DE102010036758A1 - Method for determining and predicting compressive strength of hardened concrete, involves processing measured values of physical parameter and environmental temperature, and outputting graphical/tabular representation of processed values - Google Patents

Abstract

The method involves measuring physical parameter such as chloride content of a concrete (B) by using an electronic sensor (1), and measuring environmental temperature by using an electronic sensor (4). The measured values are transferred to a data unit (2) which transmits the measured values to a computer (3). The received measured values are processed by a control unit (3-2) of computer using an algorithm. The processed values are transmitted to an output unit (3-3). The graphical or tabular representation of the transmitted values is carried out in the output unit.

Description

Technical area

The present invention relates to a method for determining and predicting the compressive strength of hardening concrete.

State of the art

Various methods for measuring and controlling the pressure resistance of freshly poured concrete using electronic sensors are known from the prior art.

From the WO 83/01411 A1 For example, a method for controlling the hardening rate of concrete is known in which, depending on the temperature of the concrete measured by a temperature sensor, the heat supply or distribution during a certain period of time is influenced and the current maturity state of the concrete is determined by the measured time course of the temperature , A disadvantage of the in the WO 83/01411 A1 The method described is that the concrete maturation only at a few sites where heat or mobile heaters are available, can be controlled or controlled. Another disadvantage of this method is the fact that both the temperature measurement and the power supply takes place exclusively via cable connections. In addition, the measurement results and calculated results on compressive strength are not visible on site, making the application very cumbersome and the entire system is by no means user-friendly. Since the system described must be reprogrammed with each new measurement, the method also has a high susceptibility to errors.

From the DE 10 2008 000 381 A1 is a formwork element with transponder and sensors known, the sensors detect, for example, data on pressure, temperature or strain profile of the concrete. This makes it possible to draw conclusions about the wear and the aging of the formwork element. From the DE 10 2006 035 187 A1 It is known to mix construction materials contactless readable transponder units to simplify the logistics and quality control. In both cases, the sensors are used for the identification and traceability of the building materials or the formwork parts. A monitoring of the compressive strength of the fresh concrete is not provided here.

There is therefore still a need for methods for determining and predicting the compressive strength of hardening concrete which overcome the disadvantages of known methods.

Presentation of the invention

This is where the invention starts. It is an inexpensive and simple method for determining and predicting the compressive strength of hardening concrete can be provided, through which the construction process can be improved. This object is achieved by the method for determining and predicting the compressive strength of hardening concrete according to independent claim 1. Further advantageous aspects, details and embodiments of the invention will become apparent from the dependent claims, the description and the drawings.

• a) Bereitstellen zumindest eines ersten elektronischen Sensors zur Erfassung zumindest eines physikalischen Parameters von erhärtendem Beton,
• b) Bereitstellen eines Datenübertragungsmittels,
• c) Bereitstellen einer Rechnereinheit umfassend zumindest eine Steuereinheit,
• d) Bereitstellen zumindest eines zweiten elektronischen Sensors zur Erfassung der Umgebungstemperatur,
• e) in Kontakt bringen des ersten elektronischen Sensors mit frisch vergossenem Beton,
• f) Messung zumindest eines physikalischen Parameters des Betons mittels des ersten elektronischen Sensors,
• g) Messung der Umgebungstemperatur mittels des zweiten elektronischen Sensors,
• h) Übertragung der in den Schritten f) und g) erfassten Messwerten den elektronischen Sensoren an das Datenübertragungsmittel,
• i) Übertragung der in Schritt h) an das Datenübertragungsmittel übertragenen Messwerte von dem Datenübertragungsmittel an die Rechnereinheit,
• j) Verarbeitung der Daten durch die Steuereinheit der Rechnereinheit mittels eines Algorithmus,
• k) Bereitstellen der verarbeiteten Daten durch die Steuereinheit in einer von einer Ausgabeeinheit darstellbaren Form,
• l) Übertragung der in Schritt k) bereitgestellten Daten zu einer Ausgabeeinheit,
• m) grafische oder tabellarische Darstellung der in Schritt l) übertragenen Daten mittels der Ausgabeeinheit.

The present invention provides a method for determining and predicting the compressive strength of hardening concrete comprising the steps of:

• a) providing at least one first electronic sensor for detecting at least one physical parameter of hardening concrete,
• b) providing a data transmission means,
• c) providing a computer unit comprising at least one control unit,
• d) providing at least one second electronic sensor for detecting the ambient temperature,
• e) contacting the first electronic sensor with freshly poured concrete,
• f) measuring at least one physical parameter of the concrete by means of the first electronic sensor,
• g) measuring the ambient temperature by means of the second electronic sensor,
• h) transmission of the measured values acquired in steps f) and g) to the electronic sensors to the data transmission means,
• i) transmission of the measured values transmitted to the data transmission means in step h) from the data transmission means to the computer unit,
• j) processing of the data by the control unit of the computer unit by means of an algorithm,
• k) providing the processed data by the control unit in a form that can be represented by an output unit,
• l) transmission of the data provided in step k) to an output unit,
• m) graphic or tabular representation of the data transmitted in step l) by means of the output unit.

When constructing concrete structures, it is essential to assess the compressive strength of the hardened concrete. For example, after hardening of the concrete, the formwork must be removed again. The stripping time is usually determined by the skilled workers working on the site based on experience. Out As a rule, security reasons are expected to last longer than is actually necessary. As a result, the formwork elements used can be reused late. In addition, the construction progress is unnecessarily delayed. An exact determination of the earliest possible Ausschalzeitpunkts therefore leads to a significant time and cost savings.

In addition, the compressive strength of hardening concrete at the age of a few hours can be decisive for, for example, the planning for applying a preload or an early load, but also for estimating a sufficient frost resistance or for predicting the transportability of a precast concrete part. Even in these cases, an accurate determination and prediction of the compressive strength of hardening concrete leads to a smooth progress of the construction progress and therefore to a time and cost optimization for the entire construction project.

By means of the method according to the invention, the maturing or hardening of the concrete can be closely monitored and, for example, the first possible breaking-off time or the earliest possible time for the partial or complete removal of the supports or for applying a preload or a load can be accurately predicted.

The essential aspect of the present invention resides in the fact that at least one physical parameter characterizing the hardening concrete as well as the ambient temperature are determined by the electronic sensors. The ambient temperature has a strong influence on the progress of the concrete maturation and therefore influences the development of the compressive strength of the concrete. The measurement of the ambient temperature therefore allows accurate predictions about the compressive strength of the concrete. The acquired measured values are transmitted to a computer unit via a data transmission means and processed by the latter without appreciable delay by means of an algorithm. The computer unit provides the processed data in a form that can be displayed by an output unit. These data are then transmitted to an output unit and represented by this graphically or in tabular form. From this representation, for example, the earliest possible Ausschalzeitpunkt but also the earliest possible time to apply a bias or a load can be read directly, whereby the construction process is significantly accelerated and optimized.

The measured values acquired by the electronic sensors are preferably digitized and forwarded via the data transmission means. For example, a data transmission by means of data line network is possible, wherein the data transmission means and the sensors or the computer unit can be networked with each other via data cable.

However, a decisive advantage is wireless data transmission. The measured values acquired by the sensors are transmitted wirelessly to the data transmission means and preferably also wirelessly from the data transmission means to the computer unit.

Wireless data transmission makes mounting the sensor fast, easy and easy. The sensor only has to be brought into contact with the freshly poured concrete on the spot. For example, the sensor may be designed as a float and then includes a housing and a downwardly directed metal tip, which is immersed in the concrete to perform the measurements. In the use position, the sensor is automatically switched on, whereby both the measurement and the transmission of data begin immediately when the sensor is placed on the freshly poured concrete. For the skilled workers working on the construction site, no programming steps or other difficult adjustments are required to put the sensor into operation or start the data transmission.

According to a preferred embodiment of the present invention, the first electronic sensor and the data transmission means are combined in one component. Particularly preferably, the data transmission means is integrated in a sensor designed as a float. This variant, which was specially developed for smaller construction projects and concrete road construction, has the great advantage that sensor and data transmission means are integrated in one component. The user only needs to use one battery and place the measuring module with sensor and integrated data transmission means on the freshly poured concrete. The measurement data is sent directly to the computer unit without the need to set up a separate data transmission means on the construction site. Installation and programming of the data transmission means by the user are omitted in this embodiment, whereby error sources are eliminated.

In addition to the simple installation of the sensor, which leads to a significant work and time savings for working on the site skilled workers, the wireless, digital data acquisition and transmission and data processing and output of the invention has the distinct advantage that a first direct reading of the processed data on-site without delay is possible. For example, the skilled worker can work directly on the construction site immediately after the beginning of the construction Data acquisition, for example, using a laptop, a PC or other means to effect a transfer of processed and provided by the control unit data. The laptop or PC then acts as the output unit and the skilled worker can follow the temperature, pressure resistance and maturity history or other measured values of the hardening concrete on the basis of the graphical or tabular representation of the data. Conventional methods, on the other hand, require the user to first process the measured data and calculate the compressive strength curve, which often results in the result being only complete after the measurements have been completed.

The graphic or tabular representation of the data processed by the computer unit can also be effected by an output unit positioned in the immediate vicinity of the computer unit. In this case, the user is informed at the construction site by, for example, an SMS or e-mail when, for example, a certain maturity, a certain compressive strength, a certain temperature or a predetermined value of another physical parameter of the concrete is achieved.

The individual transmissions of data according to the present invention preferably take place without a time delay. Thus, the measured values acquired by the electronic sensors are preferably transmitted to the data transmission means without a time delay and / or the data is transmitted from the data transmission means to the computer unit without a time delay and / or the provided data are transmitted to an output unit without a time delay. With the least possible time interval between acquisition of the measured values and representation of the processed data by the output unit can be responded to changes in the compressive strength of the concrete or changes in the environment such as changes in air temperature particularly quickly and directly.

It should be noted at this point that the user can freely choose the time sequence of the individual measurements on the construction site. The preferred immediate transmission and processing of the measured values is not intended to imply that measured values are determined in a permanent sequence. The user decides on the temporal frequency of the various measurements, which can be set variably.

The advantages mentioned are particularly useful if the processing of the measured values by the control unit and / or the representation of the processed data by the output unit are likewise carried out without a time delay. These embodiments are therefore also preferred in the context of the present invention.

According to a preferred embodiment of the present invention, the first electronic sensor is positioned on the formwork so as to be in contact with the freshly poured concrete. For example, the sensor can be positioned simultaneously with the structure of the formwork even before the concrete is poured, whereby first measured values can be recorded directly during the casting of the concrete.

Analogous advantages include a further preferred embodiment of the present invention in which the first electronic sensor is designed as a lost sensor, which is mixed into the concrete to be poured.

Preferably, the first electronic sensor is non-destructively poured into the concrete so that it is removable again, preferably within a mounting box or a built-in ear. The resulting reuse of the sensor leads to a cost reduction and is advantageous both from an economic as well as from an ecological point of view.

In principle, the first electronic sensor can be installed in any type of container and used in this form in the method according to the invention. Preferably, the first electronic sensor is a sensor contained in a wall thickness. In general, wall thicknesses are generally used in the construction of concrete structures, with different models and versions of wall thicknesses are commercially available. Due to the universal use of wall thicknesses, these are mounted on the construction sites anyway by the skilled workers. Advantageously, the installation of the sensors is thus simultaneously with the installation of the wall thickness, if the sensors are integrated in the wall thicknesses. Another advantage of using integrated in the wall thickness sensors is the fact that at each point where a sensor-containing wall thickness is used, a sensor is present, whereby the sensors are distributed over the concrete part and thus in several places on the fresh potted concrete measurements can be performed.

Of particular advantage is also the fact that the actual sensors are very small. As a result, they can be easily installed in various items, such as a cable. If such a cable vertically or horizontally in a formwork, which is to be poured out with fresh concrete, relocated, so can in several places in the concrete at the same time physical parameters are measured. This proves to be particularly advantageous when measurements in bulk concrete or in very large depths as in pile borings are necessary. The sensors can also be installed in very flat housings, allowing measurements directly on the formwork.

Particular advantages result from the fact that the first electronic sensor is a sensor for detecting the temperature, the humidity, the water content, the pressure or the chloride content of the concrete, the temperature and / or the humidity being determined by means of the first electronic sensor and / or the water content and / or the pressure and / or the chloride content of the concrete are detected. For the parallel detection of several physical parameters, it is also possible to use a plurality of sensors, one sensor of which detects one type of physical parameter in each case.

The temperature development in hardening concrete is of great practical importance. Simultaneously with the hardening of the concrete, which is caused by the hydration of the cement, heat is released. Depending on the heat transfer conditions, for example, depending on the thickness of the component, this heat of hydration can lead to significant heating of the component. Although elevated concrete temperatures in the component promote curing and thus a positive compressive strength development of the hardening concrete, but also have temperature deformations result, which can lead to forced voltages and cracking.

Among other things, the composition of the concrete has an influence on the release of the heat of hydration and thus on the temperature increase of the component. By understanding the relationship between release of hydration heat and strength development, concrete technological measures can be taken to reduce the maximum temperature as much as possible and thereby reduce the likelihood of cracking. Thus, the optimization of the concrete mix for a specific component is often unavoidable.

By measuring the temperature of the hardened concrete via a temperature sensor, the optimization of the concrete mix can be carried out in a timely manner. For example, with the aid of the method described, the temperature profile in a concrete test cube can be measured. Direct data transmission, processing and output enable the results to be tracked without time delay and appropriate measures taken to optimize concrete mixing for the specific component.

By detecting different physical parameters or different combinations of parameters, the method can be adapted to a wide variety of applications.

Preferably, a plurality of sensors are provided for detecting physical parameters of the concrete, wherein the sensors for the simultaneous detection of the physical parameters are preferably distributed over at least an area of the component. The simultaneous detection of physical parameters at multiple locations of the component may be advantageous in, for example, bored piles, since the compressive strength development is not homogeneous over the entire depth of, for example, 15-20 m due to the different soil conditions and water / cement content of the concrete. In this case, the compressive strength development is tracked over the entire depth at regular intervals. A load is applied only then or the cutting of a rip fence takes place only when the pressure resistance of the bored piles has reached the required value at all points over the entire depth.

Likewise, it may be advantageous, for example, to perform temperature measurements over the entire thickness of a concrete wall and, for example, about 5 cm apart from each outer surface, just in the middle of the wall and possibly at two other locations between the outer and central measuring points to detect the temperature to a to be able to make precise statements about the dissipation of the heat of hydration and about the local temperature increase in the concrete wall.

According to a particularly preferred embodiment of the present invention, the second electronic sensor is a sensor for detecting the ambient temperature and the wind speed. The wind speed has an immediate effect on the removal of moisture and heat and therefore influences the development of the compressive strength of the concrete. The measurement of the wind speed therefore allows more accurate predictions about the compressive strength of the concrete.

According to a particularly preferred embodiment, the method according to the invention is followed by a control step. Upon reaching certain preset limits or times, any aftertreatment systems can be controlled.

If the method according to the invention is used in the production of finished parts, a control step follows the method according to the invention in accordance with a preferred embodiment. In this case, in Dependent on the measured values automatically controlled a heating or cooling system, thereby accelerating or retarding the maturity of the concrete. In particular, such acceleration or deceleration of maturity development takes place when certain previously set values of the physical parameters are reached. However, other production processes such as hydration can also be controlled. Alternatively, it is possible to inform the user by means of a visual signaling device about the stage of development of the concrete.

Ways to carry out the invention

The invention will be explained in more detail with reference to an embodiment in conjunction with the drawings. However, it is expressly pointed out that the innovation should not be limited to the example given.

The 1 schematically shows an embodiment of a method for determining and predicting the compressive strength of hardening concrete. The arrangement for carrying out the method according to the present invention comprises a first electronic sensor 1 for detecting at least one physical parameter, a data transmission means 2 , a computer unit 3 with a storage unit 3.1 , a control unit 3.2 and an output unit 3.3 and a second electronic sensor 4 for detecting the ambient temperature.

The first electronic sensor 1 is formed in the illustrated embodiment as a float and is brought into contact with the freshly poured concrete B. This is the metal tip 1a of the swimmer 1 placed on the concrete B, the float housing 1b Do not dive deeper into the concrete. As soon as the float 1 is aligned so that the metal tip points vertically downwards, the sensor is turned on and starts immediately with the data acquisition. If you turn the float around, the sensor is switched off automatically.

For easy removal of the float 1 after the procedure has been carried out, the underside of the float can be treated, for example, with formwork oil. Alternatively, the first electronic sensor 1 For example, be designed as a cable sensor, magnetic or shuttering system sensor.

Both at the first 1 as well as the second electronic sensor 4 is in the illustrated embodiment, digital sensors that are equipped with batteries for the purpose of power supply, so that no power cord or plug for power supply are necessary. To conserve the batteries, the sensors 1 . 4 switched off when not in use.

Once the first physical parameter or the ambient temperature of the sensors 1 . 4 are detected, the measurement data to the data transmission means 2 transfer. The data transmission takes place in the illustrated example wirelessly via a data communication network, such as via GSM (Global System for Mobile Communications), which is why the construction project for use of the method described should be within a GSM network. If interference with data transmission due to interfering radio signals or other wireless data traffic may occur, one or more amplifiers may be installed on-site to correct the interference.

The data is then sent to the computer unit 3 forwarded in the storage unit 3.1 stored and by the control unit 3.2 the computer unit 3 processed by means of an algorithm. The processed data is also stored in the storage unit 3.2 saved. At the computer unit 3 it is preferably a central computer, for example in a data center. The processed data are from the control unit 3.2 in one of an output unit 3.3 representable form and to the output unit 3.3 transfer. In the embodiment shown, the output unit 3.3 Part of the computer unit 3 , The output unit 3.3 displays the processed data directly graphically or in tabular form.

The output unit 3.3 but can be spatially from the computer unit 3 be separated. In this case, the representation of the processed or evaluated data preferably takes place via a website with a personalized access code to which the skilled worker or construction manager working on the construction site has access. Using a laptop with access to the Internet, the results can be viewed and evaluated directly on site at the construction site.

LIST OF REFERENCE NUMBERS

1

first electronic sensor

1a

metal tip

1b

float bowl

2

Data transmission means

3

computer unit

3.1

storage unit

3.2

control unit

3.3

output unit

4

second electronic sensor

B

concrete

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 83/01411 A1 [0003, 0003]
• DE 102008000381 A1 [0004]
• DE 102006035187 A1 [0004]

Claims (13)

Method for determining and predicting the compressive strength of hardening concrete, comprising the steps of: a) providing at least one first electronic sensor ( 1 ) for detecting at least one physical parameter of hardening concrete (B), b) providing a data transmission means ( 2 ), c) providing a computer unit ( 3 ) comprising at least one control unit ( 3.2 d) providing at least one second electronic sensor ( 4 ) for detecting the ambient temperature, e) bringing into contact the first electronic sensor ( 1 ) with freshly poured concrete (B), f) measurement of at least one physical parameter of the concrete (B) by means of the first electronic sensor ( 1 g) measuring the ambient temperature by means of the second electronic sensor ( 4 h) transmission of the measured values recorded in steps f) and g) to the electronic sensors ( 1 . 4 ) to the data transmission means ( 2 i) transmission of the in step h) to the data transmission means ( 2 ) transmitted measured values from the data transmission means ( 2 ) to the computer unit ( 3 ), j) processing of the data by the control unit ( 3.2 ) of the computer unit ( 3 ) by means of an algorithm, k) providing the processed data by the control unit ( 3.2 ) in one of an output unit ( 3.3 ) representable form, l) transmission of the data provided in step k) to an output unit ( 3.3 ), m) graphic or tabular representation of the data transmitted in step l) by means of the output unit ( 3.3 ). A method according to claim 1, characterized in that it is in the transmission of the detected measured values of the electronic sensors ( 1 . 4 ) to the data transmission means ( 2 ) in step h) is a wireless data transmission. A method according to claim 1 or 2, characterized in that it is in the transmission of the measured values of the data transmission means ( 2 ) to the computer unit ( 3 ) in step i) is a wireless data transmission. A method according to claim 3, characterized in that it is in the transmission of the measured values of the data transmission means ( 2 ) to the computer unit ( 3 ) in step i) to a wireless remote data transmission to a remote computer unit ( 3 ). Method according to one of claims 1 to 4, characterized in that the first electronic sensor ( 1 ) is attached to a formwork. Method according to one of claims 1 to 4, characterized in that it is in the first electronic sensor ( 1 ) is a lost sensor mixed into the concrete to be poured. Method according to one of claims 1 to 4, characterized in that it is in the first electronic sensor ( 1 ) is a sensor contained in a wall thickness. Method according to one of the preceding claims, characterized in that in step l) the transmission of the data to an output unit ( 3.3 ) by remote transmission to a remote output unit. Method according to one of the preceding claims, characterized in that it is in the first electronic sensor ( 1 ) is a sensor for measuring one or more physical parameters of hardening concrete selected from the group consisting of temperature, humidity, water content, pressure, chloride content. Method according to claim 9, characterized in that by means of the first electronic sensor ( 1 ) one or more physical parameters of hardening concrete selected from the group consisting of temperature, humidity, water content, pressure, chloride content are detected. Method according to one of the preceding claims, characterized in that a plurality of sensors are provided for detecting one or more physical parameters of the concrete. Method according to one of the preceding claims, characterized in that it is in the second electronic sensor ( 4 ) is a sensor for detecting the ambient temperature and the wind speed. Method according to one of the preceding claims, characterized in that the first electronic sensor and the data transmission means are combined in one component.

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