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Re: Plain Concrete Questions

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Arvel L. Williams, P.E. wrote:
> > 1. To what maximum slump would u recommend vibrating the concrete ?
> > Mindess & Young write that vibration is needed only for concretes with a
> > slump less than 50mm. Isn't this too low a value ? Do you think it's a
> > typo and should be 5" instead ?
> I think you mean at what maximum slump is it no longer necessary to
> vibrate the concrete.

Indeed that's what I meant.

> > 3. I am to cast a slab in a few weeks in an area where snow occurs for
> > about 4 months in a year with mild temperatures, maybe an average of 8°C
> > (46°F) and a max. low of -5°C (25°F) in the coldest month. This slab
> > will be exposed to one winter season only since next year, the

> > construction of several floors above that one is planned. Do u think I
> > should use air entraining admixtures in the slab ? Also, do u think I
> > should protect the steel dowels in waiting so as not to corrode, or do u
> > think the time span is too short to cause significant corrosion.
> For one exposure cycle air may not be needed, but may be a good idea.
> When you say dowels do you mean the floor dowels or the reinforcing bars
> which extend through the floor and are to connect to the column.

I mean the reinforcing bars which extend through the floor ...

Thanks a lot for your valuable input
Moni Serhal