Dear Colleague,
I am working on a forensic engineering project and from the observation of the problem on the site I thought it is ASR problem. Therefore, I performed XRF and I am trying to know the potassium percentage on the XRF results that could give me idea if it is ASR or not?
First, what XRF system are you using? The calibrations may have a bias one way or another (full disclosure, I used to work for Bruker)
Second - why not look for Na? It seems to be a stronger predictor of ASR
Third, what may be more important than bulk Na or K is their ratio relative to one another based on this research: Article The Influence of Potassium–Sodium Ratio in Cement on Concret...
The alkalis are Lithium, Sodium, Potassium, Rubidium, Cesium and Francium. Lithium, Rubidium, Cesium and Francium are not usually found in significant quantities, so normally we look for Sodium and Potassium.
You are looking at about 2 kg/m3 sodium equivalent alkalis to get ASR, but this sodium can come from the concrete materials or the environment. The exact amount needed depends on the reactivity of the aggregate and the alkalinity of the pore water. The cement chemistry is also important, as is the presence of SCM's such as fly ash, silica fume and metakaolin..
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