Abstract:
An insulator for a drum of a concrete truck is provided. Because temperature is a factor in the time in which concrete cures, thermal conditions during transport are of paramount concern. There have been efforts to alleviate this problem by providing insulating blankets that control temperature better. However, until now, a durable system that effectively insulates concrete while in transport has not been available. Furthermore, construction of an insulating system large enough to cover a concrete mixer gives rise to numerous fabrication difficulties. With the introduction of a polyethylene foam interposed between truck tarp material, a convenient system that is easily coupled and decoupled from a truck is available that is both durable and cost effective.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority to U.S. Provisional Application 60/732,852 filed Nov. 2, 2005. 
     
    
     TECHNICAL FIELD OF INVENTION  
       [0002]     The invention relates generally to thermal insulation techniques and, more particularly, to a thermal insulating device for concrete mixing trucks.  
       BACKGROUND OF THE INVENTION  
       [0003]     Concrete mixing trucks are an integral component of construction. Concrete mixing trucks are available in a variety of sizes, and many can carry 10 cubic yards or more of concrete. They are capable of delivering concrete to job sites many miles away. However, the deliverance range is limited by numerous physical variables associated with the perishability of the contents, namely, the concrete.  
         [0004]     Concrete is a composite building material. It is unique in that it can be delivered to the construction site in a plastic state and formed to a desirable shape. The most common type of concrete is Portland cement concrete. The two major components of Portland cement concrete are cement paste and inert materials. The inert materials are normally comprised of fine (generally less than 6.4 mm/0.025 in.) and coarse (generally greater than 6.4 mm/0.25 in.) mineral aggregates. Sand is the most common fine aggregate. Gravel, crushed stone, and slag are the most common coarse aggregates.  
         [0005]     Other components of concrete include Portland cement, water, and a small amount of air. Portland cement is produced by mixing ground limestone, clay or shale, sand and iron ore. The mixture is heated in a rotary cement kiln.  
         [0006]     The heating process causes the materials to break down and recombine into new compounds that react with water in a crystallization process called hydration.  
         [0007]     Water is the essential component that chemically reacts with the cement, in the hydration reaction. When water is supplied to the concrete, it also provides the initial plasticity necessary to allow the concrete to be poured into forms.  
         [0008]     The hydration and setting of concrete is known as curing. Concrete cures in several stages. This allows it to be transported in concrete mixing trucks to construction sites and to be delivered in a condition ready for pouring. Once the concrete is mixed with water, the cement begins a slow cure and the mix hardens. Depending on the exact mixture and additives that may be present, within a day and a half, most of the hydration process is complete, but the cement will continue to cure as long as water and unhydrated compounds are present. The entire process can actually take years.  
         [0009]     While the final hardening of concrete can take years, concrete begins to harden soon after mixing. Depending upon the amount of water used, the exact composition of the concrete and ambient weather conditions, concrete will lose its plasticity within a few hours of being mixed, making it unworkable within job site forms.  
         [0010]     Workability is the ability of a fresh (plastic) concrete mix to fill the form/mold properly with the desired work (force or vibration) without reducing the concrete&#39;s strength. Workability depends on water content, additives, aggregate (shape and size distribution) and age (level of hydration). The level of hydration is very susceptible to environmental factors. In particular, moisture and temperature are critical variables in the curing of concrete.  
         [0011]     When the concrete mixing truck arrives at the job site, workability is normally tested by slump measurement. Concrete slump is a simplistic measure of fresh (plastic) concrete&#39;s workability.  
         [0012]     Concrete transport trucks are designed to transport ready-mix concrete from the concrete plant to the construction site. Rotating drums are employed to prevent premature setting of the concrete, proper mixing of the cement, aggregate, and water, and to provide a mechanism for removing the concrete from the drum. The interior of the drum on a cement truck is fitted with a spiral blade. In one rotational direction, the cement is pushed deeper into the drum while being mixed. This is the direction the drum is rotated while the concrete is being transported to the building site.  
         [0013]     In properly mixed concrete, the cementing medium of concrete and water surround the aggregate particles, and as the cement paste hardens, it binds the aggregate into a solid mass. To insure proper mixing, standards have been developed pertaining to the rotation of concrete mixing drums. For example, drums are typically rotated at 17 revolutions per minute (rpm) for approximately 5 minutes (approximately 70 rotations) before leaving the concrete plant. While on the road, the drum will be rotated at approximately 2.5 rpm for the duration of the trip. This further mixes the contents and prevents early hardening of the concrete.  
         [0014]     When the concrete transport truck reaches its destination, the rotation of the drum is reversed. When the drum is rotated in the opposite direction, the Archimedes screw-type arrangement forces the concrete out of the drum, and optionally onto slides to guide the viscous concrete, or to a concrete pumping unit.  
         [0015]     Concrete must be poured into its final form while in a plastic state, before hardening occurs. If allowed to cure excessively, the concrete will lack adequate workability to be poured into the forms. If allowed to harden, the concrete will be extremely difficult to remove from the interior and exterior surfaces of the concrete mixing truck. Typically, a caustic compound, such as a strong acid, must be used to clean the concrete trucks.  
         [0016]     One of the most determinative factors in preserving the workability of concrete in a plastic state prior to pouring is temperature. Depending on the climatic conditions of the region and the season, the cure rate for the concrete will vary dramatically. Additionally, the act of transporting the concrete exposes the concrete mixture to substantial heat transfer mechanisms acting on the concrete mixing truck.  
         [0017]     As examples of the heat transfer, conductive heat transfer occurs as a result of the direct contact between the concrete and the interior wall of the drum and the spiral mixing blade. Convective heat transfer occurs between the drum and ambient air as the concrete transport truck travels down the road at freeway speed. Convective heat transfer may be increased by engagement of seasonal winds. Radiant heating of the drum occurs when the summer sun shines on the rotating drum.  
         [0018]     In addition to normal influx or loss of heat resulting from weather conditions, concrete curing is an exothermic reaction. Depending on the specific mix of concrete, the heat of reaction can contribute significantly to thermal problems. To a lesser degree, frictional heating occurs on the interior of the drum as the concrete is mixed against the spiral blade on the interior of the drum.  
         [0019]     The heat transfer rate is accelerated by the need to rotate the drum, exposing the mixing concrete across the large interior surface of the rotating drum. These heat transfer rates can be as high as 12 BTU/hr-ft2° F. or greater.  
         [0020]     As a result, during extended transportation to a construction site, the temperature of the concrete during summer months can accelerate the curing rate such that the concrete is unworkable and/or unusable by the time the concrete mixing truck reaches the construction site. Similarly, the temperature of the concrete during winter months can decelerate the curing rate such that the concrete is unworkable, and/or unprepared for pouring by the time the concrete mixing truck reaches the construction site.  
         [0021]     Thermal variations in transported concrete thus add significantly to construction costs, risks, and waste. Delays in construction are a common result. Over the years, numerous steps have been taken by contractors to compensate for the problems associated with climatic temperature variations and heat transfer associated with the transport of viscous concrete. Each of these compensating responses has limitations and disadvantages.  
         [0022]     Chemical additives called admixtures are often used to accelerate or retard the hydration rate of the concrete in response to climatic conditions. In particular, a set-retarding admixture may be used to modify setting time in hot weather. An accelerator admixture may be used to modify setting time in cold weather. Plasticizers can also be employed to increase the workability of the concrete. However, the use of admixtures is costly and adds complexity to the process mixing and management of the concrete. Additionally, certain admixtures can undesirably alter the performance characteristics of the finished concrete product.  
         [0023]     In addition to the use of admixtures, additional measures are taken when mixing concrete during seasonal temperature extremes. For example, during winter months, preheated water (approximately 180° F.) may be mixed with the concrete in an effort to normalize the temperature of the concrete mixture and accelerate hydration. During summer months, chilled water (near 32° F.) may be mixed with the concrete to normalize the temperature of the concrete mixture and retard hydration. However, utilizing preheated water or chilled water increases the production costs of the concrete. Also, even when steps are taken to manage the initial temperature of the components of the concrete, the mixture within the drum of the concrete transport truck remains subject to rapid heat transfer through the drum resulting from exposure to the ambient weather conditions.  
         [0024]     Some other solutions posed are thermal insulation of the concrete drum. In particular, U.S. Pat. No. 6,264,361 to Kelley (“Kelley”), which is hereby incorporated by reference for all purposes, employs a cover for a drum of a concrete truck. Kelley utilizes a pair of thermal blankets over a foam rubber insulation layer to cover the entire drum, using a pair of fasteners to secure the blanket over the drum. Kelley&#39;s design, however, can be cumbersome to employ because the disclosed configuration cannot be efficiently manufactured or installed.  
         [0025]     Another disadvantage is that the zippers or other fasteners are employed along curved seams. The disclosed fasteners are difficult to secure and may not be suitable for a variety of drum configurations. Another disadvantage is that the zippers or other fasteners are exposed, presenting a safety hazard as the drum rotates. Another disadvantage is that exposure of the zippers or other fasteners to the elements, including concrete, renders them inoperable.  
         [0026]     Moreover, Kelley does not consider a number of the existing physical constraints, nor does it provide an optimized solution to several design variables. Considerations such as cost, construction, insulating factor, safety, retention, surface adhesion to concrete, durability, weight, clearances, seasonal assembly and removal, and wind resistance must be taken into account. These considerations, therefore, create a need for an optimized design for an insulating system for a concrete mixing truck.  
         [0027]     Additionally, there are other difficulties in manufacturing blankets for concrete trucks, namely difficulty in sewing due to the size. The materials that comprise the concrete truck blankets are oftentimes heavy and cumbersome as well as large in size. Because of these factors, sewing these large pieces of material is extremely difficult, and the inaccuracy of the final product decreases safety and utility. Still another disadvantage is that manufacturing an insulating system as disclosed by Kelley results in the generation of substantial material waste.  
         [0028]     Therefore, there is a need for a method and/or apparatus that addresses at least some of the problems associated with conventional insulating blankets.  
       SUMMARY OF THE INVENTION  
       [0029]     A primary advantage of the present invention is that it provides an insulation system that can be manufactured using commercial sewing technology. Another advantage of the present invention is that it provides an insulation system that can be accurately manufactured, so that the system fits tightly on the drum, adding safety and utility. Another advantage of the present invention is that it provides an insulating system that can be manufactured without excessive waste of material. Another advantage of the present invention is that it provides an insulating system that resists adhesion to concrete, and is readily washable.  
         [0030]     Another advantage of the present invention is that it utilizes a material that provides a thermally efficient insulating system. Another advantage of the present invention is that it provides an insulation system that can be readily installed and removed from the drum. Another advantage of the present invention is that it provides an insulating system that is durable. Another advantage of the present invention is that it provides a protective covering for the fastening system.  
         [0031]     In a preferred embodiment of the present invention, a concrete truck drum insulating system is provided. The concrete truck drum insulator comprises an external layer, an internal layer, and an insulation layer interposed between the internal and external layers. The insulation layer includes a low-density, closed cell, polyolefin foam.  
         [0032]     In another preferred embodiment, a longitudinal seam substantially coplanar with the azimuthal axis of the concrete drum is provided. The seam has a first edge and complementary second edge. A plurality of connectable fasteners is aligned along the first and second edges.  
         [0033]     In a more preferred embodiment, straps are attached to the first edge, and strap receptacles are attached to the second seam to form the connectable fasteners. In another preferred embodiment, the strap receptacles are D-rings attached to the second edge. In a more preferred embodiment, the D-rings are made of a stainless steel.  
         [0034]     In an optional embodiment, a longitudinal flap is attached to the external layer. A flap attachment is provided for securing the flap over the seam and fasteners when the fasteners of the first edge are connected to the fasteners of the second edge. In a more preferred embodiment, the flap attachment is a hook and loop system disposed between the flap and the external layer below the second edge.  
         [0035]     In a preferred embodiment of the present invention, the external and internal layers are comprised of a vinyl chloride coated woven polyester, and the insulation layer is comprised of a low-density closed-cell polyethylene foam. In another preferred embodiment of the present invention, the weight of the external layer is greater than the weight of the internal layer.  
         [0036]     In another preferred embodiment of the present invention, a concrete truck drum insulating system is provided having a material layer for covering the drum comprised of a plurality of sections, each section being comprised of a plurality of complementary panels. A common longitudinal seam is formed along adjacent edges of panels in each section. In another preferred embodiment, each section is comprised of three complementary panels. In an alternative embodiment, each section is comprised of four complementary panels.  
         [0037]     In the preferred embodiment, the sections include frustum sections comprised of a plurality of complementary frustum panels. Each frustum panel includes a large arc, a small arc, and a pair of linear edges angularly disposed between the large and small arcs. The large arcs of the frustum panels of at least one frustum section are connected to the small arcs of a frustum panel of an adjacent frustum section.  
         [0038]     In an optional embodiment, the material layer also includes a cylindrical section comprised of rectangular panels. The rectangular panels have a pair of radial widths, and a pair of linear edges. In this embodiment, the cylindrical panel is located between frustum panels, having each radial width connected to the long arc of a frustum panel.  
         [0039]     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0040]     The objects and features of the invention will become more readily understood from the following detailed description and appended claims when read in conjunction with the accompanying drawings in which like numerals represent like elements.  
         [0041]     The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention.  
         [0042]      FIG. 1  is a side view of a concrete truck employing an insulator in accordance with a preferred embodiment of the present invention.  
         [0043]      FIG. 2  is a top view illustrating the outside of the insulator in accordance with a preferred embodiment of the present invention.  
         [0044]      FIG. 3  is a top view illustrating the inside of the insulator in accordance with an embodiment of the present invention.  
         [0045]      FIGS. 4-9  are top views of panels used to form sections.  
         [0046]      FIGS. 10 and 11  are top views of the insulator laid out in quarter panels before assembly.  
         [0047]      FIG. 12  is a front breakout view of a strap assembly of the insulator in accordance with a preferred embodiment of the present invention.  
         [0048]      FIG. 13  is a cross-sectional breakout view of the insulation layers of the insulator in accordance with an embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0049]     In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without such specific details. In other instances, well-known elements have been illustrated in schematic or block diagram form in order not to obscure the present invention in unnecessary detail.  
         [0050]     The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.  
         [0051]     Referring to  FIG. 1  of the drawings, the reference numeral  10  generally designates a concrete truck. Concrete truck  10  has a drum  12 . An insulator  14  is adapted for secure attachment over drum  12 .  
         [0052]     As can best be seen in  FIGS. 2 and 3 , insulator  14  is a uniform insulating blanket having a front section  16 , an intermediate section  18 , and a plurality of body sections  20 ,  22 ,  24 , and  26 . A common longitudinal seam  28  traverses the length of insulator  14  terminating at opening  30  at front section  16 . A plurality of connectable fasteners  32  and  34  are located along the length of seam  28 .  
         [0053]     In the preferred embodiment, connectable fasteners  32  and  34  are strap connectors  32  and straps  34 . Strap connectors  32  and straps  34  can be coupled to one another to secure insulator  14  over drum  12 . By this method, seam  28  allows insulator  14  to be securely and easily installed and removed.  
         [0054]     Additionally, a longitudinal flap  52  and flap attachment  54  are located on opposite sides of seam  28 . In the preferred embodiment, longitudinal flap  52  and flap attachment  54  are secured to one another through a hook and loop system, thus providing a protective cover over connectable fasteners  32  and  34 .  
         [0055]     Referring to  FIG. 2 , in accordance with the preferred embodiment, and as further illustrated in  FIGS. 4-9 , each of sections  16 ,  18 ,  20 ,  22 ,  24 , and  26  are comprised of a plurality of complementary panels  116 ,  118 ,  120 ,  122 ,  124 , and  126 , respectively. In a preferred embodiment illustrated, each section is comprised of four complementary panels. In another preferred embodiment (not shown), each section is comprised of three complementary panels.  
         [0056]     The panels illustrated in  FIGS. 4-9  are quarter panels. In  FIG. 4 , front section  16  is comprised of four panels  116 . In  FIG. 5 , intermediate section  18  is comprised of four panels  118 . Similarly, in  FIGS. 6-9 , body sections  20 ,  22 ,  24 , and  26  are comprised of four panels  120 ,  122 ,  124 , and  126 , respectively.  
         [0057]     In the preferred embodiment illustrated, sections  16 ,  18 ,  20 ,  24 , and  26  are frustum sections. Corresponding panels  116 ,  118 ,  120 ,  124 , and  126  are frustum panels. The opposing linear edges of adjacent frustum panels are attached together to form each frustum section.  
         [0058]     Referring to  FIG. 9  as an example of this embodiment, each frustum panel  126  includes a large arc  196 , a small arc  194 , and a pair of linear edges  198  and  200 , angularly disposed between large arc  196  and small arc  194 . Four frustum panels  126  are adjacently located to form frustum section  26 . Three of four linear edge pairs  200  and  198  are attached to each other to form four panels  126  having three pairs of attached edges  200  and  198 . The final pair of linear edges  198  and  200  remains unattached to form seam  28 .  
         [0059]     The same geometric relationship is illustrated for frustum panels  116 ,  118 ,  120 , and  124  in each of  FIGS. 4-6  and  FIG. 8 , respectively.  
         [0060]     As best seen in  FIG. 10 , the large arc of each frustum panel is typically connected to the small arc of the adjacent frustum panel. For example, as best seen in  FIGS. 4, 5  and  10 , large arcs  154  of frustum panels  116  of frustum section  16  are connected to small arcs  160  of frustum panels  118  of adjacent frustum section  18 .  
         [0061]     In the embodiment illustrated, insulator  14  may also optionally include a cylindrical section. Section  22  is a cylindrical section located between frustum sections  20  and  24 . Cylindrical section  22  is comprised of four complementary rectangular panels  122 . Referring to  FIG. 7 , rectangular panels  122  have a pair of radial widths  178  and  180 , and a pair of linear edges  182  and  184 .  
         [0062]     Four cylindrical panels  122  are adjacently located to form cylindrical section  22 . Three of four linear edge pairs  184  and  182  are attached to each other to form four panels  122  having three pairs of attached edges  184  and  182 . The final pair of linear edges  184  and  182  remains unattached to form seam  28 .  
         [0063]     Each cylindrical panel  122  is located between a pair of frustum panels  120  and  124 . Large arcs  172  and  188  of frustum panels  120  and  126  are attached to radial widths  178  and  180 , respectively, of cylindrical panels  122 .  
         [0064]     As can best be seen in  FIG. 13 , a cross-sectional view of the insulation layers of the insulator  14  is depicted. Insulator  14  comprises an inner layer  46 , which is designed to rest adjacent to a drum  12 . Coupled to inner layer  46  is an insulation layer  48 , and coupled to insulation layer  48  is an outer layer  50 , where outer layer  50  is exposed to the external environment.  
         [0065]     In the preferred embodiment, inner layer  46  is a poly vinyl chloride coated woven polyester. In the more preferred embodiment, the material weight is approximately 18 ounces per square yard. In the preferred embodiment, inner layer  46  has physical properties near to, or superior to, those provided in Table 1 below:  
                                                 TABLE 1                       Mechanical Properties   Results   Fed. Std. 191A   ASTM                                Grab Tensile (warp)   410   lbs.   5100   D5034       Grab Tensile (fill)   400   lbs.       Strip Tensile (warp 1″)   300   lbs.   5102   D5035       Strip Tensile (fill 1″)   290   lbs       Tongue Tear (warp)   100   lbs   5134   D751       Tongue Tear (fill)   90   lbs       Abrasion (Taber)   0.045   gr   5106   D3884       wheel H-18       load 1,000 gr.       1,000 cycle, 70 rpm                  
 
         [0066]     Materials providing properties of the preferred embodiment of inner layer  46  are commercially available, such as Polymar Tarp, Style No. VCP-18NL, from Mehler Coated Fabrics, Inc., 175 Mehler Lane, Martinsville, Va., 24112.  
         [0067]     In the preferred embodiment, outer layer  50  is also a poly vinyl chloride coated woven polyester. In the more preferred embodiment, the material weight is approximately 22 ounces per square yard. In the preferred embodiment, outer layer  50  has physical properties near to, or superior to, those provided in Table 2 below:  
                                                 TABLE 2                       Mechanical Properties   Results   Fed. Std. 191A   ASTM                                Grab Tensile (warp)   430   lbs.   5100   D5034       Grab Tensile (fill)   410   lbs.       Strip Tensile (warp 1″)   320   lbs.   5102   D5035       Strip Tensile (fill 1″)   310   lbs       Tongue Tear (warp)   110   lbs   5134   D751       Tongue Tear (fill)   100   lbs       Abrasion (Taber)   0.05   gr   5106   D3884       wheel H-18       load 1,000 gr.       1,000 cycle, 70 rpm                  
 
         [0068]     Materials providing properties of the preferred embodiment of outer layer  50  are commercially available, such as Polymar Tarp, Style No. VCP-22VN, from Mehler Coated Fabrics, Inc., 175 Mehler Lane, Martinsville, Va., 24112.  
         [0069]     In another preferred embodiment, it is seen that there is an economic advantage to utilizing an external layer  50  which fabric weight exceeds the fabric weight of internal layer  46 . In another preferred embodiment of the present invention, advertising or promotional indicia are printed directly onto outer layer  50 . Silk-screen is an effective method of printing images on outer layer  50 .  
         [0070]     Insulation layer  48  is located between inner layer  46  and outer layer  50 . In the preferred embodiment, insulation layer  48  is a low-density closed-cell polyethylene foam. In another preferred embodiment, insulation layer  48  has a density of approximately 2.0 lbs/ft 3 . In the preferred embodiment, insulation layer  48  has physical properties near to, or superior to, those provided in Table 3 below:  
                                                 TABLE 3                                   Mechanical Properties   ASTM D-3575   CKJN200                                        Density   Suffix W   2.0           Tensile Strength   Suffix T   37           Elongation %   Suffix T   100           Tear Resistance   Suffix G   11           Compressive Strength   Suffix D   14.0           50% Deflection           Thermal Stability % change   Suffix S   &lt;1           (24 hours @158° F.           Water Absorption   Suffix L   &lt;0.07           Lbs/sq ft (skived)                      
 
         [0071]     Materials providing properties of the preferred embodiment of insulation layer  48  are commercially available, such as Oletex™ CKJW 200, from Armacell LLC, 7600 Oakwood Street Ext, Mebane, N.C. 27302.  
       Operation of the Preferred Embodiments  
       [0072]     Referring to  FIG. 1  of the drawings, the reference numeral  10  generally designates a concrete truck. Concrete truck  10  has a drum  12 , which is covered with an insulator  14 .  
         [0073]     As can best be seen in  FIGS. 2 and 3 , insulator  14  is a uniform insulating blanket having a front section  16 , an intermediate section  18 , and a plurality of body sections  20 ,  22 ,  24 , and  26 . In the embodiment illustrated, each body section  20 ,  24  and  26  forms a frustum, particularly a conical frustum. Body section  22  forms a cylinder. A seam  28  traverses the length of insulator  14  terminating at opening  30  within front section  16 , allowing for insulator  14  to be easily deployed or removed.  
         [0074]     In particular, insulator  14  is designed to be a flexible and foldable blanket when not in use. The inherent flexibility allows insulator  14  to be easily installed, easily folded and stored away when not in use.  
         [0075]     Insulator  14  is applicable to a number of drum  12  variations.  FIGS. 2 and 3  each depict four body sections  20 ,  22 ,  24 , and  26 ; however, it is possible to employ fewer sections or a greater number of sections. Each section  20 ,  22 ,  24 , and  26  can conform to a drum section with distinct radii, conical tapers, and so forth, so as to assist in matching the shape of drum  12 .  
         [0076]     A particular variation is depicted in  FIGS. 2-11 . This depicted version illustrates a preferred embodiment of the present invention configured to fit an 11 cubic yard mixer such as is commercially available from McNeilus™, 524 County Rd. 34, East Dodge Center, Minn. 55927, USA.  
         [0077]     Table 4 below includes dimensions which will provide a concrete truck drum insulating system for the drum described above. In this table, arcs are represented by their chord length. Sufficient material overlap is provided for sewing adjacent panels together.  
                           TABLE 4                           Large Arc   Small Arc   Linear Edge       Panel   Chord Length   Chord Length   Length                   116   4′-10⅞″   3′-10⅝″   1′-3 3/16″       118   5′-0″   4′-8¾″   5⅞″       120   6′-3¾″   5′-1¼″   2′-9 11/16″       122   6′-4¼″   6′-4¼″   3′-5⅜″       124   6′-3¾″   4′-11″   4′-3 5/16″       126   4′-11″   2′-10½″   2′-10½″                  
 
         [0078]     As described herein above, each frustum panel is comprised of a pair of arcs; the large arc having a radius of curvature r 1  and the small arc having a radius of curvature r 2 . A central angle α is disposed between the liner edges. Table 5 below includes supplemental dimensions for a concrete truck drum insulating system for the example drum described above.  
                                   TABLE 5                                   Panel   Large Arc   Small Arc   Central Angle α                           116   42″   29″   82°           118   77″   72    47°           120   91″   59″   25°           122   n/a   n/a   n/a           124   120″    70″   19°           126   114″    89″   30°                      
 
         [0079]     Front section  16  covers a closed end of drum  12 , which is typically proximate the cab of the concrete. Typically, front section  16  is comprised of four quarter panels  116  sewn together in a complementary manner to form a ring that is front section  16 . Within front section  16  is an opening  30  that accommodates an axle responsible for drum  12  rotation. As can be seen in  FIG. 1 , this front section  16  is typically curved, conforming generally to a paraboloid or spherical shape having a radius of curvature in a direction toward the azimuthal axis (Z) of drum  12 .  
         [0080]     An intermediate section  18  is then formed adjacent to front section  16 . Intermediate section  18  is comprised of four intermediate quarter panels  118  sewn together to form a ring. Typically, intermediate section  18  is employed at a juncture where a change in shape occurs. The change in shape can usually be defined as a transition from the front surface of drum  12  and the main body of drum  12 . As can be seen in  FIG. 2 , intermediate section  18  conforms to a conical, spherical, or paraboloid surface having an increasing radius relative to azimuthal axis (Z) of drum  12  in a direction away from front section  16 .  
         [0081]     Body section  20  is located adjacent to intermediate section  18 . Section  20  is also employed at a junction where a change in shape occurs. Section  20  is formed of four quarter panels  120  sewn together in a complementary manner to form a ring. Typically, as can be seen in  FIG. 2 , section  20  conforms to a conical, spherical, or paraboloid surface having an increasing radius in a direction away from front section  16 .  
         [0082]     Body section  22  is located adjacent to section  20 . Section  22 , however, may also be employed at a junction where a change in shape occurs. Section  22  is formed of four quarter panels  122  sewn together in a complementary manner. In the example embodiment illustrated, section  22  is cylindrical, and quarter panels  122  are rectangular. In some situations, however, section  22  can be employed at a junction where a non-cylindrical shape occurs.  
         [0083]     Body section  24  is located adjacent to section  22 . Section  24  is typically employed at a junction where a change in shape occurs. Section  24  is formed of four quarter panels  124  sewn together in a complementary manner to form a ring. Typically, as can be seen in  FIG. 2 , section  24  conforms to a conical, spherical, or paraboloid surface having a decreasing radius relative to azimuthal axis (Z) of drum  14  in a direction away from front section  16 .  
         [0084]     Body section  26  is located adjacent to section  24 . Section  26  is typically employed at a junction where a change in shape occurs. Section  26  is formed of four quarter panels  126  sewn together in a complementary manner to form a ring. Typically, as can be seen in  FIG. 2 , section  26  conforms to a conical, spherical, or paraboloid surface having a decreasing radius relative to azimuthal axis (Z) of drum  14  in a direction away from front section  16 .  
         [0085]     As can be seen in  FIG. 2 , a longitudinal seam  28  traverses the length of insulator  14  terminating at opening  30  at front section  16 . Along seam  28 , a plurality of strap connectors  32  and straps  34  are attached to secure the position of insulator  14  over drum  12 . In particular, a strap assembly  32  is designed and positioned along seam  28  such that one strap assembly  32  couples to one strap  34 . In this manner, a relatively uniform closing force can be applied along seam  28 , allowing insulator  14  to be securely and easily installed and removed.  
         [0086]     Referring to  FIG. 12  of the drawings, the reference numeral  32  generally designates a strap assembly. Strap assembly  32  is coupled to insulator  14  at one end. In particular, a single strap  38  is employed within each strap assembly  32 . Each end of strap  38  is then coupled to insulator  14 . In a preferred embodiment, parallel horizontal sewing seams  40  and  42  are employed in conjunction with an interconnecting sewing seam  44  to secure each end of strap  38  to insulator  14 . Therefore, strap connectors  32  are permanently affixed to insulator  14 .  
         [0087]     In one embodiment of the present invention, strap  38  is comprised of Nylon®. However, in other embodiments of the present invention, a variety of other materials can be employed.  
         [0088]     Additionally, strap  38  secures a D-hook  48 . Typically, in the preferred embodiment of the present invention, D-hooks  48  are comprised of stainless steel; however, a variety of other materials can be employed in other embodiments of the present invention. D-hook  48  is secured by strap  38  such that a straight portion of D-hook  48  is parallel to edge  36  of insulator  14 . Therefore, when strap assembly  32  engages strap  34 , strap  34  can be tied to D-hook  48 , and tied strap  34  is able to rest in a position without encumbrances resulting from edges, as would be present with a rectangular hook. Thus, the combination of strap connectors  32  in conjunction with straps  34  allows for ease of engagement and disengagement of insulator  14 .  
         [0089]     To protect straps  34  and strap connectors  32  from the environment, longitudinal flap  52  and flap attachment  54 , which traverse seam  28 , are employed. The longitudinal flap  52  can, thus, provide protection to the straps  34  and strap connectors  32  from the environment and can further insulate drum  12  by reducing the area exposed to the environment. Typically, longitudinal flap  52  and flap attachment  54  are secured to one another through a hook and loop system.  
         [0090]     However, in another preferred embodiment of the present invention, straps  34  and strap connectors  32  can be replaced with a hook and loop system.  
         [0091]     Referring to  FIG. 13  of the drawings, a cross-sectional view of the insulation layers of insulator  14  is depicted. Insulator  14  comprises an inner layer  46 , an insulation layer  48 , and outer layer  50 .  
         [0092]     Inner layer  46  rests immediately adjacent to drum  12  and protects insulation layer  48 . Inner layer  46  provides protection against environmental conditions and wear against drum  12 . Resilience to the absorption of water, chemical resistivity, and cost, were taken into account when determining the preferred material to comprise inner layer  46 . Particularly, inner layer  46  must be comprised of a material that is resistant to concrete adhesion, and be durable enough to handle trucking conditions.  
         [0093]     Outer layer  50  is coupled to insulation layer  48  to further protect insulation layer  48 . Outer layer  50  protects insulation layer  48  from the external environment. Particularly, outer layer  50  can be comprised of a variety of different materials that provide protection against harsh environmental conditions, such as the presence of strong bases or strong acids, or to provide radiation protection, such as ultraviolet (UV) protection.  
         [0094]     Other factors, such as resilience to the absorption of water, chemical resistivity, and cost, were taken into account when determining the preferred material to comprise outer layer  50 . In particular, outer layer  50  is comprised of a material that is resistant to concrete adhesion to permit water washing of insulator  14 . Outer layer  50  is durable enough to handle trucking conditions, such as scraping by tree branches and resistivity to contamination. Additionally, outer layer  50  provides good aerodynamic quality so as to not significantly reduce aerodynamic efficiency of concrete truck  10 .  
         [0095]     It is seen that there is an economic advantage to utilizing an external layer  50  which fabric weight exceeds the fabric weight of internal layer  46 . In another preferred embodiment of the present invention, advertising or promotional indicia can be printed directly onto outer layer  50 . Silk-screen is an effective method of creating images on outer layer  50 .  
         [0096]     Insulation layer  48  is located immediately adjacent to inner layer  46 . In the preferred embodiment of the present invention, a durable, light-weight foam with excellent long-term insulation properties is required. The foam must be impact resistant, rot and mildew resistant, and resistant to microorganism growth. Additionally, UV and water resistance are required. The preferred embodiments of inner layer  48  closed-cell polyethylene foam meet these requirements.  
         [0097]     A primary advantage of the present invention is that it is simple, safe, and durable. Another advantage of the present invention is that it is inexpensive to manufacture. Another advantage is that many of the fabrication difficulties associated with the assembly of insulating systems large enough to cover concrete mixers are reduced or eliminated, including handling and excessive material waste problems.  
         [0098]     Another advantage of the present invention is that it provides for a simplified, easily deployable, and easily removable system. Other advantages of the present invention will become apparent from the above descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.  
         [0099]     It will be readily apparent to those skilled in the art that the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention.  
         [0100]     Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.