Week_6___Lecture_6_-_Estimating_Concrete_Work

Measuring Concrete Work

Learning Outcomes

  • After this lecture, learners will be able to:

    • Outline the procedures used to estimate concrete work on a project.

    • Apply standard methods of measurement to concrete work.

    • Quantify various types of concrete structures.

    • Quantify reinforcing steel.

    • Identify and estimate the various elements of timber formwork.

    • Quantify formwork for a building structure.

Scope of Work – Division 3

  • Concrete:

    • Types include cast-in-place, precast, and mass concrete.

    • Strength and density are key considerations.

    • Finishing and curing processes are essential for concrete application.

  • Formwork:

    • Types include timber formwork, engineering formwork systems, reusable plastic formwork, and permanent insulated formwork (ICF).

    • Each type has specific usage scenarios.

  • Reinforcement:

    • Materials include reinforcing bars, welded wire mesh (WWM), steel deck subfloor, and fibrous reinforcement.

  • Concrete Accessories:

    • Accessories include anchors, inserts, expansion and contraction joints, saw cuts, and water stops.

Concrete Fundamentals

  • Definition:

    • A construction material composed of cement, aggregates (coarse gravel or crushed rocks and fine aggregate), water, and/or chemical admixtures.

  • Functional Forms:

    • Commonly used forms include:

      • Cast-in-place

      • Precast concrete

      • Mass concrete

Cast-in-place Concrete

  • Method involves placing mixed concrete into forms to cure in situ for structures like foundations, slabs, walls, etc.

  • Forms are removed once the concrete has gained sufficient strength.

Precast Concrete

  • Made by casting concrete in a reusable form, cured in a controlled environment, then transported and installed at the site.

  • Advantages over cast-in-place methods include:

    • Better control of material quality and workmanship.

    • Reduced costs due to form reuse.

    • Pre-stressing capabilities make incorporation simpler.

Mass Concrete

  • Refers to sizeable structures requiring special measures to manage heat generation and volume changes to minimize cracking, defined as having a minimum dimension of 3 feet.

Concrete Finishing and Curing

  • Important Processes:

    • Curing provides required moisture for proper hardening.

    • Protecting from extreme temperatures and mechanical damage ensures longevity and durability.

  • Various finishing techniques can influence aesthetic aspects, such as coloring and texture.

Concrete Strength

  • Specifications require concrete to be defined by metric class. Common strengths include:

    • 30 MPa: Used in decks, curbs, sidewalks, and sub-structures.

    • 40 MPa: Used for precast prestressed units.

Measuring Concrete Work

  1. Review specifications for requirements individually per area.

    • This includes type, strength, color, and any curing or testing specifics.

  2. Review drawings for validation of items depicted.

  3. List concrete items required for the project.

  4. Determine quantities from working drawings.

Measurement Types

  • Net in Place:

    • No wastage adjustments; waste accounted in pricing.

  • Categories:

    • Classified based on CIQS Measurement methods.

    • Includes cast-in-place, precast, and mass concrete.

Formwork and Reinforcement Measurement

  • Formwork: Measured to the actual surface in contact with concrete; deductions for openings not exceeding 10 m².

  • Reinforcing Bars:

    • Include the number of bars, lengths, bends, and allowances for splicing/lapping.

Estimation Examples

  • Example for Formwork: Using a foundation plan to calculate required formwork quantities based on perimeter centerline and dimensions.

  • Estimating Concrete Volume: Calculate using perimeter centerline and cross-sectional areas of footings and walls.

Questions

  • Open the floor for any inquiries regarding the content discussed.