Concrete blocks and cement blocks are preformed, manufactured concrete structures that are ready for on-site installation. They are manufactured, cast, and cured in factories or other production ...
639) causes me once more to draw attention to the great advantage which would be gained by the use of magnetic iron ore as a material for concrete blocks. If magnetite is used instead of ordinary ...
The concave concrete structures were designed to pick up sound waves from enemy aircraft, making it possible to predict their flight trajectory, giving enough time for ground forces to be alerted ...