Contractor's Guide: Concrete Placement and Finishing-Contractor's Guide-Concrete Placement and Finishing (PDF)

Contractor's Guide-Concrete Placement and Finishing (PDF)

Pdf Summary

Chapter 11 of "The Contractor's Guide to Quality Concrete Construction" discusses concrete placement and finishing, emphasizing the importance of selecting the most efficient method for depositing concrete. Direct depositing from a truck is convenient when accessibility isn't an issue. If the truck's chute cannot reach, alternative methods like chute extensions, buggies, conveyors, buckets, and pumps should be considered based on job requirements and concrete mix specifications.<br /><br />The specifications of the concrete mixture, including slump and aggregate type, impact the choice of placement method. Adjustments to the mixture, such as adding a superplasticizer, may be necessary to optimize placement.<br /><br />For effective placement, concrete should be deposited adjacent to previous placements to avoid honeycombing. When depositing directly from the truck, only a single water addition is typically allowed to maintain proper slump without altering the water-cement ratio. Tools like chute extensions can increase reach but require consideration of angle and concrete flow.<br /><br />For slab-on-ground construction, ensure that trucks do not compromise the prepared subgrade. If necessary, other placement methods can accommodate access restrictions.<br /><br />Each placement method, whether it is conveyors, buggies, buckets with cranes, or pumping, has specific applications. For instance, conveyors are suited for mass placements, while pumping is valuable for challenging site conditions.<br /><br />Concrete placement in varying weather conditions, such as hot or cold weather, requires special considerations to maintain quality, prevent cracking, and ensure adequate curing. Methods include cooling aggregates, carefully managing moisture, and ensuring concrete does not freeze before reaching sufficient strength.<br /><br />The chapter also covers finishing techniques, highlighting the importance of proper screeding, floating, and troweling to achieve durable surfaces. Floor surface flatness is measured using F-Numbers (FF and FL), necessitating a shared understanding between contractors and specifiers to meet specification requirements. Proper curing, essential for concrete quality, involves maintaining moisture using methods like fog spraying, ponding, or applying curing compounds.

Keywords

concrete placement

finishing techniques

efficient depositing

concrete mixture specifications

slump adjustment

placement methods

weather considerations

screeding and troweling

floor surface flatness

curing methods