Pozzolan:
Pozzolans are a broad class of siliceous and aluminous materials which, in themselves, possess little or no cementitious value but which will, in finely divided form and in the presence of water, react chemically with calcium hydroxide (Ca(OH)2) at ordinary temperature to form compounds possessing cementitious properties. The quantification of the capacity of a pozzolan to react with calcium hydroxide and water is given by measuring its pozzolanic activity. Pozzolana are naturally occurring pozzolans of volcanic origin. [Wikipedia]
I just stumbled across pozzolans, unknown to me, while researching this post. Noted in the Wikipedia article, “I-35W Saint Anthony Falls Bridge“:
In the concrete comprising the drilled shafts, piers and footings, a significant proportion of the Portland cement was replaced with slag, fly ash and other pozzolans.[36] These materials reduce the embodied energy of the structure and allow the concrete to resist the ingress of water and dissolved solids such as chloride ions. This allowed the structure to be designed to resist deterioration for much longer than structures made with conventional concrete.
I am not a civil engineer, but I know one. I might have to ask him to clarify this to me. Or maybe not. Embodied energy, while perhaps self-explanatory, eludes my sense of significance.
