VAKKA are sensors that wirelessly monitors the environmental conditions within the concrete as it hardens. The patent-pending environmental chamber is unique to the VAKKA system and allows for faster and more accurate readings. It quickly equalizes the surrounding environment allowing precise measurements to be recorded within minutes of pouring your concrete.

The free mobile app and cloud service empowers the user’s team to make faster and more confident decisions. The data can be downloaded to the app at any time when a connected device is within the 3-4 m range of the sensor and is instantly uploaded to the cloud where it is shared with the team. The app estimates the compressive strength by using the user defined maturity curve and allows instant access to the temperature and relative humidity readings, plotting data, and reports.

With the VAKKA sensors, the traditional method of braking cylinders is improved in accuracy and project cost savings by reflecting better the concrete strength gain in real-time. On the other hand, by knowing the up-to-date level of relative humidity of in-place concrete, the timing in which floor coverings are installed, such as resilient flooring, wood, epoxy or polymer-based coatings, can be optimized.

Maturity sensors.

• Estimating the compressive strength at an early age using a user defined strength-maturity relationship.
• Timing of pullout testing with LOK-TEST for early-age strength measurement.
• Evaluating the effective in-place curing temperature
• Timing the surface treatment on floor slabs.
• Monitoring water penetration in concrete

Maturity sensors

• Free mobile App for Android and IOS devices
• Wireless technology
• Easy installation and activation
• Accurate real-time data display of relative humidity and temperature
• Normalizes to ambient conditions within minutes of placement
• Long storage life with external magnetic activation
• Rugged, crush proof and waterproof design
• Full reporting
• Cloud data storage for team access to projects from any location
• Maturity methods: ASTM C1074 Nurse/Saul and Arrhenius
• Measurement interval: 30 min (fixed)
• Maximum data collection: 4,000 data points (60 days)
• Operational battery life: > 4 months (active)
• Storage battery life: 10 years (unactive)
• Temperature accuracy: +/- 0.3 ^oC
• H. accuracy:  +/-2%
• Embedment depth: 1 m or 3 m probe available for VAKKA-Tx/HTx sensors
• Attachment: Galvanized tie-wires

 Maturity sensors.

VAKKA Ordering Numbers

• Technical datasheet

ASTM C1074 -Standard Practice for Estimating Concrete Strength by the Maturity Method.

ASTM F2170 -Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes.

The CorroWatch is a multi-probe device consisting of four black steel bars acting as anodes and a noble metal as the cathode. It is attached to the rebars with plastic strips and the anodic bars are positioned at different elevations and when concrete is cast, CorroWatch allows determination of corrosion activity as a function of cover distance. The height of the anodes may be adjusted according to the thickness of the concrete cover.

In order to predict when corrosion activity has reached the anodes, the current between the individual anodes and the cathode is measured, either with a handheld Zero Ohm Ammeter or a datalogger. When corrosion starts, the measured current increases significantly.

It can also work along with the ERE-Probe (see technical data sheet) for monitoring of the electrical potentials in the anodes.

Reinforcement corrosion monitoring.

• Monitoring of reinforcement in critical areas for corrosion such as construction joints, splash zones in marine structures, bridge decks, bottoms of bridge columns exposed to ingress of chlorides, etc.
• Monitoring of the ingress of the depassivation front, due to chloride penetration or carbonation.

Reinforcement corrosion monitoring.

• Anodes: 4 black steel bars
  • Length = 60 mm
  • Diameter = 12 mm
• Anode default heights, H: 33, 38, 43 and 48 mm  
• Cathode’s chamber:
  • External diameter = 85 mm
  • Thickness = 20 mm
• Overall weight = 500 g

Reinforcement corrosion monitoring.

Ordering Numbers:

• Technical datasheet

No standards available.

The ERE-Probe (Embeddable Reference Electrode) is a stable, long life reference manganese dioxide electrode for monitoring the half-cell potential of reinforcement in concrete structures.
In new structures, the ERE-Probe is attached to the reinforcement by plastic straps before placement of the concrete. In existing structures, a hole is drilled to the required depth and the ERE-Probe is embedded using an appropriate cementitious mortar. The probe can be used for concrete exposed to chlorides or carbonation and will not induce corrosion or change the natural potential of the steel. A high impedance voltmeter is connected to the cable and used to measure the half-cell potential between the probe and the reinforcement.

Corrosion potential monitoring.

• Monitoring of reinforcement potentials in critical areas for corrosion such as construction joints, splash zones in marine structures, bridge decks, bottoms of bridge columns exposed to ingress of chlorides, etc.
• Monitoring of efficiency of cathodic protection
• Monitoring of ingress of the depassivation front, due to chloride penetration or carbonation, in combination with installing the CorroWatch (see technical data sheet)

Corrosion potential monitoring.

• Diameter ≈ 18 mm
• Length ≈ 85 mm (without protective cap)
• Typical potential = +205 ± 20 mV measured in a saturated Ca(OH)₂ solution at 23ºC vs Ag/AgCl electrode*
• Internal resistance < 5,000 Ohm measured in a saturated Ca(OH)₂ solution at 23ºC
• Variation: ±5 mV compared with the initial value at the same temperature and same electrolyte environment
• Operating temperature: 0 to +40ºC (false readings are expected during frost but they are recovered after thawing)

• Service life > 30 years

Corrosion potential monitoring.

Ordering Numbers:

• Technical datasheet

No standards available.

The COMA-Meter (COncrete MAturity-Meter) is used to measure the maturity of newly cast concrete at a depth of 80 mm from the surface.
A glass capillary tube contains a special liquid for which the rate of evaporation varies with temperature according to the Arrhenius equation that is used to determine maturity of concrete from its temperature history. After the concrete is cast, the COMA-Meter is pushed into into the fresh concrete and the liquid in the capillary tube will evaporate at a rate determined by the temperature and time. The level of the liquid, readable on the scale, measures the maturity of the concrete stated in M20 units, which is the number of equivalent days of curing at 20 ºC.

• Estimating the compressive strength at an early age using a pre-established strength-maturity relationship
• Timing of pullout testing with LOK-TEST (consult Technical Data Sheet) for early-age strength measurement
• Evaluating the effective in-place curing temperature.

• Measuring ranges:
  • COMA-5 = 0 to 5 M₂₀ days
  • COMA-14 = 0 to 14 M₂₀ days
• Precision: ±0.1 M₂₀ days
• Accuracy: ±5 % compared with maturity values calculated from direct temperature readings
• Activation energy, E ≈ 40 kJ/mol.

Parts List

• Technical datasheet

No standards available.