Hi, 

Have recently bought a house where the only space for a rotary clothes line is toward the back of the concrete drive way

The existing clothesline is supported by a cast iron garden umbrella stand that is dynabolted to the concrete drive. 

The clothesline is falling to bits and is too small for my family. 

I have a new larger span clothesline to install but the pole diameter is larger than the current one, so will not fit the current stand. 

I'm thinking that a concrete base might be the way to go, rather than drilling more holes in the driveway

I don't know whether a single large form to make a pyramid or cone shaped block of concrete is best, or several stacked doughnuts of concrete is better. 

Also don't know if the concrete should be reinforced with steel rod or anything else (equivalent but cheap)

Looking for advice on building forms, making the concrete strong / less prone to cracking, pitfalls to watch out for etc etc. 

I've not ever worked with concrete so don't really know. 

Any advice welcome 

Cheers!