A method for constructing a seawall section includes coupling an end of a substantially-waterproof barrier member to a footing. A concrete form is mounted to the footing such that a top end of the form is higher than an exposed upper surface of the footing. The concrete form defines at least part of a fill volume. Another end of the barrier member is coupled to the concrete form such that the barrier member extends over a side of the concrete form opposite the fill volume. Concrete is then poured into the fill volume and cured to form the seawall section. Prior to the curing, a body of water at the footing may be higher than the upper surface of the footing. However, the barrier member prevents water from entering the fill volume through the concrete form.

This disclosure provides hollow interconnecting prism blocks that affix together to build structures, a wall, foundation, floor, building, flotation device, gardening structure, artificial coral reefs, or toy. The hollow interconnecting prism blocks comprises a designed wall thickness, depending on the material structure of the block to create the hollow center space, whereas human hands can manipulate mechanical hardware inside two adjacent blocks to affix the blocks together. At least two faces have center face holes and connecting holes, whereas the hardware affixing the blocks together remains inside the hollow areas of the blocks, and inside the connecting holes of the blocks being connected together. Connecter couplings may be used to affix the blocks together. The center holes allow for materials such as pipes, wires, conduit, and rebar to pass through two or more blocks. Two or more connected hollow interconnected prism blocks can also be filled with fortifying material.