This guy just emailed me with this question, anyone think they can help him???Dear Sir.I am doing a project on Self Compacting Concrete.The project is the benefits of pumping SCC from the bottom of the form work, there by using the down word pressure of the weight of the concrete to get rid of most, if not all of the air that gathers on the interface of the concrete between the form work and the concrete. I want to promote better surface finish.My problem is where do I get a non return valve or how do I make one to stop the backward pressure from the concrete as the concrete rises in the form work. This valve must be connected into the base of the form work. I hope you understand what I am saying.I would really appreciate any of you help and expert opinion on this matter.