FIELD OF THE INVENTION
The present invention relates to a concrete retaining structure and, more particularly, to a concrete walkway of a concrete retaining structure.
BACKGROUND
Prestressed steel strands are often used to impart compressive stresses to concrete members in concrete construction, improving the performance of the concrete components under tension. Concrete retaining structures, such as retention tanks for water or wastewater applications, have concrete walkways that are formed of prestressed concrete members. The walkways allow a user to traverse the concrete retaining structure for inspection or other purposes.
The prestressed concrete members that form the concrete walkways have a plurality of wire strands disposed within the concrete member. The wire strands are surrounded by a sheathing and a grease coating that separate the wire strands from the concrete member. The wire strands are secured at anchors disposed within the concrete member after tensioning of the strands, but the anchors at opposite ends of the strands are the only bonding securing the stressed strands to the concrete member. The tensioned strands improve the tensile performance of the concrete members, but the limited bonding between the strands and the concrete members leads to decreased longevity and structural stability of the concrete walkway.
SUMMARY
A bonded concrete walkway segment includes a walkway body formed of a concrete material, a duct extending through the walkway body from a first end of the walkway body to an opposite second end of the walkway body, a tendon including a strand extending through the duct, and a tendon grout filled within the duct around the strand. The tendon grout is cured to fix the strand in the duct.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of example with reference to the accompanying figures, of which:
FIG. 1 is a top view of a bonded concrete walkway assembly according to an embodiment;
FIG. 2A is a sectional side view of a bonded concrete walkway segment according to an embodiment;
FIG. 2B is a detail sectional side view of a duct of the bonded concrete walkway segment;
FIG. 2C is a detail sectional end view of the duct of the bonded concrete walkway segment;
FIG. 3A is a perspective view of a duct of the bonded concrete walkway segment according to another embodiment;
FIG. 3B is a sectional side view of the duct of FIG. 3A;
FIG. 4 is a flowchart of a process of creating one of the bonded concrete walkway segments;
FIG. 5 is a sectional side view of the bonded concrete walkway segment after removal of a grout valve assembly;
FIG. 6 is a sectional side view of an extension joint between two bonded concrete walkway segments;
FIG. 7 is a sectional side view of a first intersection between two bonded concrete walkway segments;
FIG. 8 is a sectional side view of a second intersection between two bonded concrete walkway segments; and
FIG. 9 is a flowchart of a process of creating joints of the bonded concrete walkway assembly.
DETAILED DESCRIPTION OF THE EMBODIMENT(S)
Exemplary embodiments of the present disclosure will be described hereinafter in detail with reference to the attached drawings, wherein like reference numerals refer to like elements. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will convey the concept of the disclosure to those skilled in the art. In addition, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it is apparent that one or more embodiments may also be implemented without these specific details.
Throughout the specification, directional descriptors are used such as “longitudinal”, “width”, and “vertical”. These descriptors are merely for clarity of the description and for differentiation of the various directions. These directional descriptors do not imply or require any particular orientation of the disclosed elements.
Throughout the drawings, only one of a plurality of identical elements may be labeled in a figure for clarity of the drawings, but the detailed description of the element herein applies equally to each of the identically appearing elements in the figure.
A bonded concrete walkway assembly 10 according to an embodiment, as shown in FIG. 1, includes a plurality of bonded concrete walkway segments 100 attached together by a plurality of joints 200. The bonded concrete walkway assembly 10 may form a top portion of a concrete retaining structure used, for example, in the water and wastewater industries; a user may use the bonded concrete walkway assembly 10 to traverse the concrete retaining structure for inspection or other purposes.
In the following, one of the bonded concrete walkway segments 100 will first be described in detail, following by a description of the assembly of the bonded concrete walkway assembly 10 including the various joints 200.
One of the bonded concrete walkway segments 100 is shown in detail in FIG. 2A. The bonded concrete walkway segment 100 includes a walkway body 110, a duct 130 disposed in the walkway body 110, a tendon 140 disposed in the duct 130, and a tendon grout 150 disposed within the duct 130 around the tendon 140.
The walkway body 110 is formed of a concrete material and extends from a first end 112 to a second end 114 opposite the first end 112 in a longitudinal direction L or a width direction W perpendicular to the longitudinal direction L, as shown in FIG. 1. The walkway body 110, as shown in FIG. 2A, has an outer surface 120 and an inner surface 122 opposite the outer surface 120 in a vertical direction V perpendicular to the longitudinal direction L and the width direction W. In the shown embodiment, the walkway body 110 has an approximately rectangular shape. In other embodiments, the walkway body 110 may have other shapes adapted to the shape of the bonded concrete walkway assembly 10 desired for the application.
The duct 130, as shown in FIG. 2A, is positioned within the walkway body 110 and extends through the walkway body 110 from the first end 112 to the second end 114. The duct 130 has a duct body 132 defining a duct passageway 133. The duct 130 may be formed of a plastic material, such as a polyethylene or polypropylene.
In the embodiment shown in FIGS. 2A-2C, the duct body 132 is a straight cylindrical member. In another embodiment shown in FIGS. 3A and 3B, the duct 130 has a corrugated shape 134. With the corrugated shape 134, the duct 130 has a plurality of corrugations 136 spaced apart at an interval along a length of the duct 130. The corrugations 136 each protrude from the duct body 132 and, at a position of each corrugation 136, widen a diameter of the duct passageway 133 with respect to a diameter of the duct passageway 133 at the duct body 132.
With either embodiment of the duct 130 disposed in the walkway body 110, the tendon 140 is positioned in the duct passageway 133. As shown in FIGS. 2A-2C, the tendon 140 includes a pair of anchors 140 and a plurality of strands 144 extending between the pair of anchors 140. Only one anchor 140 is shown in FIG. 2A for simplicity of the drawings, but one anchor 140 is similarly disposed at each end of the strands 144, which may extend through the ducts 130 of multiple bonded concrete walkway segments 100, as described in detail below.
As shown in FIG. 2A, the anchor 142 is fixed within the walkway body 110 adjacent to the first end 112 and at an end of the duct 130. The walkway body 110 may have an access opening 116 extending into the first end 112 and providing access to the anchor 142.
The strands 144, shown in FIGS. 2B and 2C, extend from the anchor 142 and are positioned in the duct passageway 133 extending through the duct 130. The strands 144 are each formed of a metal material, such as steel, that can be placed into a tensioned state T and secured in the tensioned state T to provide a compressive force on concrete material. In the shown embodiment, the tendon 140 has seven strands 144. In other embodiments, the tendon 140 may have any other number of strands 144, including one strand 144, two to six strands 144, or eight or more strands 144.
As shown in FIGS. 2B and 2C, the tendon grout 150 is disposed within the duct passageway 133, filling the duct passageway 133 around the strands 144 of the tendon 140. The tendon grout 150 is cured in this position within the duct 130 to fixed the strands 144 in the duct 130 in the tensioned state T. The tendon grout 150 may be any cementitious grout that is a mixture of cement, water, and a grouting aid admixture capable of performing the functions described herein.
A process 300 of creating one of the bonded walkway segments 100 will now be described in greater detail primarily with reference to FIG. 4.
A grout valve assembly 160, shown in FIG. 2A, is used in the process 300 of creating the bonded walkway segment 100. The grout valve assembly 160 has a duct vent 162 at a first end, a grout pipe 164 extending from the duct vent 162, and a valve 166 connected to the grout pipe 164 at a second end opposite the first end.
In a step 310, the walkway body 110 is cast of the concrete material around the duct 130, the anchors 142, and the grout valve assembly 160. The concrete material of the walkway body 110 may be precast; formed and cured off site prior to the remainder of the steps of the process 300 described below that take place on site.
As shown in FIG. 2A, the grout valve assembly 160 is positioned in the walkway body 110 adjacent the first end 112 and extends through the outer surface 120 of the walkway body 110. The duct vent 162 is positioned within the walkway body 110 and communicates with the duct passageway 133. The grout pipe 164 extends from the duct vent 162 through the walkway body 110 and beyond the outer surface 120 of the walkway body 110. The walkway body 110 has a recess 124 at the outer surface 120 where the grout pipe 164 intersects the outer surface 120. The valve 166 is positioned outside of the walkway body 110.
In a step 320 shown in FIG. 4, the strands 144 of the tendon 140 are positioned to extend through the duct 130 with each end of the strands 144 at an anchor 142. In this step, only the strands 144 are positioned in the duct passageway 133.
The strands 144 are tensioned into the tensioned state T in the duct passageway 133 in a step 330. The strands 144 may be tensioned by any devices and methods used for stressing reinforcing strands in concrete applications. The anchors 142 secure the strands 144 in the tensioned state T, in which the strands 144 apply a compressive force onto the walkway body 110. The access opening 116 shown in FIG. 2A may be used to access the strands 144 during tensioning and secure the anchors 142 with the strands 144 in the tensioned state T. Excess length of the strands 144 beyond the anchors 142 may be removed.
In a step 340 shown in FIG. 4, the duct 130 is filled with the tendon grout 150 around the strands 144 in the tensioned state T. The tendon grout 150 is fed through the grout valve assembly 160 into the duct passageway 133; the tendon grout 150 is fed into the valve 166, through the grout pipe 164, and through the duct vent 162 into the duct passageway 133. In an embodiment described in greater detail below, multiple grout valve assemblies 160 can be positioned along the ducts 130 of multiple bonded concrete walkway segments 100 through which the strands 144 of one tendon 140 are tensioned. In this embodiment, the tendon grout 150 is fed into the ducts 130 through one of the grout valve assemblies 160 and the other grout valve assemblies 160 serve as an air valve for air to exit from the duct passageways 133.
The tendon grout 150 is cured in a step 350 shown in FIG. 4, fixing the strands 144 in the tensioned state T within the duct 130. The placement and curing of the tendon grout 150 bonds the strands 144 to the duct 130 and the walkway body 110, forming the bonded concrete walkway segment 100.
After the tendon grout 150 is cured, in a step 360 shown in FIG. 4, the grout valve assembly 160 is cut at the outer surface 120 of the walkway body 110. The grout pipe 164 is cut within the recess 124 shown in FIG. 2A, below the outer surface 120. The valve 166 is removed while a portion of the grout pipe 164 and the duct vent 162 remain within the walkway body 110. As shown in FIG. 5, the recess 124 is then filled with a body grout 126 that is flush with the outer surface 120 when cured. The body grout 126 may be a hard cementitious grout, such as ProSpec® Blendcrete, that can fill the recess 124 and remain durable during use of the bonded concrete walkway segment 100. The body grout 126 is shown filled in portions of the bonded concrete walkway segments 100 in the exemplary embodiment of FIG. 1.
The bonded concrete walkway assembly 10 including a plurality of the bonded concrete walkway segments 100 described in detail above is shown in FIG. 1. The bonded concrete walkway assembly 10 includes a plurality of joints 200 to attach the bonded concrete walkway segments 100 to each other in a desired arrangement. The arrangement of the bonded concrete walkway assembly 10 shown in FIG. 1 is merely exemplary, as the bonded concrete walkway segments 100 could be positioned in different arrangements with different joints 200. The joints 200 shown in FIG. 1, an extension joint 260, a first intersection 270, and a second intersection 280, are representative of the types found in various arrangements and will be described in detail below.
In the extension joint 260 shown in FIG. 6, the bonded concrete walkway segments 100 are positioned end-to-end to extend along a single direction. As shown in FIG. 6, the second end 114 of each of the walkway bodies 110 faces the joint 200. The second ends 114 are spaced apart by a first gap 240.
In the embodiment of FIG. 6, each of the walkway bodies 110 has a protrusion 118 at the second end 114 extending from a portion of the second end 114. In the shown embodiment, the protrusion 118 extends from approximately one-third of the second end 114 adjacent to the inner surface 122, as measured in the vertical direction V. In other embodiments, the protrusion 118 can extend from more or less of the second end 114. Between the protrusions 118, the walkway bodies 110 are spaced apart by a second gap 250. The second gap 250 is less than half a width of the first gap 240 and, in the shown embodiment, is approximately one-tenth the width of the first gap 240.
As shown in FIG. 6, the ducts 130 of each of the bonded concrete walkway segments 100 are connected by a duct connection 220 extending between the second ends 114 in the first gap 240 of the joint 200. In an embodiment, the duct connection 220 is a different material than the duct 130, such as a plastic or metal material, and may be smooth or corrugated. The duct connection 220, as shown in FIGS. 3A and 3B, is positioned at the ends of the ducts 130 of the bonded concrete walkway segments 110.
As shown in FIG. 6, at the extension joint 260, the second ends 114 of the walkway bodies 110 facing the first gap 240 have a roughened surface 202 that is roughened, for example, by a surface retarder. A reinforcement assembly 204 is positioned in the first gap 240 between the second ends 114 of the walkway bodies 110. In the shown embodiment, the reinforcement assembly 204 includes a plurality of bent bars 206 and a plurality of cross bars 208 positioned between the second ends 114. Each of the bars 206, 208 of the reinforcement assembly 204 may be formed from steel or any other type of material used in concrete reinforcement. In other embodiments, the reinforcement assembly 204 can have any other arrangement of bent bars 206 and/or cross bars 208.
The extension joint 260, as shown in FIG. 6, includes an intermediate concrete 210 filled between the walkway bodies 110 of the bonded concrete walkway segments 100. The intermediate concrete 210 fills the first gap 240 and the second gap 250 and is cured therein around the reinforcement assembly 204 and the duct connection 220. In the shown embodiment, the roughened surfaces 202 at the second ends 114 improve a bonding of the intermediate concrete 210 to the second ends 114. The intermediate concrete 210 secures the ducts 130 and the walkway bodies 110 at the joint 200. The intermediate concrete 210 may be a grout with added aggregate, a self-consolidating concrete, or any other cementitious material that can provide a durable bond in the joint 200. In an embodiment, the intermediate concrete 210 is a screed mortar with a corrosion inhibitor, such as SikaTop®-111 Plus. In the embodiment of the extension joint 260 shown in FIG. 6, the intermediate concrete 210 has a coating 214 on an outer surface 212. The coating 214 may be a bonding agent, such as Sikadur® 31.
In the embodiment shown in FIG. 6, the extension joint 260 includes an elastomeric sealant 230 disposed in the second gap 250 and contacting the protrusions 118 of both walkway bodies 110. The elastomeric sealant 230 may be formed of a polyurethane material and, in an embodiment, is Sikaflex®-1A. The elastomeric sealant 230 may be flush with the inner surfaces 122 of the walkway bodies 110 and may form a lower bound of the intermediate concrete 210 filled in the joint 200.
In the embodiments shown in FIGS. 7 and 8, the bonded concrete walkway segments 100 are positioned with the second end 114 of one of the segments 100 facing a side 119 of at least one other segment 100 to form the joint 200 as the first intersection 270 or the second intersection 280. Like reference numbers refer to like elements with respect to the joint 200 embodied as the extension joint 260 shown in FIG. 6 and primarily the differences in the embodiments shown in FIGS. 7 and 8 will be described herein.
In the first intersection 270 shown in FIG. 7, the first gap 240 is between the second end 114 of one of the walkway bodies 110 and the side 119 of the other of the walkway bodies 110. In this embodiment, only one of the walkway bodies 110 has the protrusion 118 at the first intersection 270; the protrusion 118 extends from the second end 114 of one of the walkway bodies 110, but extends further than in the embodiment shown in FIG. 6 such that the second gap 250 between the protrusion 118 and the side 119 of the other walkway body 110 is still less than half the width of the first gap 240. The elastomeric sealant 130 is disposed in the second gap 250 and the intermediate concrete 210 is filled in the first gap 240 and the second gap 250 around the reinforcement assembly 204 and the duct connection 220 connecting the ducts 130. The outer surface 212 of the intermediate concrete 210 has the coating 214.
The second intersection 280 shown in FIG. 8 is similar to the first intersection 270 shown in FIG. 7 except that the second intersection 280 has the grout valve assembly 160 shown and described in detail above with respect to FIG. 2A. The tendon grout 150 may be filled in the ducts 130 through the grout valve assembly 160 shown in FIG. 8, which would push air in the duct passageways 133 out of the other grout valve assemblies 160 connected to the same ducts 130, for example the grout valve assembly 160 shown in FIG. 2A. As described with respect to FIG. 5 above, the grout valve assembly 160 shown in FIG. 8 may also be cut at the outer surface 120 and the recess 124 filled with the body grout 126.
A process 400 of creating the joints 200 of the bonded concrete walkway assembly 10 that connect the bonded concrete walkway segments 100 will now be described in greater detail primarily with reference to FIG. 9. The process 400 applies equally to each of the extension joint 260, the first intersections 270, and the second intersections 280 shown in FIGS. 6-8.
In a step 410, the bonded concrete walkway segments 100 are positioned in the desired configuration of the bonded concrete walkway assembly 10. An exemplary configuration of the bonded concrete walkway assembly 10 is shown in FIG. 1. In other embodiments, the bonded concrete walkway assembly 10 can include different arrangements of different numbers of bonded concrete walkway segments 100 with different numbers and arrangements of extension joints 260, first intersections 270, and second intersections 280.
At each of the joints 200, in a step 420 shown in FIG. 9, the ducts 130 that protrude beyond the second end 114 or the side 119 of the walkway bodies 110 are connected by the duct connection 220.
The elastomeric sealant 230 shown in FIGS. 6-8 is positioned in the second gap 250 in a step 430 shown in FIG. 9.
Following the installation of the duct connection 220 and the positioning of the elastomeric sealant 230, the reinforcement assembly 204 is positioned in the first gap 240 in a step 440 and the second ends 114 or sides 119 are roughened to form the roughened surfaces 202 facing the first gap 240 in a step 450. In other embodiments, the steps 420, 430, 440, and 450 can be performed in a different order.
The intermediate concrete 210 is filled in the first gap 240 and the second gap 250 in an uncured state in a step 460 shown in FIG. 9. The intermediate concrete 210 surrounds portions of each of the ducts 230, the duct connection 220 connecting the ducts 230, and the reinforcement assembly 204 as shown in FIGS. 6-8. In a step 450, the intermediate concrete 210 is cured to secure the bonded concrete walkway segments 100 at the joint 200 as shown in FIGS. 6-8. The outer surface 212 of the intermediate concrete 210 may then be coated with the coating 214 in a step 480.
In the step 490 shown in FIG. 9, the grout valve assembly 160 can be cut and filled as described with respect to step 360 in FIG. 4 and in FIG. 5 above.
The bonded concrete walkway assembly 10 formed from the plurality of bonded concrete walkway segments 100 has improved longevity and structural stability. The bonding of the strands 144 in the tensioned state T to the walkway bodies 110 via the tendon grout 150 provides structural redundancy and a more durable connection between the stressed strands 144 and the walkway bodies 110. The arrangement of the elements in the joints 200 further improves the reliability of the connections between the bonded concrete walkway segments 100.
Patent Application
20240125055
