Architectural Concrete Qualifications
1. Define the joint patterns and reuse of formwork plywood.
2. Include in the proposal some number of dollars for removing and replacing the architectural concrete if the owner or owner’s representative is not satisfied. This does not include formwork breakage, major honeycombing, or issues directly related to concrete contractor underperformance. All unused money will be returned to the owner.
3. Quantify acceptable bug hole size and percentage of surface area; refer to the new ACI 347.3-13 guide.
4. Define color variations within placements and placement-to-placement.
5. The concrete contractor should have the opportunity to review and amend the architectural concrete mixture.
6. The concrete contractor must have the opportunity to patch and repair the architectural concrete and also to patch and repair both damaged and nonconforming areas. This to me is a deal breaker. No patch, no deal.
7. Define who is to evaluate the architectural concrete and the qualifications of that individual and make sure that person will be readily available to guide and approve the performance.
8. Indicate the number and scope of mockups included in the bid and what happens when the concrete contractor is asked to go beyond the bid amount.
Tips for Mockups
The mockup should be a separate standalone element, not part of the building to save money. That seldom works and is very difficult to manage or refer to later in the construction process.
Most architectural concrete specs will have a defined scope for the mockup. Here are some tips for getting a good outcome.
1. Make the mockup representative of the actual work in every detail.
2. If multiple sections of mockup are needed to represent various features of the building then include them—doors and windows, for example. It may be expensive, but it’s a lot cheaper than tear outs and schedule delays.
3. When multiple lifts are involved, pour at least the second lift. Remember that the higher you go, the harder it is to see small defects. Also, your learning curve is at the lower elevations where everyone can walk up to the work.
4. Use the same amount of rebar in the mockup as in the real structure to represent the actual congestion.
5. Placing methods must be the same. If you use a pump during construction then use a pump for the mockup.
6. Do it more than once. A couple of practice sessions are helpful.
7. Determine the curing methods, cleaning methods, and weather protection, if required. And decide who is responsible for maintaining the protection throughout the duration of the job.
8. Decide on the distance from which the architectural concrete is going to be evaluated. We all like to walk up to the work and touch it but a more normal distance recommended by ACI Committee 303 is 20 feet.
9. Areas of the mockup should represent repair and patching of the architectural concrete.
10. Most specifications allow the architect to ask for more mockups until the owner’s team is satisfied. That can be expensive--I have seldom heard a contractor say they were within their mockup budget.
11. Put the mockup someplace where it can remain until the job is complete and accepted.
12. Get acceptance, objections, or rejection in writing. Make it clear that you won’t move forward until someone evaluates the work. If the precon was performed well and the relationship is team-oriented, this will be a self-evaluation and all parties will be on the same page.