I passed your question onto Larry Novak at the Portland Cement Association. Here was his response:
The industry is currently working on a consensus documents on this very topic (one by ATC, one by ASCE/SEI).
A. For tall buildings one should decompose the deflection into the story racking...
The NRMCA prepared an article on the topic named Cement Balls or Lumps in Freshly Mixed Concrete “Causes and Cures” I have attached it here. This will only solve part of the problem. I recommend you use a UHPC mix that has about 2% fibers. There are some commercial sources, ITW Engineered...
This looks to be only an aesthetic issue. I agree that moisture was the original cause for both the efflorescence and the dark shadowing at the mortar joints. If you can't live with the look try a bond coat then a skim coat of cement paste or finely sanded grout. This will leave a slightly...
An Engineer should sign off on whatever you do. Best practices require the steel should be protected from further corrosion prior to your covering it. The ICRI (International Concrete Repair Institute) should have some good guidance on this.
Larry from Lehigh White Cement Company
Hi Alex,
The key to true GFRC is to sure to use alkali resistant glass fiber and a polymer formulated for the application. Both Ball (Smooth-on)and Nippon Electric Glass produce products under the name Forton and Polyplex respectively. Goon info on the products and process are on their...
If the concrete had achieved enough strength to weather the storm the surface would not have loose sand particles. It is possible that there was enough water on the surface to change the water to cement ratio at the very top of the slab making it weak at the surface. If this were the case...
I am new to eng-tips and want to see if there is value in the site for concrete related questions. I am happy to help with questions related to cement and concrete materials. If I don't know the answer to a concrete related question I hope to be able to forward people to appropriate places to...
