Presentation by Daksh Baweja on Concrete requirements for Industrial Pavement Design from Sydney Forum 17 November 2008
The ASCP forum on Industrial Pavements provided valuable information on design, detailing, materials and construction issues related to industrial pavements. It also highlighted several differing opinions and challenges to existing practices. This presentation by Daksh Baweja covers:
- Presentation addresses internal industrial/factory floors.
- Discusses Guides Specifications Standards for concrete and cement, controlling joint movement and cracking, the related issue of shrinkage, what does R&D on industrial pavements suggest.
- Serviceability is discussed; unplanned cracking, joints not always working, thought to be related to shrinkage, theory does not match field observations.
- Tight 56-day shrinkage strains often used to aid control of unplanned cracking, but does not work in
- R&D on a large internal floor is presented; magnitude, timing and drivers of joint opening.
- Floor description; Twenty two 50x50m, bonded post tensioned panels, joint movement measured over one year.
- Joint movement results presented; movement was greater than predicted, influence of concrete temperature on movement
- Observations are presented; joint movement starts 8-10 hours after casting, movement constant after 160 days then controlled by thermal conditions, actual movement does not match predicted.
- Results show; benefits of evaporation retarders, predicting shrinkage strains under real conditions is difficult, linking drying shrinkage theory to actual field movement requires “leap of faith”.
- Areas for future consideration; more data on early age behaviour required, new design model to reflect field conditions, identify key parameters and better test methods, the drying shrinkage test “has had its day”