Lare Section 4 - Concrete

Front 1

Curing Methods

Back 1

- Frequent sprinkling with water

- Covering the concrete with polyethylene film or waterproof Kraft paper

- Covering with wet burlap or wheat straw

- Spraying a membrane forming curing compound on the surface

Front 2

Accelerator

Back 2

Material used to speed up the setting of mortar

Front 3

Binder

Back 3

- Controls the properties of the concrete

- It is the inclusion of water (hydration) into the product that causes concrete to set, stiffen, and become hard

Front 4

Green Concrete

Back 4

- Freshly poured concrete that has not yet cured

- Generally considered green for 8-48 hours after it has set

Front 5

Soil-Cement Linings

Back 5

- Constructed with mixtures of sandy soil, cement and water, which hardens to a concrete like material

- The cement content should be from 2-8% of the soil by volume

Front 6

Pressure Test

Back 6

Measures the air trapped within the mortar of the concrete mixture

Front 7

Chace Air Indicator

Back 7

Simple and inexpensive way to check the approximate air content of freshly mixed concrete

Front 8

Kelly Ball

Back 8

- A device for determining the consistency of fresh concrete

- Sometimes used as an alternative to the slump test

Front 9

Schmidt Hammer Test

Back 9

- This test gives an estimate of the concrete's compressive strength

- This test is performed in situations where the concrete has already been poured and a cylinder test is not possible

Front 10

Rich

Back 10

- 1 part cement, 2 parts sand, 3 parts coarse aggregate

- Used for concrete roads and waterproof structures

Front 11

Standard

Back 11

- 1 part cement, 2 parts sand, 4 parts coarse aggregate

- Used for reinforced work floors, roofs, columns, arches, tanks, sewers, conduits, etc.

Front 12

Medium

Back 12

- 1 part cement, 2.5 parts sand, 5 parts coarse aggregate

- Used for foundations, walls, abutment, piers, etc.

Front 13

Lean

Back 13

- 1 part cement, 3 parts sand, 6 parts coarse aggregate

- Used for all mass concrete work, large foundations, backing for stone masonry, etc.

Front 14

Cement Types

Back 14

1. Type I Normal

2. Type II Moderate

3. Type III High Early Strength

4. Type IV Low Heat

5. Type V Sulfate Resisting

6. Types IA, IIA, and IIIA

Front 15

Decorative Concrete

Back 15

1. Acid stain (chemical stain)

2. Decorative aggregate

3. Dyes

4. Stamped concrete

5. Stenciled concrete

Front 16

Acid Stain

Back 16

A stain containing inorganic salts dissolved in an acidic, water-based solution that reacts chemically with the minerals in hardened concrete to produce permanent, transparent colors that will not peel or flake. Colors tend to be earth tones, such as tans, browns, reddish browns, and greens.

Front 17

Decorative Aggregate

Back 17

Richly colored natural stones, such as ballast, granite, quartz, or limestone, used to enhance exposed aggregate concrete or decorative toppings

Front 18

Dyes

Back 18

- Translucent color solutions containing very fine pigments that penetrate into the concrete surface

- Will not chemically react with concrete (like acid stains will)

Front 19

Stamped Concrete

Back 19

Concrete flatware that is patterned with platform tools, stamping mats, or seamless texturing skins to resemble materials such as brick, slate, stone, tile, and wood planking

Front 20

Stenciled Concrete

Back 20

- A decorative surface treatment using heavy-duty paper stencils with stone, tile, or brick patterns that are lightly pressed into fresh concrete, followed by the application of dry-shake color hardeners

- Another technique is to apply adhesive stencils and then color or sandblast the surface

Front 21

Adhesive stencils

Back 21

Adhesive backed masking patterns made of vinyl/plastic used for creating stenciled concrete effects. The adhesive keeps the patterns firmly in place on the concrete surface while the decorative treatment of choice is applied, such as acid stains, dyes, spray-down systems, etching gels, or sandblasting

Front 22

Function of Mortar

Back 22

- Bonding agent that integrates brick into a masonry assembly

- Helps to create a water resistant barrier

- Accommodates dimensional variations and physical properties of the brick

- Bond with steel reinforcement, metal ties, and anchor bolts so that they perform integrally with the masonry

- Permits some movement between units

- Allows for the use of ties and reinforcing to the unit

- Enhances the aesthetics through color and texture

Front 23

Mortar Characteristics

Back 23

- Used as a joining medium in masonry, wood, or other material, joining them into a unified mass

- Limited life 1.5-2 hours

- Mixture gradually hardens when exposed to the air

- Must fill joint completely to create a watertight and strong wall

Front 24

Mortar Types

Back 24

1. Type N

2. Type S

3. Type M

4. Type O

Front 25

Type N

Back 25

- Used in general masonry walls above grade

- Used in non-structural applications in new construction

- Has good bond qualities and good resistance to water penetration

- Recommended for chimneys and exterior walls subjected to severe weather

Front 26

Type S

Back 26

- Typically used in structural masonry applications

- Recommended for use in masonry where maximum flexural strength is required for chimneys and load bearing masonry constructions

- Very high tensile bond strength

- Excellent for masonry subject to severe weather

Front 27

Type M

Back 27

- Typically used only in below grade applications

- Very high in compressive strength and durability, but low in tensile strength and poor workability

Front 28

Type O

Back 28

- Relatively low compressive strength mortar suitable for non exposed locations and general interior use in load bearing and non-load bearing masonry

- Should not be used where it is subject to freezing

Front 29

Thin-set

Back 29

- Used to describe the installation of tile with all materials except Portland cement mortar, which is the only recognized thick-bed method

- Applied to subfloor (1/8" thin set mortar)

- Set same size stones generally 1/4" on top

- Can be placed on either concrete or wood subfloors

Front 30

Thick-set

Back 30

- Used to describe a thick layer of mortar (more than 1/2") that is used for leveling

- Apply thick layer of mortar 3/4" to subfloor

- Set in mortar in 2 ways

1. Allowed to become semi-wet then set

2. Allowed to dry completely and then stone is set with a thin layer of dry-set mortar on top of the first

- Can be bonded directly to subfloor

- Can be separated from subfloor with a cleavage membrane usually a steel reinforcing mesh in the mortar bed

Front 31

Grout

Back 31

- Cementitious or other type material used for filling joints between tile and stone

- Flexible material that allows for floor expansion

- Mixed in the same proportions as a Portland cement mortar, but does not contain hydrated lime

Front 32

Paste

Back 32

Water and cement

Front 33

Bonding Agent Types

Back 33

1. Bituminous binder

2. Casein glues

3. Construction adhesive

4. Contact Cements

5. Epoxy

6. High-Tech adhesives

7. Wall panel adhesives

8. White Glue

Front 34

Bituminous binder

Back 34

A class of black or dark-colored solid, semi-solid or viscous cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons (asphalt, tars, pitches, and asphaltites) used to cement loose materials together

Front 35

Casein Glues

Back 35

Slow setting, permitting easier construction of difficult assemblies

Front 36

Construction Adhesive

Back 36

- A high performance adhesive for multi-purpose in most interior and exterior construction projects

- Bonds all wood to wood assemblies

- Waterproof and weather proof

- Reduces Nail Pops

- Permanent bond

Front 37

Contact Cements

Back 37

Useful for applying laminates and edge stripping to plywood

Front 38

Epoxy

Back 38

- Comes in two parts which you mix together -- resin and hardener-- with varying setting times

- When fully cured, they provide a very tough, durable coating of high adhesive, cohesive, tensile and compression strength an are resistant to water, moisture and most chemicals

- Most are not formulated for wood

- Used as a bonding agent to adhere new concrete to old surfaces; to rebond or weld structural units together

Front 39

High-Tech Adhesives

Back 39

- Stronger than white glue, formulated to bond a variety of materials together including non-porous to vitreous glass to glazed ceramic

- May be water based (non-toxic) or solvent based (toxic)

Front 40

Wall Panel Adhesives

Back 40

- Handy for applying decorative paneling or facing

- May require a few nails per panel

Front 41

White Glue

Back 41

- A general class of glues which as a rule are non-toxic, washable, and which dry clear

- Best used for bonding semi-porous and porous materials

Front 42

Joint Sealants

Back 42

1. Asphalt

2. Silicone

3. Performed

4. Fuel Resistant

Front 43

Asphalt Joint Sealants

Back 43

- Hot poured liquid sealants

- Least expensive of the sealants

- Lifespan from 5-8 years

- Traffic can resume on the pavement once the sealant has cooled

Front 44

Silicone Sealants

Back 44

- Cold applied

- Highly flexible for transverse contraction and expansion joints, longitudinal, center line, and shoulder joints

- Last longer, from 10-15 years

Front 45

Performed Joint Sealants (Compressive Seals)

Back 45

- Most expensive joint sealants

- Lasts up to 20 years

- No curing time necessary

Front 46

Fuel Resistant Sealants

Back 46

- More specialized type of sealant

- Made with silicone or coal tar

- Exhibit no physical or chemical change when exposed to fuels

- Commonly used in apron areas in airports, and even roadway bridge applications

Front 47

Concrete Block: 3 Types

Back 47

1. Solid load bearing: No more than 25% of the cross sectional area is occupied by voids

2. Hollow load bearing: May have 40-50% of the cross sectional area occupied by voids

3. Hollow non-load bearing: Void space may occupy more than 50%

Hollow load bearing is most used for landscape and building construction.

Front 48

Horizontal Joint Reinforcement

Back 48

Used in masonry walls to:

- Control shrinkage cracks

- Bond multi-wythe walls together

- To anchor masonry veneer to backup masonry or wall

- To increase the structural strength of the wall

For exterior applications, masonry ties should be corrosion resistant. Galvanized or stainless steel should be required. 9 gauge standard wire is most common.

- Reinforcing material should be 2" less than the width of the wall

- Horizontal joint reinforcing should not be continued through control joints in the masonry

- Masonry veneers are usually tied to the back-up every 3 feet on center horizontally and every 16-18" vertically.

Front 49

Isolation or expansion joints

Back 49

- Used to permit differential movement between adjacent structural elements (wall and pavement, 2 pavements)

- Not required at regular intervals in paving or walls

- Extend for full depth or width of the concrete

- Usually consists of pre-molded fiber strips (1/4" x 3/8" and 1/2") placed flush or slightly recessed from the concrete surface

Front 50

Control or Contraction Joints

Back 50

- Provides a weakened place for cracking to occur

- Located at intervals in both horizontal and vertical concrete

- Length between joints should not exceed 1-1/2 times the width between the joints (12-15" usually the maximum)

- May be hand tooled while still plastic or sawn after hardening

- Should extend to 1/4 the depth of the concrete

Front 51

Construction Joints

Back 51

- Used where installation work is suspended for more than 30 minutes

- May be tooled to resemble control joint and butter together for light-duty slabs

- Keys or dowels used to prevent differential movement

- Joint sealants sometimes used to prevent freezing water from entering the joint silicone rubber and polyurethane sealants common

Front 52

Concrete Masonry Units (CMU)

Back 52

Grade N- suitable for use in all exposed weather locations above and below grade

Grade S- not suitable for use in exposed weather locations

Structural quality- based on the moisture content of the units

Type I- Most restrictive in terms o moisture content allowed

Type II- Not restricted to a certain moisture content level

For most exterior landscape applications, Grade N-I units should be specified