Posts Tagged ‘thin concrete’

How to Reduce the Amount of Cement in Your Hardscape

Monday, September 27th, 2010

Following up on my last post concerning the amount of cement in pervious concrete and all concrete.  There is a very easy way to reduce the amount of cement in any concrete flatwork.  Simply pour it thinner, as thin as 1 1/2″  and add control joints about 12″ on center.

We call this type of concrete work ‘thin concrete’ and for us it is a little more involved than simply adding a bunch of control joints.  Besides adding all those control joints can be a little too much work!  We have a whole process we implement, which you can learn more about in the energy conservation section of our website.

First I want to address cement alternatives, and I’ll forewarn you that I am a little cynical these days.  A lot of hoopla has been made about finding a replacement for portland cement or more commonly replacing portions of portland cement in concrete.  While it is true that fly ash and slag in particular can replace various amounts of cement and still leave the concrete with the same strengths or even greater than it would have had with 100% portland cement, I feel the environmental benefits that are touted for doing this are overrated.  One big factor that is overlooked is the amount of transportation that is involved in getting both of these products to us here in the Bay Area.  I believe most of the fly ash that is used locally comes from Wyoming and the slag generally comes all the way from Asia.  In addition as the EPA grapples with how toxic of a substance to define fly ash as, I think there ought to be concerns about the long term ramifications of using these products in our concrete.  For instance, what will become of it when it is crushed up to be re-used as base rock 50 years from now?

The cynical part of me questions why & by whom these cement alternatives are being pushed so hard?  I also wonder why such elegant, immediately implementable solutions such as pouring concrete thinner which could easily save 50% of the cement (and 50% embodied energy and 50% less pollution), aren’t discussed and encouraged?