1 Exam Prep Design and Control of Concrete Mixtures Tabs ... · 1 Exam Prep – Design and Control...

1 Exam Prep – Design and Control of Concrete Mixtures, 14th Edition 1

1 Exam Prep

Design and Control of Concrete Mixtures

Tabs and Highlights

These 1 Exam Prep Tabs are based on the 14th Edition of the Design and Control of Concrete Mixtures,

Kosmatka and Panarese, Portland Cement Association copyright 2008.

Each Tabs sheet has five rows of tabs. Start with the first tab at the first row at the top of the page; proceed

down that row placing the tabs at the locations listed below. Place each tab in your book setting it down one

notch until you get to the bottom of a page. Then start back at the top again. After each Tab, under

"Reason/Highlight" is a brief explanation of the purpose of the tab, and/or items to highlight in the section.

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outline of your appropriate module. Now locate and highlight several items listed in the outline just before

the topic, and just after. See how the topic fits in the outline and how it relates as a concept to the broader

concept spelled out in the outline. If you take a few minutes to do this, when you take the test key words in

the test questions will remind you of where the information is in the manual!

1 Exam Prep Tab Page # Reason/Highlight

Table of Contents iii Table of Contents

Fundamentals of 1 Fundamentals of Concrete

Concrete

Figure 1-1

Aggregate: 60% 75% of volume.

2 Freshly Mixed Concrete: Freshly mixed concrete should be plastic or

semi fluid

3 Workability: The ease of placing, consolidating, and finishing freshly

mixed concrete and the degree to which it resists segregation is called

workability.

4 Hydration, Setting Time, and Hardening: chemical reaction of

cement and water.

5 Hardened Concrete

6 Drying Rate of Concrete

Strength 7 Strength: Inversely proportional to water/cement ratio.



8 Figure 1-17: Strength verses water - cement (W/C) ratio.

Density: Conventional concrete, normally used in pavements,

buildings, and other structures, has a density in the range of 2200 to

2400.

9 Permeability and Water tightness: Concrete used in water-retaining

structures or exposed to weather or other severe exposure conditions

must be virtually … Generally, the same properties of concrete that

make it less permeable also make it more watertight.

Leakage Rate 10 Figure 1-20: Leakage Rate.

Abrasion Resistance: Floors, pavements, and hydraulic structures …

Strong concrete has more resistance to abrasion than does weak

concrete.

11 Volume Stability and Crack Control: Hardened concrete changes

volume due to changes in temperature …The rate of creep decreases

with time.

12 Two basic causes of cracks in concrete are: (1) – (2).

Joints 12 Joints: control, isolation and construction.

Durability: The durability of concrete mat be defined as the ability of

concrete to resist weathering action …curing practicing determine the

ultimate durability and the life of the concrete.

13 Alkali-Aggregate Reactivity: Alkali-aggregate reactivity is a type of

concrete … aggregates react with the alkali hydroxides in the concrete.

14 Chloride Resistance and Steel Corrosion: Seawater can destroy or

penetrate the film. Once chloride corrosion threshold (about 0.15%

water-soluble chloride by mass cement).

16 For the best defense during external sulfate attack: (1) - 2).

Types of Cement 27 Types of Portland Cement: I, II, III, IV, V.

28 Table 2-2: Types of Cement Required for Concrete Exposed to Sulfates

in Soil or Water



30 Air-Entraining Portland Cements: They correspond in composition

to ASTM Types I, II, and II.

White Portland Cements: It is made to conform to the specification s

of ASTM C 150, usually Type I or Type III.

31 Blended Hydraulic Cements: ASTM C 595 recognizes five primary

classes of blended cements as follows … Types IS, IP, P, I (PM), and

I)SM) are general purpose cements.

32 Hydraulic Cements: ASTM C1157 provides six types of hydraulic

cement as follows:

33 Table 2-3: Applications for Commonly Used Cements

Masonry and Mortar Cements: Masonry and mortar cements are

hydraulic cements designed for … They consist of a mixture of

Portland cement or blended hydraulic cement and plasticizing

materials.

35 Plastic Cements: Plastic cement is a hydraulic cement that meets the

requirements of ASRTM C 1328. It is used to make portland cement

based plaster or stucco.

47 Compressive Strength

Heat of Hydration

Figure 2-42: Type cement verses strength

48 Figure 2-43

52 Transportation and Packaging: Cement weight: 94 pounds per bag

Mixing Water 73 Mixing water for Concrete

75 Chloride: The ACI 318 building code limits water soluble chloride ion

content in reinforced concrete to the following percentages by mass of

cement: Prestressed concrete 0.06% - Other reinforced concrete

construction 0.30%.



76 Seawater: Sewater containing up to 35,000 ppm of dissolved salts is

generally suitable as mixing water for concrete not containing steel.

Aggregates for 79 The fine and coarse aggregates generally occupy 60% to 70% of the

Concrete concrete volume … crushed stone with particles predominately larger

than 5 mm and generally between 9.5 mm and 37.5 mm

83 Fine-Aggregate Grading

Table 5-3: Fine-Aggregate Grading Limits (ASTM C 33/AASHTO M

6)

Coarse-Aggregate Grading: The maximum size of coarse aggregate

used in concrete has a bearing on the economy … The optimum

maximum size of coarse aggregate for higher strength depends on

factors such as relative strength of the cement paste, cement aggregate

bond, and strength of the aggregate particles.

Aggregate 86 Gap-Graded Aggregates: For an aggregate of 19-mmm …

usually the 4.75 mm to 19 mm sizes are omitted.

88 Absorption and Surface Moisture: The moisture conditions of

aggregates are shown in. 5-12. They are designated as: 1-4. n Fig

Moisture size.

Figure 5-12: Moisture conditions of aggregate.

Bulking: Bulking is an increase in total volume of moist fine aggregate

over the same mass dry.

91 Resistance to Acid and Other Corrosive Substances: other

pozzolans, helps keep the corrosive agent from penetrating into the

concrete.

130 Figure 8-2: Percent air verses freeze/thaw cycles.

132 Resistance to deicers and salts.

Admixtures 105 Admixtures for Concrete: Admixtures can be classified by function as

follows: 1-11.

The major reasons for using admixtures are: 1-4.



Figure 6-1: Concrete Admixtures

Trial mixtures should be made with the admixture …anticipated on the

job.

106 Table 6-1: Concrete Admixtures by Classification

113-114 Accelerating admixtures: Calcium chloride: 2% by weight of cement

114 Applications where calcium chloride should be used with caution: 1-8.

Bonding 116 Bonding Admixtures & Bonding Agents

125 Figure 7-7: Polypropylene fibers are produced either as fine fibrils with

rectangular cross section.

Air-Entrained 129 Air-Entrained Concrete

Concrete

Deicer-Scaling Resistance

134 Air Drying: The resistance of air-entrained concrete to freeze-thaw

cycles and deicers is greatly increased by an air drying period after

initial moist curing.

Strength: When the air content is maintained constant … however,

necessitate some increase in cement content.

136 Workability: Air entrained improves the workability of concrete …

Workability of mixes with angular and poorly graded aggregates is

similarly improved.

Factors Affecting Air Content

Cement: As cement content increases, the air content decreases for a

set dosage of air-entraining admixture per unit of cement within the

normal range of cement within the normal range of cement contents.

138 Figure 8-16

Mixing Water and Slump

141 Slump and Vibration



142 Concrete Temperature: Temperature of the concrete affects air

content, as shown in Fig. 8-19. Less air entrained as the temperature of

the concrete increases.

Air Contents 145 Recommended Air Contents

Proportioning 149 Designing and Proportioning Normal Concrete Mixtures: A

Mixtures properly proportioned concrete mix should possess these qualities: 1-3.

Water-Cementing Materials Ratio and Strength Relationship:

Within the normal range of strengths used in concrete construction, the

compressive strength is inversely related to the water cement ratio or

water-cementing materials ratio.

150 Table 9-1 Maximum water-cement (W/C) ratio

Water 151 Table 9-3 Maximum water-cement (WIC) ratio verses strength

153 Slump

154 Table 9-5 Water verses aggregate size verses slump.

155 Table 9-6 Recommended slumps

157 Proportioning: proportioning methods have evolved from the arbitrary

volumetric method (1:2:3- cement: sand: coarse aggregate) of the early

1900s.

161 FineAggregate Content: Volume computations are as follows: (know

all formulas).

164 Trial Batch: At this stage, the estimated batch weights should be

checked … of concrete or 2/27 cu yd. (know formulas).

173 Fine Aggregate Content: Volumetric computations are as follows:

(know formulas)

Concrete for 174 Concrete for Small Jobs

Small Jobs



Batching, Mixing 179 Batching, Mixing, Transporting and Handling Concrete

Moving Concrete

Batching: Specifications generally require that materials be measured

for individual batches with the following percentages of accuracy:

180 Mixing Concrete: Maximum allowable difference to evaluate mixing

uniformity within a batch of ready mixed concrete as given in ASTM C

94.

Stationary Mixing: Careful attention should be paid to the required

mixing time … provided all of the water is added before one-fourth of

the mixing has elapsed.

Under usual conditions, up to about 10% of the mixing water should be

placed in the drum before the solid materials are added.

If retarding or water-reducing admixtures are used … last three-fourths

of the mixing cycle, whichever occurs first.

Ready Mixed Concrete: Ready mixed concrete is proportioned and

mixed off the project site and is delivered to the construction area in a

freshly mixed and unhardened state. It can be manufactured by any of

the following methods: 1-3.

ASTM C 94 notes that when a truck mixer is used for complete mixing

… after 100 should be at a rate of rotation designated by the

manufacturer as a agitating speed.

183 Transporting and handling Concrete

Delays

Early Stiffening and Drying Out: Concrete is kept agitated generally

can be placed and compacted within 1 ½ hours after mixing unless hot

concrete temperatures or high cement contents speed up hydration

excessively.

184 Segregation

Table 10-1



188 Work At and Below Ground Level: Possibly the concrete can be

chuted directly from the truck mixer to the point needed …Long chutes

over 6 meters, or those not meeting slope standards must discharge into

a hopper before distribution to point of need.

Placing and 191 Placing and Finishing Concrete

Finishing

192 Depositing the Concrete

Vibration 195 Vibration: Vibration, either internal or external, is the most widely

used method for consolidating concrete.

Table 11-1 shows the range of characteristics and applications for

internal vibrators for various applications.

196 Table 11-1: Range of Characteristics, Performance, and Applications of

Internal Vibrators. (Note Group 5).

199 Subgrade Preparation

200 Forms: The forms should be straight and free from warping and have

sufficient strength to resist concrete pressure without bulging. They

should be strong enough to support any mechanical placing and

finishing equipment used.

202 Any finishing operation performed on the surface of a concrete slab

while bleed water is present can cause crazing, dusting, or scaling.

Floating: The purpose of floating is threefold: (1) – (3).

Hand floats are made of fiberglass … more readily over the concrete

surface.

206 Making Joints in Floors and Walls

Isolation Joints: can be as thin as 6 mm or less, but 13-mm material is

commonly used.



Contraction Joints: Contraction joints, whether sawed, grooved, or

preformed, should extend into the slab to a depth of at least ¼ the slab

thickness.

206 Figure 11-27: Contraction joints provide …

208 Table 11-2: Spacing of Contraction Joints

Figure 11-29

210 Unjoined Floors: Three unjoined floor methods are suggested: Note

number 3

Form Removal 210-211 Removing Forms: In any case, shoring should not be removed until

the concrete is strong enough ….Advice on reshoring is provided by

ACI Committee 347.

Patching, Cleaning, and Finishing: After forms are removed, all

bulges … cut back to a depth of 13 mmm from the concrete surface.

211 Holes, Defects, Overlays: The mortar should be tamped into place in

layers about 13 mm thick.

The minimum thickness for most patches and overlays us 20 mm.

Some structures, like bridge decks, should have a minimum repair

thickness of 40 mm (1 ½).

Shallow patches can be filled with a dry-pack mortar … 13 mm thick,

with each layer given a scratch finish to improve bond with subsequent

layer.

Figure 11-33: Patch Installation

213 Finishing Formed Surfaces: These surfaces are divided into two

general classes: smooth an textured or patterned.

Curing 219 Curing is the maintenance of a satisfactory moisture content … so that

the desired properties may develop.

Figure 12-2. Curing time verses strength



220 Curing Methods and Materials: Concrete can be kept moist by three

curing methods: 1-3. (Special attention to number 2)

221 Wet Coverings:

222 Alternate cycles of wetting and drying, during the early curing period

may cause crazing of the surface.

223 Figure 12-8: Luquid membrane-forming curing compounds …

225-226 Curing Period and Temperature: Ambient 40˚F minimum for 7 days.

226 Figure 12-11

Hot Weather 229 Hot Weather Concreting

Concrete

230 Effects of High Concrete Temperatures: As shown in Fig 13-2, if

the temperature of freshly mixed concrete is increased from 10 to

38 .

Figure 13-2. Water verses temperature (3" slump).

231 Cooling Concrete Materials: The aggregates and mixing water should

be kept as cool as practicable … after mixing than other ingredients.

232 Cooling the mix water temperature … more than about 4.5 C by

cooling the water alone.

To lower the temperature of concrete 0.5 C requires only a 0.8 C to

1.1 C reduction in temperature of the coarse aggregate.

234 Cement temperature has only a minor effect on the temperature of

freshly mixed concrete … temperature change of 5 C generally will

change the concrete temperature by only 0.5 C.

235 Plastic Shrinkage Cracking: The following conditions, singly or

collectively, increase evaporation of surface moisture and increase the

possibility of plastic shrinkage cracking: 1-4.

The crack length is generally 50 to 1000 mm in length and they are

usually spaced … with certainty when plastic shrinkage will occur.



236 One or more of the precautions listed below can minimize the

occurrence of plastic shrinkage cracking: 1-5.

237 Fogging the concrete before and after the final finishing is the most

effective way to minimize evaporation and reduce plastic shrinkage

cracking.

Curing and Protection

238 Moist-cured surfaces should dry out slowly after the curing period …

The cracks encompass small concrete areas less than 50 mm in

dimension, forming a chicken-wire like pattern.

Cold-Weather 239 Concrete can be placed safely without damage from freezing …

Concrete Normal concreting practices can be resumed once the ambient

temperature is above 10 C for more than half a day.

242 Special Concrete Mixtures

Concrete Testing 275 Concrete Testing

Classes of Tests: Project specifications may affect (1) – (2).

Tests of aggregates have two major purposes: (1) – (2).

Frequency of Testing: Frequency of testing is a significant factor in

the effectiveness of quality control of concrete.

Strength Test 276 Frequency of Testing: The number of strength tests will be made will

depend on the job specifications … tested provide an early indication of

strength development.

Slump Test 279 Testing Freshly Mixed Concrete: Samples should be obtained and

handled directly in accordance with ASTM C172 … purposes be at

least 28 liter.

Consistency: The test equipment consists of a slump cone … long

with a hemispherically shaped tip.

286 Measured strengths varied up to 25%, depending on the time and type

of conditioning prior to testing.



High-Performance 299 High-Performance Concrete

Concrete

300 High-Early Strength Concrete: The time period in which a specified

strength could be achieved may range from a few hours to several days.

Special Types of 315 Structural Light Weight Concrete: 85 to 115 PCF/2500 PSI.

Concrete

Table 18-1: Some Special Types of Concrete

317 Slump

Vibration

318 Insulating and Moderate Strength Lightweight Concretes

- Group I

- Group II

- Group III

319 Workability

325 No-Slump Concrete

326 Roller-Compacted Concrete

Shotcrete 327 Soil-Cement

Shotcrete

Appendix 335 Appendix- Glossary

- Bulking

- Contraction Joint

- Normal weight concrete

- Pozzolan

- Scaling

348 Metric Conversion Factors:

Length: foot to meter

Mass: Pound to kilogram

Index 351 Index

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