huangyhg

microsilica vs. dci corrosion inhibitor
disclaimer: i tried to post this in the concrete general forum, but i received no response. i haven't checked the alexa ratings, but i'm assuming more people peruse the "other topics" forum. so here goes...
i'm working on an unbonded pt parking garage in chicaco. our concrete spec calls for a microsilica admixture for corrosion protection. the contractor submitted an rfi asking if a grace dci corrosion inhibiting admixture would be an acceptable subsitute, on the basis that the microsilica mix requires a longer curing time. i have read some information on both systems, and it appears this might be acceptable. in your professional opinions, might this be acceptable? are there any adverse repercussions that i am not considering? as a follow up question, from my understanding, the horizontal elements are more critical for corrosion protection of the reinforcement. is it possible that the vertical elements (columns and shear walls) be poured with a separate mix devoid of this admixture? or is that not general practice? i'm relatively new to the industry, and i would appreciate the thoughts of those more experienced. many thanks.
...and now, back to basketball.
re microsilica & grace dci corrosion inhibiting admixtures.
you can use both. the microsilica helps by making the concrete less permeable (physical protection), while the grace product has nitrate which chemically protects the steel.
i knew a concrete worker who worked on both the construction of a chicago parking garage and its demolition about 7 years later (due to corroded rebar). ca. late 70s-early 80s.
kenvlach,
thanks for the response. i knew the microsilica protects the rebar by 'densifying' the concrete. it seems this would have other beneficial effects as well, and i just wasn't sure if the dci could be considered an "or equal."

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