Precast concrete sandwich panels and system for constructing panels

The present invention is a precast concrete sandwich panel utilizing a low density polyethylene channel with basalt fiber rod attached to the side of the channel during construction, and utilizing spray foam insulation as the inner layer between the two concrete outer panels (wythes).

FIELD OF THE INVENTION

The present invention relates to constructing precast concrete sandwich panels utilizing a low density polyethylene channel with basalt fiber rod attached to the side of the channel and utilizing a polyurethane spray foam insulation as the inner layer between the two concrete outer panels (wythes).

BACKGROUND OF THE INVENTION

Concrete sandwich panels are used in concrete and precast wall construction. A sandwich panel consists of three layers, commonly called wythes. The two outer layers are concrete with reinforced and the inner layer is comprised of insulating material. The purpose is for the insulating layer to have a high R-factor (measure of thermal resistance) and provide an energy efficient complete wall system in one panel. The standard insulating panel is composed of polystyrene and the like. Ties are used in connection with the insulating panel to mechanically join the insulating layer and the two concrete reinforced panels.

The current invention is directed to a new method for constructing a concrete sandwich panel. Among the improvements is the liquid application of polyurethane foam as the insulating layer during construction. Additionally, a polyethylene channel with basalt fiber rods in wave or square pattern affixed to opposed sides of the channel is employed as a tie during the construction process to join the two concrete panels.

SUMMARY OF THE INVENTION

The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a new and improved system for constructing a precast concrete sandwich panel.

The precast concrete sandwich panel is comprised of opposed wythes having a foam insulation layer disposed between the wythes. During construction a series of low density polyethylene channels with basalt fiber rod attached to the side of the channels are utilized as ties to join the wythes and provide structural integrity to the finished panel.

A plurality of brace inserts and lift inserts are mounted on the channels during construction.

DETAILED DESCRIPTION OF THE INVENTION

Referring generally to theFIGS. 1, 4-8, the invention10is illustrated. A precast concrete panel10has a concrete lower wythe12, a concrete upper wythe14and an inner layer16comprised of insulating material disposed between the wythes12,14. The wythes12,14have reinforced materials, embeds and other necessary non-insulating elements disposed therein.

FIG. 2illustrates a channel20used in the construction of the insulation system for concrete tilt-up panels. The channel20has a base wall22and a pair of opposed side walls24. The side walls24are aligned perpendicular to each other. The channel20is preferably formed of low density polyethylene (LDPE). A pair of basalt fiber rods26are permanently affixed to the outer surface of the opposed walls. The channel20is designed to facilitate the alignment of the rods26during construction. The rods26inFIG. 2are in a sine wave pattern defined by peaks spaced at a regular interval and with peak-to-peak amplitude greater than the insulating layer. The rods26mechanically join with the lower wythe and the upper wythe. The rods26are composed of basalt fiber, which has superior structural capacity in comparison to fiberglass and is less expensive than carbon fibers. The use of fiberglass and carbon fibers are already known in wave-shaped ties used in concrete sandwich panel construction.

An alternative embodiment of the channel30and rods36is illustrated inFIG. 3. The channel30has a base wall32and a pair of opposed side walls34. The rods36are in a square shaped pattern, and have peaks at regular intervals engaging with the wythes12,14. The square pattern is possible without affecting the integrity of the channel20.

The channel20aligns and orients the rods26to provide shear force resistance for the sandwich panel. As illustrated inFIG. 1, the rounded corners of the sine wave pattern assist in distributing connection forces.

The system of construction of the panel10is illustrated inFIGS. 4-8. On a suitable flat surface mold which defines the geometric shape and perimeter of a constructed panel is laid out, and the casting surface prepared. Reinforcement material is mounted for the lower wythe of the mold.

Concrete is deposited in the mold to a thickness of the lower wythe12. The consistency of the concrete performs optimally with a higher slump from self-consolidating to 6″ (low viscosity). While the concrete is still plastic, connective means to secure the lower and upper concrete wythes are employed. The channel20is positioned and mounted for appropriate alignment. The channel20properly orients the rods and is of sufficient weight to sink the rods into the lower wythe12, yet light enough and of sufficient width to float on the concrete. The use of two opposed rods26helps lower the point loads of the connection between the upper and lower wythes.

The insulating layer16is then applied. As noted above, the standard insulating panel is normally composed of solid materials, such as polystyrene and the like. The present invention provides an expanding polyurethane foam as the insulating layer and is applied as a liquid on the surface of the lower wythe12. The upper portions of the rods26are left exposed. The amount of foam insulation is determined by the insulation requirements based upon the required R value and the total structural thickness of a completed panel. The lower wythe12can be cured or uncured. If uncured, then an additional thin sacrificial layer of foam is applied prior to the application of the polyurethane foam. The foam provides a vapor barrier without joints. Board foam is has joints.

Brace inserts40and lift inserts60are mounted on the base walls22,32of the channels20,30. While the concrete is still plastic, additional connective means to secure the lower wythe12and upper concrete wythe14are employed.

As illustrated inFIGS. 9 and 10, the brace insert40comprises a frame42having a pedestal44with arms46oriented perpendicular to each other. Appendages48depend downwardly from a lower surface of the antis46. A plastic bolt52is positioned medially on the pedestal44. A plastic cap50with extensions54is placed on the bolt52. The extensions54make the location, of the insert40easier to find when it is cast in concrete. The pedestal44of the brace insert40is of pre-determined size to allow the insert40to be mounted on the channel20, and allows the insert40to remain stable during installation process. The brace insert40provides for ease of bolt connection to temporary bracing during construction.

As illustrated inFIGS. 11 and 12, the lift insert60comprises an upper section62and a pair of columns64with base feet66. The insert60mounts snugly into platforms68. As shown, the insert60and platforms68are mountable on the channel20, and allow for an attachment for moving and handling of the panel10.

Construction continues with reinforcement material is mounted for the upper wythe14of concrete. Concrete is deposited in the upper wythe14. Once the concrete is set the completed panel is disengaged from the mold and transported to its final vertical position in the structure.

It should be noted that there are no limitations on the composition of the channel and the rods because of the number of variables involved. It should be noted that the dimensions of the channels may change as needed in the industry. As can be readily seen, the channel with affixed rods provides improved connection means between the upper and lower wythes.

Multiple channels20,30are available for on-site construction and stacking feature of the channels20,30provides for proficient shipping and increased installation rate.

The channel20,30can also operate as a caddy to place lifting devices and other connection hardware. At times it may be necessary it is necessary to obtain increased depth of the top layer of concrete without applying foam to increase the capacity of the inserted lifter or connection. The base wall of the channels provide a thermal break and minimal insulation, while forming a pocket in the foam achieving minimal thermal resistance.

Additionally, the channels20,30provide a visual cue to ascertain the amount of foam being applied during installation. There is no limitation on the type of foam as the insulating layer used in the precast concrete sandwich panels as there may be changes as needed in the industry.