The Cathedral of Our Lady of theR f l MRafael Moneo

e Angels. Los Angeles, California

Concrete MG l D i i t• Goal: Design a mixtureminimum cement and a

• Cement• Cement101.88 $/ton (8/1/1

• Aggregates• Aggregates6-8 $/ton (6/1/11)

• Minimize cement conte• Minimize cement conte– Use lowest w/c ratio allow– Use largest size aggregaUse largest size aggrega– Do not use too much fine– Use admixtures – fly ash

Mix Designf ti t th te of optimum strength at

acceptable workability

1)

ententwable ate with good gradationate with good gradatione aggregate, superplasticizers, etc.

How do I design Produce a trial batch using the1 Water and air entrainment d1. Water and air entrainment d2. w/c determines strength (du3 Compute cement from 1 &3. Compute cement from 1 & 4. Use as much coarse aggre

from empirical tables).from empirical tables).5. Fine aggregate fills the rest

subtracting other ingredientg gestimated weight)

1. Adjust weights of aggregatej g gg gadded based on moisture cabsorption capacity of the ap p y

a concrete mix? ACI 211 Design Procedure:determines slumpdetermines slumpurability requirements also)22.gate as you can (compute

t of the space (compute by ts from total

e and water contents and aggregatesgg g

Trial BatchTrial Batch

Use Table 1 to determine th• Use Table 1 to determine threq’d to obtain the desired s

• Use Table 2 to determine thdesired strength

• Calculate the amount of cem• Use Table 3 to determine th• Use Table 3 to determine th• Calculate the amount of fine

weight of concrete from Tab

Fine Weight = Total Weight – Coarse W

Adjust the amounts of coars• Adjust the amounts of coarsamount of mix water baaggregateaggregate

hing Stepshing Steps

e amount of water per cubic yarde amount of water per cubic yard lump e w/c ratio req’d to obtain the

mente amount of coarse aggregatee amount of coarse aggregate

e aggregate using the estimated le 4

Weight – Cement Weight – Water Weight

e and fine aggregates ande and fine aggregates and ased on level of moisture in

Mix DeMix DeConcrete for an interior column in a th

The desired properties are:• Slump = 3” – 4”

28 d i t th f’• 28-day compressive strength, f’c =• No air-entrainment required

Coarse aggregate:• Coarse aggregate: – Nominal maximum size = 1”– Dry-rodded weight = 105 lb/ft3

Absorption capacity (AC) = 1 0– Absorption capacity (AC) = 1.0– Moisture content (MC) = 0.5%

• Fine aggregate:• Fine aggregate: – Fineness modulus (FM) = 2.70– Absorption capacity (AC) = 0.7– Moisture content (MC) = 1 5%– Moisture content (MC) = 1.5%

esign Iesign Ihree-story building

4000 i= 4000 psi

3

0%0% %

0 7%

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Tabble 1

TablTablle 2le 2

TabTabble 3ble 3

TabTabble 4ble 4

Level of MoistuLevel of Moistu• Oven-dry (OD). All moisture is

the surface are empty and thethe surface are empty and the

• Air dry (AD). All surface moistconnected to the surface are pconnected to the surface are paggregate is somewhat absorb

• Saturated surface dry (SSD). Aare filled with water but the suare filled with water, but the suneither absorbent nor does it c

• Wet. All internal pores connecWet. All internal pores connecwater and there is excess moisaggregate contributes water to

re in Aggregatere in Aggregates removed. All pores connected to aggregate is fully absorbentaggregate is fully absorbent.

ure is removed, but internal pores partially filled with water. Thepartially filled with water. The bent.

All pores connected to the surface rface is dry The aggregate isrface is dry. The aggregate is

contribute water to the concrete mix.

cted to the surface are filled withcted to the surface are filled with sture on the surface. The

o the concrete mix.

Adjustments for AAdjustments for A

Aggregate weights. Aggregate quoven dry (OD) unit weights, but agon actual weight Therefore any mon actual weight. Therefore, any mincrease its weight and stockpiled some moisture.Without correction the batched agWithout correction, the batched ag

A t f i i t If th b tAmount of mixing water. If the batsaturated surface dry (SSD) it will dry (AD)) or give up water (if wet) tnet change in the amount of waterof water added to the mix must be

ggregate Moistureggregate Moisture

antities are calculated based on ggregate is typically batched based moisture in the aggregate willmoisture in the aggregate will aggregates almost always contain

ggregate volumes will be incorrectggregate volumes will be incorrect.

t h d t i thi b ttched aggregate is anything but absorb water (if oven dry (OD) or air to the cement paste. This causes a r available in the mix and the amount adjusted accordingly.

Adjusting for agg• The actual quantities of aggregat

of a concrete mix must allow for tthe aggregatethe aggregate.

• Generally, the aggregates will bebe increased by the amount of waand surfaceand surface.

• The mixing water added to the baequal to the free moisture contribmoisture content of the mix minusmoisture content of the mix minusor the what is reported as the sur

• Remember that water absorbed ipart of the available mixing waterpart of the available mixing water

• If the MC is less than the AC, moas some of the mix water will be a

• If the MC is more than the AC, thmix and less mix water needs to

gregate moisturete to be weighed out during batching the specific amount of moisture in

moist and their dry weights should ater they contain, both absorbed

atch must be reduced by an amount buted by the aggregate (i.e., s absorption capacity of aggregates absorption capacity of aggregate, rface moisture).nto the aggregate does not become rr.ore mix water needs to be provided absorbed by the aggregate. en surface water is included in the be added.

On-Going Reesearch Area

Mix DeMix DeConcrete for an exterior slab of a park

The desired properties are:• Slump = 1” – 2”

28 d i t th f’• 28-day compressive strength, f’c =• Air-entrainment required

Coarse aggregate:• Coarse aggregate: – Nominal maximum size = 3/4”– Dry-rodded weight = 100 lb/ft3

Absorption capacity (AC) = 1 5– Absorption capacity (AC) = 1.5– Moisture content (MC) = 1.8%

• Fine aggregate:• Fine aggregate: – Fineness modulus (FM) = 2.60– Absorption capacity (AC) = 1.0– Moisture content (MC) = 2 0%– Moisture content (MC) = 2.0%

esign IIesign IIking deck

3500 i= 3500 psi

3

5%5% %

0 0%

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