huangyhg

cmu astm c90 ?
i have a copy of astm c90-06.
astm revised c90-06 to c90-06a and again to c90-06b.
geeeeez, if they revise the thing twice in one year i think i need a freebie...
anyway, i'm looking at the general notes on a set of structural drawings and the eor has a masonry note that requires cmus meeting the requirements of astm c90 type i class n.
well i know that previous to 2006 astm c90 defined two types of concrete masonry units: type-i moisture-controlled units, and type-ii non-moisture-controlled units. c90-06 no longer defines type i and type ii units.
but what is the "class n" reference?
it's wrong, but i think they want "normal weight" cmu.
it should be class 1.
on a side rant, astm has a nice racket going. it costs about $9k (maybe more)for a set of astms, which technically are out of date immediately. and there's no way to freely access them on line.
i work in a large office, so we might get an update every 10 years or so, but i don't know how the smaller guys do it.
boffintech -
the "class n" has no meaning in a reasonably current astm c90 specification. also, the type i or ii to differentiate the moisture control types also has no meaning since the other codes and standards have been changed to reflect the updating of the standards and testing procedures.
if you have a spec that refers to a type i or ii block or even a "class n" you are lookonh at a very old boiler-plate spec written by a out of date specifier. that places a burden on you since the specs are many years behind.
if you look at astm c90 you will not find a reference to types or a manufacturer that even bothers to test for that certification if they can find a lab the follows the "olde" standards.
astm technical committees(composed of producers, specifiers and users) has meetings twice a year and crates new versions (denoted by a, b) when they go through the several year period to get approval.
jed-
the n does not refer to the density. if you look at any reasonably recent (5 or 10 years or possibly more), you will find the cmus are specified by density range. normal weight is over 125 pcf, which is a very low value, but valuable in certain situuations.
unfortunately, you do not work in an office that keeps current on the current material standards. it is very cheap to keep current if you have an interest in any area. the secret is a personal membership. this gets you a membership (professional/specifier ot possibly user if you qualify), a free volume (book or standards) of specs of your choice (usually $100 cost or more) each year and discounts on any downloads or books you choose. you also can participate in the writing of the standards you are interested if you are patient to get on the voting list since the voting membership is carefully balanced. you get this for about $85(?)/year and it is a legitimate business/corporate expense. when it come to committe work and voting, the votes are personal and not corporate because of the balanced voting committee membeship.
i, as a professional engineer, but had to wait about 10 years to be able to vote, because i worked for a producer and there is a limit on voting to maintain a balance. i was the only member from my company, but the balance had to be maintained. if you miss 2 ballots, you lose voting rights.
for your $9k, you could afford to have 10 memberships per year in selected areas, plus you would get the education, learn about new standards and procedures, the oportunity to participate plus the current books of standards that can be changed annually.
if you are professional, keeping current is a small investment and is educational. there is no free lunch.
the only bad thing is that astm has long (3 to 5 days) meetings (commitees and sub-committees) twice a year at rather nice expensive places. the good thing is that you can keep current and vote online, but you miss the contact with other professionals. - in a year or two, i may chose to get involved in a committee on the standards for olympic high speed swimming suits, flooring materials or golf ball testing - these are the people that really pay the bills to keep the association going.
dick

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