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Includes the Adobe Acrobat Reader for reading and printing publications.
Numerous illustrations and matrices.
Contains the following key public domain (not copyrighted) U.S. Government publication(s) on one CD-ROM in both Microsoft PowerPoint and Adobe Acrobat PDF file formats:
TITLE
Concrete Construction PowerPoint Compilation, 2005, 299 pages (slides)
SLIDE TOPICS, SUBTOPICS and CONTENTS:
Safety Requirements: None
Risk Assessment Level: Low
Environmental Considerations: None
Evaluation: Vertical Construction Exam (8 questions)
Discuss the basic components and properties of concrete, to include:
Concrete Components Concrete Properties Curing Concrete Temperature Effects Concrete Joints Finishing & Placing Concrete Quality Control Measures WHAT IS CONCRETE? Water Portland Cement Air Coarse Aggregate (Gravel or Crushed stone) Fine Aggregate (Sand)
WATER Weight 8.33 lbs per gallon 62.4 lbs per cubic foot
If water is good enough to drink, it’s good enough for concrete.
Using sea water reduces the concrete strength 10% to 20%. SPECIFIC GRAVITY The ratio of the weight of a given solid to the weight of an equal volume of water.
Concrete Paste Consists of water, air, and Portland Cement
Makes up approximately 20% - 40% of overall concrete mixture Hydration The chemical reaction between cement and water that hardens the concrete paste.
The hydration process produces heat.
CONCRETE ADMIXTURES Added to fresh concrete (fluid ounces per 100 lbs of cement) to make the cement act a certain way:
Accelerators Retarders Air-Entraining Agents Water Reducers (Plasticizers)
DESIRABLE PROPERTIES PLASTIC CONCRETE Plastic Concrete: a concrete mix that is easily or readily molded, yet changes shape slowly if the mold is removed immediately.
Workable Homogeneous Uniform
DESIRABLE PROPERTIES HARDENED CONCRETE Hardened Concrete: the end product of any concrete design; concrete has set and it’s volume established.
Strength Durability Watertightness
WATER-CEMENT (WC) Ratio Determined by the strength, durability, and water tightness requirements of the hardened concrete.
The ratio of the amount of water by weight to the amount of cement by weight in a concrete mix.
This ratio can be expressed in gallons per sack of cement.
WC Ratio can also be expressed in gallons of water per sack of cement.
5.6 gal/sack x 8.33 lbs/gal = 0.496 (0.5) 94 lbs/sack
CONCRETE ADVANTAGES Strong Water Resistant Durable Economical Bondable Continuous Easy to Manufacture Fireproof CONCRETE LIMITATIONS Low Tensile Strength (200-650 psi)
Thermal Movement
Shrinkage
Creep
Permeability
CURING Theoretically, there is enough water in the mix to ensure complete hydration. However, in reality, water is lost from the paste by evaporation, absorption, formwork, and subgrade.
If the internal relative humidity drops below 80%, hydration will stop and strength development will cease. CURING METHODS Supply additional water Sprinkling continually with water Covering with wet materials Flooding with water
Prevent moisture loss Waterproof covering Curing compounds Forms
High Temperature Effects on Concrete Workability and slump decrease Hot temps accelerate evaporation
Cracks Rapid evaporation can cause plastic shrinkage before and after hardening Requires an increase to W/C ratio
Decreases strength Hot Weather Placement of Concrete (Max temp of plastic concrete shall be specified as 90°F) Methods to reduce concrete temp cool coarse aggregate with water add ice to mixing water (extreme cases) working at night
Cold Temperature Effects on Concrete Hydration rate slows down
Prone to freezing until concrete reaches minimum strength of 500 psi Can take as long as 3 days with Type I cement @ WC ratio of 0.4
(Fig. 5-26 of FM 5-428, pg. 5-42)
Cold Weather Placement of Concrete (Min temp of plastic concrete shall be specified as 55°F) Methods to increase temp of plastic concrete Heat the materials (aggregate, water) Use high-early-strength concrete Use accelerators
Methods to ensure concrete doesn’t freeze (prior to 500 psi) Prepare (thaw/heat) the subgrade Protect during curing Use steam Insulate the concrete Use heated enclosures
FIELD TESTING of PLASTIC CONCRETE Slump Test Normally 3” (depends on mix design)
Air-Entrainment Meter 4% to 6%
Cylinders or Beams 3 to 4 cylinders a day or every 50 cy (1-7 day lab, 2-28 day lab, 1 field cured)
SUMMARY Concrete Components Concrete Properties Curing Concrete Temperature Effects Concrete Joints Finishing & Placing Concrete Quality Control Measures
Discuss reinforced concrete design, to include:
Purpose of Reinforcement Identify Size and Grade of Reinforcement Hooks and Laps Determine Required Cover over Reinforcement Develop a Reinforcing Schedule Estimate Required Amount of Concrete STRESSES IN CONCRETE Volume shrinkage during hydration
Temperature changes: expansion and contraction
Loading conditions TYPES OF REINFORCEMENT
TEMPERATURE & SHRINKAGE STEEL (0.18%) Used to keep concrete together after it cracks
STRUCTURAL STEEL ( __% based on steel design) Placed on tension & shear sides of concrete structure TEMPERATURE & SHRINKAGE STEEL SLAB ON GRADE Welded Wire Fabric (or) Wire Mesh Size Designation 6 x 6 - 10 x 10 (or) 6 x 6 - W5 x W5 TEMPERATURE & SHRINKAGE STEEL SLAB ON GRADE STRUCTURAL PROPERTIES REINFORCING BAR GRADE MARKINGS (DEFORMED BARS) REINFORCING BAR GRADE MARKINGS (DEFORMED BARS) Table 6-1: Standard Steel Reinforcing Bars*
BEAMS - Columns Rebar should be placed in areas of tension FOOTINGS Rebar should be placed in areas of tension BEAMS - Cantilever Has no column support! Rebar should be placed in areas of tension BEAMS – Continuous Frame Must identify areas in tension! Rebar should be placed in areas of tension STRUCTURAL STEEL SLAB ON GRADE TYPES OF SHEAR STRESSES BEAMS Diagonal Tension Reinforcing
Table 6-4. Minimum Splice Overlap
Table 6-2. Minimum Concrete Cover Requirements for Steel Reinforcement Determine the reinforcing requirements for the retaining wall shown on handout. Develop a reinforcing schedule showing location, size and spacing, length in place, number required, and appropriate remarks. Note: Design strength at 28 days is 3,000 psi.
RETAINING WALL TOP VIEW Table 6-2. Minimum Concrete Cover Requirements for Steel Reinforcement RETAINING WALL TOP VIEW RUN OF HORIZONTAL REBAR Table 6-4. Minimum Splice Overlap RUN OF HORIZONTAL REBAR RUN OF HORIZONTAL REBAR RUN OF HORIZONTAL REBAR
BAR SCHEDULE RETAINING WALL TOP VIEW Table 6-2. Minimum Concrete Cover Requirements for Steel Reinforcement RETAINING WALL TOP VIEW NUMBER OF VERTICAL BARS BAR SCHEDULE
Materials Estimation (Para 3-20, FM 5-428, pg 3-18)
EXAMPLE PROBLEM (Pg. 18 WB): Estimate the amount of concrete required to construct the retaining wall.
SUMMARY
Purpose of reinforcement Identify size & grade of reinforcement Hooks & Laps Required cover of reinforcement Develop a reinforcing schedule Estimating required amount of concrete
LESSON 3A OBJECTIVES
Mix portion methods
Concrete Mix Proportion Methods 1:2:3 method Using previous or generic mix designs Small concrete pour tables M-5 TM mixes Ready-mix designs Developing a mix design First step for all methods is determining the maximum allowable aggregate size (MSA) To determine the MSA, there is a 4 step process to follow. VERTICAL STRUCTURES STEP 1 Maximum Size Aggregate (MSA)
1/5 x Thickness (t) of wall or column
MSA t
VERTICAL STRUCTURES Example Maximum Size Aggregate MSA t
HORIZONTAL STRUCTURES STEP 2 Maximum Size Aggregate
1/3 Depth of Slab or Footing
HORIZONTAL STRUCTURES Example Maximum Size Aggregate REINFORCED STRUCTURES STEP 3 Minimum Clear Space (MCS)
MSA3/4 MCS or 3/4 distance between rebar REINFORCED STRUCTURES Example Minimum Clear Space (MCS)
MSA3/4 MCS or 3/4 distance between rebar COARSE AGGREGATE STEP 4 MSA for the type of equipment 3” for S16 1 1/2” for M919 1” for M5
1:2:3 Method (PARTS BY VOLUME) 1 part cement 2 parts fine aggregate (sand) 3 parts coarse aggregate (gravel) Small concrete pour tables See pg. 19 of WB for tables. M-5 TM Mixes See pg. 20 of WB for tables. Ready-mix designs
FINE AGGREGATE
LESSON 3B OBJECTIVES
Field testing moisture content of sand Adjusting mix water in concrete for varying moisture contents of aggregates Field testing sand for excessive fines Proper storage of cement
Summary 1:2:3 method Using previous or generic mix designs Small concrete pour tables M5 TM mixes Ready-mix designs Developed a mix design using absolute volume method Adjusting weights of aggregates due to excess moisture Testing for excess fines in sand Storage of cement
LESSON 4 OBJECTIVES
DESIRABLE PROPERTIES OF FORMS WALLFORM DESIGN Concrete Forms Forms for concrete must be: Tight Rigid Strong Concrete Forms Lumber for forms should be: Straight Structurally sound Strong Thoroughly seasoned Surfaced on side in contact with concrete Treated with oil to prevent absorption of water
Adjustment for Changes in Concrete Temperature Summary
DESIRABLE PROPERTIES OF FORMS WALLFORM DESIGN
LESSON 5A OBJECTIVES
SLAB ON GRADE FORMS SLAB ON GRADE REINFORCEMENT DETERMINING REQUIRED SLAB THICKNESS
LESSON 5B OBJECTIVES
CONCRETE MIXING EQUIPMENT
Concrete Mixing Equipment Mixers Military 16S M919 M5 Civilian Ready-mix trucks 16S 16 cf capacity 10 cy/hr production rate
SLAB ON GRADE FORMS SLAB ON GRADE REINFORCEMENT DETERMINING REQUIRED SLAB THICKNESS CONCRETE MIXING EQUIPMENT
LESSON 6 OBJECTIVES
AVAILABLE MODES OF M5 MAJOR COMPONENTS OF M5 STANDARD CONCRETE MIXES FOR M5 INGREDIENTS PROPORTIONING CONTROL DATA WORK SHEET CALCULATING AMOUNTS OF ADMIXTURES FIELD TESTING CALIBRATIONS
MAJOR COMPONENTS OF THE M5 Aggregate bins Water tanks Cement bins Strike-off gates Conveyor Mixer Power Supply
Ingredients Proportioning Control Data Worksheet Basic Required Information Ingredients Data Weight of Sand (cu ft) Weight of Stone (cu ft) Fineness Modulus Sand Vehicle Data Cement Meter Count Cement Discharge Time Mix Design Data Concrete Strength Pounds of Sand (cy) Pounds of Stone (cy) Pounds of Cement (cy) Bags of Cement (cy) Gallons of Water (cy) Moisture Content of Sand (%) Summary
AVAILABLE MODES OF M5 MAJOR COMPONENTS OF M5 STANDARD CONCRETE MIXES FOR M5 INGREDIENTS PROPORTIONING CONTROL DATA WORK SHEET CALCULATING AMOUNTS OF ADMIXTURES FIELD TESTING CALIBRATIONS
*The estimated delivery time is based on the seller's handling time, the shipping service selected, and when the seller receives cleared payment. Sellers are not responsible for shipping service transit times. Transit times may vary, particularly during peak periods.
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