A two-part polyurethane foam for lifting concrete. The two parts are mixed at a 1:1 ratio where the first part is isocyanate (Part A), and second part (Part B) is a polyol. The second part is comprised of recycled polyurethane foam and other polyols.

The joint comprises a pair (12, 14) of complementary engineering grade polymer injection mouldings. Each moulding is comprised of generally equal length oblique webs (15), set at 60 to a mid-plane (16) of the assembled joint, shorter, inner webs (17) and a longer, outer webs (18). Centrally of each outer web (18) is an aperture (21) and centrally of each inner web is a pin (22) with a step (23) and a pointed head (24). The heads of one moulding clip into the apertures of the other whilst the steps determine their separation gap (25). The trapezium wave shape of the joint provides re-entrants (31) from the plane of the outer webs (18) towards that of the inner webs. Outwards of the re-entrants extend anchoring formations (33). Behind each re-entrant these formations are joined by a tab (34).

A system, device, and method for plugging core holes. A core hole plug includes a to compression plate, a bottom compression plate, and a rubber expansion ring that separates the top and bottom compression plates. A beveled screw hole can be created on the top compression plate. The beveled screw hole matches the angle of bottom surface of the head of a flat head bolt to ensure that the bolt remains flush with the top compression plate. The rubber expansion ring can be squeezed between the top and bottom compression plates as the flat head bolt is screwed into a threaded receiver nut formed on the bottom compression plate. An installation tool can be utilized to install the core hole plug so that the top compression plate remains flush with an existing floor surface.

A system for raising and leveling a floor above a crawl space has lift apparatus having an upper support plate engaging a first plurality of threaded posts in a pattern, extending downward, a horizontally oriented stand element having vertical through holes in the pattern, the threaded posts passing through the holes in the stand element, hex nuts threaded onto the first threaded posts above the first stand element, the stand element engaging a first vertically-oriented steel pipe, and base plate rigidly joined orthogonally to a lower end of the first vertically-oriented steel pipe. The upper support plate is positioned under a floor joist, with the base plate flat on a ground surface of the crawl space, and the hex nuts are manipulated to raise and support the floor joist.