AU2022200950A1 - Systems and methods for curing concrete - Google Patents

Abstract

A system for curing concrete is disclosed. The system comprises: a pipe circuit comprising a temperature control element configured to be embedded within concrete, wherein the pipe circuit is configured to be in fluid communication with a heating fluid source and a cooling fluid source; a pump system to direct fluid flow through the pipe circuit, the pump system comprising: a pump; a first valve configured to control flow of heating fluid pumped from the heating fluid source; and a second valve configured to control flow of cooling fluid pumped from the cooling fluid source; a temperature sensor module configured to measure concrete temperature information at first and second locations of the concrete; and a controller in communication with the temperature sensor module and the pump system, the controller configured to control operations of the pump system based on the concrete temperature information to heat and cool the temperature control element to cure the concrete. 2/13 100 Heating fluid source 150 Heating Heating fluid mechanism 156 return valve 154B Heating fluid tank Heating fluid 152 return valve 154A Concrete 102 Controller L Temperature 140 sensor module 130 Pump system 12013 Processor 142 12 Pump 122e Pipe circuit 110 Ote Memory 144 IltOte -eoy1 114A -Mo Temperature - 1 116A First valve 124 control Failsafe 146 Inlet element 112 - Outlet 114B 116B Second valve 126 ---- --- Coolingfluid source160 Cooling fluid tank Cooling fluid 162 return valve 164A Userinterface Cooling Cooling fluid 170 mechanism166 return valve 164B Fig.1B

Description

2/13

100

Heating fluid source 150

Heating Heating fluid mechanism 156 return valve 154B

Heating fluid tank Heating fluid 152 return valve 154A

Concrete 102

Controller L Temperature 140 sensor module 130 Pump system 12013 Processor 142 12 Pump 122e Pipe circuit 110 Ote Memory 144 IltOte -eoy1 114A -Mo Temperature - 1 116A First valve 124 control Inlet element 112 - Outlet Failsafe 146 114B 116B Second valve 126 ---- ---

Coolingfluid source160

Cooling fluid tank Cooling fluid 162 return valve 164A

Userinterface Cooling Cooling fluid 170 mechanism166 return valve 164B

Fig.1B

"Systems and methods for curing concrete"

Technical Field

[0001] The present disclosure relates to systems and methods for curing concrete.

Background

[0002] Reinforced concrete is widely used in building and infrastructure construction. To achieve the design strength specified in the relevant building and structural codes, the concrete generally needs to be cured for several days depending on site and environmental conditions. In some instances, it can take at least seven days for the concrete to reach roughly 80% of its design strength.

[0003] The duration of time for which the concrete needs to cure affects the completion schedule for the project. For example, in road projects a section of road may need to be closed or narrowed to allow the works to be performed. If the curing time of the concrete can be reduced while still safely achieving the required design strength, the project can be completed sooner. This reduces inconvenience and/or loss of revenue while the road is out of service.

[0004] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

[0005] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Summary

[0006] Some embodiments relate to a system for curing concrete, the system comprising: a pipe circuit comprising a temperature control element configured to be embedded within concrete, wherein the pipe circuit is configured to be in fluid communication with a heating fluid source and a cooling fluid source; a pump system to direct fluid flow through the temperature control element of the pipe circuit, the pump system comprising: a pump; a first valve configured to control flow of heating fluid pumped from the heating fluid source; and a second valve configured to control flow of cooling fluid pumped from the cooling fluid source; a temperature sensor module configured to measure concrete temperature information at first and second locations of the concrete; and a controller in communication with the temperature sensor module and the pump system, the controller configured to control operations of the pump system based on the concrete temperature information to heat and cool the temperature control element to cure the concrete.

[0007] The heating fluid source may comprise: a heating fluid reservoir for receiving the heating fluid; and a heating mechanism for heating and maintaining the heating fluid contained in the heating fluid reservoir at a heating fluid temperature.

[0008] The cooling fluid source may comprise: a cooling fluid reservoir for receiving the cooling fluid; and a cooling mechanism for cooling and maintaining the cooling fluid contained in the cooling fluid reservoir at a cooling fluid temperature.

[0009] The temperature sensor module may comprise a first temperature sensor configured to measure temperature at the first location of the concrete, and a second temperature sensor configured to measure temperature at the second location of the concrete.

[0010] The first temperature sensor maybe configured to measure temperature adjacent to the temperature control element, and the second temperature sensor may be configured to measure temperature spaced away from the temperature control element.

[0011] The temperature sensor module may further comprise a plurality of temperature sensors configured to be spaced apart within the concrete.

[0012] The controller maybe configured to determine, based on the concrete temperature information, at least one of the following measurements: i.concrete maturity; ii.a concrete temperature increase rate; iii.a concrete temperature decrease rate; and iv.a concrete temperature differential.

[0013] The controller maybe configured to determine a compressive strength of the concrete based on:

F,'= a In e Ta- Ts At) -b

wherein: F1' compressive strength a calculated rate of change of compressive strength to equivalent age Q activation energy Ta average temperature (in degrees Kelvin) of concrete during time interval T, =specified temperature (in degrees Kelvin) At time interval (days or hours) b = calculated compressive strength constant

[0014] The controller maybe configured to: i.operate the first valve of the pump system until the compressive strength reaches a predetermined compressive strength threshold, and ii.responsive to the compressive strength reaching the predetermined compressive strength threshold, operate the second valve of the pump system.

[0015] The compressive strength of the concrete maybe determined atpredetermined intervals.

[0016] The controller may determine the measurements at predetermined intervals.

[0017] The controller being configured to determine the concrete temperature differential may comprise calculating the difference between the concrete temperatures at the first and the second locations at a specific time.

[0018] The controller maybe configured to operate a failsafe to prevent a temperature of the concrete exceeding a predetermined maximum temperature, wherein the failsafe closes the first valve. The failsafe may open the second valve.

[0019] The pipe circuit maybe configured to circulate the heating fluid and the cooling fluid through the temperature control element and return the fluids to the heating and cooling fluid sources respectively.

[0020] The system may further comprise an insulation material for the concrete. The insulation may be a layer of insulating material. The insulation may be a ceramic coating. The insulation may have a thermal conductivity of approximately 0.021 W/m/degrees Celsius.

[0021] The pipe circuit may comprise a first circuit portion and a second circuit portion, the first circuit portion may be configured to be disposed within the concrete at the first location, and the second circuit portion may be configured to be disposed within the concrete at the second location.

[0022] The first and second circuit portions may not be in fluid communication with each other to enable independent heating and cooling of the first and second circuit portions. The first and second circuit portions may comprise a coiled arrangement. The first circuit portion may be nested within the second circuit portion.

[0023] The pipe circuit may comprise pipe having a diameter of 20mm.

[0024] The pump and controller may be mounted on a mobile vehicle.

[0025] Some embodiments relate to a controller configured to control a process for curing concrete, the controller configured to communicate with a pump system for directing fluid flow through a pipe circuit at least partially embedded within concrete, and to communicate with a temperature sensor module configured to measure temperature at a plurality of locations in the concrete, the controller comprising: one or more processors; and memory, accessible to the one or more processors, and comprising computer executable instructions, which when executed by the one or more processors, cause the controller to: receive, from the temperature sensor module, concrete temperature information; determine, based on the concrete temperature information, a compressive strength of the concrete; and operate the pump system until the compressive strength of the concrete reaches a predetermined compressive strength threshold.

[0026] Determining the compressive strength of the concrete may comprise using at least one of the following measurements: i. concrete maturity; ii. a concrete temperature increase rate; iii. a concrete temperature decrease rate; and iv. a concrete temperature differential.

[0027] Some embodiments relate to a method of curing concrete, the method comprising: pouring concrete into formwork to define a concrete structure, wherein a portion of a pipe circuit is embedded in the concrete; leaving the concrete to mature for a maturity time; heating the concrete by flowing a heating fluid through the pipe circuit; measuring a first concrete temperature of the concrete structure adjacent to the pipe circuit; measuring a second concrete temperature of the concrete structure remote to the pipe circuit; determining, based on the first and second concrete temperatures: i. concrete maturity; ii. a concrete temperature increase rate iii. a concrete temperature decrease rate; and iv. a concrete temperature differential; controlling the heating fluid temperature so that: i. the concrete temperature increase rate does not exceed a predetermined temperature increase rate; and ii. the concrete temperature differential does not exceed a predetermined temperature differential; calculating a compressive strength of the concrete based on the concrete maturity; when a compressive strength threshold is reached, cooling the concrete by flowing a cooling fluid through the pipe circuit, the cooling fluid having a cooling fluid temperature; controlling the cooling fluid temperature so that: i. the concrete temperature decrease rate does not exceed a predetermined temperature decrease rate; and ii. the concrete temperature differential does not exceed the predetermined temperature differential; and stopping the cooling when the concrete temperature is within a predetermined temperature range of ambient temperature.

[0028] The flowing of the heating fluid and the flowing of the cooling fluid may be alternated.

[0029] The flowing of the heating fluid may be directed into a first circuit portion of the pipe circuit, and wherein the flowing of the cooling fluid may be directed into a second circuit portion of the pipe circuit, the first and second circuit portions not being in fluid communication so that the flowing of the heating fluid and the flowing of the cooling fluid occurs simultaneously.

[0030] The predetermined temperature increase rate may be 24°C per hour.

[0031] The predetermined temperature differential maybe 20°C.

[0032] The predetermined temperature decrease rate may be 30°C per hour.

[0033] The predetermined temperature range may be 30°C.

[0034] Some embodiments relate to a concrete structure produced using the system as described above, the controller as described above, or the method as described above.

Brief Description of Drawings

[0035] Fig. 1A is a schematic of a system for controlling temperature in concrete as it cures, according to some embodiments;

[0036] Fig. 1B is a schematic of a system for controlling temperature in concrete as it cures, according to some embodiments;

[0037] Fig. 2 is a perspective view of a concrete column indicating example placement of a temperature control element of the system of Fig. 1A or IB, according to some embodiments;

[0038] Fig. 3 is a first cross section view of a concrete column indicating example placement of a temperature control element of the system of Fig. 1A or IB, and temperature sensors, according to some embodiments;

[0039] Fig. 4A is a second cross section view of a concrete column indicating example placement of a temperature control element of the system of Fig. 1A or IB, and temperature sensors, according to some embodiments;

[0040] Fig. 4B is a graph showing temperature data obtained during test curing of a concrete column using the system of Fig. 1A or IB, according to some embodiments;

[0041] Fig. 4C is a graph showing temperature differential data obtained during test curing of a concrete column using the system of Fig. 1A orIB, according to some embodiments;

[0042] Fig. 4D is a graph showing 15 minute temperature change data obtained during test curing of a concrete column using the system of Fig. 1A orIB, according to some embodiments;

[0043] Fig. 4E is a graph showing hourly temperature change data obtained during test curing of a concrete column using the system of Fig. 1A orIB, according to some embodiments;

[0044] Fig. 4F is a graph showing water inlet/outlet temperature differential data obtained during test curing of a concrete column using the system of Fig. 1A or IB, according to some embodiments;

[0045] Fig. 4G is a graph showing core-ambient temperature comparison data obtained during test curing of a concrete column using the system of Fig. 1A or 1B, according to some embodiments;

[0046] Fig. 4H is a graph showing a maturity curve for test curing of a concrete column using the system of Fig. 1A or 1B, according to some embodiments; and

[0047] Fig. 5 is a graph showing a method for curing of a concrete column using the system of Fig. 1A or 1B, according to some embodiments;

Detailed Description

[0048] The present disclosure relates to systems and methods for curing concrete. The curing process is a balance between moisture/humidity and temperature over time. Controlling these variables allows the concrete to reach the desired strength and durability. Some methods for accelerating the curing process include steam curing and radiant curing. Steam curing involves the application of steam to concrete in a steam chamber or enclosure. Radiant curing involves the application of heat from heating elements adjacent to the concrete.

[0049] Concrete hardens by the hydration of cement, which is greatly exothermic (generates heat/energy while occurring) at the initial stage while forming Tricalcium Silicates and is thermo-activated (reaction accelerates in the presence of heat). The heat from the reaction is usually lost to the environment within 24-48 hours depending on weather conditions and formwork used. This energy loss lowers the temperature of the concrete and slows down the hydration reaction and the strength gain. If the energy from the hydration can be limited from escaping, and additional energy is provided to the system, this can accelerate the reaction further, and therefore accelerate the strength gain of concrete.

[0050] Concrete maturity testing is one method of determining concrete strength. Maturity testing considers the relationship between the age of the concrete and cumulative temperature, and uses this to calculate an estimated compressive strength of the concrete. Other methods of determining concrete strength include destructive testing of concrete test cylinders.

[0051] The system and method maybe used in conjunction with other curing techniques to maintain the humidity of the concrete as it cures. For example, the concrete may be covered with tarpaulin/plastic sheets or sprayed with water to mitigate moisture loss from the concrete as it cures. An example of such sheets is Pavecure A or W supplied by Aitken Freeman. Parchem and Sika also produce similar sheets.

[0052] The desired strength of the concrete may vary depending on the project requirements. In some instances, the concrete may only need to be cured to within a certain range of its final compressive strength to allow subsequent steps in the construction to occur. For example, the concrete may only need to be brought within 80% of its final compressive strength, at which point the concrete is strong enough to be loaded onto a truck for transport from the factory to the worksite.

[0053] Different projects may also have different technical requirements. In Victoria, Australia, the relevant technical requirements for road projects are prepared by the Victorian road authority (VicRoads). For structural concrete, VicRoads specifies technical constraints in Technical Specification Section 610. Some of these constraints are listed in Table 1 below. VicRoads Specification 610 allows the use of concrete maturity testing in lieu of test cylinders.

Table 1

Vicroads Specification 610 Clause Constraint and Comment 610.23 CURING (h) Radiant Heat Curing (iii) The water temperature shall be controlled by Temperature Controls a thermostat and shall not exceed 70°C 610.23 CURING (h) Radiant Heat Curing (iii) The corresponding maximum temperature of Temperature Controls the concrete shall not exceed 75°C 610.23 CURING (i) Delayed Ettringite Formation 610.22 CONTROL OF EARLY AGE The temperature differential across the THERMAL CRACKING OF LARGE AND concrete member being constructed shall not RESTRAINED MEMBERS exceed 20°C during the period of curing. 610.23 CURING (g) Steam Curing (iii) Steam/radiant heat curing shall continue at a Curing Cycle rate such that the concrete temperature rise 610.23 CURING (h) Radiant Heat Curing (ii) shall not exceed 24°C per hour. Curing Cycle In addition, the temperature rise in any one fifteen minute period shall not exceed 6°C.

610.23 CURING (g) Steam Curing (iii) Steam/radiant heat curing covers shall not be Curing Cycle removed nor any part of the concrete units 610.23 CURING (h) Radiant Heat Curing (ii) and test cylinders disturbed or operated upon Curing Cycle in any way until the temperature under the steam covers has fallen to within 30°C of the ambient temperature. The rate of loss of temperature under the covers after shutting off system shall not exceed 30°C per hour. This may help reduce the likelihood of concrete cracking. 610.23 CURING (g) Steam Curing (vi) Steam/radiant heat curing shall be Extent of Steam Curing continuously applied until at least the 7 day 610.23 CURING (h) Radiant Heat Curing (v) compressive strength for the specified Extent of Radiant Heat Curing concrete grade is obtained. 610.23 CURING (g) Steam Curing (iii) After an initial 'maturity' of 40°C hours, but Curing Cycle not less than two hours after batching the last 610.23 CURING (h) Radiant Heat Curing (ii) batch of concrete for the units, steam/water Curing Cycle will be admitted to the systems. 610.23 CURING (h) Radiant Heat Curing (iii) The temperature difference between ingoing Temperature Controls and outgoing water shall be maintained at less than 10°C 610.23 CURING (h) Radiant Heat Curing (iii) Monitor the temperature of the test cylinder Temperature Controls heating box by means of a recording thermometer. The difference in temperature between the test cylinder heating box and any point along the hot water heating system shall not exceed 10°C. 610.23 CURING (h) Radiant Heat Curing (ii) The top surface of the finished concrete shall Curing Cycle be kept moist throughout the curing cycle. 610.23 CURING (g) Steam Curing (iv) The following information shall be recorded: Temperature Controls 1. Date on which steaming/Radiant Heat 610.23 CURING (h) Radiant Heat Curing (iii) Curing commenced Temperature Controls 2. Unique identification and description of concrete unit

3. Temperature correction, if any 4. Time correction, if any 5. Batching of concrete 6. Temperature of concrete when placed 7. Ambient temperature at time of removal of steam covers 8. Name of Contractor or manufacturer. 610.23 (g) Steam Curing (viii) Curing of Test Concrete cylinders shall be placed near Cylinders concrete units and cured prior to sending to approved laboratory

[0054] These parameters may change subject to environmental parameters or technical developments. For example, for one VicRoads project, an exemption was obtained from the constraints in 610.25 Table 610.251, allowing the "Minimum Period before Removal of Formwork and Formwork Supports" for concrete soffits to change from 7 days elapsed to 80% F'c (compressive strength).

[0055] The minimum compressive strength requirements for each concrete grade are shown in VicRoads Specification 610 Table 610.051, reproduced below.

Table 610.051 Concrete Minimum Compressive Strength (MPa)

Grade 3 days 7 days 28 days

VR330/32 14 20 32

VR400/40 17 26 40

VR450/50 23 35 50

VR470/55 25 40 55

VR520/60 27 45 60

VR535/65 29 48 65

VR550/70 31 52 70

VR580/80 34 60 80

VR610/90 38 67 90

VR640/100 42 75 100

[0056] The present disclosure relates to a system and method of controlling the temperature of the concrete during the curing process. Described embodiments involve using a pump system to pump heated fluid and cooled fluid into a temperature control element embedded within the concrete to accelerate and maintain the exothermic reaction. The formwork supporting the concrete may be insulated to control the temperature loss of the concrete. Embodiments of the system and method may accelerate the curing process. Embodiments of the system and method may achieve the target design strength in a reduced timeframe compared to conventional accelerated curing techniques. This may allow the early removal of formwork from the concrete members, for example when the concrete has become self-supporting.

[0057] Fig. 1A is a schematic of a system 100 for curing concrete 102, according to some embodiments. The system 100 comprises a pipe circuit 110, a portion 112 of which is configured to be embedded within concrete 102 to be cured. The pipe circuit 110 is arranged to be in fluid communication with a heating fluid source 150 and a cooling fluid source 160. The system 100 comprises a pump system 120 for controlling fluid flow through the pipe circuit 110 and within the concrete 102. The system 100 comprises a temperature sensor module 130 for monitoring temperature information at a plurality of sites or locations at (i.e. on and/or within) the concrete 102. The system 100 comprises a controller 140 to communicate with the temperature sensor module 130 arranged to measure concrete temperature at a plurality of locations of the concrete 102 and to cooperate with the pump system 120 to control fluid flow through the embedded portion 112 to control the temperature of the concrete 102 during the curing process.

[0058] In some embodiments, the pump system 120 and the controller 140 are portable or mobile, and may be provided within a truck, to allow the system 100 to move between worksites. Once curing begins, at least the embedded portion 112 of the pipe circuit 110 and the temperature sensor module 130 remain within the concrete structure at the worksite. Accordingly, the other components of the system 100, for example, non-embedded portions of the pipe circuit 110, the heating fluid source 150, cooling fluid source 160, the pump system 120 and/or the controller 140, may be decoupled or disconnected from the components arranged to remain in the concrete 102 once cured (for example, leaving the embedded portion of the pipe circuit 110 and/or the temperature sensor module 130).

[0059] The pipe circuit 110 comprises a pipe wall which defines a lumen therein. The pipe circuit 110 is configured to be in fluid communication with a fluid source. Fluid from the fluid source may be conveyed or flow through the lumen of the pipe circuit 110. The fluid may be a heating fluid from the heating fluid source 150. The fluid may be a cooling fluid from the cooling fluid source 160. The heating fluid heats up the pipe wall as it passes through the lumen of the pipe circuit 110. Similarly, the cooling fluid cools the pipe wall as it passes through the lumen of the pipe circuit 110.

[0060] The heating fluid may be hot water, hot oil, and/or steam. In some embodiments, the cooling fluid may be a mixture, such as water with a coolant added to it. The cooling fluid may be a gas, such as cold air and/or a refrigerant. The temperature of the heating and cooling fluid is selected to respectively heat and cool the concrete in a gradual and controlled manner. For example, the VicRoads Specification 610 defines the maximum rate at which the concrete temperature can increase to a maximum of 24 degrees an hour and six degrees in any 15 minutes. This is because a sudden increase in concrete temperatures can lead to the inadequate hydration of the cement, and a more porous (i.e. weaker) concrete as a result. Furthermore, a sudden change in temperature may result in a large temperature differential between different parts of the concrete and cracking occurring.

[0061] The pipe circuit 110 comprises several sections, including the embedded portion 112 (which may alternatively be referred to as a temperature control element 112), an inlet portion 114, and an outlet portion 116. The temperature control element 112, inlet portion 114, and outlet portion 116 may be coaxial. In some embodiments, the temperature control element 112 may branch out from the inlet portion 114 and reconnect at the outlet portion 116. The different sections of the pipe circuit 110 may be formed from an interconnected plurality of tubes, hoses, and/or conduits. All or part of the pipe circuit 110 may be rigid or flexible depending on the shape required.

[0062] The temperature control element 112 is configured to be heated and/or cooled by the fluid passing therethrough so as to heat and/or cool its surroundings. In some embodiments, the pipe circuit 110 comprises a plurality of the temperature control element 112. Each one of the plurality of the temperature control element 112 may be connected to each other. In some embodiments, each one of the plurality of the temperature control element 112 may not be connected to each other, thereby allowing independent control of the temperature in each of the elements 112.

[0063] The inlet portion 114 and the outlet portion 116 are disposed at opposite ends of the temperature control element 112. In some embodiments, the temperature control element 112 is configured to be embedded within concrete, with the inlet and outlet portions 114, 116 extending from the concrete. The inlet portion 114 may be covered with insulation material to reduce temperature change of the fluid as it is conveyed to the temperature control element 112.

[0064] Fig. lB is a schematic of a system 100 for curing concrete 102, according to some embodiments. In some embodiments, the inlet portion 114 comprises a heating fluid inlet portion 114A and a cooling fluid inlet portion 114B. In some embodiments, the outlet portion 116 comprises a heating fluid outlet portion 116A and a cooling fluid outlet portion 116B. The heating fluid source 150 is configured to be in fluid communication with the heating fluid inlet portion 114A and the heating fluid outlet portion 116A. The cooling fluid source 160 is configured to be in fluid communication with the cooling fluid inlet portion 116A and the cooling fluid outlet portion 116B. Having separate inlet and outlet valves for heating and cooling allows the system of Fig. lB to simultaneously heat and cool the concrete 102. For example, this may be in a two zone configuration, where the concrete temperature is being independently controlled in two different zones/portions of the concrete 102. In some embodiments, the heating fluid inlet and outlet portions 114A, 116A comprises a plurality of heating fluid inlet and outlet portions, wherein each portion corresponds to an independent zone/portion of the concrete 102. In some embodiments, the cooling fluid inlet and outlet portions 114B, 116B comprise a plurality of heating fluid inlet and outlet portions, wherein each portion corresponds to an independent zone/portion of the concrete 102.

[0065] The pipe wall in the temperature control element 112 maybe made from a material having a cross sectional shape and/or material properties that are sufficient to withstand temperature changes and the forces exerted by the surrounding concrete when embedded therein. For example, the pipe wall in the temperature control element 112 may be made from cross linked polyethylene (PEX) hose, which has a circular cross section to evenly distribute forces and is rated to handle temperatures above 50°C. The pipe lumen may have a diameter of 16mm to 25mm.

[0066] PEX hose has a thermal conductivity approximately three times higher than rubber, which improves the rate of heating/cooling transmission from the temperature control element 112 to the surrounding concrete. Metal pipes may be used, however this has been found to be too thermally conductive which may lead to sudden changes in temperature, and therefore increase the likelihood of cracking due to the resultant temperature differentials.

[0067] The heating fluid source 150 and the cooling fluid source 160 may comprise tanks 152, 162 or reservoirs configured to contain the respective fluids. The tanks 152, 162 may be insulated. Turning to the embodiment of Fig. 1A, the heating fluid source 150 may comprise a heating fluid inlet or return valve 154, which controls the flow of the heating fluid into the heating fluid tank 152. The cooling fluid source 160 may comprise a cooling fluid inlet or return valve 164, which controls the flow of the cooling fluid into the cooling fluid tank 162. In the embodiment of Fig. IB, there are a plurality of return valves, such as two heating return valves 154A, 154B and two cooling return valves 164A, 164B. The plurality of return valves may be configured to correspond to the number of zones/portions that are being independently heated and/or cooled. For example, the heating return valve 154A may be configured to receive heating fluid being returned from a first zone/portion of the concrete 102, while the heating return valve 154B may be configured to receive heating fluid being returned from a second zone/portion of the concrete 102.

[0068] The heating fluid source 150 may comprise a heating mechanism 156 such as a heater to heat the heating fluid to (and maintain it at) the desired heating temperature. The cooling fluid source may comprise a cooling mechanism 166 such as a cooler to cool the cooling fluid to (and maintain it at) the desired cooling temperature. For example, where the heating fluid is water, the heating fluid source 150 may be a hot water tank 152 heated by Stokes 2inch BSP Triple Immersion Elements 156, with a thermostat to regulate the water temperature. The water temperature may be set up to 70°C for compliance with VicRoads Specification 610.23 (as summarised in Table 1), or any other suitable threshold.

[0069] The pump system 120 is configured to direct fluid flow through the pipe circuit 110. The pump system 120 may comprise a pump 122, a first valve 124 configured to control flow of heating fluid pumped from the heating fluid source 150, and a second valve 126 configured to control flow of cooling fluid pumped from the cooling fluid source 160. The pump 122 may be a circulation pump manufactured by Vada. Some embodiments of the pump system 120 may comprise a plurality of pumps 122.

[0070] When the first valve 124 is opened (for example, as may be controlled by the controller 140 cooperating or sending a signal or instructions to the pump system 120), the heating fluid flows from the heating fluid source 150, through the first valve 124, and into the pipe circuit 110 via the inlet portion 114. The heating fluid then passes through the temperature control element 112, which gradually heats the surrounding concrete, and exits the pipe circuit 110 via the outlet portion 116. The outlet portion 116 may be configured to return the heating fluid to the heating fluid source 150, where it can be reheated and recirculated through the pipe circuit 110. When the second valve 126 is opened, the cooling fluid takes a similar path.

[0071] In some embodiments, the first valve 124 is in fluid communication with the heating fluid inlet portion 114A, and the second valve 126 is in fluid communication with the cooling fluid inlet portion 114B. This allows the heating fluid and the cooling fluid to remain separate when entering the temperature control element 112. The fluid may exit the temperature control element 112 through the respective outlet portions 116A, 116B as it is directed back to the respective fluid sources 150, 160 through return valves 154, 164. The valves 124, 126, 154, 164 may be solenoid operated valves.

[0072] In some embodiments, the outlet portion 116 maybe configured to expel the heating fluid and/or the cooling fluid from the pipe circuit 110, for example to a collection vessel (not shown) or to the ground.

[0073] The heating and cooling fluid tanks 152, 162 may be sized to contain more fluid than needed to pass through the pipe circuit 110. This allows the heating and cooling fluid tanks 152, 162 to provide a continuous supply of fluid at (or within a few degrees of) a set temperature, rather than waiting for the returned fluid to be heated or cooled before being recirculated through the pipe circuit 110.

[0074] The operation of the pump system 120 is controlled by the controller 140 based on concrete temperature information measured by the temperature sensor module 130. The measured concrete temperature information indicates to the controller 130 whether the concrete is being heated or cooled too much, too quickly, and/or too unevenly. By adjusting the amount, temperature, timing, and/or duration of the heating and/or cooling fluid flowing through the pipe circuit 110, the controller 140 is able to heat and/or cool the temperature control element to cure the concrete. The heating and cooling can be controlled in a manner that improves the strength of the concrete in a shorter time period while minimising cracking associated with sudden changes in temperature.

[0075] The temperature sensor module 130 is configured to determine or measure concrete temperature information in the concrete 102. In some embodiments, the temperature sensor module 130 comprises one or more sensors or probes disposed at respective one or more sites or locations on and/or within the concrete 102. For example, the temperature sensor module 130 may be configured to measure concrete temperature information at first and second locations 104, 106 of the concrete 102. The first location 104 may be an inner (core) portion of the concrete 102, and the second location 106 may be an outer portion of the concrete 102 that is spaced away from the core portion (first location 104). This allows for an estimate of the temperature differential across the concrete 102 to be determined. Excluding the heating/cooling effect of the pipe circuit 110, the exothermic reaction during the concrete curing process means that the core portion of the concrete 102 tends to be hotter than the outer portion. The outer portion also tends to cool quicker given its proximity to the ambient temperature air.

[0076] The temperature sensor module 130 may comprise the plurality of temperature sensors 132 or probes embedded in the concrete 102 as it is poured/cures. The temperature sensors 132 are secured to the steel reinforcement 210 (refer Fig. 2) used to reinforce the concrete 102. The plurality of temperature sensors 132 may comprise a first temperature sensor Sl, a second temperature sensor S2, a third temperature sensor S3, and so on, each of which is in communication with the controller 140. In some embodiments, there is a first set of the temperature sensors S1, a second set of the temperature sensors S2, and so on, in order to provide multiple temperature readings at a particular portion of the concrete 102.

[0077] In some embodiments, the controller 140 comprises one or more processors 142 and memory 144. The memory 144 is accessible to the one or more processors 142, and comprises computer executable instructions, which when executed by the one or more processors 142, cause the controller 140 to perform functionality to control the temperature of the concrete 102 during the curing process. The controller 140 may be configured to receive, from the temperature sensor module 130, the concrete temperature information. The controller 140 may be configured to monitor the temperature of the concrete 102 by receiving the concrete temperature information continuously, periodically or aperiodically. The controller 140 may be configured to determine compressive strength of the concrete 102 based on the temperature information. The controller 140 is configured to operate the pump system 120 until a compressive strength of the concrete 102 reaches a predetermined compressive strength threshold. In some embodiments, the predetermined compressive strength threshold may be the 28 day compressive strength summarised in the VicRoads Specification 610 Table 610.051 reproduced above. For example, for some road and rail projects, concrete with a 28 day compressive strength of 40MPa to 60MPa may be used. However, it will be appreciated that any suitable compressive strength threshold may be used.

[0078] Fig. 2 is a simplified view of an example reinforced concrete column 200 that has been cured using the system 100. The overall shape of the column 200 is a cylinder, as defined by formwork 310 (Fig. 3). The column 200 contains steel reinforcement 210, which comprises bars 220 and ligatures 230. The bars 220 are spaced around the column 200 towards its circumference and are oriented along the elongate axis of the column 200. The ligatures 230 are bars that have been bent into a circle to connect the bars 220 circumferentially. The bars 220 and the ligatures 230 may be welded to each other to secure their relative positions. The steel reinforcement 210 may further comprise ties 240 which extend between oppositely disposed bars 220 to act as cross bracing for the steel reinforcement 210. The number of bars 220, ligatures 230, and/or ties 240 may vary depending on the size and design loading of the column 200. For clarity, the steel reinforcement 210 of Fig. 2 comprises fewer bars 220 and ligatures 230 than may be typical.

[0079] As illustrated, the temperature control element 112 may be connected to the steel reinforcement 210, for example by cable ties. The temperature control element 112 is a continuous length of pipe, hose, or tube that forms optionally loops within the column 200 and extends along the length of the column 200, such as in a helical or coiled configuration. An example configuration of pipe circuit 110 in the column 200 is shown in dashed lines. However, it will be appreciated that any suitable configuration of temperature control element 112 may be used to provide the desired extent and concentration of temperature control in the concrete 102. For example, the temperature control element 112 may be more concentrated in some portions of the concrete 102, or may not extend to certain parts of the concrete 102. This may be because of the shape of the concrete 102 and/or the project requirements.

[0080] Fig. 3 is a cross section view of a column 300, similar in configuration to the column 200. To form the column 200, 300, the steel reinforcement 210 is placed inside the formwork 310 (with the temperature control element 112 attached). Concrete is then poured into the formwork 310, where it flows over and around the various bars 220, ligatures 230, and/or ties 240, encasing the steel reinforcement 210. The concrete is then left to cure, with the system 100 used to accelerate the curing process as described herein, as described below in more detail with reference to Fig. 5. In some embodiments, the system 100 includes insulation to minimise or control heat loss through the formwork 310. The insulation may be a layer of insulating material such as Kooltherm K1O supplied by Kingspan, closed cell foam, or a ceramic coating such as

Thermoshield. The insulation may have a thermal conductivity of approximately 0.021 W/m/degrees Celsius.

[0081] To monitor the temperature of the concrete 102 as it cures (concrete temperature information), the temperature sensor module 132 may determine or measure the temperature adjacent to the temperature control element 112 and at a location at or spaced away from the temperature control element 112. Alternatively or in combination, a plurality of temperature sensors 132 may be configured to be spaced apart within the concrete 102. For example, if the temperature control element 112 is positioned near the core 104 of the column 200, 300, the first temperature sensor Si may be positioned close to the temperature control element 112, and the second temperature sensor S2 positioned near or towards the outer portion 106 of the column 200, 300. Other temperature sensors S3, S4 may be spaced apart within the concrete 102 to corroborate measurements of the concrete temperature information, and/or to obtain a fuller picture of how the temperature is distributed through the concrete column 200, 300. For example, the plurality of temperature sensors 132 of the temperature sensor module 130 may be disposed in a spaced apart manner along the length and/or at various heights of the concrete (such as shown in Fig. 4A).

[0082] Depending on the cross sectional shape and area of the column 300, the temperature control element 112 may be arranged at a single radial location (distance from the centre of the column 300) so that the temperature control element 112 can evenly heat and cool the inner (core) and outer portions 104, 106 of the concrete column 300. Where the column 300 is larger and/or irregularly shaped, the temperature control element 112 may be arranged at multiple radial locations. The same principle applies to other shapes such as slabs, wherein the temperature control element 112 may have a first portion disposed within the concrete at afirst location, and a second portion disposed within the concrete 102 at a second location spaced apart from the first location. Some concrete structures may have internal piping 108 such as drain pipes or cable/services conduits.

[0083] As shown in Fig. 3, in some embodiments the pipe circuit 110 comprises afirst circuit portion and a second circuit portion. For example, the first circuit portion is afirst temperature control element 112A that is positioned adjacent to the inner (core) portion 104 of the concrete column 300, while the second circuit portion is a second temperature control element 112B positioned adjacent to or towards the outer portion 106 of the concrete column 300. The first temperature control element 112A may be nested inside the second temperature control element 112B.

[0084] The inner temperature control element 112A and the outer temperature control element 112B may be connected so that heating of one results in heating of the other temperature control element. This allows uniform heating (and conversely, cooling) of the concrete 102. In some embodiments, the inner and outer temperature control elements 112A, 112B are not connected i.e. are independently operable. This still allows uniform heating and cooling to occur when both temperature control elements 112A, 112B are operated at the same time, but additionally allows the option of heating and cooling different portions of the concrete 102 at different times and rates to further control the temperature differentials and maturity.

[0085] In the configuration shown in Fig. 3, the first temperature sensor Sl maybe positioned close to the first temperature control element 112A in an inner portion 104 of the concrete 102. The second temperature sensor S2 is positioned towards/at an outer extreme of the outer portion 106 of the concrete column 300 and away from the second temperature control element 112B. The temperature control module 130 may further comprise third and fourth temperature sensors S3, S4 that are positioned between the first and second sensors S1, S2. For example, the sensor S3 is positioned equidistant from the first and second temperature elements 112A, 112B. Meanwhile, sensor S4 is positioned close to the second temperature control element 112B, but not at the outer extreme of the column 300. Sensors S and S4, being closest to the temperature control elements 112A, 112B respectively, may therefore indicate the heating/cooling effect in the immediate vicinity of the temperature control elements 112A, 112B.

[0086] This spacing of the temperature sensors 132 allows the temperatures across the column 300 to be measured and communicated to the controller 140. The controller 140 is configured to determine, based on this concrete temperature information, at least one of: an average concrete temperature; concrete maturity; a concrete temperature increase rate; a concrete temperature decrease rate; and a concrete temperature differential. The controller 140 may do this determining at predetermined intervals, such as every minute. The controller 140 may determine the concrete temperature differential at a specific time, such as at exactly two hours after the first valve 124 is opened.

[0087] The average concrete temperature is the average temperature over a predetermined time interval for each individual location in the concrete 102. The temperature sensor may determine or measure the temperature in real time in the concrete 102, and the controller 140 may determine or calculate the average temperature for the predetermined time interval e.g. each minute based on received temperature information. The predetermined time interval may be shorter, such as 30 seconds, or longer, such as two minutes.

[0088] The average concrete temperature may be used to determine the concrete temperature differential across the concrete column 300. The average concrete temperature may also be used to calculate the "degree hours" of the concrete 102, which another measurement of concrete maturity (temperature time relationship, where concrete age is related to its strength). The "degree hours" is determined by multiplying the time period by the average temperature measured.

[0089] Fig. 4A is a cross section of a column 400, similar to the column 200, 300 shown in Figs. 2 and 3. The column 400 was used for testing of the system 100 for compliance with the VicRoads Specification 610 for a project. Fig. 4A shows the distribution of the steel reinforcement, the temperature control elements and the temperature sensors in the column 400.

[0090] In Fig. 4A, eight temperature sensors are shown, labelled S1-S8. Sensor S is positioned on the surface of the drain pipe. In contrast to Figs. 1-3, the outermost sensor is S8. A plurality of the sensors 132 may be positioned at various heights in the concrete 102, but at the same radial locations (distance from centreline A-A)

[0091] Figs. 4B-4G are graphs representing the full set of data obtained during testing, including temperatures measured at specific time intervals. The following parameters were used:

• Maximum inlet water temperature: 65°C

• Target max concrete temperature: Under 70°C, around 65°C

• Duration: Heat accelerated curing to continue until maturity has been confirmed to be

reached. At which time cooling cycle is to be activated.

• Compressive Strength: 80%F'c

• Set up temperature sensors at horizontal offsets to centre as per Table 3, with 3 rows of sensors distributed along the column.

The testing method used:

1. Build concrete column 400 as per Fig. 4A, including insulation Kingspan Kooltherm KI0 around the outside of the formwork, PEX pipe system 110 for radiant heat.

2. Set up system 100. Fluid sources 150, 160 connected to the pipe system 110 with a single inlet 114 on the internal coil 112A and a single outlet 116 on the external coil 112B. Internal coil 112A and external coil 112B are fluidly connected.

3. 4 hours prior to concrete pour, turn heating mechanism 156 on to bring heating fluid to desired temperature. Turn on cooling mechanism 166 to bring cooling fluid to desired temperature.

4. Set up temperature sensors 132.

5. Pour concrete into formwork 310.

6. After pouring is finished and 40-degree hours of maturity is achieved, and a minimum of 2hours have passed, turn on temperature control system 100.

7. Analyse results continuously from controller 140 until 80%F'c maturity is achieved using the Equivalent Age method, cooling cycle turned on after (cooling source 160).

8. Remove formwork when concrete temperature is within 30°C of ambient.

9. Continue to monitor concrete temperature after formwork removal for approximately 4 hours.

[0092] The summary of testing results is in Table 2.

Table 2

Achieved Section 610 Criteria Compliance result Specified Constraint Maximum Concrete Temperature 67°C 75°C Yes (°C) Maximum Concrete Temperature Change Over 15 Minutes (°C/15 1.98 0 C /15 min 6 0 C/15 min Yes min) Maximum Concrete Temperature 6.78 0 C/hr 24 0 C/hr 6.78C/h 24°/hrYes Change Over 60 Minutes (°C/hr) Maximum Concrete Temperature 18.2 0 C 182C20°C Yes Differential (°C) Maximum Water Temperature 61.9 0 C 619C70°C Yes (°C) Maximum water temperature 2.7°C 10°C Yes differential of inlet and outlet (°C) Curing to Continue Until 7 day 80% F'c 26MPa Yes Strength of design mix (F'c) (32MPa) Removal of Formwork Strength 80% F'c 26MPa Yes requirement (32MPa)

Removal of Formwork duration 80% F'c Complieswith 7 days project requirement (32MPa) specification

Stripping of Formwork with 300 C Removal within Yes of ambient 30 0C of ambient Duration Until of Curing Until 30.5 hrs after - N/A Maturity achieved pour

[0093] The maximum and minimum temperatures measured by the sensors S1-S8 are summarised in Table 3. Table 3 also indicates the radial locations of each of the sensors S1-S8. The temperatures generally decrease from the core portion 104 to the outer portion 106 of the concrete 102. At radial locations 375mm and 675mm, the temperatures increase slightly as this is where the first and second temperature control elements 112A, 112B are located.

Table 3

Offset from centre (Radial Locations) +75m +175m +275m +375m +475m +575m +675m +805m m m m m m m m m Senso Si S2 S3 S4 S5 S6 S7 S8 r Max Temp 65.9 63.7 61.1 61.5 58.1 56.6 67.3 63.2

(°C) Min Temp 18.2 17.8 16.4 16.4 15.4 16.4 12.3 11.2

(0 C)

[0094] The column 400 has a radius X. The bars 220 are spaced from the outside of the column 400 by a distance XI. Two sets of steel reinforcement are present in the column 400, and the two sets of the bars 220 are spaced apart by a distance X2. The bars 220 are spaced from the drain pipe by a distance X3. The ligatures 230 are spaced from the outside of the column 400 by a distance Yl. The ligatures 230 are spaced apart by a distance Y2. The ligatures 230 are spaced from the drain pipe by a distance X3. The temperature control element is similarly spaced by virtue of being attached to the steel reinforcement.

[0095] In testing, the following sizes/distances were used: XO=850mm XI = 175mm X2 = 300mm X3=300mm Y1 = 150mm Y2 = 200mm

The spacing of the temperature control element at 200mm to 300mm allows precise temperature control. If the temperature control elements were further spaced, this may result in colder spots between the temperature control elements, and thereby increase the likelihood of concrete crack formation due to large temperature differentials occurring.

[0096] To calculate the concrete maturity, various methods including the Nurse Saul method and the Equivalent Age method can be used. The Nurse Saul method assumes a linear relationship between concrete maturity and temperature, whereas the Equivalent Age method assumes an exponential relationship between concrete maturity and temperature. The Nurse Saul method may be quicker to calculate, but may be less accurate than the Equivalent Age method when a wider range of temperatures is considered.

[0097] The controller 140 may be configured to determine a compressive strength of the concrete using the Arrhenius equation below, which is based on the Equivalent Age method:

F,'= a In e Ta F. Ts At) -b

wherein: F1' compressive strength a calculated rate of change of compressive strength to equivalent age Q activation energy Ta average temperature (in degrees Kelvin) of concrete during time interval T, =specified temperature (in degrees Kelvin) At time interval (days or hours) b = calculated compressive strength constant

Fig. 4H is a graph showing a maturity curve obtained using this equation. Fig. 4H shows that 24 hours after pouring the concrete 102, the column 400 reached an equivalent age of 26MPa using the system 100. Fig. 4H shows that 30 hours after pouring the concrete 102, the column 400 reached an equivalent age of 32MPa (being 80% of the target compressive strength of 40MPa for this project) using the system 100, compared to a typical curing time of approximately 7 days.

[0098] The activation energy "Q" can be found in the Holcim Strength-Maturity Report (Maturity Curve), 4208. The activation energy Q may change depending on the constants "a" and "b", The specified temperature varies according to the environment, and is typically 23°C (300°K) for Australia.

[0099] The values of constants "a" and "b" can vary depending on which quarry the aggregate is sourced, which plant the concrete is mixed, the concrete mix design strength, and differing admixtures used. The values of constants "a" and "b" are determined through testing and must be retested every 6 months.

[0100] From the experimental data obtained and summarised in Tables 2 and 3, "a" was found to be 15.48 and "b" was found to be 38.886.

[0101] The controller 140 is configured to operate the first valve 124 of the pump system 120, allowing the heating fluid to heat the concrete 102 until the calculated compressive strength reaches a predetermined compressive strength threshold. The controller 140 may be configured to determine the compressive strength of the concrete 102 at predetermined intervals, such as every minute.

[0102] Based on this information, the controller 140, responsive to the compressive strength reaching the predetermined compressive strength threshold, may then operate the second valve 126 of the pump system 120, cooling the concrete 102 to avoid the concrete 102 losing too much moisture too quickly, and/or to prevent cracking.

[0103] The operation of the first and second valves 124, 126 may be sequential or alternating. In sequential operation, as described above, the first valve 124 opens to allow heating to occur first, and once the temperature sensor module 130 detects the concrete 102 has reached the maximum temperature the first valve 124 is closed and the second valve 126 opened to cool the concrete 102. In alternating operation, the sequential operation repeats itself, meaning the concrete curing process may require repeat cycles of heating and cooling, for example if the temperature sensor module 130 detects that the concrete 102 has reached the maximum temperature too quickly.

[0104] The operation of the first and second valves 124, 126 may be simultaneous. In some embodiments, the pipe circuit 110 comprises multiple temperature control elements 112 that are independently operable with respective first and second valves 124, 126. For example, the controller 140 may open the first valve 124 to allow heating fluid to heat a first portion (e.g. a colder portion) of the concrete 102, while simultaneously opening the second valve 126 to allow cooling fluid to cool a second portion (e.g. a hotter portion) of the concrete 102, thereby minimising the temperature differential between the first and second portions of the concrete 102. The first and second valves 124, 126 may be opened (and stay open) at the same time, and either one may be closed sooner depending on the concrete temperature information measured by the temperature sensor module 130.

[0105] The system 100 may comprise a failsafe 146 which is configured to prevent a temperature of the concrete 102 exceeding a predetermined maximum temperature. The controller 140 is in communication with the failsafe 146, wherein when the failsafe 146 is activated, the failsafe 146 closes the first valve 124. The failsafe 146 may also initiate operation of the second valve 126 to cool the concrete 102.

[0106] In some embodiments, the system 100 further comprises a user interface 170. The user interface 170 allows the user to input parameters into the system 100 (such as into the controller 140). Parameters may include the predetermined compressive strength thresholds, the predetermined time intervals, the predetermined temperature increase/decrease rates, and others as described herein. The user interface 170 may also allow the user to manually override or control specific functions of the system 100, such as the operation of the valves 124, 126. The user interface 170 may display information to the user, such as operational updates or a safety warning when a predetermined threshold is exceeded. The user interface 170 may comprise a remote device, wherein the controller 140 is configured to send information thereto. The remote device may be a mobile phone, to which the controller 140 may send a text message notifying the user of an issue. For example, the controller 140 may send a text message or email when: the concrete goes over the specified/predetermined maximum allowed temperature, if a temperature differential between two temperature sensors/probes is greater than the specified/predetermined allowed temperature, if fluid flow should be detected through flow meters but is not, if power loss is detected to system, if the temperature of the heating fluid in the heating fluid tank 152 is below a predetermined temperature, and/or if the temperature of the cooling fluid in the cooling fluid tank 162 is above a predetermined temperature. The controller 140 may comprise a modem to allow internet/phone communication.

[0107] Fig. 5 is a flowchart of a method 500 of curing concrete, according to some embodiments. In some embodiments, the system 100 is configured to perform method 500.

[0108] At 502, concrete is poured into formworkto define a concrete structure, wherein a portion of a pipe circuit is embedded in the concrete.

[0109] At 504, the concrete is left to mature for a maturity time. The maturity time is typically degree hours minimum according to VicRoads Specification 610 (although it can vary by project), and no less than two hours. This allows the concrete time to gain strength before accelerated curing, for example by using the system 100. The degree hours measurement is a cumulative measurement of the relationship between temperature and time; for example, allowing the concrete to cure for two hours at 20°C, or for one hour at 10°C and one hour at 0 C.

[0110] At 506, the concrete is heated by flowing a heating fluid through the pipe circuit. The pipe circuit may be bled, or a vacuum/reduced pressure created therein, prior to the heating fluid being supplied. The heating fluid may be supplied using a pump system, such as the pump system 120 of system 100. In some embodiments, the heating fluid has a maximum temperature of 70 0 C. For example, in some embodiments, the controller 140 instructs the pump system 120 to activate the first valve 124 to allow heating fluid to flow through the pipe circuit 110.

[0111] At 508, a first concrete temperature of the concrete structure adjacent to the pipe circuit isdetermined. This maybe at the inner (core) portion 104 of the concrete. At550,asecond concrete temperature of the concrete structure remote to the pipe circuit is determined. This may be at the outer portion 106 of the concrete. In some embodiments, the temperature sensor module 130 of system 100 is configured to determine thefirst and second concrete temperatures, and to provide the first and second concrete temperatures to the controller 140.

[0112] At 510, based on the first and second concrete temperatures, the following are determined: i. concrete maturity; ii. a concrete temperature increase rate iii. a concrete temperature decrease rate; and iv. a concrete temperature differential;

[0113] For example, the controller 140 maybe configured to determine variable i, ii, iii, and/or iv based on thefirst and second concrete temperatures.

[0114] At 512, delivery of the heating fluid to the pipe circuit is controlled so that: i. the concrete temperature increase rate does not exceed a predetermined temperature increase rate; and ii. the concrete temperature differential does not exceed a predetermined temperature differential.

[0115] In some embodiments, the flow rate for the heating fluid and the cooling fluid is identical. The flow rate of the pumps maybe approximately 15L/minute. Testinghasshown that this flow rate is sufficient to keep the differential temperature between the inlet and the outlet to be less than 10°C.

[0116] The predetermined temperature increase rate may be 24°C per hour. The predetermined temperature differential may be 20°C. In some embodiments, the controller 140 is configured to keep the concrete temperature increase and the concrete temperature differential below the predetermined rates.

[0117] At 514, a compressive strength of the concrete is determined based on the concrete maturity. When a compressive strength threshold is reached, at 516, the concrete is cooled by flowing a cooling fluid through the pipe circuit, the cooling fluid having a cooling fluid temperature. For example, in some embodiments, responsive to the controller 140 determining that the compressive strength threshold is reached, the controller 140 instructs the pump system 120 to activate the second valve 126 to allow cooling fluid to flow through the pipe circuit.

[0118] At 518, delivery of the cooling fluid to the pipe circuit is controlled so that:

i. the concrete temperature decrease rate does not exceed a predetermined temperature decrease rate; and ii. the concrete temperature differential does not exceed the predetermined temperature differential;

[0119] The predetermined temperature decrease rate maybe 30°C per hour. The predetermined temperature differential may be 20°C. In some embodiments, the controller 140 is configured to keep the concrete temperature decrease and the concrete temperature differential below the predetermined rates.

[0120] At 520, the cooling is stopped (for example, the deliver or flow of cooling fluid to the pipe circuit is stopped) when the concrete temperature is within a predetermined temperature range of ambient temperature. The predetermined temperature range may be 30°C. In some embodiments, the controller 140 is configured to keep the concrete temperature within the predetermined range.

[0121] At 506 and 516, the flowing of the heating fluid and the flowing of the cooling fluid may be alternated to produce repeated heating and cooling cycles. In some embodiments, the controller 140 is configured to selectively cause activation of the first and/or second valves, for example by sending instructions to the pump system, to selectively stop and start the flow of heating fluid and/or cooling fluid to the pipe circuit.

[0122] In some embodiments, at 506, the flowing of the heating fluid maybe directed into a first circuit portion of the pipe circuit, and at 516, the flowing of the cooling fluid is directed into a second circuit portion of the pipe circuit. The first and second circuit portions may not be in fluid communication so that the flowing of the heating fluid and the flowing of the cooling fluid can occur simultaneously.

[0123] When the curing process is completed, the pipe circuit 110 is flushed, drained, and filled with grout. The inlet and outlet portions 114, 116, which extend from the surface of the formed concrete 102, are then cut to sit flush with the formed concrete structure. Grout may then be used to fill any gaps so that the exposed ends of the inlet and outlet portions 114, 116 are covered.

[0124] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (35)

CLAIMS:

1. A system for curing concrete, the system comprising: a pipe circuit comprising a temperature control element configured to be embedded within concrete, wherein the pipe circuit is configured to be in fluid communication with a heating fluid source and a cooling fluid source; a pump system to direct fluid flow through the temperature control element of the pipe circuit, the pump system comprising: a pump; a first valve configured to control flow of heating fluid pumped from the heating fluid source; and a second valve configured to control flow of cooling fluid pumped from the cooling fluid source; a temperature sensor module configured to measure concrete temperature information at first and second locations of the concrete; and a controller in communication with the temperature sensor module and the pump system, the controller configured to control operations of the pump system based on the concrete temperature information to heat and cool the temperature control element to cure the concrete.

2. The system of claim 1, wherein the heating fluid source comprises: a heating fluid reservoir for receiving the heating fluid; and a heating mechanism for heating and maintaining the heating fluid contained in the heating fluid reservoir at a heating fluid temperature.

3. The system of claim 1 or claim 2, wherein the cooling fluid source comprises: a cooling fluid reservoir for receiving the cooling fluid; and a cooling mechanism for cooling and maintaining the cooling fluid contained in the cooling fluid reservoir at a cooling fluid temperature.

4. The system of any one of the preceding claims, wherein the temperature sensor module comprises a first temperature sensor configured to measure temperature at the first location of the concrete, and a second temperature sensor configured to measure temperature at the second location of the concrete.

5. The system of claim 4, wherein the first temperature sensor is configured to measure temperature adjacent to the temperature control element, and the second temperature sensor is configured to measure temperature spaced away from the temperature control element.

6. The system of claim 4 or claim 5, wherein the temperature sensor module further comprises a plurality of temperature sensors configured to be spaced apart within the concrete.

7. The system of any one of the preceding claims, wherein the controller is configured to determine, based on the concrete temperature information, at least one of the following measurements: i. concrete maturity; ii. a concrete temperature increase rate; iii. a concrete temperature decrease rate; and iv. a concrete temperature differential.

8. The system of claim 7, wherein the controller is configured to determine a compressive strength of the concrete based on:

F,'= a In e Ta F. Ts At) - b

wherein: F1' compressive strength a calculated rate of change of compressive strength to equivalent age Q activation energy Ta average temperature (in degrees Kelvin) of concrete during time interval T, =specified temperature (in degrees Kelvin) At time interval (days or hours) b = calculated compressive strength constant

9. The system of claim 8, wherein the controller is configured to: i. operate the first valve of the pump system until the compressive strength reaches a predetermined compressive strength threshold, and ii. responsive to the compressive strength reaching the predetermined compressive strength threshold, operate the second valve of the pump system.

10. The system of claim 8 or claim 9, wherein the compressive strength of the concrete is determined at predetermined intervals.

11. The system of any one of claims 7 to 10, wherein the controller determines the measurements at predetermined intervals.

12. The system of any one of claims 7 to 11, wherein the controller being configured to determine the concrete temperature differential comprises calculating the difference between the concrete temperatures at the first and the second locations at a specific time.

13. The system of any one of the preceding claims, wherein the controller is configured to operate a failsafe to prevent a temperature of the concrete exceeding a predetermined maximum temperature, wherein the failsafe closes the first valve.

14. The system of claim 13, wherein the failsafe opens the second valve.

15. The system of any one of the preceding claims, wherein the pipe circuit is configured to circulate the heating fluid and the cooling fluid through the temperature control element and return the fluids to the heating and cooling fluid sources respectively.

16. The system of any one of the preceding claims, further comprising an insulation material for the concrete.

17. The system of claim 16, wherein the insulation is a layer of insulating material.

18. The system of claim 16, wherein the insulation is a ceramic coating.

19. The system of any one of claims 16 to 18, the insulation having a thermal conductivity of approximately 0.021 W/m/degrees Celsius.

20. The system of any one of the preceding claims, wherein the pipe circuit comprises a first circuit portion and a second circuit portion, the first circuit portion configured to be disposed within the concrete at the first location, and the second circuit portion configured to be disposed within the concrete at the second location.

21. The system of claim 20, wherein the first and second circuit portions are not in fluid communication with each other to enable independent heating and cooling of the first and second circuit portions.

22. The system of claim 20 or claim 21, wherein the first and second circuit portions comprise a coiled arrangement.

23. The system of claim 22, wherein the first circuit portion is nested within the second circuit portion.

24. The system of any one of the preceding claims, wherein the pipe circuit comprises pipe having a diameter of 20mm.

25. The system of any one of the preceding claims, wherein the pump and controller are mounted on a mobile vehicle.

26. A controller configured to control a process for curing concrete, the controller configured to communicate with a pump system for directing fluid flow through a pipe circuit at least partially embedded within concrete, and to communicate with a temperature sensor module configured to measure temperature at a plurality of locations in the concrete, the controller comprising: one or more processors; and memory, accessible to the one or more processors, and comprising computer executable instructions, which when executed by the one or more processors, cause the controller to: receive, from the temperature sensor module, concrete temperature information; determine, based on the concrete temperature information, a compressive strength of the concrete; and operate the pump system until the compressive strength of the concrete reaches a predetermined compressive strength threshold.

27. The controller of claim 26, wherein determining the compressive strength of the concrete comprises using at least one of the following measurements: i. concrete maturity; ii. a concrete temperature increase rate; iii. a concrete temperature decrease rate; and iv. a concrete temperature differential.

28. A method of curing concrete, the method comprising: pouring concrete into formwork to define a concrete structure, wherein a portion of a pipe circuit is embedded in the concrete; leaving the concrete to mature for a maturity time; heating the concrete by flowing a heating fluid through the pipe circuit; measuring a first concrete temperature of the concrete structure adjacent to the pipe circuit; measuring a second concrete temperature of the concrete structure remote to the pipe circuit; determining, based on the first and second concrete temperatures: i. concrete maturity; ii. a concrete temperature increase rate iii. a concrete temperature decrease rate; and iv. a concrete temperature differential; controlling the heating fluid temperature so that: i. the concrete temperature increase rate does not exceed a predetermined temperature increase rate; and ii. the concrete temperature differential does not exceed a predetermined temperature differential; calculating a compressive strength of the concrete based on the concrete maturity; when a compressive strength threshold is reached, cooling the concrete by flowing a cooling fluid through the pipe circuit, the cooling fluid having a cooling fluid temperature; controlling the cooling fluid temperature so that: i. the concrete temperature decrease rate does not exceed a predetermined temperature decrease rate; and ii. the concrete temperature differential does not exceed the predetermined temperature differential; and stopping the cooling when the concrete temperature is within a predetermined temperature range of ambient temperature.

29. The method of claim 28, wherein the flowing of the heating fluid and the flowing of the cooling fluid is alternated.

30. The method of claim 28, wherein the flowing of the heating fluid is directed into a first circuit portion of the pipe circuit, and wherein the flowing of the cooling fluid is directed into a second circuit portion of the pipe circuit, the first and second circuit portions not being in fluid communication so that the flowing of the heating fluid and the flowing of the cooling fluid occurs simultaneously.

31. The method of any one of claims 28 to 30, wherein the predetermined temperature increase rate is 24°C per hour.

32. The method of any one of claims 28 to 31, wherein the predetermined temperature differential is 20°C.

33. The method of any one of claims 28 to 32, wherein the predetermined temperature decrease rate is 30°C per hour.

34. The method of any one of claims 28 to 33, wherein the predetermined temperature range is 30°C.

35. A concrete structure produced using the system of any one of claims I to 25, the controller of claim 26 or claim 27, or the method of any one of claims 28 to 34.