Abstract:
The present disclosure describes a curing box including a circulation assembly which substantially eliminates temperature stratification of a first fluid within the box. Additionally, the curing box includes an internal temperature sensor and an external temperature sensor which provide data to a control module. The control module permits adjustment of the fluid temperature within the box. The present disclosure additionally provides a method for curing a specimen in the curing box. The method compares the temperature signal from the external sensor to the internal sensor and adjusts the temperature of the fluid in the box to match the temperature reported by the external sensor. Additionally, the method controls the flow of a second fluid into the box thereby circulating the first fluid to substantially eliminate temperature stratification of the first fluid in the box. Thus, the method provides a controlled environment for curing the specimen.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 61/432,268, filed on Jan. 13, 2011, and incorporated herein by reference. 
    
    
     FIELD OF DISCLOSURE 
     The inventive concept(s) disclosed herein generally relates to concrete curing boxes, and more particularly, but not by way of limitation to a wet concrete curing box for curing concrete test specimens with a built-in temperature control system. 
     BACKGROUND 
     It is standard practice in the construction industry to test samples of various materials used during construction. This is especially true of concrete, where many field cured specimens are generally required when structural concrete is poured. These specimens are taken from a number of locations across the element or slab when it is poured, and are typically formed as concrete test cylinders. 
     The American Society for Testing and Materials (ASTM), the American Concrete Institute (ACI), and the American Association of State Highways and Transportation Officials (AASHTO) have developed certain criteria for the formation and testing of concrete test specimens. For examples of such standards see ASTM C 31/C 31M, ACI-301, ACI-318, ASTM C94, and AASHTO T-23. Any deviation from standard testing procedures is grounds for invalidating the obtained test results. Local and national governmental bodies have likewise adopted certain standards for concrete acceptance testing. 
     One important concrete acceptance testing criteria is that the field cured test specimens represent accurate samples of the cured concrete slab. Concrete curing is an exothermic process (gives off heat) due to the heat released by a hydration reaction which occurs. The build-up of too much heat or the lowering of the temperature beyond proper curing levels can result in concrete strength reduction, cracking, and/or other structural defects. Therefore, the temperature at which the test cylinders are cured is important for the proper testing of concrete. For example, the current ASTM C31/C31M standard specifies a constant curing temperature of 73° Fahrenheit, with a tolerance of ±3° Fahrenheit. 
     Accordingly, ASTM standards require that field cured concrete specimens, which are cast separately from the concrete slab, be treated during curing to closely approximate the heat developed during the curing process in the more massive concrete slab. If the concrete specimens are not in situ, this is difficult to achieve. Also, the specimens are kept moist until the cure is complete, just as in the case of the poured slab. Any significant variation in the procedure can result in the specimens being an inaccurate representation of the actual qualities of the cast slab they are supposed to represent. 
     Recently, wet concrete curing boxes have been used to provide stable environments for the curing of concrete test cylinders in situ in order to comply with ASTM standards. The existing curing boxes generally are insulated boxes which have temperature control systems installed in order to heat or cool the inside of the box as needed. The boxes also have a rack to support the test cylinders, which is typically made by bending a sheet of 14 gauge steel into a “U” shape to form the rack, and then forming holes into the top of the rack to allow for water circulation. The rack rests on corner supports extending from the bottom of the prior art curing boxes, and supports the concrete test cylinders submerged under water. 
     Another recent technological development has introduced the use of “loggers” disposed in the concrete slabs. See, for example, U.S. Pat. No. 6,865,515, the entire contents of which are hereby expressly incorporated herein by reference. 
     Some prior art wet concrete curing boxes use water pumps having an impeller within a housing above the rack for mixing the water above the rack during the curing process. However, cement dust and other abrasive particles inside the box tend to reduce the service life of the water pumps, which typically results in increased expense and/or delays. Further, curing typically takes about twenty-eight days, which can increase the chance of failure of such prior art water pumps. Additionally, the rack can form a convective barrier which may cause a temperature stratification within the water. 
     Accordingly, a need exists for a curing box capable of providing reliable in situ concrete test specimens. It is to such a concrete cylinder curing box that the inventive concept(s) disclosed herein is directed. 
     SUMMARY 
     The present disclosure provides a curing box for curing a specimen. In a first embodiment, the curing box includes a box containing a liquid and having a fluid conduit positioned therein. The fluid conduit is in fluid communication with the exterior of the box. The fluid conduit carries a plurality of emitters that provide fluid communication between the fluid conduit and the interior of the box. Further, the curing box includes a fluid source in fluid communication with the fluid conduit. The fluid source is configured to provide a volume of fluid under pressure to the fluid conduit. 
     In another embodiment, the curing box previously described in the first embodiment additionally includes a heating element, a cooling element, a first sensor, a second sensor, and a control module. The heating and the cooling element adjust the temperature of the liquid in the box. The first sensor monitors the temperature of the liquid in the box. The second sensor is positioned in an external location from the box for monitoring a second temperature of the external location. The control module receives and records the temperature from the first sensor and receives and records the second temperature from the second sensor. Further, the control module controls the activation and deactivation of the cooling element, and the activation and deactivation of the heating element to thereby adjust the temperature of the liquid to substantially correspond to the second temperature. 
     In yet another embodiment, the curing box previously described in the first embodiment additionally includes a heating element, a cooling element, a first sensor, a user input device, and a control module. The heating and the cooling element adjust the temperature of the liquid in the box. The first sensor monitors the temperature of the liquid in the box. The control module receives and records the temperature from the first sensor and receives and records a preset temperature from the user input device. Further, the control module controls the activation and deactivation of the cooling element, and the activation and deactivation of the heating element to thereby adjust the temperature of the liquid to substantially correspond to the preset temperature. 
     Further, the present disclosure provides a method for curing a specimen. The method requires immersion of the specimen in a first fluid in a curing box. In one embodiment, the method utilizes a preset temperature for the first fluid in the curing box and monitors the temperature of the first fluid. To maintain the first fluid at the preset temperature, the method provides for heating or cooling the first fluid in the curing box to adjust the first fluid temperature to substantially correspond to the preset temperature. The method also provides a second fluid to the curing box and distributes the second fluid through a fluid conduit in the curing box. The distribution of the second fluid circulates the first fluid throughout the curing box in a manner to preclude temperature stratification in the first fluid. 
     In another embodiment, the method monitors the temperature of a second specimen positioned external to the curing box. Then the method adjusts the temperature of the first fluid in response to the monitored temperature of the second specimen. Typically, the adjustment of the temperature of the first fluid produces a temperature substantially similar to that of the second specimen. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Like reference numerals in the FIGS. represent and refer to the same element or function. Implementations of the disclosure may be better understood when consideration is given to the following detailed description thereof. Such description makes reference to the annexed pictorial illustrations, schematics, graphs, drawings, and appendices. In the drawings: 
         FIG. 1  is a partial cutout perspective view of a prior art concrete curing box. 
         FIG. 2  is a top view of a prior art concrete curing box with the lid and rack omitted for clarity. 
         FIG. 3  is a perspective partial cutout view of an embodiment of a concrete curing box constructed according to the present disclosure. 
         FIG. 4  is a top view of an embodiment of the concrete curing box shown in  FIG. 3  with the rack omitted for clarity. 
         FIG. 5  is an end view of an embodiment of a concrete curing box according to the present disclosure with the temperature control assembly omitted for clarity. 
         FIG. 6  is a perspective view of an embodiment of a rack constructed according to the present disclosure. 
         FIG. 7A  is a bottom sectional view of an embodiment of a fluid conduit according to the present disclosure. 
         FIG. 7B  is a perspective view of an embodiment of a rack support member according to the present disclosure. 
         FIG. 7C  is a perspective view of an alternative embodiment of a rack support member according to the present disclosure. 
         FIG. 8  is an exploded view of an embodiment of a concrete curing box constructed according to the present disclosure. 
         FIG. 9  is a block diagram of an embodiment of a control module according to the present disclosure. 
         FIG. 10A  is a block diagram of an embodiment of a logger according to the present disclosure. 
         FIG. 10B  is an end, perspective view of an embodiment of a logger according to the present disclosure. 
         FIG. 11  is a partial cutout perspective view of a prior art curing box retrofitted with a circulator assembly according to the present disclosure, with the rack omitted for clarity. 
         FIG. 12A  is a graphic plot of variations in temperature measured at the top, at the center, at the rack, and at the temperature sensor of a prior art curing box. 
         FIG. 12B  is a graphic plot of variations in temperature measured at the top, at the center, at the rack, and at the temperature sensor of a curing box constructed according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Before explaining at least one embodiment of the inventive concept(s) disclosed herein in detail, it is to be understood that the inventive concept(s) is not limited in its application to the details of construction and the arrangement of the components or steps or methodologies set forth in the following description or illustrated in the drawings. The inventive concept(s) disclosed herein is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
     In the following detailed description of embodiments of the disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the inventive concept(s) disclosed herein. However, it will be apparent to one of ordinary skill in the art that the inventive concept(s) within the disclosure may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description. The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. 
     The inventive concept(s) disclosed herein generally relates to concrete curing boxes, and more particularly, but not by way of limitation to a concrete curing box for concrete test cylinders with built in temperature control system and a water circulation system. 
     1. Description of the State of the Prior Art 
     An exemplary prior art concrete curing box is shown in  FIGS. 1-2 . Therein, prior art curing box  100  comprises an insulated box  102 , a support rack assembly  104 , and a temperature control system  106 . 
     The insulated box  102  comprises a bottom  108 , walls  110 , and a lid  112 , cooperating to define a substantially rectangular enclosure  114 . The enclosure  114  can be watertight. Further, the box  102  may have a control panel assembly  116  attached to the outside of one of the walls  110 . 
     The bottom  108  is preferably substantially rectangular. Alternatively a drainage aperture may be located in one or more of the walls  110 . 
     The walls  110  extend substantially vertically from the bottom  108  and are perpendicular to one another and connect at corners  118 . 
     The support rack assembly  104  comprises a rack  120  and four rack supports  122 . The four rack supports  122  extend from the bottom  108  and are each connected to two walls  110  at corners  118 . The four rack supports  122  extend a distance above the bottom  108 , such that the rack  120  is supported at a distance from the bottom  108 . 
     The rack  120  is U-shaped and sized to fit inside the enclosure  114 . The rack  120  has two long sides  124  and two short sides  126 . The rack  120  has two legs  128  extending from its long sides  124  adapted to be placed upon two of the four rack supports  122  each, such that the rack  120  is supported at a distance from the bottom  108 . The rack  120  functions to support the substantial weight of several concrete test cylinders (not shown). The rack  120  is made from a sheet of 14-gauge stainless steel which is bent to a U-shaped configuration to form the two legs  128 . Apertures  132  are then formed into a flat surface  130  in order to allow water passage therethrough. The rack  120  is sized to fit inside the enclosure  114 , such that when weight is placed upon the rack  120  it is supported by the legs  128  to prevent buckling of the rack  120 . The rack  120  separates the enclosure  114  into an upper portion and a lower portion which are in fluid communication with one another via its apertures  132 . 
     Referring now to  FIG. 2 , the temperature control system  106  comprises a heating element  138 , a cooling element  140 , and a temperature sensor  142 . The temperature control system  106  also has a control module (not shown) disposed inside the control panel assembly  116  of the box  102 . The heating element  138 , the cooling element  140 , and the temperature sensor  142  are disposed inside the lower portion of the enclosure  114  and extend parallel to the legs  128  of the rack  120 . The control module regulates the temperature inside the enclosure  114  by selectively activating the heating element  138  and/or the cooling element  140  in response to data received from the temperature sensor  142 , in order to maintain a pre-set temperature inside the enclosure  114 . 
     2. Detailed Description of the Inventive Concept(s) 
     Referring now to  FIGS. 3-4 , shown therein is an example of a curing box  150  constructed in accordance with the present disclosure. Generally the curing box  150  comprises a box assembly  152 , a temperature control assembly  154 , and a rack assembly  156 . 
     The box assembly  152  has a bottom  158 , walls  160 , a lid  162 , and a control module housing  164 . 
     The bottom  158 , walls  160 , and lid  162  cooperate to form a cavity  166 , which can be substantially watertight. The cavity  166  has a length x and a width y. The bottom  158  is preferably substantially rectangular in shape. The walls  160  may have one or more closeable drainage apertures (not shown) formed therein in order to selectively drain the water from the curing box  150  for easier transportation and/or storage. The bottom  158  may have one or more insulating layers therein and can be made of any non-corrosive material having sufficient strength and durability such as plastic for example. One or more optional casters (not shown) may be attached to the bottom  158  in order to allow the curing box  150  to be wheeled to a desired location. It is to be understood that the bottom  158  may have other suitable shapes and geometries as will become apparent to a person of ordinary skill in the art in light of the present disclosure. 
     The walls  160  preferably extend substantially vertically from the bottom  158 , and are preferably substantially perpendicular to one another and connect to one another at corners  168 . The walls  160  can be made of any suitable non-corrosive material having sufficient strength and durability such as plastic for example, and may have one or more insulating layers therein. It is to be understood that while four walls  160  are shown, the curing box  150  according to the inventive concept(s) disclosed herein can have any number of walls  160 , can be of any suitable size, and may have geometries other than substantially rectangular. Further, the walls  160  can be constructed from an opaque material to shield the cavity  166  from direct sunlight and, if used, radiant heating devices. 
     The lid  162  is preferably substantially rectangular in shape and is sized to span the distance between the walls  160 . The lid  162  can be removably positioned on top of walls  160 . The lid  162  may alternatively be pivotably or slidably connected to one or more of the walls  160 , such that it can be selectively opened and closed. The lid  162  can be made of any suitable non-corrosive material having sufficient strength and durability such as plastic for example, and may have one or more insulating layers built therein. The lid  162  can have an optional latch (not shown) which may be lockable to prevent tampering as well as an optional seal to reduce evaporation, but which is preferably not airtight to allow venting. Additionally, the lid  162  can be attached to one or more of the walls  160  by any other suitable means such as slides as will become apparent to a person of ordinary skill in the art in light of the present disclosure. 
     The control module housing  164  preferably comprises a box  170 , which is preferably attached to one of the walls  160  and may be disposed outside of the cavity  166 . The control module housing  164  functions to house components of the temperature control assembly  154  as will be discussed below. The control module housing  164  may also house any other components of the curing box  150  that are kept outside of the cavity  166  but should be protected from the environment. The control module housing  164  can be made of any suitable non-corrosive material such as plastic or galvanized steel for example, and may optionally be water and/or airtight. The control module housing  164  protects its contents from the environment and may have an optional latch  172 , which may be lockable to prevent tampering. The control module housing  164  may also have a transparent portion (not shown) such that readouts from a control module display (not shown) can be observed without opening the control module housing  164 . Additionally, the control module housing  164  may define one or more ports (not shown) in the surface thereof. Such ports can function to allow a power cord (not shown) to enter the control module housing  164 , or to allow other wired connections such as for example Ethernet cables, coaxial cables, or USB-cables. At least a portion of the control module housing  164  may optionally be permeable to wireless signals, to allow wireless communication with temperature control assembly  154 . 
     Referring now to  FIGS. 3-7C , the rack assembly  156  comprises a plurality of support members  174  and a rack  176 . 
     The plurality of support members  174  extend substantially vertically from the bottom  158 . Referring now to  FIGS. 4-5 , the plurality of support members  174  are shown as being disposed symmetrically about the bottom  158 . The plurality of support members  174  have one or more notches  178  formed therein to allow the passage of one or more heating element  192 , one or more cooling element  194 , and one or more fluid conduit  208  therethrough. 
     An exemplary embodiment of the plurality of support members  174  is shown in  FIG. 7B  as being T-shaped. The horizontal arm of the “T” is disposed on the bottom  158  of the box  150 , and the vertical arm of the “T” extends vertically therefrom and has the notch  178  formed therein and adapted to receive one or more of the heating element  192 , the cooling element  194 , and the fluid conduit  208 . 
     Another embodiment of the plurality of support members  174  is shown in  FIG. 7C  as being “V”-shaped. The “V” shape is positioned such that the arms of the “V” extend vertically from the bottom  158  of the box  150 , and the one or more notch  178  preferably formed into the point of the “V” allows the passage of one or more of the heating element  192 , the cooling element  194 , and the fluid conduit  208  therethrough. 
     The plurality of support members  174  are shown as T-shaped and/or V-shaped support members  174 , but it is to be understood that any suitable shapes can be used for the support members  174 , such as square, triangular, cylindrical, star-shaped, or elliptical for example. The plurality of support members  174  function to partially support the weight of the rack  176  and one or more concrete test specimens. The plurality of support members  174  can also function to suspend the temperature control assembly  154  a distance above the bottom  158  such that the components of the temperature control assembly  154  are held in a concentric coplanar orientation by the plurality of support members  174 . It is to be understood that while the plurality of support members  174  and the bottom  158  are shown as separate components, the plurality of support members  174  and the bottom  158  can alternatively be formed as a unitary structure. For example, one of the support members  174  can be a long piece of angle iron extending along the length and down the middle of the rack  176  that is perforated to allow for fluid circulation. 
     In general, the rack  176  is optional and may be eliminated if the temperature control assembly  154  is built into the bottom  158  and/or the walls  160  of the box  150 . The rack  176  can have a top surface  180 , a bottom surface  182 , and legs  184  extending substantially perpendicularly (e.g. between about 85-95 degrees) below the bottom surface  182 . The legs  184  may rest on the bottom  158  and can at least partially support the weight of the rack  176  and the concrete test cylinders (not shown) placed thereon. The legs  184  and the rack  176  can for example be formed by bending a single sheet of non-corrosive perforated rigid material such as stainless steel, or the legs  184  can be attached to the rack  176  by any suitable means such as welds, brackets, flanges, bolts, rivets, and adhesives for example. The bottom surface  182  can rest on one or more of the plurality of support members  174 , such that the rack  176  is at least partially supported by one or more of the plurality of support members  174 . While two legs  184  are shown in the FIGS., it is to be understood that varying numbers of legs  184  are contemplated for use with the inventive concept(s) disclosed herein, which legs  184  can have varying orientations and configurations. When the rack  176  is placed inside the box  150 , the rack  176  separates the box  150  into an upper portion  186  (see  FIG. 5 ) and a lower portion  188  (see  FIG. 5 ). The rack  176  can be made of a sheet of stainless steel having a gauge of less than 14 such as 16 gauge so that the rack  176  is less costly than the prior art rack  120 . The rack  176  can have a plurality of apertures  190  formed in the top surface  180  and/or the legs  184  thereof. The apertures  190  can have varying shapes and sizes and function to provide fluid communication pathways between the lower portion  188  and the upper portion  186  of the box  150 . The apertures  190  can be formed into the top surface  180  and/or legs  184  prior to forming the legs  184 , or alternatively after forming the legs  184 . Because the weight of the concrete cylinders is supported by the legs  184  and the plurality of support members  174 , the apertures  190  can comprise more than 50% of the surface of the rack  176 , such as for example between 50-70% to increase the amount of water circulation between the upper portion  186  and the lower portion  188  while still maintaining sufficient strength to support the test specimens. It has been found that when the rack  176  is constructed of perforated 14 gauge stainless steel, a suitable ratio of collective area for apertures/total surface area is 60%. However, this can be varied depending upon the type of material being used to form the rack  176 . For example, the ratio can be increased by using a smaller gauge (e.g., 12 gauge) of stainless steel. 
     The temperature control assembly  154  preferably comprises the heating element  192 , the cooling element  194 , a temperature sensor  196 , a circulator assembly  198 , a control module  200 , and a logger  202 . 
     The heating element  192  can be disposed in a lower portion  188  of the box  150  and is shown as a U-shaped tubular element extending inwardly from one of the walls  160  and disposed substantially parallel to the bottom  158 . The heating element  192  can be sized such that it spans more than 50% of the length x of the box  150 . In the embodiment shown, the heating element  192  is not supported by any of the support members  174 ; however, if additional support for the rack  176  is desired, then the heating element  192  can pass through the notches  178  within the support members  174 . In this embodiment, the support members  174  should be constructed of a material that will not be melted by the heating element  192 . The material can be a metal, such as stainless steel and/or a plastic having a melting point above a maximum temperature achieved by the heating element  192 . The heating element  192  can be any heating element known in the art such as a resistive heating element, Peltier-type heating element, a heat pump, and/or a heat exchanger for example. It is to be understood that while the heating element  192  is shown as a U-shaped element, suitable heating elements having varying shapes, sizes, and orientations can be used within the scope of the inventive concept(s) disclosed herein as will be apparent to a person of ordinary skill in the art in light of the present disclosure. Additionally, two or more heating elements  192  can be used rather than one heating element  192 . In an embodiment where the heating element comprises a Peltier heating element or a thermoelectric heat pump, the cooling element  194  may be omitted due to the ability of each device to both heat and cool. 
     The cooling element  194  can be disposed in the lower portion  188  of the box  150  and is shown as a U-shaped element extending inwardly from one of the walls  160  and disposed substantially parallel to the bottom  158 . The cooling element  194  can be sized such that it extends past 50% of the length x of the cavity  166 . The cooling element  194  preferably passes through one or more of the notches  178  formed in the plurality of support members  174  and is supported at a distance from the bottom  158  by one or more of the plurality of support members  174 . The cooling element  194  can be a U-shaped loop and can be sized to be smaller than the heating element  192 , such that the heating element  192  and the cooling element  194  are arranged in a coplanar concentric configuration. While the cooling element  194  is shown as a U-shaped element it is to be understood that cooling elements having varying shapes, sizes, and configurations can be used within the scope of the inventive concept(s) disclosed herein, as long as such cooling elements  194  function to dissipate heat from the box  150 . The cooling element  194  can be a Peltier-type cooling element, a heat sink, a heat pump, a heat exchanger, or can alternatively be a thermally-conductive conduit through which a refrigerant such as a refrigerant of the type R134a is circulated via a vapor-compression refrigeration system. Other suitable refrigerants, such as cool air, cold water, carbon dioxide (CO 2 ), chlorofluorocarbon (CFC) and/or hydrofluorocarbon (HFC) based compounds, ammonia, and nitrogen, for example, can alternatively be used with the inventive concept(s) disclosed herein. In one embodiment where a Peltier-type cooling element is used, the heating element  192  may be omitted due to the ability of the Peltier-type cooling element to both heat and cool in a single device. 
     The temperature sensor  196  is in thermal communication with the cavity  166  of the box  150 , such that the temperature sensor  196  is capable of measuring the temperature of the fluid inside the box  150  while the concrete test specimens are curing. The temperature sensor  196  can be partially or completely disposed inside the box  150  and is configured to communicate the measured data to the control module  200 . The temperature sensor  196  can be any temperature sensor known in the art such as a thermocouple or a thermistor for example. It is to be understood that more than one temperature sensor  196  can be used, and if two or more temperature sensors  196  are used they may be vertically and/or horizontally offset inside the cavity  166  of the box  150 . For example, one or more temperature sensors  196  may be disposed inside a lower portion  188 , and one or more temperature sensors  196  may be disposed in an upper portion  186  of the box  150 . 
     The circulator assembly  198  is adapted to circulate the fluid inside the box  150  to help provide a homogenous temperature distribution within the fluid. Preferably, the circulator assembly  198  circulates the fluid inside the box  150  without an impeller within a housing engaging the fluid surrounding the concrete test specimens, which improves the reliability of the circulator assembly  198  over prior art circulator assemblies. In one embodiment, the circulator assembly  198  comprises a fluid source  204 , and a fluid distribution assembly  206  positioned underneath the rack  176  to form bubbles which move the fluid through the rack  176  to circulate the fluid inside the box  150 . The rack  176  may form a convective barrier that causes stratification of the fluid within the cavity  166 . Preferably, the fluid distribution assembly  206  is positioned underneath the rack  176  and designed to force or move the fluid through the rack  176  to destratify the fluid. The fluid distribution assembly  206  can be implemented in other ways, such as a pump or an acoustic driver (not shown) providing electrically alternating current signals to one or more speaker (not shown) and/or solenoid (not shown) positioned in the bottom  158  and/or the walls  160  to introduce acoustic and/or pressure waves into the fluid. Alternatively, the fluid distribution assembly  206  can be positioned above the rack  176  to force fluid above the rack  176  to be underneath the rack  176  to reduce any stratification caused by the rack  176 . For example, the fluid distribution assembly  206  can include one or more pumps having inlet(s) positioned to receive fluid above the rack  176  and outlet(s) positioned to direct fluid underneath the rack  176 . 
     The fluid source  204  can circulate air or a gas within the fluid inside the box  150  to stir or mix the fluid. For example, the fluid source  204  can be an air pump capable of providing a certain volume of a gas or a liquid at a certain pressure which volume and pressure may vary according to the box  150  sizes and configurations. The fluid source  204  may have varying input capabilities in which case the fluid source may be controlled by the control module  200 . The fluid source  204  can be at least partially housed inside the control module housing  164 , housed in a separate housing (not shown) and/or housed inside the box  150 . The fluid source  204  is preferably positioned above the level of the liquid inside the box  150  in order to prevent backflow of liquid into the fluid source  204  when the fluid source  204  is not operating, or in case of a power failure. Alternatively, one or more one-way valves (not shown) can be used to prevent the backflow of liquid into the fluid source  204 . The air or gas that the fluid source  204  circulates within the fluid inside the box  150  can come from a variety of sources, such as ambient air, a compressed gas container, or the inside of the box  150  for example. When the air or gas circulated by the fluid source  204  comes from inside the box  150 , such air or gas may be obtained by a conduit (not shown) in fluid communication with the inside of the box  150  and the fluid source  204 , and installed such that it extends above the expected maximum level of the liquid inside the box  150 . This configuration would allow for the pressure inside the box  150  to remain substantially unchanged by the operation of the fluid source  204  as any air or gas that is be circulated within the fluid inside the box  150  would be withdrawn from the inside of the box  150  above the level of the fluid. The fluid source  204  is in fluid communication with the fluid distribution assembly  206  as will be described below. 
     The fluid distribution assembly  206  is immersed within the fluid inside the box  150  so that the air or gas provided by the fluid source  204  escapes from the fluid distribution assembly  206  to form bubbles in the fluid and thereby mix the fluid in the box  150 . The fluid distribution assembly  206  preferably comprises a fluid conduit  208 , and emitters  210 . 
     The fluid conduit  208  is disposed in the lower portion  188  of the cavity  166  and preferably extends substantially perpendicularly from the wall  160  adjacent to the control module  200 . The fluid conduit  208  can be attached to the wall  160 , or may extend through an aperture (not shown) formed into the wall  160 . The fluid conduit  208  is shown as a straight conduit extending over the center line of the bottom  158 , and sized to span about 90% of the length x of the cavity  166 . The fluid conduit  208  may extend substantially parallel to the bottom  158 , and can pass through one or more of the notches  178  formed in the plurality of support members  174 . The fluid conduit  208  may also be parallel to and disposed in a coplanar orientation relative to the heating element  192  and the cooling element  194 . The fluid conduit  208  has an open end to receive the air or gas, a closed end, a top surface  212  and a bottom surface  214  ( FIG. 7A ). 
     Referring now to  FIG. 7A , the emitters  210  are preferably disposed along the bottom surface  214  of the fluid conduit  208  so that bubbles emitted by the emitters  210  clean the fluid conduit  208  while also helping it prevent debris from entering or interfering with the emitters  210 . Three emitters  210  are shown in a group  216 , such that the emitters  210  are vertically and laterally offset from one another along the bottom surface  214  of the fluid conduit  208  although the number of emitters  210  in each group  216  may be more or less than three. Also, the relative positions of the emitters  210  can be changed. The emitters  210  are in fluid communication with the fluid conduit  208  and with the cavity  166 . Each group  216  can have one, two, three, or more emitters  210  disposed along the bottom surface  214  and/or other location on the fluid conduit  208 , such as the top surface  212 , and/or the side of the fluid conduit. The emitters  210  and the groups  216  are preferably positioned to cause mixing along the length and the width of box  150 . One arrangement that has been found especially desirable is to provide three groups  216  with one group  216  positioned substantially centrally on the fluid conduit  208 , and the other two groups  216  symmetrically offset therefrom along the fluid conduit  208  and positioned within a distance of about 25% of the length x of the box  150  from the walls  160  as shown in  FIG. 4 . It is to be understood that other arrangements for the emitters  210  may also be used. The emitters  210  can have varying shapes and sizes, can be grouped in groups of varying numbers, or ungrouped. It is to be also understood that emitters  210  can be disposed in varying directions and at varying positions along the fluid conduit  208 . An alternative embodiment (not shown) may have more than one fluid conduit  208 , and/or may have only a single emitter  210 . In another embodiment, the emitters  210  may comprise one or more air stones (not shown) or one or more nozzles (not shown). The gas and/or air may be heated or cooled as needed to substantially correspond to the temperature inside the box  150  prior to being introduced inside the box  150 . For example, the fluid source  204  can have an intake positioned inside the box  150  to receive gas and/or air from within the box  150 , but above the expected level of fluid within the box  150 , such that the air and/or gas is recirculated within the box  150 . Alternatively, the fluid source  204  can have an intake positioned outside of the box  150  to draw ambient air into the box  150 . In one embodiment, the walls  160  of the box  150  have a height and the intake is positioned above three-quarters of the height of the walls  160  to be above the expected level of fluid within the box  150 . It is to be understood that gasses other than air and/or liquids other than water are contemplated for use with the inventive concept(s) disclosed herein. 
     An exemplary embodiment of a control module  200  according to the inventive concept(s) disclosed herein is shown in  FIG. 9 . The control module  200  is adapted to control the heating element  192 , the cooling element  194 , and the circulator assembly  198 . The control module  200  is further adapted to receive and/or record data from the temperature sensor  196  and/or from the logger  202 , and/or from a match temperature sensor  217  (not shown). The control module  200  is at least partially housed inside the control module housing  164 . The control module  200  can have one or more processors  218 , one or more output devices  220 , one or more input devices  222 , and one or more memory devices  224 . The one or more processors  218  may be any processor known in the art such as one or more of: a Central Processing Unit (CPU), a microprocessor, a Field Programmable Gate Array (FGPA), or the like, or combinations thereof, for example. The one or more processors may function to control the operation of the temperature control assembly  154  and/or the circulator assembly  198  as will be described below. The one or more memory devices  224  can be a hard drive, a solid state drive, Random Access Memory (RAM), a flash memory, a floppy drive, or an Electronically Erasable Programmable Read-only Memory (EEPROM), or combinations thereof, for example. The one or more memory devices  224  can include a first memory device  224   a  and a second memory device  224   b . The second memory device  224   b  can be a removable memory device such that the second memory device  224   b  can be sent off-site to a quality control lab, for example, such that the quality control lab can access and verify data contained in the second memory device  224   b . The one or more memory devices  224  can store computer executable code and/or other data. The computer executable code stored in the one or more memory devices  224  can be accessed by the one or more processor  218  to obtain the data stored therein in situ, or over a network such as a Local Area Network (LAN), wireless network, or the Internet. Data contained in the one or more memory devices  224  may also be remotely accessible over a network such as LAN, a cellular phone network, a Wi-Fi network, or the Internet, for example, by using a transceiver  226 . The control module  200  can monitor the temperature inside the box  150  via the temperature sensor  196  in real time and adjust the heating element  192  and/or the cooling element  194  accordingly via a heating element system  227  and/or a cooling element system  228 . The heating element system  227  can be provided with relays, circuitry and/or controllers to adjust the heat being generated and/or absorbed by the heating element  192 . The cooling element system  228  can function based upon the principles of absorption, heat pump cycles, or refrigeration cycles, and may include components such as one or more compressor, heat pump, condenser, expansion valve, evaporator, controller and/or other devices and/or circuitry working together to adjust the heat absorption of the cooling element  194 . 
     If the temperature inside the box  150  is higher than the preset temperature, the control module  200  can deactivate the heating element  192  and/or activate the cooling element  194 . If the temperature inside the box  150  is lower than the preset temperature, the control module  200  can deactivate the cooling element  194  and/or activate the heating element  192 . If the temperature inside the box  150  is equal to the preset temperature, or falls within an acceptable tolerance window, the control module  200  can deactivate both the cooling element  194  and the heating element  192 . The control module  200  can operate the circulator assembly  198  continuously or intermittingly throughout the curing process. Alternatively, the circulator assembly  198  may be controlled and operated by a separate control module (not shown) such as an on/off switch for example. 
     The output device  220  can be a Light Emitting Diode display (LED), a Liquid Crystal Display (LCD), a touchscreen display, an analog temperature gauge, or a digital temperature gauge, for example. The control module  200  can produce audible and/or visible alert signals when the temperature inside the box  150  varies from a pre-set value and/or tolerance, such as 73° F.±3° F., for example. The alert signal can be displayed such that it is visible to a worker observing the box  150 , or can be transmitted to a location remote from the box  150  to an onsite construction office, or to an off-site control center. A user may manually adjust the temperature inside the box  150  via the input device  222 , or pre-set a temperature to be automatically maintained by the control module  200  inside the box  150 . The processor  218  may also execute instructions to enable a user to adjust and/or monitor the temperature inside the box  150  remotely over a network such as a wireless network, a LAN, a telephone network, the Internet, and/or a cellular network. For example, the processor  218  can be programmed to host a web-site having a Uniform Resource Locator and/or an IP address accessible via the Internet to permit the user to adjust and/or monitor the temperature. Further, the processor  218  may receive a temperature log from an in-situ specimen and/or the input device  222  and/or a remote network and control the temperature inside the box  150  to substantially correspond to the temperature log. 
     The control module  200  can be powered by any suitable power source, such as one or more of: a conventional/rechargeable battery, a car battery, a solar cell, a portable generator, and/or by the electrical grid. Power source redundancy can be assured, for example, by having a primary power source and one or more backup power sources to endure power throughout the curing process. The control module  200  can preferably encrypt data before recording and/or transmitting it to ensure data integrity. 
     The control module  200  may be programmed to facilitate match curing in a new and inventive way. Match curing is a concept known in the art in which a controller is utilized to read temperatures from an in-situ curing concrete mass, such as a road, and a temperature sensor on the concrete specimen curing in a dry environment. The controller regulates a heating element connected to a metal mold of the concrete specimen so that the temperature of the concrete specimen substantially corresponds to the temperature of the in-situ curing concrete mass. In accordance with the present disclosure, the match temperature sensor (not shown) can be mounted in or on an in-situ curing concrete mass, such as a road, while one or more concrete test specimens are cured within the box  150  in a wet environment. The control module  200  is programmed and operated to cause the temperature within the fluid of the box  150  (as read by the temperature sensor  196 ) to substantially correspond to the temperature of the in-situ concrete mass read by the match temperature sensor (not shown). Thus, in the present disclosure, the temperature of the concrete test specimens is regulated indirectly in a wet environment via temperature readings and temperature control of the fluid in a new and inventive manner. 
     Referring now to  FIGS. 10A and 10B , the logger  202  can be a data logger that is adapted to record at least one data input. The logger  202  can be partially or completely housed inside the control module housing  164 . The logger  202  can be adapted to log temperature and/or other data from the temperature sensor  196  and/or the logger  202  can be a totally separate from the control module  200  and/or have a temperature sensor  230  separate from the temperature sensor  196 . The logger  202  can be a sensor/recorder device which monitors and logs certain variables inside the box  150 , such as temperature, pH, etc. The data can be extracted from the logger  202  and used to assess the compliance of this particular process batch with applicable ASTM or other standards, or contractor requirements. In order to ensure quality control, the data recorded in the logger  202  can be encrypted and/or unalterable once recorded by the logger  202 . The data can be extracted and/or transmitted to an external device  233  and sent to a remote location and decrypted/verified by an independent quality control entity and/or the project managers. Exemplary embodiments of the external device  233  are described in U.S. Pat. No. 6,865,515, which is incorporated herein by reference. 
     In one embodiment shown in  FIG. 10B , the logger  202  may comprise a separate device, which is simply placed, lowered, or dropped inside the cavity  166  such that the logger  202  is in thermal communication with the liquid inside the box  150 . In another embodiment, the logger  202  may be a separate device suspended inside the cavity  166  by use of wires, ropes, strings, or chains for example, such that the logger  202  is in thermal communication with the liquid inside the box  150 . 
     The logger  202  can optionally save such data on a removable memory (not shown), and/or can transmit and/or receive data to the external device  233  wirelessly and/or over a network such as a LAN or the Internet via a wireless or wired transceiver. Additionally, the logger  202  may also receive and log data from thermometers and/or humidity sensors embedded in the main concrete body, and may cooperate with the control module  200  to maintain the concrete test specimens at the same temperature as the main concrete body, in order to obtain more representative test specimens. The logger  202  may be powered by one or more of: a conventional/rechargeable battery, a car battery, a solar cell, a portable generator, or by the electrical grid in order to provide for uninterrupted data logging throughout the curing process. Power supply redundancy can be built in for example by securing one primary and one or more secondary power sources for the logger  202 . Examples of a suitable logger  202  are described in U.S. Pat. No. 6,865,515. 
     The logger  202  can include at least one temperature sensor  230 , a first memory device  232 , one or more processor  234 , and a power source. The first memory device  232  may be one of several memory devices, such as a RAM device within a computer, flash memory, or a EEPROM. Within the logger  202 , the temperature sensor  230  is connected to the processor  234  preferably by a signal conditioning circuit  236  and/or an Analog to Digital (A/D) converter  238 . The temperature sensor  230  is typically a thermistor for which the electrical resistance changes in an electrical circuit based on the changes of temperature sensed. The temperature sensor  230  sends temperature dependent data signals to the processor  234  for processing. The processor  234  may be any processor known in the art, such as one or more microprocessor, a CPU, one or more FGPA, a microcontroller, and/or combinations thereof, for example. The logger  202  may be housed inside the control module housing  164 , or may be housed in a separate housing (not shown). The logger  202  may be a part of the control module  200  such that the logger  202  receives data from the temperature sensor  196 . Alternatively, the logger  202  may be a separate device. It is to be understood that more than one logger  202  may be used with the inventive concept(s) disclosed herein. 
     In operation, the curing box  150  preferably operates as follows: one or more concrete test cylinders (not shown) are placed inside the box  150  onto the rack  176 . The box  150  is filled with water or another suitable liquid. The lid  162  is closed, and the control module  200  is operated to set the temperature inside the box  150 . It is to be understood that the box  150  may alternatively be filled with liquid and heated/cooled to a desired pre-set temperature prior to inserting the concrete test cylinders inside the box  150 . The circulator assembly  198  can be operated to circulate the liquid inside the box  150 , by pumping air, or another suitable gas/liquid through the fluid conduit  208  and the emitters  210 . Gas bubbles can rise upward from the lower portion  188 , through the apertures  190  of the rack  176 , and through the upper portion  186 . The gas bubbles rising through the liquid inside the box  150  can cause the liquid to be circulated throughout the box  150 . The box  150  may be locked or sealed while the concrete inside the concrete test cylinders cure, which typically takes about twenty eight days. Once the concrete has cured, the concrete test cylinders are removed from the box  150 , and are sent to an off-site location for quality control and/or concrete strength testing. The data recorded by the logger  202  can also be sent to the control lab with the concrete test cylinders to establish proper on-site handling procedures. 
     The curing box  150  is preferably designed to meet applicable industry standards. For example, Section 929.03.6 of Rhode Island&#39;s requirements for wet concrete curing boxes lists the following requirements: approximate internal dimensions of 54 inches in length; 18 inches in width; and 17 inches in depth. The requirements specify that the box must be insulated, hinged at the back, and have a lock at the front; be leak-proof and be able to hold a pool of water at the bottom of the cavity approximately 4 inches deep. The requirements further specify a drainpipe provided through the side of the box for maintenance purposes. Suitable means of support are required to hold the concrete cylinders above the water surface. A thermometer which can be read from the outside is also required to be installed to measure the internal temperature of the box. A thermostat is required to maintain the water at a uniform temperature of 73° F.±3° F. using heating or cooling cycles throughout an ambient temperature range of −10° F. to 100° F. The requirements in Rhode Island also state that a concrete curing box of a design and manufacture different from that described above, but which possesses equal characteristics may be employed provided that it is approved in writing by an engineer in charge of the project. 
     As another example, the State of Georgia requires a curing box constructed of non-corroding materials and capable of storing a minimum of 22 concrete test cylinders measuring 6 inch×12 inch (150 mm×300 mm) each, to be stored vertically with the lid closed. Additionally, Georgia requires that the wet curing box meets the moisture and temperature requirements of AASHTO T-23. 
     As yet another example, the State of Alabama has similar test cylinder capacity requirements for wet concrete curing boxes, but further requires approval by a Materials and Tests Engineer prior to beginning any concrete placement. 
     It is to be understood that the above requirements are exemplary only, and are not to be construed as limitations on the size or configurations of embodiments of the inventive concept(s) disclosed herein. It is to be further understood that other public and/or private entities, as well as other national and international bodies may specify different requirements for wet concrete curing boxes, which requirements can be implemented in the curing box  150  without departing from the scope of the inventive concept(s) disclosed herein. 
     An exemplary embodiment of a retrofitted curing box  240  having a circulator assembly  198  according to the inventive concept(s) disclosed herein is shown in  FIG. 11 . Generally, the retrofitted curing box  240  comprises a prior art curing box  100  which further comprises a retrofitted circulator assembly  198  as described herein above. Most existing prior art curing boxes  100  can easily be retrofitted with a circulator assembly  198  as disclosed herein with minimal investment of effort and money. The choice of an appropriate fluid source size, fluid conduit sizes, numbers and configurations, and emitter sizes, number, and configurations, will be dependent upon the size of the curing box  240  and can be determined by a person of ordinary skill in the art without undue experimentation when presented with the instant disclosure. 
     In order to demonstrate the reduced temperature stratification provided by the present disclosure, the temperature in a prior art curing box and a curing box constructed according to the present disclosure were equalized at 73 degrees. Ten concrete cylinder specimens were placed in each curing box along with IntelliRock™ brand loggers to monitor temperatures at the top and the bottom of each curing box, and in two specimens in each curing box. The specimens were left in each curing box for 18 hours. 
     After 18 hours, the digital display for each curing box indicated the internal temperature was 73 degrees. However, the actual temperature at the top of the prior art curing box was 76.5 degrees, while the actual temperature at the top of the inventive curing box was 73.2 degrees. The specimens in the prior art curing box had a temperature of 78.1 degrees with the temperature decreasing to 72.5 at the bottom of the specimens. The specimens in the inventive curing box had an even temperature from top to bottom of 74.7 degrees. 
     Reduction in temperature stratification is also shown in  FIGS. 12A and 12B .  FIG. 12A  provides a graphical plot of temperature versus time including temperatures measured at the top, at the center, at the rack, and at the temperature sensor of a prior art curing box during curing.  FIG. 12B  provides a graphical plot of temperature versus time including temperatures measured at the top, at the center, at the rack, and at the sensor of the inventive curing box during curing. The temperature plots depicted in  FIG. 12A  show variations in the magnitude of the temperature measured each location, while the temperature plots of  FIG. 12B  are substantially similar in magnitude at each location. Thus,  FIG. 12B  demonstrates the ability of the inventive curing box to avoid temperature stratification. 
     From the above description, it is clear that the inventive concept(s) disclosed herein is well adapted to carry out the objects and to attain the advantages mentioned herein as well as those inherent in the inventive concept(s) disclosed herein. While presently preferred embodiments of the inventive concept(s) disclosed herein have been described for purposes of this disclosure, it will be understood that numerous changes may be made in the construction and the operation of the various components, elements and assemblies described herein, and/or in the steps or the sequence of steps of the methods described herein, which will readily suggest themselves to those skilled in the art and which are accomplished within the scope of the inventive concept(s) disclosed and claimed herein.