Description:Title:
An improved maturity meter for precise maturity estimation of concrete.

Field of invention:
The present invention relates to an improved maturity meter for precise maturity estimation of concrete. More particularly it relates to the said meter which circumvents sensor limitations of the meters of the prior art, uses temperature profiling method and adds measured parameters to obtain more precise maturity estimation concrete.

Background of Invention:
Concrete setting is an exothermic process, with the temperature typically topping off around 40° C. Strength attained at any point is proportional to the area under the curve for temperature and time. It is possible to characterize a particular concrete mixture based on its temperature against time graph, and use area under the curve to calculate attained strength. Apart from mechanical impedance measurement, area under the curve or similar temperature against time curve analysis the most common method of calculating strength attained by concrete during its set period.

Since the final analysis is based on temperature against time data, the temperature data needs to be stored, either on the instrument or to some data storage mechanism that can be accessed for analysis of the temperature data. Additionally, since different concrete mixtures will have different characteristics (amount of time to set, temperature profile, final strength attained etc.) the concrete type related configuration also needs to be stored.

Most of the instruments perform analysis of the stored data on the instrument itself and provide some mechanism of displaying current state of the concrete that is being monitored. With the ease of availability of online space (cloud storage), aesthetically better and remote representation of data, as well as availability of cloud computing tools allowing greater flexibility in applying various analysis methods to the gathered data, newer trend is to provide data transfer to an online storage and analyze the data on cloud. These instruments either allow the user to avail the data through a wired or wireless data transfer mechanism.

On the design front the instruments available in the market, use wired sensors with data being stored and analyzed on the instrument. The instrument has a single battery system and the same battery is used to provide power to the sensors as well as data processing unit.

In most of the instruments available in the market the sensors are connected over wires to the main instrument and the only wireless interface (if any) is usually from the instrument to a mobile phone for configuration or data retrieval purposes. This limits the area coverable by a single measurement station.

The wired sensors limit the numbers of sensors which could be used for collection of maturity data. This obviously limits the area of the concrete of which the maturity needs to be determined. Sensors are also not individually programmed to collect the data at different situations and different conditions.

Concrete needs to be wetted regularly to maintain the correct setting gradient. If this is not maintained the structure can develop cracks due to non-uniform setting if different parts of the structure and this, not only aesthetically hinders the structure but can also compromise structural integrity.

Without any in-situ humidity measurement (of the environment as well as the concrete) the wetting is carried out in a scheduled manner or based on a schedule set by someone’s wisdom. However, this means that there can be subjective variations in wetting treatment of the concrete, and this can yield different outcomes for the same concrete mix. Additionally, scheduled wetting irrespective of external humidity conditions means that water maybe wasted.

The typical concrete meter of the closest prior has been described and claimed in our co-pending patent application No. 201921022295 and ……………… which provided these sensors.

Therefore, there is a need to provide sensors that incorporate not only measurement, but also data storage and power source. The power source maybe a battery (chargeable or non-rechargeable) or a super-capacitor being charged using a solar or similar energy source.

The sensors also need to be wireless and standalone programmable so that they communicate with the mechanism to convey data to the central station.

The wireless technologies (Including but not limited to Bluetooth) need to be provided to allow for mesh type network configuration. In such networks signal strength no longer limits the distance at which a sensor can be placed from the central stations. The provision for the sensors is necessary so that each sensor can effectively act as a transmitter (of its own data) as well as a repeater (for other sensor’s data). The only limit placed on any central station may then be the maximum number of devices as dictated by the selected communications protocol. This means that for each central station a much larger area of monitoring can be covered, without the tedium of wires.

There is also need to provision for each sensor being capable of programming for different sample intervals allowing more accurate maturity measurement in possibly layered structures. Since the sensors are individual, self-contained data acquiring units it is possible for each sensor to be differently programmed. It is also necessary for more precise estimation of the maturity of the concrete that all the sensors not have the same data acquisition schedule (though all of them will start at the same time through a common trigger mechanism/signal). This will allow the central station’s firmware/software to gather data points at different time intervals, allowing for better characterization of different/new concrete mixtures and setting characteristics in possibly layered structures.

Also such standalone programmable wireless sensors can incorporate humidity measurement for incorporating possibility of correct wetting schedule and allowing a humidity measurement integration in the sensor can allow for a more uniform wetting treatment of the concrete as it sets and can also lead to saving of substantial amounts of water.

To summarize the prior art maturity determination meters suffered from following drawbacks:
• Maximum number of sensors were limited.
• Wired sensing limiting sensor distance from the meter necessitating meter placement close to the sensors.
• A dedicated mobile application was required to gather sensor data where bluetooth based sensors were being used (e.g. from Command Center).
• Sensor was sacrificial, and/or retrieval was a very tedious non-standard procedure
• Battery operated sensors used non-rechargeable cell pairs having a higher environmental impact.
• The products themselves were expensive and some have a subscription model (recurring costs) for the analysis software features.

The main object of the present invention therefore is to provide a maturity meter with standalone wireless sensors which are configurable with own power source so that they can collect the data in different situations and conditions with respect to time.

Another object is to provide a maturity meter having no obvious limitation on deployed number of sensors per station.

Yet another object is to provide the maturity meter wherein each of the senor is capable of programming for different sample intervals allowing more accurate maturity measurement in possibly layered structures.

Still another object is to provide the maturity meter capable of humidity measurement to for incorporating possibility of correct wetting schedule.

Summary of the invention.

The present invention provides an improved maturity meter for precise maturity estimation of concrete characterised by wireless self contained stand alone independently programmable sensors, the said maturity meter comprising a central station, plurality of stand alone sensors with power supply, sensing circuit, controller for power switching and having connectivity options such as short range communication devices, provision for data storage and connectivity options. The central station comprises provision for uninterrupted power supply, sensing circuits for battery protection charging and power distribution controller for power switching, power supply conditioning and monitoring, external connections for charging and data transfer, a controller equipped with short range communication device, data storage devices and connectivity options and wireless connectivity such as GPRS or wi-fi. Each stand alone censor comprises of a inner tube made up of stainless steel or non-corroding material, the said tube having threads on outside for fitment in the sleeve, cables connecting sensor PCB to logger electronics, a PCB on which parameter sensor is mounted, a drill for locating and fixing rivet sensor electronics on PCB.

The invention described in the present application is described with drawings and figures accompanying this specification, the said drawings and figures are illustrative only and should not be construed to limit the scope of the present invention in any manner.

The following table (1) describes the legends used in the drawings accompanying this specification.
TABLE (1)
Legend Number Description
01 Threads on outside of inner tube for fitment in the sleeve
02 Inner tube made from SS304 or similar non-corroding material
03 Cables connecting sensor PCB to logger electronics
04 PCB on which parameter sensor is mounted
05 Drill for locating and fixing rivet
06 Sensor electronics on PCB
07 Inner tube SS304 of similar material
08 Slot on side for screw driver blade to engage to allow tightening of the inner tube in the sleeve.
09 Inner thread on sleeve to engage inner tube
10 Sleeve tube SS304 or similar material
11 Outer thread on sleeve to engage end cap
12 Inner thread on end cap to engage on sleeve end
13 End cap SS304 or similar heat conducting material
16 Battery for powering the internal electronics of the station
17 Sensing circuit for battery protection
18 Charging and power distribution controller for power switching
19 Power supply conditioning and monitoring
20 External connection for charging and data transfer
21 Controller with Bluetooth, Data Storage and connectivity options
22 Wireless connectivity (GPRS, WiFi or other)
23 Battery for powering the internal electronics of the station
24 Sensing circuit for battery protection
25 Charging and power distribution controller for power switching
26 Power supply conditioning and monitoring
27 External connection for charging and data transfer
28 Controller with Bluetooth, Data Storage and connectivity options
29 Signal conditioning for sensor
30 Sensor Probe (Items 01 to 15 integrated)
31 Sensor parameter communications node (Items 23 to 30)
32 Bluetooth or similar wireless interface antenna
33 Central receiving station (Items 16 to 22)
34 Wireless and/or GPRS antenna for internet connectivity
35 Bluetooth or similar wireless interface antenna.

Brief description of the drawings:

Fig. No. 1: Shows schematic electronic block diagram of Central Station.
Fig. No. 2: Shows Sensor electronics block diagram
Fig. No. 3: Shows Vertical section view of the sensor.
Fig. No. 4: Shows Sectioned View of Inner tube of sensor
Fig. No. 5: Shows End view of inner tube
Fig. No. 6: End cap for fitting over sensor PCB
Fig. No. 7: Shows outer sleeve for insertion in concrete
Fig. No. 8: Shows sensor interconnection.

Detailed description of the drawings.

Referring to Fig. (1) and (8), the improved maturity meter for precise maturity estimation of concrete characterised by wireless self-contained, standalone independently programmable sensor probes, the said maturity meter comprising a central station, plurality of standalone sensor probes (30), provision batteries (16) for uninterrupted power supply, sensing circuits for battery protection (17), charging and power distribution controller for power switching (18), power supply conditioning and monitoring (19), external connections for charging and data transfer (20), a controller (21) equipped with short range communication device, data storage devices and connectivity options and wireless connectivity (22) exemplifies by GPRS or wi-fi, a sleeve tube (10), an end cap (13)

Referring to Fig. (2) the central station electronics comprises battery (23) for powering the internal electronics of the station Sensing circuit (24) for battery protection, charging and power distribution controller (25) for power switching power supply conditioning and monitoring device (26), external connection (27) for charging and data transfer and a controller (28) with short communication device, data storage and connectivity options.

Referring to Fig. 3 each sensor probe (30) is made up of non-corrosive inner tube (2) having , the said tube having threads (1) for fitment in the sleeve on outside of inner tube (2) at one end, at the other end of the said inner tube (2), have the cables (3) connecting sensor PCB (4) on which parameter sensor is mounted, a drill (5) for locating and fixing rivet and a sensor electronics PCB (6), sleeve tube (10) and end cap (13)

Referring to Figure (5) and (6) the sleeve tube (10) may be made up of stainless steel having inner thread (9) on one end of the to engage inner tube and outer threads (11) to engage end cap (13).

Referring to Fig. fig. (7) the end cap (13) has inner threads (12) for engaging with the outer threads (11) of the sleeve tube (10).

In one of the embodiments of the present invention the sleeve tube (10), the end cap (13) may be made up of heat conducting non corrosive materials preferably stainless steel.

In still another embodiment the controller (25) and sensor probe (30) are programmed to receive, communicate and analyze the data collected by the sensor probe (30).

In yet another preferred embodiment the sensor probe (30) may be programmed to collect the data on predetermined time scale of 5 to 20 hours, store the same on its data storage device and communicate the same to the controller (25).

Working of the invention:
The instrument working is divided into the following parts:
1. Installation of the sensor probe. This is a multi-step process.
2. Installation of electronics section.
3. Data Acquisition. This phase lasts between 3 to 30 days depending upon configuration.
4. Strength estimation. This process requires a set of data points to be available before estimations can be made. Estimation accuracy increases with increase in available data.
The text below describes the steps listed above. References made to various part numbers relate to the tables listed elsewhere in the patent document.

Installation of sensor probe.
1. Take the sensor probe outer cap (13). Fill with heat sink compound to 10mm height.
2. Take the sensor probe outer tube (10). Put teflon tape in correct manner over outer threads (11). Make sure threads are completely covered by no more than two layers and no less than 1 layer of the tape.
3. Screw on the output cap (13) over the teflon tape covered threads (11).
4. Take the sensor inner sleeve (02).
5. Place temperature sensor PCB (04) in provided location and align PCB drill with fixing rivet drill (05).ve informed you
6. Lock PCB with rivet or screw (not shown in drawing.).
7. Make sure the temperature sensor cables (03) are correctly drawn out of the other end of the tube (02).
8. Push the sleeve (02) mounted with the PCB (04) inside the outer tube (10).
9. Screw in the sleeve using the slot provided (08) into the outer tube (10) over the threads (01 and 09).

Installation of electronics section (This is draft. Operational details may change
depending upon on field experiment).
1. Take the sensor electronics (31).
2. Engage the cables (03) with sensor electronics (31).
3. Start sensor electronics.
4. Open PC/Laptop.
5. Connect USB-Bluetooth device to the laptop/PC.
6. Start hyper terminal (or any similar serial port terminal program).
7. Set serial port parameters for the USB-Bluetooth device to 57600, 8N1.
8. Send command to electronics to open configuration dialog.
9. Configure electronics for logging interval, logging time and other parameters as needed.
10. End configuration session. The sensor/logger will automatically switch to temperature advertisement and logging mode with low power operation.
11. Switch on central gateway/central receiving station (33).
12. Connect to central receiving station using the same procedure as above for server IP address, port, sensors to log data from and other parameters as required.
13. End configuration session.

Data Acquisition
1. The sensor electronics will log data in the memory provided with the controller (21).
2. It will broadcast it’s unique identifier and instantaneous data at interval as configured above using the antenna (32).
3. This instantaneous data is collected by central receiving station(33) to ascertain sensor’s (31) correct operation.
4. If central receiving station (33) detects abnormal reported data (e.g., low battery, incorrect sensor data or other conditions) it will report over the secondary interface using the antenna (34) and interface controller (22).
5. At end of acquisition time or based on other conditions (battery conditions, abnormal operation etc.) the central station(33) will initiate transfer from each sensor (31) using the wireless interface connected to antennae (32 and 35).
6. Depending upon configuration the central receiving station (33) may transfer this data over internet connection using appropriate electronics sections in its design (34 and 22) to a centralized location/cloud for further analysis.

Advantages of the present invention:

• Sensors are wireless and transmit data using wireless protocol.
• Each sensor is self-contained (power, data storage, time-keeping) to avoid single point failure leading to data loss, so a loss of wireless range or central station failure will not cause loss of acquired data.
• All sensors are independently programmable with regards to sampling duration and acquisition interval.
• The sensor (actual temperature transducer) and its processing electronics has been separated from each other allowing the (cheaper) non-transducer section to be sacrificed while recovering the temperature sensor and processing electronics.
, Claims:1. An improved maturity meter for precise maturity estimation of concrete characterised by wireless self-contained, standalone independently programmable sensor probes, the said maturity meter comprising a central station, plurality of standalone sensor probes (30), provision batteries (16) for uninterrupted power supply, sensing circuits for battery protection (17), charging and power distribution controller for power switching (18), power supply conditioning and monitoring (19), external connections for charging and data transfer (20), a controller (21) equipped with short range communication device, data storage devices and connectivity options and wireless connectivity (22) exemplifies by GPRS or wi-fi, a sleeve tube (10), an end cap (13)

2. The improved maturity meter as claimed in claim (1) wherein the central station electronics comprises battery (23) for powering the internal electronics of the station Sensing circuit (24) for battery protection, charging and power distribution controller (25) for power switching power supply conditioning and monitoring device (26), external connection (27) for charging and data transfer and a controller (28) with short communication device, data storage and connectivity options.

3. The improved maturity meter as claimed in claim (1) to (2) wherein each sensor probe (30) is made up of non-corrosive inner tube (2) having , the said tube having threads (1) for fitment in the sleeve on outside of inner tube (2) at one end, at the other end of the said inner tube (2), have the cables (3) connecting sensor PCB (4) on which parameter sensor is mounted, a drill (5) for locating and fixing rivet and a sensor electronics PCB (6), sleeve tube (10) and end cap (13).

4. The improved maturity meter as claimed in claim (1) to (3) wherein the sleeve tube (10) is made up of stainless steel having inner thread (9) on one end of the to engage inner tube and outer threads (11) to engage end cap (13).

5. The improved maturity meter as claimed in claim (1) to (4) wherein the end cap (13) has inner threads (12) for engaging with the outer threads (11) of the sleeve tube (10).

6. The improved maturity meter as claimed in claim (1) to (5) wherein the sleeve tube (10), the end cap (13) is made up of heat conducting non corrosive materials preferably stainless steel.

7. The improved maturity meter as claimed in claim (1) to (6) wherein the controller (25) and sensor probe (30) are programmed to receive, communicate and analyze the data collected by the sensor probe (30).

8. The improved maturity meter as claimed in claim (1) to (7) wherein the sensor probe (30) may be programmed to collect the data on predetermined time scale of 5 to 20 hours, store the same on its data storage device and communicate the same to the controller (25).