CONCRETE/CEMENT VS TARMAC

As initial material to start experimenting with I am faced with weighing up the pros/cons of either concrete and tarmac as to which one is a) going to be more cost effective b) be easily or at least possible to manipulate c) is most identifiable with being cold or bleak an relating to urban landscapes.

Concrete

From what ive learnt, cement needs to be mixed with sand to be completely strong for large scale works. It will be like a sloppy paste at first and then sets- suggesting I would need to make some kind of mould for it to pour into, especially if i want it to do things that require 'defying gravity'. However it is cheaper than the cold lay tarmac and the technicians are experienced in this material yet know nothing about cold lay tarmac. I will still need to source it myself- it is recommended that I dont use sand because of the appearance yet I run the risk of it not being strong enough. Another downfall is that I have seen concrete/cement used before yet not aware of any artists using tarmac.

Tarmac

Before coming to the conclusion about what tarmac to use I had to do a lot of research into how it could be practically used in the 3D work shop as different substances have to be heated and/or may smell. This cold-lay asphalt is pressed and then using cold air and time sets hard, used to fill pot holes. The downside is I won't know until I experiment as to wether I will need a mould for this, how well it will 'defy gravity' or even how long it takes to set. However I am very drawn to the look of this material but again, no body knows how to use it and its quite expensive. Which all adds up if I decide to do a large scale work.

Regardless, the best art comes from not following the rules so Im going to buy some cold lay tarmac...