100C to 110C for 4 hours. 3- Place the production in a cylindrical mold and tamped in a prescribed manner. A plunger is put on top of the aggregate and the whole assembly is placed in a compression testing machine and subjected to load 400KN over the grass area of the plunger, the load being increased gradually over a period of 10min. 4- After releasing the load, the aggregate is removed and sieved on a 2.36mm test sieve. 5- When Aggregate crashing value is greater, the strength of aggregate is low (weak aggregate).  If the aggregate have been crashed before the full load of 400KN the aggregate is weak material so that we use a 10 per cent fines value test.

3- Toughness:  Toughness: resistance of aggregate to failure by impact.  To determine the toughness value of aggregate we must determine the aggregate impact value of bulk aggregate.  The aggregate impact value test is similar to aggregate crashed value but the load (400KN) is put on sample 15 times.  When aggregate impact value is increase, the hardness of aggregate is increase.

4- Hardness:  It is depend on attrition and abrasion between particles.  Attrition: friction particles to each other.  Abrasion: friction particles to other particles.  To measure the hardness of aggregate, there are many tests: 1- Aggregate abrasion value (AAV). 2- Polished stone value (PSV). 3- Loss Anglos test: we use this test to different sizes.

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 Physical properties: 1- Specific gravity:  Specific gravity: the ratio of the density of materials to the density of distilled water at a stated temperature (voids in aggregate).

 Specific gravity .

 It depends on different types of voids.  The types of voids: 1- Permeable: open voids. 2- Impermeable: close voids.  The specific gravity of aggregate is ranging between 2.6 to 2.7  The types of specific gravity is: 1- Absolute specific gravity: us excluding any type of voids (permeable voids and impermeable voids). 2- Apparent specific gravity: is including impermeable voids only. 3- Bulk specific gravity: is including permeable voids only.

2- Bulk density:  Bulk density: actual mass that would fill a container of unit volume and the density is used to convert the quantities by mass to quantities by volume (voids between aggregate).  Bulk density is depend on: 1- Degree of compaction. 2- Consequently. 3- On the size distribution and shape particles.  The maximum bulk density of mixture of fine aggregate and course aggregate when the mass of fine aggregate is equal 35% to 40% of the total mass of mixture of aggregate.  The minimum bulk density is more better than maximum bulk density because when the bulk density is increase the voids between aggregate will increase so that we need more paste to fill this voids that mean more cement & more cost in general any engineer seeks to create mixture contains minimum voids).

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