Maricopa Community Colleges  CON202   19964-20046 
Official Course Description: MCCCD Approval: 04/23/96
CON202 19964-20046 LEC 1 Credit(s) 1 Period(s)
Design and Control of Concrete Mixtures
Characteristics of and methods of proportioning concrete mixtures. Specific methods of batching, mixing, transporting, handling and curing concrete. The effects of high and low temperatures on concrete and methods to alleviate these effects. Prerequisites: (Indentured status with the Arizona Concrete Contractors Association and CON101) or permission of the apprenticeship coordinator.
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MCCCD Official Course Competencies:
 
CON202   19964-20046 Design and Control of Concrete Mixtures
1. Describe mixture characteristics and their impact on the properties of the finished concrete. (I)
2. Explain specific methods of proportioning concrete mixtures. (II)
3. Describe specific methods of batching and mixing concrete. (III)
4. Explain problems inherent in transporting and handling concrete. (IV)
5. Explain the objectives and specific methods for curing concrete. (V)
6. Describe the effects of high temperatures on concrete materials and methods to alleviate these effects. (VI)
7. Describe the effects of low temperatures on concrete materials and methods to alleviate these effects. (VII)
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MCCCD Official Course Outline:
 
CON202   19964-20046 Design and Control of Concrete Mixtures
    I. Mixture characteristics
        A. Water-cement ratio
          1. formula
          2. compressive strength
        B. Aggregates
          1. grading
          2. nature of particles
        C. Entrained air
          1. air entraining portland cement
          2. air entraining admixture
          3. levels of exposure
        D. Slump
          1. workability
          2. consistency
          3. plasticity
        E. Water content
        F. Cement content and type
          1. minimum content
          2. type requirements
        G. Admixtures
      II. Proportioning concrete mixtures
          A. Proportioning from field data
          B. Proportioning by trial mixtures
            1. unit weight and yield
            2. absolute volume
          C. Absolute volume method
          D. Water-cement ratio method
        III. Batching and mixing concrete
            A. Batching
              1. measurement
              2. tolerances
            B. Mixing
              1. stationary
              2. ready mixed
              3. mobile batcher mixed (continuous mixer)
              4. high energy mixers
              5. remixing
          IV. Transporting and handling concrete
              A. Delays
              B. Early stiffening and drying
              C. Segregation
              D. Equipment
                1. truck mixers
                2. mobile batcher mixers
                3. belt conveyers
                4. buckets
                5. chutes
                6. cranes
                7. pumps
                8. other
              E. Below ground level
              F. Above ground level
            V. Curing concrete
                A. Objectives
                  1. prevent loss of moisture
                  2. maintain favorable temperature
                B. Methods and materials
                  1. ponding or immersion
                  2. spraying or fogging
                  3. wet coverings
                  4. impervious paper
                  5. plastic sheets
                  6. membrane-forming curing compounds
                  7. forms left in place
                  8. steam
                  9. insulating blankets/covers
                  10. electrical, oil and infrared
                C. Curing period and temperature
              VI. Hot weather concreting
                  A. Effects of high concrete temperatures
                    1. slump loss
                    2. strength reduction
                    3. reduced setting time
                    4. cracking
                    5. reduced air entrainment
                  B. Cooling concrete materials
                    1. water
                    2. aggregates
                  C. Site preparation
                  D. Transporting, placing and finishing
                  E. Plastic shrinkage cracking
                    1. moisten subgrade and forms
                    2. moisten aggregates
                    3. erect windbreaks and sunshades
                    4. keep freshly mixed concrete temperature low
                  F. Curing and protection
                  G. Retarding admixtures
                  H. Heat of hydration
                VII. Cold weather concreting
                    A. Effects of freezing fresh concrete
                    B. Strength gain at low temperatures
                    C. Heat of hydration
                    D. Special concrete mixtures
                      1. type III cement
                      2. additional cement
                      3. chemical accelerators
                    E. Air entrained concrete
                    F. Temperature of concrete
                      1. aggregate temperature
                      2. mixing-water temperature
                      3. placed and maintained concrete temperature
                    G. Control tests
                    H. Concreting on ground
                      1. thawed ground
                      2. heat from hydration
                      3. enclosure and blankets
                      4. vented heaters
                    I. Concreting aboveground
                      1. high strength mixture
                      2. enclosures
                      3. insulating materials
                      4. heaters
                    J. Duration of heating
                      1. maturity concept
                      2. moist curing
                      3. heating termination
                    K. Form removal and reshoring
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