This disclosure describes devices and methods for forming voids in or adjacent concrete structures. In some embodiments, a device may include a structure. The structure may be substantially planar. The structure may include a plurality of channels extending therefrom. In some embodiments, the channels are closed at a first end distal from the structure. In some embodiments, the channels are open at a second end proximal to the structure. In some embodiments, the device may be formed from a molded pulp. The molded pulp may be configured to inhibit penetration of water. In some embodiments, the device may be configured to substantially support poured concrete during at least a portion of a curing process of the poured concrete.

A void form is composed of molded pulp and includes bottom-facing openings. Fresh concrete placed on top of a substrate material covering the void form structure is formed with a void space underneath that allows soil to expand.

A method and apparatus for forming a formwork for a ribbed or waffle concrete slab is provided. The apparatus includes a rectangular block having a ledge around the base, the ledge having a dimension of half the desired width of the base ribs of the concrete slab, and a keystone connector. The keystone connector has an engagement portion configured to attach to an engagement portion on each block. In a method, the blocks are laid out so that the ledges of adjacent blocks are in contact. A keystone connector is then placed at each intersection of four blocks by attaching the respective engagement portions of the keystone connector and each block so that the keystone connector holds each of the four blocks in place relative to one another. The keystone connector is also configured to retain a reinforcing rod laid in the channel between adjacent blocks.

A method and apparatus for forming a formwork for a ribbed or waffle concrete slab is provided. The apparatus includes a rectangular block having a ledge around the base, the ledge having a dimension of half the desired width of the base ribs of the concrete slab, and a keystone connector. The keystone connector has an engagement portion configured to attach to an engagement portion on each block. In a method, the blocks are laid out so that the ledges of adjacent blocks are in contact. A keystone connector is then placed at each intersection of four blocks by attaching the respective engagement portions of the keystone connector and each block so that the keystone connector holds each of the four blocks in place relative to one another. The keystone connector is also configured to retain a reinforcing rod laid in the channel between adjacent blocks.

This disclosure describes devices and methods for forming voids in or adjacent concrete structures. In some embodiments, a device may include a structure. The structure may be substantially planar. The structure may include a plurality of channels extending therefrom. In some embodiments, the channels are closed at a first end distal from the structure. In some embodiments, the channels are open at a second end proximal to the structure. In some embodiments, the device may be formed from a molded pulp. The molded pulp may be configured to inhibit penetration of water. In some embodiments, the device may be configured to substantially support poured concrete during at least a portion of a curing process of the poured concrete.

A void form is composed of molded pulp and includes bottom-facing openings. Fresh concrete placed on top of a substrate material covering the void form structure is formed with a void space underneath that allows soil to expand.

The present application includes a void form unit for creating a void space between concrete structures and expansive soil. The unit includes a cellular structure surrounded by a paper based shell. The cellular structure is impervious to moisture. Together the cellular structure and the shell make a singular rigid member. The rigid member is configured to temporarily support concrete and gradually increase in flexure so as to flex with the movement of the expansive soil. The shell is configured to weaken over time from the regulated absorption of moisture. The flexure of the cellular structure configured to increase with the deterioration of the shell.

This disclosure describes devices and methods for forming voids in or adjacent concrete structures. In some embodiments, a device may include a structure. The structure may be substantially planar. The structure may include a plurality of channels extending therefrom. In some embodiments, the channels are closed at a first end distal from the structure. In some embodiments, the channels are open at a second end proximal to the structure. In some embodiments, the device may be formed from a molded pulp. The molded pulp may be configured to inhibit penetration of water. In some embodiments, the device may be configured to substantially support poured concrete during at least a portion of a curing process of the poured concrete.

An apparatus, and a method of use of the apparatus, for forming a concrete slab are provided. A formwork may include a support element having a layer of active material bonded on each side to a backing sheet. The active material is chosen to slowly compress over time when placed under a load, and the rate of compression is chosen such that the layer of active material continues to support the slab until such time as the slab becomes self-supporting (i.e., the concrete has cured/set). Another feature is the inclusion of a surface of the backing sheet with a relatively low coefficient of friction. When two support elements are laid one on top of the other with the surfaces in contact, the upper support element may slide over the lower support element, for example during a seismic event.

The present application includes a void form unit for creating a void space between concrete structures and expansive soil. The unit includes a cellular structure surrounded by a paper based shell. The cellular structure is impervious to moisture. Together the cellular structure and the shell make a singular rigid member. The rigid member is configured to temporarily support concrete and gradually increase in flexure so as to flex with the movement of the expansive soil. The shell is configured to weaken over time from the regulated absorption of moisture. The flexure of the cellular structure configured to increase with the deterioration of the shell.