Presentation slides from the American Concrete Pipe Association February 12, 2015 presentation
The ACPA offers practical advice on how to inspect precast concrete before and after the pour. Not only does pre- and post-pour inspection prevent waste, but it ensures quality and long-term functionality and customer satisfaction. The best practices captured in the presentation give guidance on documentation, measuring equipment, proper storage and maintenance, pre-pour inspections, proper application of reinforcement, and different types of release agents and their uses. The post-pour advice describes common problems and how to inspect for different issues.
Documentation is not just recording for posterity. Performing this duty provides a legal record of what steps were taken throughout the pouring process. Should a claim come up downstream, the documentation can show exactly what happened and when. Without documentation, quality control is meaningless. This part of the process allows you to duplicate success, analyze failures, and prove compliance. This is a major benefit to any company and to the industry in general.
Some examples of documentation forms:
- Joint forming equipment
- Pipe, manhole and pre-cast reinforcing
- Pipe, manhole and pre-cast post-pour
- Box culvert equipment set-up
- Box culvert reinforcing
- Box culvert post-pour
2. Pre-pour Inspection
The first step in the pre-pour inspection is to measure the incoming equipment. This is important for accuracy of the pipe or culvert. On the off-chance you were given the wrong size, a quick measurement check could prevent a costly error. Form equipment and joint forming equipment are key to measure prior to pouring.
Proper storage and maintenance will assure the pre-pour inspection goes smoothly. That means storing headers and pallets flat, covering or coating these parts, either priming, sand blasting or re-painting, and cleaning after each use. Performing these maintenance procedures will extend the life of the forms, headers and pallets.
Inspect equipment prior to each use for:
- Excess build-up
- other impurities
- Check the condition of equipment for:
- Also check vibrator mounts, seams, gates, lifting lugs, latching devices, bolts and welds
3. Form Release
The purpose of the form release agent is to prevent hardened concrete from adhering to the form. Not only does it protect the form, but it improves the appearance of the concrete. There are a few options in terms of concrete release forms. There are barrier (non-reactive) releases, chemically reactive releases, or some combination of the prior options. While barrier release agents create a physical barrier between the form and the concrete, there are some disadvantages.
1. You need a thick application of the barrier agent to get an easy release (200-400 ft2/gal)
2. Can cause staining or bugholes
3. May not meet VOC requirements
4. Can cause buildup on forms
Chemically reactive agents are fatty acids (vegetable and mineral oils) that combine with calcium in fresh cement paste to produce a soap-like film between the concrete and the form. Some of the advantages include:
1.Prevents bonding of concrete to form
2. Ultra-thin Layer (approximately 0.005")
3. Reduce bugholes, stains, dusting
4. Typically meets VOC requirements (verify)
Download the full presentation for the full report.
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