Abstract: An apparatus for testing the relative permeability of materials, particularly concrete structures, comprises a transparent, optically non-distorting head having a gasket, which together with the head defines a head chamber, and which allows the head to be sealed against the structure when a partial vacuum is induced in the head chamber. The decay of the vacuum may be measured, and the rate of decay provides an index of permeability. A liquid may be applied to the surface being tested and will foan to allow identification of cracks and fissures. In alternative embodiment, a fluid is introduced into a secondary chamber defined by a secondary gasket and the head, and the rate of permeation of the fluid into the structure provides a measure of permeability.

Abstract: Reinforced cement structures are provided which are reinforced in three dimensions and comprise at least one nonwoven spatial fabric reinforcing material encapsulated in a cementitious composition which preferably has controlled water bleed characteristics. The cementitious composition comprises, for example, hydraulic cement, a gelling agent, water and optionally a dispersing agent. The nonwoven fabric reinforcing material can extend substantially throughout the whole of the cement structure. Alternatively, a plurality of reinforcing layers can be utilized in a sandwich or composite type structure in which the various reinforcing layers are separated by a layer of cementitious composition. The nonwoven fabric reinforcing material can also have, on at least one of its surfaces, a woven or non-woven scrim reinforcing material to impart additional strength properties to the structure.The structures can take the form of panels which can be cold formed into curved structures.

Abstract: A reinforcing tendon assembly for use in a concrete structure is disclosed which includes a pair of tendon anchorages, an elongated reinforcing tendon extending between and anchored by the anchorages and an electrically insulating conduit mounted on the tendon and extending between the anchorages. The improvement in the assembly is comprised of electrically insulating anchorage envelopes mounted at each of the anchorages in sealed relation to the conduit. The envelopes extend around the anchorages and isolate the tendon assembly from the concrete structure. Several isolating envelope constructions are disclosed, which include collars that encircle the tendon and are sealed to the tendon conduit and anchorage surrounding portions which extend from the bearing surface side around the outwardly facing side of the anchorage. A method for forming an electrically insolated tendon assembly is also disclosed.

Abstract: Reinforced panel structures include a panel core formed from a cementitious composition that has controlled bleed characteristics. For example, the cementitious composition may comprise hydraulic cement, a dispersing agent, a gelling agent, and water. At least one woven, fabric reinforcing layer in the form of a sheet is laminated in the panel core closely adjacent at least one of its faces. The controlled bleed characteristic of the core composition insures that the reinforcing layer is bonded tightly thereto. The fabric from which the layer is made has a tensile strain that is compatible with the compression strain of the panel core to permit the panel to be cold formed.