environmental technology i – systems and materials ready mix concrete plant tour – nov. 2010

Environmental Technology I – Systems and Materials Ready Mix Concrete Plant Tour – Nov. 2010

Tuesday Nov. 2• Concrete Lecture • Steel building team Powerpoint

presentations

F u t u r e

• Thursday Nov. 4 Concrete Plant Field Trip• Thursday Nov. 11 Concrete Tile Lab

Field Trip Field Trip Thursday Nov. 4Thursday Nov. 4: 4:15PM. : 4:15PM. PROMPTPROMPT Structures will be dismissed @ 3:30 Structures will be dismissed @ 3:30 PROMPTPROMPT Ready Mix Concrete Plant and testing lab in Ready Mix Concrete Plant and testing lab in Woodstock, GA. (17.2 miles) Ready Mix USA Woodstock, GA. (17.2 miles) Ready Mix USA 106 Bell Parkway, Woodstock, GA 30188106 Bell Parkway, Woodstock, GA 30188

-Must have long pants, closed toe work -Must have long pants, closed toe work shoes. shoes. www.readymixusa.com/www.readymixusa.com/

EXIT 8

1.7 miles

.3 miles

14.4 miles to SPSU

Concrete Module Outline

History of ConcreteHistory of Concrete Concrete CharacteristicsConcrete Characteristics Site cast ConcreteSite cast Concrete Precast ConcretePrecast Concrete MasonryMasonry

• ConcreteConcrete• BrickBrick

History of ConcreteHistory of Concrete

After the fall of Roman empire, the secret of concrete was lost for 1300 yearsuntil 1756, when the British engineer John Smeaton pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate.

Portland cement was first used in concrete in the early 1840s.

The Romans - first developed ConcreteThe Romans - first developed Concrete

Hadrian’s Villa , Rome 125 A.D. Segovia Aqueduct, Segovia, Spain 200 A.D.masonry cladding to a concrete core

The Pantheon, Rome 125AD the interior dome is unclad concrete.

The Romans - first developed ConcreteThe Romans - first developed Concrete

The Swiss engineer Robert Maillart (1872-1940) built bridges and The Swiss engineer Robert Maillart (1872-1940) built bridges and industrial buildings of startling originality. His innovative use of industrial buildings of startling originality. His innovative use of concrete, especially in the design of thin arch structures, and his concrete, especially in the design of thin arch structures, and his introduction of a wide range of new engineering forms, make him a introduction of a wide range of new engineering forms, make him a seminal figure in the history of modern engineering.seminal figure in the history of modern engineering.

Primarily an engineer, Maillart gained notoriety through his innovative bridge designs. Maillart utilized the structural strength and expressive potential of reinforced concrete to generate a modern form for his bridges. To avoid structural beams and arches, he established a structural form based on both flat and curved concrete slabs reinforced with steel.

The Salginatobel Bridge, Switzerland, 1930Designed by Robert MaillartHollow-box, reinforced concrete arch, with a span of 295 feet.

Auguste Perret was another innovator with concrete. However, he used material for structural frames in simple rectangular shapes. The area between the concrete frame was frequently filled with other materials.

25 bis Rue Benjamin Franklin, Paris, France: 1903

Architects Auguste and Gustave Perret.

Notre Dame du Raincy 1922

Auguste Perret

Pier Luigi Nervi used reinforced concrete for many of his most innovative structures. His stadiums at Florence, bridges and airport hangers use exposed concrete in daring and innovative forms. His most famous works include the Exhibition Building in Turin (1948) and the sports palace in Rome (1957).

Airport Hanger, Italy,1938

Pier Luigi Nervi

The Exhibition Building in Turin (1948) A ribbed concrete frame is combined with glass to create a shell enclosure

1931-36, Hoover Dam

The first major concrete dam.  The horizontal arch design of Hoover Dam ensures that the great compression strength of  concrete is employed. The immense force of Lake Mead‘s waters wedge

the dam into the mountain creating a very strong structure. 

Johnson-Wax Building

Racine, Wisconsin

Frank Lloyd Wright, 1937–39

Unity Temple Frank Lloyd Wright, Oak Park, Illinois, 1937–39First cast-in-place-concrete structure in the US where the building exterior surface is also the building structure.

Notre Dame du Haut in Ronchamp Le Corbusier , 1954

Guggenheim Museum Frank Lloyd Wright 1959

Dulles Airport Chantilly, Virginia , Eero Saarinen, 1962

Cable structure supporting thin shell concrete roof

Transamerica Tower San Francisco, William Pereira , 1969The four-story base of the building contains a total of 16,000 cubic yards of concrete and over 300 miles (483 km) of steel rebar. The building's foundation is 9 feet thick and was the result of a 24-hour continuous concrete pour.

Falling Water Frank Lloyd Wright, Mill Run, Pennsylvania, 1938

Fallingwater is the only major Wright-designed house to open to the public with its furnishings, artwork, and setting intact .

http://www.fallingwater.org

Expression of surface texture and color

Church of the Light, Ibaraki, Osaka, Japan Architect: Tadao Ando

Surface

Concrete Characteristics

What is Concrete?Concrete is a manufactured construction material consisting

of a mixture of fine aggregate (sand), coarse aggregate (gravel or crushed rock), portland cement, and water.

The aggregates in concrete are the inert ingredients, while cement and water are the active ingredients.

The aggregates are first mixed thoroughly with the cement. As water is added, a chemical reaction called hydration takes place between the water and cement that creates heat and causes the concrete to harden.

The chemical reaction rather than the drying out of the mix, causes hardening. Concrete must be kept moist for satisfactory hydration of the cement.

sand gravel cement water.

The proportioning of the ingredients that comprise concrete is referred to as the mix.

For example, a typical concrete mix [1:2:3 mix] consists of one part cement; two parts fine aggregate (sand); and three parts coarse aggregate (crushed rock or gravel)

Proportioning

cement sand gravel

Water is then added to make the mix workable – not too soupy nor stiff

Water Cement Ratio

The weight of water compared to the weight of the portland cement. The higher the

number, the weaker the concrete.Normal range is .45 to .60 Should not exceed .60 for most applications.

typically .55 for 3000 psi concrete .48 for 4000 psi concrete

The principal factor that determines concrete strength is the amount of cement in the mix and the water-cement ratio.

Excess water reduces the concrete’s strength and durability.

AggregateSize of the aggregate is significant because the largest unit must be small enough to pass easily between the most closely spaced reinforcing bars andnot so large to compromise structural integrity.

The maximum aggregate size should be no greater than 1/3 the thickness of concrete slabs, or ¾ of the minimum space between reinforcing bars.

Lightweight aggregates are used to reduce the weight of the concrete,thus effecting the overall structural system size.

Lightweight aggregate of vermiculite and perlite is used in non-structural lightweight concrete insulating roof toppings. Non structural lightweight concrete has a density of 1/4 to 1/6 that of normal concrete.

Mixing

All concrete should be thoroughly mixed until it is uniform in appearance and all ingredients are evenly distributed.

For small jobs, concrete may be mixed at the site, but this method is slow, relatively imprecise, and generally not recommended for quantities in excess of a few cubic yards. More commonly, concrete is mixed in a truck.

Ready-mixed concrete is formulated to exact specifications at a central mixing plant and transported to the site in an agitator truck with a revolving chamber. Concrete typically must be placed within 90 minutes after water is added to the mix.

The curing of concrete consists of maintaining the proper humidity and temperature for a period of time after it is placed, to assure satisfactory hydration of the cement to achieve design strength.

The typical compressive strength of concrete is 3,000 psi after 28 days of curing. Special admixtures can be introduced reducing curing time to 7 to 14 days.

During the curing process the contractor must prevent:

Freezing by protecting or using admixtures.Overheating by adding ice or bubbling in liquid nitrogen.Drying out by:1) Supplying moisture to concrete surface, by ponding or sprinkling.

2) Providing a wet cover, such as moist sand, burlap, or straw.

3) Covering the surface with a membrane or applying a curing compound that prevents evaporation.

4) Leaving wood forms in place and keeping them moist.

Curing

Concrete Types

Type I is used for most purposes

rarely used any longer by ReadyMix Concrete Co.

Admixtures

Ingredients added to concrete mixes for the Ingredients added to concrete mixes for the purpose of altering one or more properties of purpose of altering one or more properties of the concrete. the concrete.

Fly Ash

Fly Ash is a fine powder that is a waste product from coal-fired power plants. It is an inexpensive admixture that increases concrete strength, acts like “ball bearings” to increase workability and pump ability, reduces mixing water, and aids in water retention by reducing temperature rise during curing.

Can help qualify the concrete in the project for LEED points

Air EntrainingAir-entraining cements contain admixtures that cause microscopic (not visible to the eye) air bubbles to form in the concrete during mixing.

Main purpose is to keep concrete from being damaged by cycles of freezing and thawing.

It also gives improved workability during the placement of concrete.

The greatest negative is that it decreases the strength of concrete.When too much air is added, this error is responsible for most damages and lawsuits in the concrete supply industry.

Entrapped air is visible air bubbles in the concrete mixed caused by lack of vibration of the concrete during placement or too stiff of a mix to allow proper flow into forms and around reinforcing. This is NOT what is meant by air-entrained concrete.

Segregation is prevented by controlling

the distance from which the concrete is dropped

(3-4ft max) Use drop chute, hose, buckets & buggies.

Vibration/Segregation

Self-Consolidating Concrete has more fine aggregate tha course aggregate and special superplasticizing admixtures.Allows easy placement around high concentrations of rebar and eliminates the need for vibration(higher material cost)

In order to verify that the concrete used on a project has the required strength, several tests maybe preformed. The most common are the slump test and cylinder test.

Testing

Slump Test measures the consistency and workability of the concrete mix and is usually performed in the field.

The test employs a standard slump cone mold that is set on a level surface and filled with concrete taken directly from the mixer.

Slump Test

Cylinder Test measures the compressive strength of Cylinder Test measures the compressive strength of concrete and utilizes standard test cylinders 6 inches in concrete and utilizes standard test cylinders 6 inches in diameter and 12 inches long. diameter and 12 inches long.

From each patch of concrete at least two cylinders are cast, From each patch of concrete at least two cylinders are cast, laboratory-cured for 7 and 28 days, then tested. laboratory-cured for 7 and 28 days, then tested.

The CORE CYLINDER TEST is used when a portion of the The CORE CYLINDER TEST is used when a portion of the structure is in place and cured, but needs to be tested. A structure is in place and cured, but needs to be tested. A cylinder is drilled out of the concrete and tested (off-site) in cylinder is drilled out of the concrete and tested (off-site) in the laboratory to determine its compressive strength.the laboratory to determine its compressive strength.

Cylinder Test

The IMPACT HAMMER TEST is a nondestructive way to test concrete strength after it is hardened. A spring-loaded plunger is snapped against a concrete surface, and the amount of rebound is measured. This test gives an approximate reading of the concrete’s strength.

Impact Hammer Test

Tuesday Nov. 9• Steel Test Review• Instructions review for Concrete Tile Lab• Concrete Lecture

F u t u r e

• Thursday Nov. 11 Concrete Tile Lab 4PM – 7PM• Tuesday Nov. 16 Concrete Lecture• Thursday Nov. 18 Concrete Test Review• Tuesday Nov. 23 Concrete Test• Thursday Nov. 25 No class – Thanksgiving Holiday

erwin hauer

• http://www.google.com/images?q=erwin%20hauer&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=og&sa=N&hl=en&tab=wi&biw=1016&bih=570

Reinforcing Bar (Rebar)

Concrete is strong on compression, but weak in tension. By embedding reinforcing steel in concrete to resist tension, we have a composite material known as reinforced concrete.

Concrete and reinforcing bar are compatible materials:

>Same coefficient of thermal expansion, so temperature change does not introduce significant stresses

>Concrete protects the reinforcing steel from corrosion and fire

>Concrete bonds well to steel.

The most common designation for reinforcing bars used in buildings is ASTM A615 Grade 60

Reinforcing Bar (Rebar)

Reinforcing Bar (Rebar)

Rebar manufacturingRebar manufacturing

http://www.youtube.com/watch?v=mHKlz7Ng1HYhttp://www.youtube.com/watch?v=mHKlz7Ng1HY

Tensile strength Compressive strength

steel

concrete 0 psi

wood 700 psi

22,000 psi

1,350 psi

1,100 psi

Concrete strong is compression, but weak in tension.

Steel is embedded in concrete to resist tension forces.

22,000 psi

ASTM A36

(average)

(average)

Reinforcing bars are generally spliced by lapping them with a specified number of bar diameters. In some cases rebar maybe butted end-to-end and spliced by welding or using mechanical devices, such as wire ties.

Devices hold the rebar in its required location:

Chairs

Bolsters

Welded Wire Fabric (WWF) is a grid of smooth or deformed Welded Wire Fabric (WWF) is a grid of smooth or deformed cold-drawn steel wires welded at all points of cold-drawn steel wires welded at all points of intersection. intersection.

The advantage of its use over individual rebar is The advantage of its use over individual rebar is economy of laboreconomy of labor

This type of reinforcement may be used for:This type of reinforcement may be used for:

FloorsFloors

WallsWalls

RoofsRoofs

Other large expanses Other large expanses

of concreteof concrete

WWF is overlapped where two sheets join

Welded Wire Fabric (WWF)

Advantages of reinforced concrete:1. Can be cast to desired shapes.

2. Better resistance to fire than steel

3. Long service life with low maintenance cost

4. Good thermal insulating properties

5. Good sound control properties

Disadvantages of reinforced concrete:1. Low tensile strength

2. Requires controlled mixing, casting, and curing, all of which can affect the final strength of concrete

3. Cost of the forms.

4. It has low compressive strength as compared to steel (the ratio is 1:10, depending on materials), which leads to large sections in columns of multistory buildings

5. Cracks can develop in concrete due to shrinkage and the application of live loads.

Reinforced Concrete

Concrete is good in compression, Steel is good in tension, therefore, place steel reinforcing where there are tensile forces and let the concrete resist compression forces.

Steel reinforcing follows the lines of tensile forces through the use of bottom bars, top bars, stirrups, hooks and chairs

Compatibility of steel and concrete

Similar coefficients of thermal expansion

Chemically compatible (no corrosion)

Concrete adhesion to steel

Steel Reinforcing of a Simple Beam

Directions of force in a simple beam with uniform load

Steel reinforcing for a simple beam

- top bars

- bottom bars

- stirrups

One-way Slab and Beam Floor

Steel Reinforcing of a One-way Slab and Beam Floor

Control joints a retooled, sawed, or premolded joints to allow for shrinkage of large concrete areas.

Control joints create a weakened section that indices cracking to occur along the joint, rather than in a random fashion.

Isolation joints provide a separation between a slab on grade and columns or walls, so that each can move independently.

Concrete Joints

In a four-inch thick concrete walkway, what is the typical spacing for expansion joints?

In a four-inch thick concrete walkway, what is the typical spacing for expansion joints? 20 feet on center

accommodates movement due to both expansion and contraction

control joint

future isolation joint

Expansion joints are designed to allow free movement of adjacent parts due to expansion or contraction of the concrete.

This movement may be caused by shrinkage or changes in temperature.

Expansion joints provide complete separation through a structure, from top of the footings to the roof; are waterproof; weather tight, and generally filled with an elastic filler.

Expansion Joints

The Concept of

Prestressed Concrete

Figure 13.34page 494

Prestressed Concrete by Pretensioning

always done in the factory

Figure 13.35page 495

Pre-cast Pre-tensioned ConcreteCables positioned and tensioned before pouring concrete

Pour concrete and bonds with tensioned cable

Bonded cables are cut at each end which puts beam in compression

High early cement allows beam to be removed from form in one or two days

Nearly all precast concrete members are pre-tensioned

done on the building site

Figure 13.36page 496

Prestressed Concrete by Posttensioning

Posttensioning cable in spools, before placement in concreteslab forms

post-tension cable endspost-tensioned monolithic floor slab: www.youtube.com/watch?v=d51lciZRwF0

Site cast Concrete

Requires extensive on-site custom wood forming

Generally slower than precast construction

Uses steel reinforcement bar

Site cast Concrete

Formwork

Formwork refers to the system of boards, ties, and bracing Formwork refers to the system of boards, ties, and bracing required to construct the mold in which wet concrete is required to construct the mold in which wet concrete is placed. placed.

Formwork must be strong enough to withstand the weight Formwork must be strong enough to withstand the weight and pressure created by the wet concrete and must be easy and pressure created by the wet concrete and must be easy to erect and remove.to erect and remove.

Formwork maybe job-constructed or prefabricated units of Formwork maybe job-constructed or prefabricated units of standard lumber, plywood, metal, fiberboard, or a variety of standard lumber, plywood, metal, fiberboard, or a variety of reinforced synthetic materials. reinforced synthetic materials.

3

1

2

Flat Slab Floor

dropped panelon flat slab

Flat Slab Floor

dropped panel

Tuesday Nov. 16• Concrete Lecture – Precast & Masonry• Concrete Construction Sites Team Presentations

F u t u r e

• Thursday Nov. 18 Concrete Tile Presentations 4:30PM • Thursday Nov. 18 Concrete Lecture – Conc. Wall Section details• Thursday Nov. 18 Concrete Test Review• Tuesday Nov. 23 Concrete Test• Thursday Nov. 25 No class – Thanksgiving Holiday

Concrete tile grading display

Flat Slab Floor

Two-way slab Floor

One-way Slab and Beam Floor

Ribbed Concrete Floor

Two-Way Concrete Joist System(Waffle Slab)

Two-Way Concrete Joist System(Waffle Slab)

TWA Terminal Eero Saarinen 1962 Thin shell concrete system

Precast Concrete

Precast Concrete

Precasting is the casting of Precasting is the casting of concrete members at a concrete members at a location other than its final location other than its final position in the structure, as position in the structure, as opposed to cast-in-place opposed to cast-in-place concrete.concrete.

Precast concrete is usually Precast concrete is usually cast in fabricating plants cast in fabricating plants where conditions can be where conditions can be more carefully controlled more carefully controlled and where work can proceed and where work can proceed regardless of the weather.regardless of the weather.

Precast ConcretePrecast Concrete

Precast concrete has the greatest economic advantage Precast concrete has the greatest economic advantage when there are many identical members to be cast, as when there are many identical members to be cast, as the same forms can be used many times. Again, there are the same forms can be used many times. Again, there are advantages to precasting:advantages to precasting:

1) Better quality control of concrete1) Better quality control of concrete

2) Better control over curing2) Better control over curing

3) Members castable in all weather3) Members castable in all weather

4) Members erectable in all weather4) Members erectable in all weather

5) Faster actual construction time5) Faster actual construction time

Precast Concrete

Disadvantages:

Development of connections between elements is difficult and there is an inherent lack of continuity. Difficulty integrating other building systems (ducts, wiring). Often heavy and long adds difficulty in handling and transportation; cost of manufacturing must be offset by use of repetitive members.

Flat slab Hollow Core slab Double-Tee Single-Tee

Typical Precast Concrete Members

Typical Precast Concrete Members

stretching steel prestressingcables across the casting bedfor pretensioning a structuralprecast beam.

Hollow core slabs

Hollow core slabs

Architectural Precast Concrete

Precast Concrete Cladding

is the building of structures from individual units laid in and bound together by mortar. The common materials of masonry construction are brick, stone such as granite, travertine, limestone; concrete block, glass block, and tile. Masonry is generally a highly durable form of construction. However, the materials used, the quality of the mortar and workmanship, and the pattern the units are laid in can strongly affect the durability of the overall masonry construction.

Masonry

Advantages•The use of materials such as brick and stone can increase the thermal mass of a building, giving increased comfort in the heat of summer and the cold of winter and can be ideal for passive solar applications.

•Brick typically will not require painting, providing a surface with reduced life-cycle costs.

•Masonry’s appearance can give an impression of solidity and permanence.

• Is very heat resistant and provides good fire protection

Disadvantages•Extreme weather may cause degradation of the surface due to frost damage. This type of damage is common with certain types of brick, though relatively rare with concrete block. If non-concrete (clay-based) brick is to be used, care should be taken to select bricks suitable for the climate in question.

•The high weight increases structural requirements.

Building brick, sometimes referred to as common brick, is the type most widely used in construction.

Brick is specified in accordance with the use and exposure to which it will be subjected, as follows:

• Grade SW (Severe weathering) Used in areas of heavy rain, snow, or continual freezing.

•Grade MW (Moderate weathering) Used in areas of average rain and moderate freezing.

• Grade NW (No weathering) Used in areas of minimal rain and no freezing, as in sheltered or indoor locations.

Face brick is brick that will be exposed to view, and is made with controlled mixtures of clay or shale.

Fire brick is made with great resistance to high temperatures, as in fireplaces.

Paving brick is very hard and dense used in pavements.

Adobe brick is made from a mixture of natural clay and straw, placed in molds, and dried in the sun. Requires protection from rain and subsurface moisture.

MORTAR is a cementious material used to hold masonry units together. It must be compatible with the masonry units being used, the strength required, and environmental conditions.

There are four basic types of mortar: Types M, S, N, and O. Each has a different proportion of cement, lime, and aggregate, and each has a different compressive strength.

GROUT is similar to mortar, but it is mixed to a pouring consistency and used to fill cavities or cores of masonry units.

Efflorescence is a white powdery deposit or crystallization on the masonry surface caused by soluble salts in the units or mortar.

These salts are leached out by water that penetrates the masonry and results in unsightly patches of discoloration.

When efflorescence appears, it can be removed by washing with high pressure water, by light sandblasting, or most commonly by washing with 5-percent solution of muriatic acid in water.

efflorescence removal by pressure washing

Brick Courses

(a course is one continuous horizontal layer of masonry)

Brick Courses

(a course is one continuous horizontal layer of masonry)

Brick Bond

Patterns

Custom Coursing

is unlimited

Herring Hall

Rice University

Houston, Texas

César Pelli & Associates

1984

Brick Joints

Joints are a critical part of a masonry wall. The mortar in the joints not only holds the entire wall together, it also prevents infiltration of water and air. Bricks should be set in full beds of mortar, on both the bed joints and head joints.

After the brick is laid, the joints must be tooled. Tooling imparts a decorative effect on the wall, but more important, it makes the joint more watertight by compressing the mortar near the exposed surface.

Typical Concrete Block Shapes Typical Concrete Masonry Wall, Reinforced & Grouted

Concrete Masonry Units (CMU)

Tuesday Nov. 18• Thursday Nov. 18 Concrete Tile Presentations 4:30PM • Thursday Nov. 18 Concrete Lecture – Conc. Wall Section

details• Thursday Nov. 18 Concrete Test Review

F u t u r e

• Tuesday Nov. 23 Concrete Test• Thursday Nov. 25 No class – Thanksgiving Holiday

Question:

You are designing a building in a city with a moderate climate and you have specified Grade MW brick for the exterior walls.The contractor proposes to substitute Grade SW since he can get it more cheaply and wants to use a more affordable brick. What should your response be?

A. Accept the substitution.

B. Reject the substitution.

C. Accept the substitution, provided masonry prism tests indicate that the brick have adequate strength.

D. Allow for SW grade bricks to be used for interior walls only.

Question:

You are designing a building in a city with a moderate climate and you have specified Grade MW brick for the exterior walls.The contractor proposes to substitute Grade SW since he can get it more cheaply and wants to use a more affordable brick. What should your response be?

A. Accept the substitution.

B. Reject the substitution.

C. Accept the substitution, provided masonry prism tests indicate that the brick have adequate strength.

D. Allow for SW grade bricks to be used for interior walls only.

Grade SW (Severe weathering) Used in areas of heavy rain, snow, or continual freezing.

Grade MW (Moderate weathering) Used in areas of average rain and moderate freezing.

Grade NW (No weathering) Used in areas of minimal rain and no freezing, as in sheltered or indoor locations.

Question:

During a weekly job-site visit, the architect notices that a mason has used troweled joints on an exposed exterior masonry wall, instead of weather-struck joints that were specified. In the interest of practicality, the architect should:

A. Accept the change, because there is little difference between the joints.

B. Accept the change, because there is no practical way to modify the troweled joints.

C. Reject the work and have the mason trowel additional mortar over every horizontal joint.

D. Reject the wall and have the wall rebuilt.

Question:

During a weekly job-site visit, the architect notices that a mason has used troweled joints on an exposed exterior masonry wall, instead of weather-struck joints that were specified. In the interest of practicality, the architect should:

A. Accept the change, because there is little difference between the joints.

B. Accept the change, because there is no practical way to modify the troweled joints.

C. Reject the work and have the mason trowel additional mortar over every horizontal joint.

D. Reject the wall and have the wall rebuilt.

D. Water tends to collect and remain in the troweled joints, so it is likley that if left alone the mortar would eventually deteriorate, causing leaks and loose units. Since weather-struck joints were specified, the architect has the authority to reject the work.

Ready Mix Field Trip notes

• 50 – 75% of mix is aggregate which is the least expensive ingredient so more aggregate less cost

• Concrete varies from region to region because both cement and aggregate are acquired locally

• In Atlanta, aggregate is primarily granite rock• Before finishing a concrete surface, allow the bleed water to rise

or else surface spalding will occur.• In air entraining, the higher the amount of air, the lower the

strength• Concrete pumping tend to take the air out of the concrete.• Fiber reinforcement gives some tensile strength, but mainly

used to reduce surface cracks

concrete section

drawingterms

1. precast concrete parapet cap2. parapet flashing3. roofing4. cant strip5. brick ties6. 2” cavity7. cavity drainage material8. continuous membrane flashing9. weep holes10.steel shelf angle11.sealant & backer rod12.window unit13.sloped brick sill14.concrete masonry unit (CMU)15.horizontal joint reinforcing16.vertical reinforcement in solid

grouted cells17.moisture barrier18. one way slab & beam system19. concrete slab20. foundation wall