Least Desirable hydration product in concrete

[physicsss]

I'm debating between ettringite and calcium hydroxide...ettringite is responsible for expansion in volume during a sulfate attack while calcium hydroxide affects the durability of concrete...any ideas?

 

[Astronuc]

I found the hardness for ettringite to be 2-2.5 - Gypsum-Finger Nail
from - http://webmineral.com/data/Ettringite.shtml

I tried find the same information for Ca(OH)₂ but was unsuccessful. I suspect it is softer.

BTW, what are you debating?

This site might be useful - http://www.cement.org/basics/concretebasics_history.asp

 

[ravenprp]

Both ettringite and calcium hydroxide can have negative effects on the durability of concrete, but if I had to choose the least desirable hydration product, I would go with ettringite. While calcium hydroxide can lead to increased porosity and decreased strength in concrete, ettringite can cause even more significant issues such as expansion and cracking during a sulfate attack. This can greatly compromise the structural integrity of the concrete and potentially lead to costly repairs or replacements. In contrast, the impact of calcium hydroxide can be mitigated through proper mix design and curing techniques. However, both hydration products should be carefully monitored and controlled in order to ensure the overall durability of concrete.