Abstract: Pre-cast concrete stairs, molds for making pre-cast concrete stairs, and methods of casting pre-cast concrete stairs are provided. The stair is constructed with two beams that are cast with the stair steps as an integral monolithic structure. One of the beams (integral down edge beam) projects below the steps on one side, and the other (integral up edge beam) projects above the steps on the other side. The weight of the stairs and the weight of traffic on the steps creates compression on the tops of the integral down edge beam and integral up edge beam, and tension on the bottoms of the integral down edge beam and integral up edge beam, which enhances the combined strength of the beams. The asymmetric orientation of the members creates a stronger cross-section than if the beams were in the same plane horizontally, allowing greater load handing capability. Lightweight steps are suspended between the two beams.

Abstract: A lightweight cementitious composition containing from 10 to 90 volume percent of a cement composition, from 10 to 90 volume percent of particles having an average particle diameter of from 0.2 mm to 8 mm, a bulk density of from 0.03 g/cc to 0.64 g/cc, an aspect ratio of from 1 to 3, and from 10 to 50 volume percent of sand and/or other fine aggregate, where at least a portion of the sand and/or fine aggregate has a fineness modulus of less than 2; where the sum of components used does not exceed 100 volume percent, and where after the lightweight cementitious composition is set it has a compressive strength of at least 1700 psi as tested according to ASTM C39 after seven days. The cementitious composition can be used to make concrete masonry units, construction panels, road beds and other articles.

Abstract: A lightweight cementitious composition containing from 10 to 90 volume percent of a cement composition, from 10 to 90 volume percent of particles having an average particle diameter of from 0.2 mm to 8 mm, a bulk density of from 0.03 g/cc to 0.64 g/cc, an aspect ratio of from 1 to 3, and from 10 to 50 volume percent of sand and/or other fine aggregate, where at least a portion of the sand and/or fine aggregate has a fineness modulus of less than 2; where the sum of components used does not exceed 100 volume percent, and where after the lightweight cementitious composition is set it has a compressive strength of at least 1700 psi as tested according to ASTM C39 after seven days. The cementitious composition can be used to make concrete masonry units, construction panels, road beds and other articles.