TECHNICAL FIELD
The present application relates generally to polymer concrete pipe, and more particularly to polymer concrete pipe having a cost-saving configuration.
BACKGROUND
Polymer concretes have been known and used for various purposes for some time. Examples of polymer concrete compositions include those described in U.S. Pat. Nos. 6,048,593; 6,034,155; 4,737,538 and 4,371,639.
One of the primary obstacles to widespread use of polymer concrete compositions is the cost associated with such compositions. For example, standard Portland cement concretes tend to cost about one fifth (⅕) that of a typical polymer concrete mix. To date, use of polymer concrete compositions has been mostly limited to specialized applications where the price of the structure formed of the polymer concrete composition can be justified and obtained in the marketplace. In most applications for concrete pipe, the additional cost cannot be justified in the marketplace. However, in certain concrete pipe applications it would be desirable to use pipe having the advantageous properties of polymer concrete. Those advantageous properties include added strength and exceptional chemical and corrosion resistance.
Accordingly, it would be desirable to provide a polymer concrete pipe configuration that provides the advantages of polymer concrete while at the same time reducing the impact of the high price of polymer concrete.
SUMMARY
Polymer concrete pipe configurations are formed to reduce the required amount of polymer concrete.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-section along a longitudinal axis of one embodiment of a polymer concrete pipe incorporating a series of spaced apart ribs;
FIG. 2 is a partial cross-section along a longitudinal axis of another embodiment of a polymer concrete pipe incorporating a series of spaced apart ribs;
FIGS. 3 and 3A illustrate another embodiment of a polymer pipe using a reinforcing void form;
FIGS. 4A-4C are cross-section views of various reinforcing void form embodiments; and
FIG. 5 is a partial cross-section along a longitudinal axis of another embodiment of a polymer concrete pipe.
DETAILED DESCRIPTION
Referring to FIG. 1, an exemplary polymer concrete pipe 10 has inner diameter D and includes a unitary tubular member 12 having a primary wall portion 14 and a plurality of reinforcing ribs 16 extending radially outwardly from the wall portion's periphery, positioned at selected locations along a length of the tubular member. The reinforcing ribs 16 are sized and positioned to reinforce the primary wall portion 14 and can be formed of the same polymer concrete forming the primary wall portion 14 of the tubular member 12. The ribs may be unitary with the primary wall where the primary wall and the ribs are formed simultaneously with each other. In the example of FIG. 1, the ribs are generally annular in configuration.
In the illustrated embodiment of FIG. 1, reinforcing members 18 located in the primary wall have a solid, circular cross-section and are arranged in an overlapping cross-hatch style forming a layer or region 21 located within the primary wall portion, while reinforcing members 18′ are shaped as individual bands or rings located in the ribs 16. Suitable materials for forming the reinforcing members include metal, such as steel, and/or fiberglass rods or strands. As will be described below, other configurations for reinforcing members are contemplated, such as helical coil forms, void forms, elliptical, triangular, rectangular cross-sections, etc. It is recognized that in some cases, such as in relatively low load carrying applications, it is possible for only the reinforcing ribs 16 to include the reinforcing member or material. It is also recognized that each rib may include more than one reinforcing member.
The reinforcing members are arranged to carry tension and compression forces. The area of concrete that can be replaced by 1 square inch of reinforcement is generally determined by the ratio of the Young's modulus of the two materials. With steel reinforcements for example, this ratio is expressed in E steel/E concrete, which in the case of polymer concrete can be in the range of 15 to 30, as compared to normal Portland cement concrete where the ratio is typically in the range of 7 to 10. Even though steel is roughly three (3) times as expensive as polymer concrete on a per pound basis and roughly nine (9) times more expensive by volume, the savings can be significant.
Referring still to FIG. 1, by utilizing ribs with reinforcing members 18′ formed of reinforcing steel, polymer concrete pipe 10 having a primary wall thickness of ¾ T can be provided with strength characteristics comparable to a smooth walled concrete pipe having a wall thickness of T, but at a reduction in required concrete of about 20 percent or more (in some embodiments, about 30-40 percent). This reduction in the amount of required concrete can decrease the cost of the polymer concrete pipe 10 as compared to a comparable strength smooth walled pipe.
In one example, a pipe has an inner diameter D of about 48 inches, a primary wall thickness T′ is about 2 inches and the reinforcing ribs 16 are (i) spaced apart a length L of approximately 12 inches, (ii) raised from the wall portion 14 a height H of approximately 1.5 inches and (iii) tapered, having a base width W of about 3 inches and a top width w of about 1.5 inches, (resulting in a trapezoidal-shaped cross-section. FIG. 2 shows a partial cross-section (wall and ribs only) for another example of ribbed polymer concrete pipe having a 96 inch inner diameter and a primary wall thickness T′ of about 2.5 inches. The ribs 16 are spaced apart a length L of approximately 12 inches, are raised from the wall portion 14 a height H of approximately 2.5 inches, are tapered, having a base width W of about 4 inches and a top width w of about 1.5 inches. In both illustrated examples of FIGS. 1 and 2, the primary wall portion 14 is cylindrical (both at its inner and outer surfaces), particularly right circular, and the ribs 18 extend circumferentially about the primary wall portion. However, other configurations for the primary wall portion are contemplated, including non-cylindrical pipe shapes and arch shapes (for one or both of the inner and outer surfaces). Accordingly, many variations are possible.
Reinforcing ribs 16 may be spaced and sized as necessary to provide the needed reinforcement in the exterior of the pipe. Besides bending tension, the reinforcement in the reinforcing rib carries the bending and ring compression loads that otherwise would have been at least partially carried by the polymer concrete portion that, in a smooth walled pipe, would fill the “valley” (void space) 35 between the ribs.
Referring now to FIGS. 3 and 5, exemplary polymer pipe configurations using void form reinforcing members 34 (FIGS. 4A-4C) are shown. In the case of each example, a unitary tubular member 30 is formed of polymer concrete and has a wall 32. A void form reinforcing member 34 is located in the wall to displace polymer concrete and to provide compressive and tensile strength. In FIGS. 3 and 3A, the reinforcing member 34 is helically wound to form a coil having a relatively open, constant pitch with polymer concrete disposed between the individual turns. As above, the void form reinforcing member can be of any suitable configuration that provides the requisite reinforcement for the wall. In another example, a polymer concrete pupe such as that shown in FIGS. 3 and 3A could utilize a solid, rod-type reinforcing member in place of a void form reinforcing member.
In FIG. 5, the wall 32 includes a primary wall portion 40 and circumferential ribs 42, but a helical rib could also be used, in which case void form reinforcing member 34 could also be helical. In some cases, and as shown by FIGS. 3 and 3A, a rib may not be included.
The void form reinforcing members can be tubular metal such as steel, or possibly tubular fiberglass. Other variations might be used. Referring also to FIGS. 4A-4C, the void form may have a cross-section that is rectangular, triangular, round, or some other shape.
Any suitable polymer concrete material can be used to form the polymer concrete pipe. Examples of potentially suitable polymer concrete material are described in U.S. Pat. Nos. 6,048,593; 6,034,155; 4,737,538 and 4,371,639, the disclosures of which are hereby incorporated by reference as if fully set forth herein.
It is to be clearly understood that the above description is intended by way of illustration and example only and is not intended to be taken by way of limitation. Other changes and modifications could be made, including both narrowing and broadening variations of the previously described embodiments and examples.
Patent Application
20050108960
