Patent Application
20100037555
The present invention relates to stack concrete masonry systems for building structural load bearing and non-load bearing walls and, more particularly, to a system and method that utilizes precision grinding of a small top portion of masonry blocks in addition to a masonry adhesive or grout that “self-levels” the masonry blocks to provide for accurate and simplified assembly of concrete masonry.
Present masonry construction techniques provide for essentially two masonry construction techniques: the traditional mortared block technique where motor is place between each block both on a horizontal face as well as a vertical face; and a newer technique of dry stacking where blocks are designed to be simply placed one upon the other in some arrangement without any mortar between the blocks themselves (although cement may be later placed in spaces within the stacked blocks). An advantage of dry stack masonry systems is that the labor component of installation can be dramatically reduced. Some studies have shown that dry stack masonry systems are up to ten times faster to install than conventional joint mortared masonry systems and require a significantly less skilled labor force to install them. Because these systems do not use bonding mortar to provide joint support, it may be necessary to use other means of developing wall strength to meet various building codes.
For example, various building codes may require dry-stacked concrete block cells to be filled with cement in order to provide specified structural integrity. Some applications may require all the cells to be filled with concrete. Other applications may require the concrete to be poured into distinct vertical columns and only in certain cells or cores of the block. These applications may require cells, for example, to be filled generally at four foot on center increments and/or at wall corners and jambs of windows and doors or various load points. A general overview of the use of current dry stack methods in masonry wall construction can be found in National Concrete Masonry Association's (NCMA) technical publication TEK 14-22 “Design and Construction of Dry-Stack Masonry Walls” Incorporated herein by reference.
Currently, the accepted practice for constructing with concrete masonry units using the traditional mortared technique (structural concrete block) requires that the blocks be mortared together with a code approved masonry mortar mix. Typical masonry mortar mixes contain portland cement, lime and mason sand, as well as additives for improving workability. These masonry mortar mixes are applied and installed by an experienced mason using a trowel. The trowel has been used in constructing masonry walls for thousands of years. As a result, the availability of a skilled mason applying mortar with a trowel becomes the limiting factor in the how fast a masonry wall can be constructed. The amount of labor cost to install a masonry wall is currently in the range of 66% to 75% of the overall masonry construction costs.
There have been attempts to change the dynamics of the masonry construction market in an attempt to lower the labor expenses associated with typical block concrete construction. As a result, many systems have attempted to eliminate the need for mortar during construction of the wall. The dry-stack masonry wall describe above is one such example. By eliminating the mortar step, the installer should be able to go much faster in erecting walls. The issue with current mortar less systems, however, is that these systems do not have sufficient height control to duplicate the height control capability of a mortar joint between block that can be adjusted to take care of concrete masonry units block height irregularities. The mortar, besides providing bonding and sealing, also serves as a leveling mix that provides a way for the wall builder to adjust the height and level of the courses to meet the specific dimensions for openings and top of wall elevations. Moreover, dry stack masonry walls may not have the same load strength as traditional mortared masonry walls and many building codes recognize this and are reluctant to change to allow dry-stack masonry walls in many applications.
Accordingly, a need exists for a system and method that provides a masonry block having predetermined area (that is smaller than full top surface area of the masonry block) that can be ground down to a precise level to ensure that there will be no “rocking” or un-levelness in the stacked blocks and that are installed using a non-trowel applied grout or adhesive which serves to adhere the blocks together without the need to use skilled masons using trowels.
In order to solve the problems associated with conventional mortared masonry and with the mortar less/dry-stacked methods of building masonry walls, a new system was developed. This novel system combines wet-stacking with self-leveling and a precision grinding method. This system eliminates the need for trowel-applied mortar. The system dramatically reduces the need for highly skilled masons in the overall construction crew, while also providing nearly the speed of conventional dry-stack systems.
In one aspect the invention features a method of producing a stackable building block for constructing a masonry wall. The method comprises the acts of molding a concrete block having a front section coupled to and substantially parallel with a rear section. Each front and rear sections has a bottom surface and a top surface, wherein the top surface on both the front and rear sections includes a central region having a height which is greater than the first and second end regions located on either side of the central region. The method also includes grinding the central region of the top surface of the front and rear block sections to a predetermined height.
The method of producing a stackable building block for constructing a masonry wall utilizes a building block that is a dry stackable concrete block. Alternatively, the method of producing a stackable building block for constructing a masonry wall utilizes a building block that is a wet stackable concrete block.
In another aspect of the invention, the method of producing a stackable building block for constructing a masonry wall includes a central region that has an undulating surface.
In a further embodiment of the invention, the method of producing a stacked building block wall utilizing the stackable building block further comprises applying a flowable, thin set mortar onto the top surface of the stackable building block using a high speed applicator. The high speed application may be a grout bag. The mortar is applied to a thickness of ⅛ of an inch or less.
In another embodiment of the invention, the grinding of the higher surface of the top surface is precision ground to provide a stack building block of a specific precision height.
In an additional embodiment of the invention, the central region of the top surface further includes a plurality of indents or serrations or channels. The method of producing a stacked building block wall utilizing the stackable building block further comprises the acts of applying a flowable, thin set mortar onto the top surface of the stackable building block using a high speed applicator and allowing the mortar to enter the plurality of indents or serrations or channels on the central region of the top surface, wherein the addition of the mortar does not significantly increase the specific precision height of the stackable building block.
Another embodiment of the application further comprises stacking a second duplicate stack block staged halfway off-center and stacking a third duplicate stack block staged halfway off-center in a direction opposite and adjacent to the second stack block.
In a further aspect of the invention, the stack building block has a chamfered or beveled edge on one more exterior edges of the building block.
It is important to note that the present invention is not intended to be limited to a system or method which must satisfy one or more of any stated objects or features of the invention. It is also important to note that the present invention is not limited to the preferred, exemplary, or primary embodiment(s) described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention.
These and other features and advantages of the present invention will be better understood by reading the following detailed description, taken together with the drawings wherein:
A corner wall structure 200 may use a stretcher unit 202 and a corner unit 204 to construct the corner and straight portions of a wall, as shown in
The stretcher units 202 have a front section and a rear section. One or more webs or ribs couple the front section to the rear section. The one or more webs may extend just below the top surface of the stretcher unit 202 or may extend all the way to the top surface of the stretcher unit 202. The stretcher units 202 also have lugs that extend above the top surface of the stretcher unit 202. The stretcher unit 202 and other exemplary embodiments of the stretcher unit 202 will be described in greater detail later herein. The corner units 204 may also have a front section, rear section, and one or more webs coupling the front section and rear section. The corner unit also has a side section. The side section provides a ninety-degree corner in the wall. The corner unit 204 provides a uniform surface at the corner of the wall. The corner units 204 are staggered with each successive row. The corner unit 204 and other exemplary embodiments of the stretcher unit 202 will be described in greater detail later herein.
The corner unit 204 may not have lugs extending from the top. Deformable pegs 208 in peg holes 210 may be used to position the corner unit 204 during construction. The deformable pegs 208 may be made of, for example, copper tubing. The exemplary dimensions of the copper tubing may be about ¼ inch diameter with length of about one inch. The copper tubing allows the peg 208 to deform with relative little force and remain in the deformed shaped. The distorted shape of the deformable peg 208 holds the units in a plumb and square position during construction phase. The deformable pegs 208, are not limited to a metal tubing. The deformable peg 208 may be made from a variety of materials that sufficiently lack memory and provide desired strength, for example, metals, metal alloys, composites, plastics, and polymers. The deformable pegs 208 are not limited to a tubular structure. The deformable peg 208 may be, for example, solid, a variety of cross-sectional shapes, and/or a variety dimensions.
Referring to
The next successive unit is positioned so that the deformable peg 208 aligns with the bottom receiving hole 712. The top and bottom receiving holes 710, 712 may be constructed in a variety of methods. For example, the receiving holes 710, 712 may be molded or punched in the block unit prior to curing, the receiving holes 710, 712 may be drilled into the block unit on-site, or a combination of construction. For example, the top receiving hole 712 may be punched in the unit prior to curing and the bottom receiving hole 710 may be drilled. The positioning of the receiving holes 710, 712 may be dependent on the number of pegs per block unit, the overall wall construction shape (i.e. 90 degree corner, 45 degree corner, or end of a wall), and other construction aspects.
Once the unit is maneuvered in place, the unit may be positioned for greater accuracy by tapping the unit with a mallet or other tool. The positioning may be accomplished immediately after place of the unit or after successive layers of units have been positioned. The positioning by tapping the unit causes the deformable peg 208 to bend or deform into a new semi angled shape. The new shape aids in holding the units in a correct position or place until concrete secures the wall permanently. The deformable peg may allow for multiple positioning. For example a unit may be tapped successively throughout the dry stacking process of the wall in order to adjust positioning of the wall. The deformable pegs 208 may be used for corners or other portions of the wall in which additional adjustment may be beneficial.
The corner unit 204 may not have lugs extending from the top. The corner unit may be used in a straight wall portion, as shown in
The exemplary embodiments shown in
The exemplary embodiments shown in
An exemplary embodiment of the invention with webs at right angles is shown in
A first lug of the pair of lugs is coupled against a first surface of a first web and an inner surface of the rear section. A second lug of the pair of lugs is coupled against a second surface of the first web and the inner surface of the front section. A second pair of lugs for the stretcher unit has a first lug of the second pair coupled against a first surface of a second web and an inner surface of the front section. A second lug of the second pair of lugs is coupled against a second surface of the second web and the inner surface of the rear section. Each of the lugs in the first pair of lugs is positioned on alternating sides of the first web. Each lug of the second pair of lugs is also positioned on alternating sides of the second web; however, the lugs are on opposite sides from the first web. This allows the successive layer of stretcher units to rest on the stretcher unit and allows the lugs 508 of the stretcher unit 500 to protrude into the cells of the successive layer of stretcher units without interfering with the lugs of the successive layer of stretcher units.
When the wall is constructed the stretcher units may be staged half way off-center for each successive row. This allows the alternating pairs of lugs to straddle the webs of successive rows of stretcher units. The stretcher unit 500 is supported in the lateral direction by a lug positioned between the inner surface of the front or rear section and the web. The constructed wall locks together by the protruding lugs extending into the cells and straddling the webs of successive rows of stretcher units above and below the stretcher unit.
The stretcher unit 500 may also have a beveled profile on the outer surface of the front section and rear section. The stretcher unit 500 may also have a chamfered side edge for coupling to adjacent units. In addition, the stretcher unit may have a knock-out portion for producing a bonding-beam. These features are similar to those previously described herein with respect to the exemplary embodiment disclosing the exemplary stretcher unit 400 with angled webs.
An exemplary embodiment of the invention with beveled lug profiles is shown in
All or only a limited portion of top surface 610 of front section 606 and the rear section 608 may be ground to provide a greater degree of accuracy in of the height for the stretcher unit. This greater degree of accuracy may be used to allow for dry stacking the units without the need for shims or leveling supports. The units may be molded using convention block molding techniques. The grinding is preformed after curing. As will be discussed later herein, the lugs 604 may have a recess to provide better alignment. All or only a portion of the top surfaces 610 of the front section 606 and rear section are ground to the desired level. A tolerance of about less than +/−0.015 inches (0.4 mm) may be achieved to provide consistent flat and level surface for precise height for successive stacking of the units. Since the bottom of the unit is typically molded on a flat surface, a consistent and precise block height may be achieved by only grinding the top surface 610.
A corner unit 700 according to an exemplary embodiment of the invention is shown in
The web 708 is spaced to receive lugs from a previous row of stretcher units off-set by half a unit length. The web is spaced within the corner unit so as to align on top of the web of a previous row of stretcher units allowing the lugs of the previous row of stretcher units to straddle the web. The corner unit may also be used in the construction of a linear position of a wall as shown in
The stretcher units may assemble into a linear wall structure 800 as shown in
An exemplary embodiment of the invention includes a beveled or chamfered edge profiles. The beveled edge may extend around the both sides and the top edges of the stretcher unit as previously discussed in
Referring to
Referring to
Referring to
According to an exemplary edge-grinding embodiment of the invention, the top surface 1109 may be divided into regions of varying levels during the molding process. The stretcher unit 1102 may be molded with a central region 1111 having a slightly higher surface than the adjacent top surfaces 1113 which have a lower profile by approximately ⅛ inch. After the molding process, the top surface 1109 which may be in the range of 2″ to 7″ in length (and preferably only about 3″ in length) are ground to provide a more accurate height of the stretcher unit 1102.
The lower surface areas 1113 are molded at a height slightly below the ultimate desired height of the stretcher unit 1102, while the higher surface region 1111 in the central part of the block front and rear sections are molded slightly higher than the desired height of the stretcher unit 1102. Since masonry blocks are typically made from a mixture of concrete, sand and small stones, the ultimate height and “levelness” of each block can and does vary, particularly because of the effects of the small stones which may protrude upwards from the concrete clock. During the grinding process, these height irregularities will be eliminated. The grinder will either not or perhaps barely grind the lower surface 1113 due to the height being just shy of the set grinding height. As the higher surface 1111 passes under the grinder, the grinder removes a portion of the concrete block unit material that exceeds the desired height providing a more accurate stretcher unit 1102 height in view of the molded height. By reducing the amount (length) of the stretcher unit 1102 to be ground down (i.e. a rather short 3″ or so central region 1111), there is improved grinding performance resulting from an increase in the throughput speed as well as reduced wear on the grinding heads.
For example, when manufacturing an eight-inch high unit, the block may be molded with lower surface 1113 being a one-sixteenth ( 1/16) of an inch shy of eight inches and a higher surface 1111 being a one-sixteenth ( 1/16) of an inch above eight inches. During the grinding process, the grinder may remove portions of the higher surface 1111 providing a height that is eight (8) inches to a greater degree of an one-eighth (⅛) or less of an inch accuracy. This accuracy allows for good overall height control of the wall and levelness without block “rocking” which is normally not a problem in a mortared wall since the mortar takes up any unevenness in the blocks.
The precision ground block units provide for precision height control even when mortared together. The design provides for lower surfaces 1113 and a higher surface 1111, which reduces the amount of influence the mortar has on adding height to the courses of the wall. The higher surface 1111 may further have an appropriate number of indentations (grooves or channels) 1115 that serve to reduce the mortar influence in height control to almost zero by providing channels or grooves into which any adhesive, grout or thin mortar may flow. Any grout, adhesive or this mortar in the grooves or indentations 1115 will still serve to adhere the top surface of this block with the bottom region of a block placed on top of the block. This higher surface 1111 is then ground to the desired height to provide units of precision height. The geometry of the higher and lower surfaces 1111, 1113 and the indents 1115 in the top surface 1109 are designed in such a way as to provide a self-leveling aspect to the wall construction. The self-leveling feature allows for high stacking productivity even if the field conditions are not perfect. The self-leveling provides for a near fool-proof solution that allows the construction of the concrete block wall to be more forgiving. As an example, if foreign materials are present in one level of the stacking, as subsequent courses are stacked, there is little or no potential for “rocking” of a block. The precision ground region of the higher surface 1111 located in the top surface 1109 of the block's face will implement the self-leveling feature and allow for an instant remedy to blocks that would otherwise by crooked or at an angle. The problem of angled or crooked blocks can be remedied immediately without the need for shims or grinding.
The edge-grinding embodiment is not limited to the lower surface 1113 being lower than the desired height. The lower surface 1113 may be molded to the exact height of the desired stretcher unit 1102. In this example additional grinding may be required with the bulk of the grinding occurring on the higher surface 1111. Additionally, the edge-grinding embodiment may have different lengths of higher surfaces 1111 and lower surfaces 1113. In the example shown in
In the previously discussed embodiment, a top web surface 1106 is molded to a height of the lower surface 1113. This allows the grinding process to avoid the lugs and/or to facilitate multiple grinding processes. However, the embodiment is not limited to the top web surface 1106 being molded to a height of the lower surface 1113.
After manufacturing of the stretcher units 1102, the stretcher units 1102 may be assembled as previously discussed herein. In the preferred embodiment of the method of the present invention, an adhesive (also termed grout or thin mortar) is applied between each course of the stretcher units 1102. The adhesive may be squeezed from the areas between the higher surface 1111 and the bottom of the next course of units. The adhesive may also remain in areas between the lower surface 1113 and the bottom of the next course of units. Once the adhesive cures, the adhesive may provide additional load barring support that typically meets or exceeds code specifications. The adhesive may be an expandable adhesive to aid in the filling of voids between surfaces. The adhesive in this case is selected to provide a desired expansion force that prevents movement of the stretcher unit 1102 after proper positioning while expanding to file any voids or spaces between surfaces of blocks stacked one on top of the other.
An exemplary code compliant mortar/grout/adhesive according to one feature of the present invention was designed and developed to be applied without a trowel but rather, using a high-speed applicator. Examples of such a high-speed applicator include a grout bag or a grout pump well known in the industry for applying grout to tiles or to the exterior face of previously erected block walls. The stackable block design of the present invention allows for the new mortar to be easily squeezed between the subsequent blocks to a thickness of less than ⅛ of an inch so that the mortar is not dictating the height of the wall. Rather, the height of the wall is dictated by the high-speed grinding height gauging process that each block passes through to make it a precision height unit with tolerances that are an order of magnitude better than in the ASTM C-90 block standard. Fine grained thin set mortar readily available in general home building supply stores like that used for laying tile on floors or walls will work well with the present invention.
The mortar may also be provided that has properties that conform to the Masonry Standard for Unit Mortared Masonry but is also designed so that it can be applied at high speeds without a trowel or experienced applicator and applied so that it does not interfere with the height control aspects of the precision block of the invention. Such a code approved mortar can be applied at a thickness as thin as 1/64 of an inch. The mortar is ultra fine grained and made with cements, aggregates and chemical modifiers as in thin set motors that give it its unique properties. The particles in the mortar are less than 5/1000 of an inch. The mortar should have good water retention and does not dry out through evaporation or through suction from the dry block to which it is applied. The water retention of the mortar allows the mortar to remain flowable after application to the block allowing all unnecessary motor to flow or squeeze out from between two blocks. If the mortar where to lose its ability to flow, the mortar would add too much thickness between the blocks and would affect the ability of the wall to be built to meet specified elevations.
Referring to
Referring to
Modifications may be made to fit particular operating requirements and environments as will be apparent to those skilled in the art, the invention is not considered limited to the examples chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention.
The present application claims priority to U.S. provisional Patent Application 61/053,463 filed on May 15, 2008 entitled “Web Offset Lug Dry-Stack System”, which is incorporated fully herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61053463 | May 2008 | US |
