A concrete anchor capable of resisting large loads while requiring minimal embedment depth. The system includes a concrete structure including a cylindrical opening in the concrete surface thereof. The system also uses an anchor which includes a sleeve and a plug. The sleeve includes at least two legs extending toward a first end of the sleeve. The plug includes an increasing diameter portion disposed toward a first end of the plug. The plug includes a locking opening. After installation, legs of the sleeve extend radially outward past the wall and the increasing diameter portion prevents inward movement of the legs to lock the sleeve and the plug in turn in the concrete cylindrical opening. Furthermore, dynamic loading on the plug via the locking opening when the anchor is in use generates a dynamic radially outward force on the legs to secure the anchor in the concrete hole.

Construction materials intended for use as structural elements, such as structural blocks, used in the construction of buildings and civil engineering structures. The blocks can comprise hemp hurd and fibers, flax fiber, hydraulic lime and hydrated lime. In one aspect, the blocks may comprise a body shape configured so as to allow it to interlock with other blocks in the construction of a structure. In another aspect, the blocks may be adapted to incorporate tensioning means. Methods for manufacturing the blocks and structures comprising such materials and methods for building such structures are also disclosed.