Patent Publication Number: US-2023148127-A1

Title: System and method for shotcrete construction

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 17/360,186, filed on Jun. 28, 2021, which is a continuation of U.S. patent application Ser. No. 16/736,540, filed on Jan. 7, 2020, now U.S. Pat. No. 11,072,932, issued on Jul. 27, 2021, the entire contents of which are incorporated herein by reference. 
    
    
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not Applicable 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates generally to the art of concrete construction, and more particularly, to a system and method for facilitating the construction of walls, ceilings and other surfaces from concrete. 
     2. Related Art 
     In the art of concrete construction, it is commonplace to form concrete walls, ceilings, and other concrete surfaces using shotcrete, also known as sprayed concrete or gunite. Shotcrete, which can refer to both the material and the construction technique itself, involves pneumatically projecting concrete or mortal at high velocity onto a surface, typically a surface that has been prepared in advanced by the placement of reinforcing material such as steel rods, steel mesh, or fibers, such that the sprayed shotcrete will encase the reinforcing material. Shotcrete has many advantages over other methods of concrete construction and offers many benefits in terms of speed, cost, and ease of installation in relation to conventional poured concrete techniques. 
     However, conventional methods of shotcrete construction suffer from several deficiencies, especially in relation to architectural projects requiring more complex designs or fine attention to aesthetics and detail. Unlike poured concrete where more complex shapes and designs can be achieved via the fabrication of molds, shotcrete is significantly less precise. As such, the primary applications of shotcrete have been in relation to industrial uses of concrete where aesthetics are of less importance, such as in the stabilization of excavation walls or cliffsides, or the lining of swimming pools prior to the placement of tile. 
     A major deficiency of shotcrete is that it is very difficult for even a skilled artisan to produce a shotcrete wall having different thicknesses at different points on the wall in order to produce a wall or other surface having arcuate, curvilinear, or other exotic characteristics across various dimensions. Previously, in order to accomplish this, protruding dowels, rods, or pins would be placed at various locations protruding from the shotcrete receiving surface to predetermined distances, optionally with wires tied therebetween, and the shotcrete installer would use the length of the rods and/or the wires tied therebetween as a gauge to produce a shotcrete wall having the desired depth at the desired locations. Following this, the shotcrete installer would adjust the wall using a hand tool in their best attempt to blend the areas of differing depths to produce the desired arcuate, curvilinear, or other exotic surface. This technique is extremely imprecise and labor intensive, and frequently fails to meet the aesthetic needs of the project. Further, to produce designs with more extreme arcuate, curvilinear, or other exotic characteristics may require an unwieldy amount of guide rods to be placed and may require such extreme labor and attention to detail, both before, during, and after the shotcrete spraying, that the advantages of shotcrete construction over poured concrete construction entirely disappear. 
     As such, it may be seen that novel shotcrete construction techniques which may remedy these and other deficiencies associated with the prior art are desirable. 
     BRIEF SUMMARY 
     To solve these and other problems, systems and methods of shotcrete construction are contemplated whereby, in an exemplary embodiment, guide rails are placed in proximity and forward to a shotcrete receiving surface, with the guide rails disposed directly in front of the shotcrete receiving surface being configured to be offset therefrom such that shotcrete may be sprayed against the receiving surface behind the offset guide rails to form an uninterrupted shotcrete surface. Following application of shotcrete to the receiving surface, a screed configured to engage with and traverse along at least two of the guide rails may be used to rod the shotcrete via a protruding region of the screed extending beyond the guide rails, thereby removing excess shotcrete and imparting to the shotcrete a contour at least partially defined by the configuration of the guide rails. Likewise, the protruding region itself of the screed may also be varied to further define the contour of the shotcrete. It may thus be seen that complex, precise, and even exotic architectural shotcrete installations may be created in this fashion by providing a suitable set of guide rails and screed, representing in a substantial increase in precision and speed over conventional architectural shotcrete techniques. 
     According to one embodiment of the present disclosure, a system for shotcrete construction is contemplated, the system comprising a plurality of guide rails configured for placement proximal to a shotcrete receiving surface and in substantially parallel alignment to one another, at least one of the guide rails having a spaced region configured to be forwardly offset from the shotcrete receiving surface such that when the spaced region of the guide rail is placed in front of the shotcrete receiving surface, shotcrete may be applied against the portion of the shotcrete receiving surface behind the spaced region, and a screed configured for simultaneous engagement with and traversal along at least a portion of at least two of the guide rails, the screed having a protruding region such that when the screed is engaged with and traversed along at least a portion of at least two chosen guide rails following application of shotcrete against the shotcrete receiving surface, the protruding region is operative to rod the shotcrete so as to impart a contour to the shotcrete at least partially defined by the configuration of the at least two chosen guide rails. 
     At least two guide rails may be configured for substantially vertical alignment proximal to a shotcrete receiving surface, with the screed configured for substantially horizontal simultaneous engagement with at least two guide rails. Each of the plurality of guide rails may be substantially identical configured such that the contour imparted to the shotcrete is substantially similar along the direction of the shotcrete surface substantially perpendicular to the substantially parallel direction of the guide rails. Alternatively, at least two of the plurality of guide rails may be substantially differently configured such that the contour imparted to the shotcrete is substantially dissimilar along the direction of the shotcrete surface substantially perpendicular to the substantially parallel direction of the guide rails. 
     More particular embodiments having at least three guide rails are also contemplated, with each of the least three guide rails being configured for placement at a regular predefined interval from one or more adjacent guide rails. In such embodiments, the screed may be configured to permit simultaneous engagement with and traversal along any adjacent pair of the at least three guide rails. 
     The screed may be configured to engage with and traverse along at least one guide rail via sliding frictional engagement. The screed may also be configured to engage with and traverse along at least one guide rail via coupling engagement. The protruding region of the screed operative to rod the shotcrete may also be configured to be one or more of: linear, arcuate, curvilinear, serrated, smooth, or combinations thereof. 
     According to another exemplary embodiment of the present disclosure, a method for shotcrete construction is contemplated, the method comprising at least the steps of (1) providing a plurality of guide rails in proximity to a shotcrete receiving surface in substantially parallel alignment to one another and a screed configured for simultaneous engagement with and traversal along at least a portion of at least two of the guide rails, at least one of the guide rails having a spaced region configured to be forwardly offset from the shotcrete receiving surface such that when the spaced region of the guide rail is placed in front of the shotcrete receiving surface, shotcrete may be applied against the portion of the shotcrete receiving surface behind the spaced region, the screed having a protruding region, (2) applying shotcrete to the shotcrete receiving surface; and (3) simultaneously engaging the screed with and traversing the screed along at least a portion of at least chosen two guide rails to cause the protruding region to rod the shotcrete and impart a contour thereto at least partially defined by the configuration of the at least two chosen guide rails. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the various embodiments disclosed herein are better understood with respect to the following descriptions and drawings, in which: 
         FIG.  1    is a side view illustrating shotcrete wall formed via conventional prior art methods; 
         FIG.  2    is a perspective view illustrating a conventional prior art system for shotcrete wall construction; 
         FIG.  3    is perspective view of an exemplary embodiment of a system for shotcrete construction placed proximal to a shotcrete receiving surface; 
         FIG.  4    is a perspective view showing shotcrete being applied to the shotcrete receiving surface illustrated in  FIG.  3   ; 
         FIG.  5    is a perspective view showing a shotcrete wall formed from the practice of an exemplary method for shotcrete construction using the system of shotcrete construction illustrated in  FIG.  3   ; 
         FIG.  6    is a side view of the shotcrete wall shown in  FIG.  5   ; 
         FIG.  7    is a perspective view illustrating, in an exemplary embodiment of a method for shotcrete construction, the step of engaging and traversing the screed along the guide rails to remove excess shotcrete and to impart a contour to the shotcrete surface; 
         FIG.  8    is a perspective view illustrating the application of a coating to a completed shotcrete wall; 
         FIG.  9    is a top view illustrating an exemplary embodiment of a screed having a linear protruding surface and being configured for sliding frictional engagement with an adjacent pair of guide rails; and 
         FIG.  10    is a top view of an exemplary embodiment of a screed having an arcuate protruding surface and being configured for sliding frictional engagement. 
     
    
    
     Common reference numerals are used throughout the drawings and the detailed description to indicate the same elements. 
     DETAILED DESCRIPTION 
     According to various aspects of the present disclosure, systems and methods of shotcrete construction are contemplated, wherein according to an exemplary embodiment, guide rails are placed in proximity and forward to a shotcrete receiving surface, with the guide rails disposed directly in front of the shotcrete receiving surface being configured to be offset therefrom such that shotcrete may be sprayed against the receiving surface behind the offset guide rails to form an uninterrupted shotcrete surface. Following application of shotcrete to the receiving surface, a screed configured to engage with and traverse along at least two of the guide rails may be used to rod the shotcrete via a protruding region of the screed extending beyond the guide rails, both removing excess shotcrete and furthermore imparting to the shotcrete a contour at least partially defined by the configuration of the guide rails and which may be at least partially defined by the configuration of the screed. 
     Turning now to  FIG.  1   , a prior art method of shotcrete construction is illustrated whereby pencil rods  20  are located at the shotcrete receiving surface, alone or in combination with guide wires  22 , with such pencil rods and/or guide wires being used to visually judge the correct depth of shotcrete to be applied to the shotcrete receiving surface  12  and the intended contour to impart to the shotcrete surface, with such pencil rods  20  ultimately being embedded within the shotcrete. In view of the herein described system and method, the deficiencies of this conventional system become clear, as not only is this conventional system substantially less precise than the herein described system and method due to generally relying on human optical judgment alone, but it may also be seen that production of more complex contours in concrete surface rapidly becomes more and more labor and material intensive, and may require an extremely unwieldly amount of pencil rods  20  to be utilized, which may require such a substantial amount of time and labor such that the advantages of shotcrete techniques over poured techniques become entirely offset. Furthermore, such prior art techniques rely, during the rodding step, on the capability of the individual using the screed to blend together the regions between the pencil rods  20  to achieve a desired contour. Such human ability to produce adequate blending is notoriously difficult and unreliable, and generally requires a great amount of skill and effort, often resulting in the fabrication of a wall having a imperfect contour which in many cases will not meet the needs of a more demanding architect, especially when the shotcrete is designed to at least partially fulfill aesthetic purposes and not merely for structural purposes alone where aesthetics are substantially less important. 
     Turning now to  FIG.  2   , the above described prior art system of pencil rods  20  and guide wires  22  may more fully be seen prior to the application of shotcrete. 
     Turning now to  FIG.  3   , an exemplary embodiment of a portion of a system for shotcrete construction  10  placed proximal to a shotcrete receiving surface  12  is illustrated. The system for shotcrete construction  10  may be seen to comprise a plurality of guide rails  14  placed proximally the shotcrete receiving surface  12 , with the guide rails  14  being generally aligned in a substantially parallel direction, which may be seen to be along the vertical axis in the illustrated exemplary embodiment. However, it may be seen that in other embodiments, the plurality of guide rails  14  may be generally parallel aligned in a different direction, such as horizontally or in any other direction as suitable for the needs of the constructor. It may also be seen that in certain embodiments, there may be multiple pluralities of guide rails  14 , with each distinct plurality of guide rails  14  being aligned to be generally parallel in different directions, which may facilitate construction of more exotic contours of shotcrete walls. 
     At least one of the guide rails  14  may have spaced region  16  configured to be forwardly offset from the shotcrete receiving surface  12  such that when the spaced region  16  of the guide rail  14  is placed in front of the shotcrete receiving surface  12 , shotcrete may be deposited against the portion of the shotcrete receiving surface  12  beyond the spaced region. In this way, it may be seen that even when the guide rails  14  are emplaced prior to the spraying of shotcrete, such placement would not interfere with the ability of the applicator to apply a continuous shotcrete surface to the shotcrete receiving surface  12 . In some embodiments, the spaced region  16  may be the majority of or substantially all of at least one of the guide rail  14 . However, in other embodiments, it may be seen that the spaced region may form only a portion of a guide rail  14 . It may also be seen that others of the guide rails  14  may not be configured with a spaced region. For example, it may be seen that according to certain embodiments such as the embodiment illustrated in  FIG.  3   , the guide rails  14  located at the periphery of the shotcrete receiving surface may also serve as a lateral containing surface for containing the lateral installation of shotcrete at the periphery of the shotcrete receiving surface  12 , and as such it may not be desirable for such guide rails  14  to be configured with a spaced region  16 , but rather for such guide rails  14  to be in contact with the shotcrete receiving surface  12  or otherwise occlusive of the continuous lateral application of shotcrete. 
     The guide rails  14  may be constructed from any material known to be useful or usable in the construction or concrete industries for formwork or scaffolding, including but not limited to timber, plywood, metal, plastic, fiberglass, precast concrete, or any other material suitable to or which may be adapted to the herein purposes, or any combination of such materials. In the exemplary embodiment, the guide rails  14  are simple protruding members which extend forwardly from the shotcrete receiving surface  12  at a distance configured to be further than the intended depth of the shotcrete application. Such forward extension distance may be constant along the length of the guide rail  14 , or more commonly, may vary along the length of the guide rail  14 . Generally, it will be an objective of certain embodiments described herein that the forward extension difference in each area of the guide rail  14  will be more distant that the intended depth of shotcrete application of at the local region of the shotcrete receiving surface  12  proximal to that area of the guide rail  14 , such that in the case of guide rails  14  configured with a spaced region  16 , the spaced region  16  of the guide rail  14  does not occlude the creation of a continuous surface of shotcrete at the region of the shotcrete receiving surface  12  behind the spaced region  16  such that the spaced region  16  does not become contained within the applied shotcrete. In the case of certain peripheral guide rails  14  which do not contain a spaced region  16  but instead may be used to contain the lateral application of shotcrete, it may still be desirable for the forward extension of the guide rail  14  from the shotcrete receiving surface to be further than the intended depth of the shotcrete proximal thereto, so that the guide rail  14  may still function to laterally contain the shotcrete. 
     Turning now to  FIG.  4   , an exemplary embodiment of a step of applying shotcrete to the shotcrete receiving surface  12  is shown. It is to be understood that such step of applying shotcrete may be any method of shotcrete application known or future developed and furthermore, is not necessarily to be limited to the application of concrete or mortar via a pneumatic method or even limited to any method of projecting concrete or mortar, but that the presently contemplated methods, and indeed, the term “shotcrete” as recited here, when referring to a construction technique, is to be understood as encompassing any and all known or future enveloped methods of applying concrete or mortar to a surface or area, including hand application or pouring, and when referring to the physical material used in any such construction technique, may encompass all concretes or mortars or any other material utilized in such construction technique, even if such construction technique does not involve pneumatic or other projection methods. It may even be seen that the presently described or contemplated systems and methods may not necessarily be limited to vertical, upright, or ceiling-like surfaces where shotcrete is typically utilized, but that the presently described or contemplated systems and methods may also be utilized in conventional horizontal poured concrete installation where the guide rails  14  may be, for example, horizontally aligned atop the shotcrete receiving surface  12  of the horizontal poured concrete installation. 
     As may be seen in  FIG.  4   , the freshly applied shotcrete may not have a substantially uniform surface or distribution against the shotcrete receiving surface  12 , but rather it is highly typical for freshly applied shotcrete to vary in depth to form an irregular fresh shotcrete surface. As such, in order to produce a more regular or otherwise contoured shotcrete surface, the freshly applied shotcrete must be rodded or otherwise manipulated so as to contour the surface of the freshly applied shotcrete in order for the freshly applied shotcrete to cure or dry in the appropriately desired configuration with the desired contour. 
     Turning now to  FIG.  5   , an example of a shotcrete wall is illustrated which has been rodded according to an exemplary embodiment of the presently contemplated methods using an exemplary embodiment of a presently contemplated system for shotcrete construction  10  is illustrated, prior to the removal of the system for shotcrete construction  10  and/or the shotcrete receiving surface  12 . As may be seen, the contour of the resulting shotcrete wall may depend substantially on the configuration of the guide rails  14 . 
     Turning now to  FIG.  6   , a side view of a shotcrete wall is illustrated which has been rodded according to an exemplary embodiment of the presently contemplated methods using an exemplary embodiment of a presently contemplated system for shotcrete construction  10  is illustrated, prior to the removal of the system for shotcrete construction  10  and/or the shotcrete receiving surface  12 . As may be more fully seen by this figure, the contour of the resulting shotcrete wall may depend substantially on the configuration of the guide rails  14 . In particular, it may be seen that via the use of a screed to rod the shotcrete via simultaneous engagement with and traversal along at least a portion of at least two of the guide rails  14 , the shotcrete may be contoured so as to result a substantially precise screeding distance  18  between the guide rails  14  and the surface of the resulted contoured shotcrete at all locations. In this way, it may thus be seen that complex contours may be imparted to the shotcrete merely by fabricating guide rails  14  which are adapted to produce such desired complex contours and by ensuring that during the step of rodding the concrete, the screed is maintained in continuous engagement with the guide rails  14  during the traversal thereof. Such complex contours may be, for example but without limitation, arcuate, curvilinear, jagged, or even highly exotic forms. To produce, as in the illustrated embodiment, a shotcrete wall having a contour with a substantially similar cross-sectional thickness across any horizontal portion of the wall, with variation in cross-sectional thickness only across a single dimensional axis of the wall, it may be seen that similarly or identically contoured guide rails  14  may be utilized across the shotcrete receiving surface. However, it may also be seen that to produce even more complex contours, such that those which may vary in cross-sectional thickness across multiple dimensional axis of the shotcrete surface, it may be desirable to utilize differently contoured guide rails  14 . Further, it may be seen that multiple separate assemblies of guide rails  14  may be placed and/or utilized simultaneously or in sequence to rod the shotcrete to produce a desired contour of the shotcrete. 
     Turning now to  FIG.  7   , an exemplary embodiment of a step of simultaneously engaging the screed with and traversing a screed  24  along at least a portion of at least chosen two guide rails  14  to cause a protruding region of the screed  24  to rod the shotcrete and impart a contour thereto at least partially defined by the configuration of the at least two chosen guide rails  14  is illustrated. As seen by this illustrated exemplary embodiment, it may be seen that engaging and traversing the screed  24  may comprise physically contacting the screed  24  with the forward surfaces of guide rails  14  and maintaining such engagement while traversing the screed  24  along the guide rails  14  via sliding frictional engagement, and that the system for shotcrete construction  10  may be configured to accomplish this step. However, it may also be seen that in other embodiments of the herein contemplated systems and methods, other ways of the screed  24  engaging with and traversing along the guide rails  14  may be utilized. For example, it may be seen that one or more guide rails  14  may be configured to accept or be accepted by a corresponding feature on the screed  24  so as to result in a coupling between the screed  24  and the guide rails  14 . In this way, it may be seen that the requirement to manually apply pressure to the screed to maintain contact against the guide rails  14  may be reduced or eliminated. Examples of such couplings may be, for example and without limitation, features such as bearing surfaces, wheeled or tracked engagements, dovetails, notches, grooves, or any other known or future developed forms of coupling engagement. Versions of screeds  24  are also contemplated wherein manual manipulation of the screed may not even be necessary, for example, in embodiments where the screed may be actuated and traversed along the guide rails  14  via a motor or other form of powered mechanical motion. It may even be seen that, according to more advanced versions of herein contemplated systems, the screed  24  may not necessary be a distinct part from the guide rails  14 , but may be integrated therewith, and when not in use, may be positioned at a location on the guide rails  14  which does not interfere with the application of the shotcrete. 
     It may also be seen that it may be desirable in certain instances that, when three or more guide rails  14  are utilized, for the lateral distance between each respective laterally adjacent guide rail  14  to be substantially identical. This may permit the use of a single screed to rod the shotcrete, rather than requiring use of multiple separately configured screeds for each respective pair of guide rails  14 . It may also be seen, however, that other configurations of lateral spacing between guide rails  14  may be utilized, and that corresponding screeds  24  may be utilized to adapt to the lateral spacing of the guide rails  14 . It is also envisioned that a single screed  24  may be configured so as to be utilized with different or multiple configurations of lateral spacing between guide rails  14 , for example, by including a feature on the screed that permits adjustment of an engagement point on the screed or by including multiple optional engagement points. For example, it is contemplated that the screed  24  may be configured to be telescoping so as to permit adjustment of the distance between two engagement points thereupon so that the screed  24  may be utilized with many possible configurations of lateral distances between guide rails  24 . 
     Turning now to  FIG.  8   , it may be desirable, following the step of rodding the shotcrete, to apply a coating or covering to the shotcrete surface, through any known technique for applying coatings or coverings to shotcrete surfaces, such as spraying or manual application. Such coatings may be, for example but without limitations, aesthetic or protective coatings, or combinations thereof, or coatings to impart other desired characteristics. It may also be seen that besides coatings, other manipulations to the shotcrete surface may be made after the desired contour is achieved via rodding the shotcrete with the screed  24 , such as embedding of particulate materials, the installation of tile, a physical manipulation of the shotcrete surface via an abrasive, mechanical or chemical method of altering the shotcrete surface, or any other known or future developed manipulation of the shotcrete surface, all of which are at least equally achievable in a shotcrete surface produced via the herein contemplated methods as compared to known conventional methods, if not more achievable. 
     Turning now to  FIG.  9   , a screed  24  according to an exemplary embodiment of the present disclosure is more fully illustrated, including the protruding region  26  of the screed. It may be seen that the protruding region  26  of the screed  24  may be configured to protrude beyond the spaced region  16  of one or more corresponding guide rails  14  to rod the shotcrete when engaged with two or more of the corresponding guide rails  14  and traversed along the length of the shotcrete, in order to produce a contoured shotcrete at least partially defined by the configuration of the guide rails. In the illustrated embodiment of the screed  24 , it may be seen that the protruding region  26  is substantially linear, which may be seen to generally result in the production of a contoured shotcrete which is substantially linearly contoured transverse to the direction across which the screed is traversed. However, it may be seen that in other embodiments, the protruding region  26  of the screed  24  may be configured in other ways, such as arcuate, curvilinear, jagged, stepped, or any other configuration which may at least partially contribute to the production of a contoured shotcrete. Further, embodiments of a screed are also contemplated in which the protruding region may extend laterally behind a spaced region  16  of a guide rail  14  in order to rod shotcrete applied to the shotcrete receiving surface  12  in the region behind a spaced region. 
     Turning now to  FIG.  10   , another embodiment of a screed  24  is illustrated, wherein the protruding region  26  is configured to be arcuate so to at least partially define an arcuate contour in the shotcrete, which may be useful especially for creating arcuate walls or surfaces It may be seen that according to the particular embodiment illustrated, the engagement points on the screed may not be configured to engage with guide rails  24  having the same coordinated profile as in the screed illustrate in  FIG.  9   , but rather may be configured to engage with differently configured guide rails  24 , such as guide rails which may extend forward from linearly from an shotcrete receiving surface  12  having a substantially similarly arcuate profile to the screed  24 , or with guide rails which are canted outward from a more linear shotcrete receiving surface  12 . Regardless, however, it may be seen that there may exist an essentially infinite variety of screeds with different configurations, each of which is contemplated as falling with the scope and spirit of the present disclosure. 
     The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the exemplary embodiments.