A lining mixture for concrete pipes comprises mineral particles such as sand or asbestos fragments, a cement which sets upon or soon after hydration, and a stable aqueous emulsion of bituminous or other plastic materials, such as resinous or wax-like material, ligrin-containing material or synthetic resins, which have greater resistance than cement concrete to the action of acids, alkalis and salts likely to occur in sewage &c. Two examples are given comprising in stated proportions:- (1) granite sand, Portland cement, bitumen emulsion and water, (2) pit sand, Portland cement, rubber latex and water.