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The sensors communicate by Bluetooth or Long-Range Wide Area Network (LoRaWAN) with the Hilti
Concrete Sensors application and the data are transmitted to a suitable mobile device.
3.5
Overview: Sensor models
Model designation
HCS T1
HCS T1-B3
HCS T1-B8
HCS T1-B15
HCS T2
HCS T2-B3
HCS T2-B8
HCS T2-B15
3.6
Measurement data
3.6.1
Hilti concrete sensors laboratory services
The most widely accepted industry standard for monitoring strength is the ASTM C1074 Maturity Method.
This standard requires a calibration test in advance for each concrete mix design. There are two types of
test within this standard. The test of equivalent age (also referred to as the Arrhenius equation) requires the
metering, pouring, hydration and breaking (or crushing) of cylinder and cube samples cured over a hydration
time of 28 days. The cylinders are hydrated at room temperature and the cubes are divided into groups and
hydrated at 3 different temperatures at least.
The Hilti concrete sensor laboratory service permits the most accurate estimate of strength in that it exceeds
the requirements of ASTM C1074 Appendix X1. This service makes preparing concrete mixes easy. Support
commences prior to testing and extends through to delivery of the concrete to site.
This is done in order to ascertain temperature sensitivity on the basis of the chemical composition of the draft
mix design. Hilti Concrete Sensors conducts the Equivalent Age test but at 4 different temperatures for the
sake of increased accuracy. The less comprehensive time/temperature test (also known as the Nurse Saul
maturity test) requires the mixing, pouring, hydration and crushing of cylinders cured at only one temperature
and therefore of limited accuracy to account for fluctuations in the in-place concrete temperatures over the
project. For these advance tests our team has to collaborate with the corresponding project stakeholders to
confirm the concrete mixing instructions and the list of materials and then procure these materials in order
to conduct the 28-day maturity test. As soon as the test is completed, the ID number of the draft mix design
is filed in our in-app library under the supplier's company name.
To confirm accuracy, ASTM recommends a verification exercise in which a project stakeholder installs in-situ
sensors on typical cylinders that are poured by a third-party lab technician in the field, so that the strength
data recorded in the app can be compared to the physical results obtained from crushing the third-party
cylinders. It is important to note that the strength data returned by our software are not accurate if the
supplier makes a significant change to the draft mix design filed beforehand in our in-app library and that
new tests (calibration) are necessary.
3.6.2
Concrete strength and degree of hydration
Hilti concrete sensors enable construction companies to monitor the strength development of concrete in
real time. When the constituents of concrete are brought into contact with water on mixing, the mix starts to
set and gain compressive strength, in the process commonly referred to as hydration. Compressive pressure
is generally measured in pounds per square inch (psi) or megapascals (MPa).
*2399131*
Connection method
Bluetooth
Bluetooth
Bluetooth
Bluetooth
LoRaWAN
LoRaWAN
LoRaWAN
LoRaWAN
2399131
Measured/processed data
Strength, temperature
Strength, temperature
Strength, temperature
Strength, temperature
Strength, temperature
Strength, temperature
Strength, temperature
Strength, temperature
Max. in-
stalled depth
150 mm
(5.9 in)
1,000 mm
(39.4 in)
2,600 mm
(102.4 in)
4,700 mm
(185.0 in)
150 mm
(5.9 in)
1,000 mm
(39.4 in)
2,600 mm
(102.4 in)
4,700 mm
(185.0 in)
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