Not sure how many iPhone users there are in the forum, but i Just created an app that helps with calculating the volume and cost of Concrete either by truck or 20KG pre-mixed bags.

The app is called DIY Concrete and the link to the website is:
http://www.daydreemin.com/diyConcrete

I would appreciate any thoughts and suggestions for improvements.

I am working on adding an Imperial section at the moment.

Thanks, Steve