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 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.

An insert with a steel disc, 25 mm in diameter at a depth of 25 mm, is cast into concrete. Once the concrete has hardened, the disc is pulled centrally against a 55 mm diameter counter pressure ring bearing on the testing surface. The force F required to pullout the insert generates compression stresses in the strut between the disc and the counter pressure ring. Loading is performed either to a required force, in which case the test is nondestructive, or to the peak-load, which results in a slightly raised, 55-mm diameter circular crack on the surface. If pulled out, the conical hole can be easily patched with a repair non-shrink mortar.

Pull out test.

• Determining whether in-place concrete strength is sufficient for timing of early and safe loading operations, such as due to formwork removal or application of prestressing.
• Determining whether the in-place strength is sufficient for terminating curing and thermal protection. 
• Quickly evaluating the quality of the critical cover layer protecting the reinforcement in the finished structure.
• Substituting laboratory testing cylinders or cubes for testing final strength of structures on-site. 

Pull out test.

• Handheld hydraulic pulling machine with electronic gauge. 
• Digital display resolution = 0.1 kN
• Maximum force: 100 kN 
• Maximum stroke: 6 mm
• Accuracy of measurements: ± 0.1 kN
• Operating conditions: -10 to 50°C, max. RH = 95%
• Memory capacity: 512 measurements (peak-value, time and date of testing)
• AMIGAS Software for PC communication and printout

LOK-TEST Kit

Includes:

Item Order # Hydraulic pull machine with electronic gauge L-11-1 AMIGAS Printout software L-13 Cable for printout L-14 Centering plate L-15 Coupling L-16 Pull bolt L-17 Stem removal tool L-18 Bolt handle L-19 Adjustable pliers L-20 Oil refilling cup L-24 Oil refilling bottle L-25 Large screwdriver C-149 Small screwdriver C-157 Calibration table L-32 Manual L-33 Attaché case L-34

Consumables:

Inserts

*For testing high strength inserts, a special high-strength pull bolt with flange is needed, L-17-1, along with the high-strength coupling device C-141. Undamaged inserts may be re-used provided the discs are thread locked to the stems and coated with a coating agent, L-29. 

To be ordered separately

Load Verification Unit

• Technical data sheet
• Publications

More documentation is available upon request.

• ASTM C900, Standard Test Method for Pullout Strength of Hardened Concrete.

• BS 1881-207:1992, Testing concrete. Recommendations for the assessment of concrete strength by near-to-surface tests.

• BS EN 12504-3:2005, Testing concrete in structures. Determination of pull-out force

CORECASE has a thin-walled aluminium coring barrel that along with high-performance diamond bits and a special coupling for the drill machine that minimizes vibration, allow taking cores that are accurate in diameter, have straight and smooth sides, and are perpendicular to the surface.

Concrete core drill machine.

• Visual inspection of the concrete interior
• Determination of in-place compressive strength or other mechanical properties
• Verification of flaws identified by NDT methods such as the s’MASH impulse-response system; the DOCter impact-echo system; and the MIRA and EyeCon pulse-echo systems
• Preparing a partially drilled core for conducting a pull-off test with BOND-TEST following BS 1881:207 or ASTM C1583
• Other laboratory tests such as rapid chloride penetration using the PROOVE’it system, bulk conductivity/resistivity using Merlin, air-void parameters using the RapidAir system, or for petrographic analysis

*without drill or coring bit

Concrete core drill machine.

CORECASE CS-75 (75-mm core) Kit

Includes:

Optional Items:

Item	Order #
Suction plate	CC-160
Vacuum pump	CC-170
1150 W electric drill	CC-180
Extension rods, 100 mm long, for drilling deeper than 110 mm	CC-190

 CORECASE CEL-100 (100 mm core) Kit

Includes:

Item	Order #
Coring rig with coupling	CC-15
Handles for coring rig, 3 pcs	CC-20
Coring bit, 100 mm x 210 mm	CCB-100/210
Water pump with 2 hoses	CC-30
Clamping pliers, adjustable, 2	CC-40
Set of anchoring tools, 12 mm	CC-55
12 mm expansion anchors, 20	CC-65
Chisel	CC-75
Hammer	CC-80
Core lifter, 100-mm diameter	CC-95
Wrench, 14 mm	CC-100
Measuring tape	CC-110
Set of spare bearings for coring rig	CC-120
Reinforcement locator	CC-130
Manual	CC-145
Attaché case	CC-155

Optional Items:

To be ordered separately

• Technical data-sheet 

• ASTM C42: “Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete”

• EN 12504-1: “Testing concrete in structures. Cored specimens. Taking, examining and testing in compression”

A disc is bonded to a prepared testing surface and a partial core is cut around the disc. The disc is then pull off with the handheld hydraulic pulling machine.  The pull-off force register by the electronic gauge is divided by the cross-sectional area of the partial core to obtain the pull-off strength.  

• To evaluate the in-place bond strength between a repair overlay or patch and the substrate
• To evaluate the in-place tensile strength of concrete or other materials
• To evaluate the effect of surface preparation procedures on the tensile strength of the substrate before applying a repair material or overlay
• To evaluate the adhesion of diverse materials like metal plates, tiles, thick coatings, FRP’s, etc., on concrete or masonry surfaces

• Battery powered handheld hydraulic pulling machine with robust steel-aluminum body
• Digital display resolution = 0.1 kN
• Maximum force: 100 kN (about 22 MPa for 75 mm discs)
• Maximum stroke: 6 mm
• Accuracy of measurements: < 2%
• Operating conditions: -10 to 50°C, max. RH = 95%
• Memory capacity: 512 measurements (peak-value, time and date of testing)
• AMIGAS Software for PC communication and printout
• Coefficient of variation of replicate test results for the pull-off test method = 8 – 10% for 75 mm discs and 14 – 16% for 50 mm discs

B-13000 BOND-TEST Pull Machine Kit

Includes:

Item	Order #
Hydraulic pull machine with electronic gauge	L-11-1
AMIGAS printout software	L-13
Cable for printout	L-14
Strength conversion table and manual	B-13001
Counter pressure ring	B-13002
Centering piece	B-13003
Coupling	L-16
Pull bolt	L-17
Bolt handle	L-19
Oil refilling cup	L-24
Oil refilling bottle	L-25
Large screwdriver	C-149
Small screwdriver	C-157
Attaché case	B-13004

BOND-TEST Accessories

B-10000 DSV-Kit: For surface planing, bonding the disc, and attaching the coring rig to produce the partial core without anchoring. Includes:

Item	Order #
Diamond planing wheel unit	B-10010
Suction plate with valve and gauge	B-10020
Two adjustable clamping pliers	B-10030
Centering plate for 75 mm disc Optionally, centering plate for 50 mm disc	B-10040 B-10050
Vacuum pump with hose	B-10060
Wrench, 17 mm	B-10070
Small screwdriver	B-10080
Attaché case	B-10090

B-11000 BOND-TEST Preparation Kit: For removing the center knob after surface planing, cleaning the surface, bonding the discs, and heating the discs in cold weather conditions. Includes:

Item	Order #
Grinder with cup stone	B-11010
Heat gun	B-11020
Steel brush	B-11030
75 mm discs, 6 pcs Optionally, 50 mm discs, 6 pcs	B-11040 B-11050
GRA glue box (Part A: 100 gr + Part B: 2 x 40 ml)	B-11060
Putty knife	B-11070
Araldite epoxy (for acrylic-based materials)	B-11080
Attaché case	B-11090

CORECASE CS-75 Kit: Coring device for producing the partial core. Includes:

Item	Order #
Coring rig with coupling	CC-10
Handles for coring rig, 3 pcs	CC-20
Coring bit, 75 mm x 110 mm	CCB-75/110
Water pump with 2 hoses	CC-30
Clamping pliers, adjustable, 2 pcs	CC-40
Set of anchoring tools, 8 mm	CC-50
8 mm expansion anchors, 20	CC-60
Chisel	CC-70
Hammer	CC-80
Corelifter, 75 mm diameter	CC-90
Wrench, 14 mm	CC-100
Measuring tape	CC-110
Set of spare bearings for coring rig	CC-120
Reinforcement locator	CC-130
Manual	CC-140
Attaché case	CC-150

*Drill machine not included

• Technical datasheet

• Publications

More documentation is available upon request

• ASTM C1583: Standard Test Method for Tensile Strength of Concrete Surfaces and the Bond Strength or Tensile Strength of Concrete Repair and Overlay Materials by Direct Tension (Pull-off Method).

• BS EN 1542: Products and systems for the protection and repair of concrete structures. Test methods. Measurement of bond strength by pull-off.