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RE: Spec needed for 3000 psi concrete[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: Spec needed for 3000 psi concrete
- From: "Dennis Wish" <dennis.wish(--nospam--at)verizon.net>
- Date: Sun, 10 Oct 2004 00:36:38 -0700
Sorry to write back so late, but my e-mail was on the blink. As it turns out, the deputy inspector for the job is the local testing company. They received the spec from the concrete company and called me to inform me that they would not accept the mix. They sent me the basic information I included in the e-mail, but the Architect and General Contractor asked me to write a spec for the concrete other than to specify the strength.
I received a standard spec from Randy Collier after asking for the help. This is a project for the city of Coachella and they require complete specifications on materials, so I took the spec that Randy sent me and forwarded it to the special inspector for the testing company. He made changes and added requirements for cylinder testing at the end of the spec. I felt is was as good as it can get based on the inspectors special knowledge of what he expects for this area. I was not trying to create a spec based on my lack of construction methodology experience. The spec is a standard and it looks to me to very complete, but needed to be modified for this area – which was done.
The responsibility still lies on the GC for placement of the concrete and on the concrete company to supply the mix that will be tested by the testing company that the special inspector works. As you can till I am trying to leave out names, but Joe knows who I mean as this is just too small a town for much competition in this area.
At least the inspector had the foresight to contact me and tell me of his concern. He based his changes to the spec on other jobs that he inspected in this area previously so I know he was at the least, conservative.
Chuck, to answer your question about the strength, this is being used for a grade beam that will take the moment at the base of the frame columns used to seismically retrofit the front of an existing 1929 cast-in-place concrete fire station (reinforced). It is an open front and one of the existing reinforced concrete columns has been removed due to deterioration and replaced by one of the steel columns of the frame. The existing reinforcement did not appear to satisfy lateral restraint and the building has existed since it was built with a soft-story condition. I’ve reinforced this area and the huge red fire station doors are being reconstructed so that at night we can close up the building and make it look as it did in the 30’s as a fire station. During the day, the doors are opened and a new store front presents the Riverside County Credit Union. While not on the state registry, the building has historic value to the city and they wanted to preserve as much of this history as possible. I think we did a good job on the building.
Thanks for all the advice and help. I am still waiting for some feed back on the spec that was completed today as I submitted it to the inspector and to the others on the job in a protected PDF format (protected from editing).
Thanks again to everyone who responded so quickly to help me.
Dennis S. Wish, PE
Structural Engineering Consultant
Do try not to get sucked in to do the contractors job. If you do he will point the finger at you for all his job problems. I the contractor and/or his superintendent is not qualified inform your client and let him deal with it. It is not the engineers responsibility to fix job problems that are not his fault. As far as the mix design, as Nels indicated, let the concrete supplier provide a 3000 psi mix, with cylinder break history. That way if any problems arise the supplier has to fix them not you. In contractor terms pull you pants over your but and get of the job site.
Sometimes it's the sly contractor who sucks everyone else into his problems and he shares the expenses with your dollars.
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