Module 11 French

American Concrete Institute © 2015. All rights reserved. No part of this publication may be reproduced, copied, distributed, or transmitted in any form. 1

WWW.CONCRETE.ORG/ACI318 1

Chapter 19 – Concrete: Design and Durability

ACI 318-14:Reorganized for Design


Ch. 19 – Concrete: Design and Durability Requirements

• Gathers all concrete-related design properties and durability requirements – Limits on f’c

– Equations for design properties– Durability requirements for concrete– Durability requirements for grout



How is this chapter used?

• Referenced in whole by member chapters• Used as a reference and a checklist• Design properties

– Analysis– Strength

• Durability requirements– Specifications– Drawings


Durability Requirements

• What is “durability”?• How does the Code address it?

(Credit: PCA)



Durability is a function of several factors

• Materials• Mixture proportions• Environment• Design• Construction• …


Code approach to durability

• Limit materials, proportions, and strength of concrete for particular exposures

• Limit permeability• Rely on limits for w/cm• Allowable supplementary cementitious

materials• Balance with shrinkage and cracking• Strength limited as a test of w/cm



Exposure categories

• Code requirements address 4 exposures– F – Freezing and thawing cycles– S – Sulfates– W – In contact with water *– C – Corrosion protection of reinforcement

• Not applicable to severe exposure• Refer to ACI 201.2R-08, “Guide to Durable

Concrete”


Freezing and Thawing

• Cycles of freezing thawing• Internal moisture• Better resistance if properly cured and with

longer time before first cycle• Dry concrete (<~75%-80% internal RH)

normally immune• Different forms of damage• Air entrainment



Freezing and Thawing

(Credit: CTLGroup)


Freezing and Thawing – Scaling

(Credit: CTLGroup)



Freezing and Thawing – Popouts

(Credit: CTLGroup)


Freeze – Thaw Resistance vs. Air Entrainment

(Credit: PCA)



Test for air content *

Concrete air content shall be measured in accordance with ASTM C231 or ASTM C173 (ACI 318-14, 19.3.3.2)*

– ASTM C231 – Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method

– ASTM C173 – Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method


Freeze – Thaw Resistance vs. w/c

Type I cement

(Credit: PCA)



Exposure Category F Class Condition (Table 19.3.1.1) Examples (Table R19.3.1)

F0 Concrete not exposed to freezing‐and‐thawing cycles

• Non‐freezing climates• Interior members • Foundations not exposed to freezing• Members buried below the frost line

F1 Concrete exposed to freezing‐and‐thawing cycles with limited exposure to water

• Members not subject to snow and ice accumulation,• Foundation walls, depending upon their likelihood of being saturated

F2 Concrete exposed to freezing‐and‐thawing cycles with frequent exposure to water

• Members subject to snow and ice accumulation, such as exterior elevated slabs• Foundation walls extending above grade with snow and ice buildup against them

F3 Concrete exposed to freezing‐and‐thawing cycles with frequent exposure to water and exposure to deicing chemicals

• Members exposed to deicing chemicals, such as horizontal members in parking structures• Foundation or basement walls extending above grade that can experience accumulation of snow and ice with deicing chemicals


Exposure Category F (Table 19.3.2.1)Class Max.

w/cmMin. f’c,

psiAir Content Limits on cementitious

materials

F0 N/A 2500 N/A N/A

F1 0.55* 3500* Table 19.3.3.1 N/A

F2 0.45 4500 Table 19.3.3.1 N/A

F3 0.40* 5000* Table 19.3.3.1 26.4.2.2(b)

Nominal maximumaggregate size, in.

Target air content, %

F1 F2 and F3

… 3/4 5 6

1 4.5 6

1‐1/2 … 4.5 5.5



Max. w/cm ratio and min. f’c *

Changes in Table 19.3.2.1 F1 and F3 exposure classes

Exposure Class

ACI 318‐11 ACI 318‐14

Max. w/cm Min. f’c Max. w/cm Min. f’cI, psi

F0 N/A 2500 N/A 2500

F1 0.45 4500 0.55 3500

F2 0.45 4500 0.45 4500

F3 0.45 4500 0.40 5000

*

*


Sulfate Attack

• Sources: – Sulfate bearing soils – Sulfate bearing groundwater – Sea water

• Factors affecting reaction rate– Soil saturation– Temperature– Concentration

• How to minimize possible deterioration



Sulfate Attack

(Credit: PCA)


Sulfate AttackType V cement, w/c = 0.65 Type V cement, w/c = 0.39

(Credit: PCA)



Sulfate Attack

• How to minimize possible deterioration – Low w/c– Minimize cracking– Appropriate cement

type / other cementitious materials

(Credit: PCA)


Exposure Category S (Table 19.3.1.1)

Class Water‐soluble sulfate (SO42–) in

soil, percent by massDissolved sulfate (SO4

2–) in water, ppm

S0 SO42– < 0.10 SO4

2– < 150

S1 0.10 ≤ SO42– < 0.20

150 ≤ SO42– < 1500

or seawater

S2 0.20 ≤ SO42– < 2.00 1500 ≤ SO4

2– < 10,000

S3 SO42– > 2.00 SO4

2– > 10,000



Exposure Category S (Table 19.3.2.1)

Class Max.w/cm

Min. f’c, psi

Cementitious materials, type Calcium chloride admixture

C150 C595 C1157

S0 N/A 2500 No restriction

S1 0.50 4000 II IP, IS, or IT with (MS)

MSNo restriction

S2 0.45 4500 V IP, IS, or IT with (HS)

HSNot permitted

S3 0.45 4500 V + Pozz or slag

IP, IS, or IT with (HS) +Pozz or slag

HS + Pozz or slag

Not permitted


Cement types *Blended hydraulic cement type IT permitted

Exposure Class

ASTM C595

ACI 318‐11 ACI 318‐14

S0 No type restriction No type restriction

S1 IP(MS), IS (<70) (MS) Types IP, IS, or IT with (MS) designation

S2 IP (HS) IS (<70) (HS) Types IP, IS, or IT with (HS) designation

S3 IP (HS) + pozzolan or slag|| or IS (<70) (HS) +pozzolan or slag

Types IP, IS, or IT with (HS) designation plus pozzolans or slag cement

*

*

*



Water penetration

• Factors affecting permeability– Low w/cm– Extended curing

(Credit: PCA)


Exposure Category W

Class Condition Example

W0 Concrete dry in service Concrete in contact with water and low permeability is not required

Interior concrete

W1Concrete in contact with water and low permeability is required

Foundation wall below the water table

Class Max. w/cm Min. f’c, psi Limits on cementitious materials

W0 N/A 2500 None

W1 0.50 4000 None



Corrosion

• Mechanism– Chlorides– Carbonation– Galvanic coupling– Expansion of

corrosion products• Factors affecting

corrosion

(Credit: CTLGroup)


Corrosion

• How to minimize possible deterioration:– Increased cover– Low permeability

concrete (low w/c, SCM)

– Corrosion inhibiting admixtures

(Credit: CTLGroup)



Exposure Category C (Table 19.3.1.1)

Class Condition Examples

C0 Concrete dry or protected from moisture

Interior concrete

C1Concrete exposed to moisture but not to an external source of chlorides

Grade beams, exterior walls

C2 Concrete exposed to moisture and an external source of chlorides from deicing chemicals, salt, brackish water, seawater, or spray from these sources

Parking deck, building wall near roadway


Exposure Category C (Table 19.3.2.1)

Class Max.w/cm

Min. f’c, psi

Maximum water‐soluble chloride ion (Cl–) content in concrete, percent by

weight of cement

Additional provisions

Nonprestressedconcrete

Prestressedconcrete

C0 N/A 2500 1.00 0.06 None

C1 N/A 2500 0.30 0.06

C2 0.40 5000 0.15 0.06 Cover per 20.6



Cooling tower foundation example

• Exposures– Freezing-and-thawing– Sulfates– Corrosion


Chapter 20 – Steel, Reinforcement Properties, Durability, and Embedments

ACI 318-14:Reorganized for Design



Steel

• Chapter sub-headings– 20.1 Scope– 20.2 Nonprestressed bars and wires– 20.3 Prestressing strands, wires, and bars– 20.4 Structural steel, pipe, and tubing for

composite columns– 20.5 Headed shear stud reinforcement– 20.6 Provisions for durability of steel

reinforcement– 20.7 Embedments


Steel, Reinforcement Properties, Durability, and Embedments

• Referenced in whole by member chapters• Used as a reference and a checklist• Design requirements

– Analysis– Strength

• Durability requirements



Nonprestressed bars and wires

• Material properties– Method of determining yield strength *– Allowable standards by application

• Design properties– Modulus of elasticity– Yield strength– Limits based on application

• Summary Tables 20.2.2.4a and b


Yield strength determination *

318-11, 3.5.3.2: …for bars with fy at least 60,000 psi, the yield strength shall be taken as the stress corresponding to a strain of 0.35 percent.

318-14, 20.2.1.2: Yield strength … shall be determined by either (a) or (b): (a) The offset method, using an offset of 0.2 percent in accordance with ASTM A370 *(b) The yield point by the halt-of-force method, provided the nonprestressed bar or wire has a sharp-kneed or well-defined yield point.



Several tables created *


Elongation of ASTM A615 steel *

For seismic design, elongation % based on bar size• Match elongation of ASTM A615 with ASTM A706

Grade 60 deformed bars *• Provides adequate ductility (minimum

tensile/yield ratio of 1.25) (ACI 318-14, 20.2.2.5)



Clarify language *

318-11, 3.5.6.2: Wire, strands, and bars not specifically listed in ASTM A421, A416, or A722 are allowed provided they … do not have properties that make them less satisfactory than those listed in ASTM A421, A416, or A722.318-14, 20.3.1.3: Prestressing strands, wires, and bars not listed in ASTM A416, A421, or A722 are permitted provided they … are shown by test or analysis not to impair the performance of the member.*


Max. tensile strength of prestressing reinforcement *

Summary of maximum permitted design values for prestressing strand, wire, and bar *



Provisions for durability

• Cover– Minimum specified cover based

on exposure, member, and bar size

– Does not consider fire protection– Development/splice length

considerations• Reinforcement coatings• Prestressing component

protection


Post-tensioning friction losses *

• The Code no longer has a prescriptive method. *

• The commentary states that estimation of friction losses in post-tensioned tendons is addressed in PTI TAB.1. *

Documents

Module 11 French