ULTRASONIC PULSE VELOCITY (U.P.V) TESTING SERVICES

Ultrasonic Pulse Velocity (UPV) is an effective non-destructive testing (NDT) method for quality control of concrete materials, and detecting damages in structural components. The UPV methods have traditionally been used for the quality control of materials, mostly homogeneous materials such as metals and welded connections. With the recent advancement in transducer technology, the test has been widely accepted in testing concrete materials. Ultrasonic testing of concrete is an effective way for quality assessment and uniformity, and crack depth estimation. The test procedure has been standardized as the “Standard Test Method for Pulse Velocity through Concrete”

An ultrasonic pulse velocity test is Nondestructive test to check the quality of concrete and natural rocks. In this test, the strength and quality of concrete or rock is assessed by measuring the velocity of an ultrasonic pulse passing through a concrete structure or natural rock formation.

This test is conducted by passing a pulse of ultrasonic through concrete to be tested and measuring the time taken by pulse to get through the structure. Higher velocities indicate good quality and continuity of the material, while slower velocities may indicate concrete with many cracks or voids.

Ultrasonic testing equipment includes a pulse generation circuit, consisting of electronic circuit for generating pulses and a transducer for transforming electronic pulse into mechanical pulse having an oscillation frequency in range of 40 kHz to 50 kHz, and a pulse reception circuit that receives the signal.

The transducer, clock, oscillation circuit, and power source are assembled for use. After calibration to a standard sample of material with known properties, the transducers are placed on opposite sides of the material.

REBOUND HAMMER TESTING SERVICES

Rebound Hammer test is a Non-destructive testing method of concrete which provide a convenient and rapid indication of the compressive strength of the concrete. The rebound hammer is also called as Schmidt hammer that consist of a spring controlled mass that slides on a plunger within a tubular housing. When the plunger of rebound hammer is pressed against the surface of concrete, a spring controlled mass with a constant energy is made to hit concrete surface to rebound back. The extent of rebound, which is a measure of surface hardness, is measured on a graduated scale. This measured value is designated as Rebound Number (rebound index). A concrete with low strength and low stiffness will absorb more energy to yield in a lower rebound value.The hammer measures the rebound of a spring-loaded mass impacting against the surface of a sample. The test hammer hits the concrete at a defined energy. Its rebound is dependent on the hardness of the concrete and is measured by the test equipment. By reference to a conversion chart, the rebound value can be used to determine the concrete's compressive strength. When conducting the test, the hammer should be held at right angles to the surface, which in turn should be flat and smooth. The rebound reading will be affected by the orientation of the hammer: when used oriented upward (for example, on the underside of a suspended slab), gravity will increase the rebound distance of the mass, and vice versa for a test conducted on a floor slab. Schmidt hammer measurements are on an arbitrary scale ranging from 10 to 100.

HALF-CELL POTENTIAL TESTING SERVICES

The instrument measures the potential and the electrical resistance between the reinforcement and the surface to evaluate the corrosion activity as well as the actual condition of the cover layer during testing. The electrical activity of the steel reinforcement and the concrete leads them to be considered as one half of weak battery cell with the steel acting as one electrode and the concrete as the electrolyte. The name half-cell surveying derives from the fact that the one half of the battery cell is considered to be the steel reinforcing bar and the surrounding concrete. The electrical potential of a point on the surface of steel reinforcing bar can be measured comparing its potential with that of copper – copper sulphate reference electrode on the surface. Practically this achieved by connecting a wire from one terminal of a voltmeter to the reinforcement and another wire to the copper sulphate reference electrode. Then generally readings taken are at grid of 1 x 1 m for slabs, walls and at 0.5 m c/c for Column, beams.

The half-cell potential is the potential developed at the electrode of a half cell due to the process of oxidation or reduction. This potential is used to indicate corrosion activity, and measures the tendency of one reaction, like oxidation, to proceed at its one half-cell electrode and similarly measures the corresponding tendency for reduction to proceed at the other half-cell electrode.

Each half-cell potential is associated with an electrode-solution potential difference. The potential magnitude depends on the nature of the specific electrode reaction and on the concentrations of the dissolved solution. The sign of this potential difference depends on the direction (oxidation or reduction) in which the electrode reaction proceeds.

A half-cell potential measurement is a non-destructive method to assess the corrosion risk of steels in concrete. This method is cheaper and can be easily used. In reinforcing concrete, an electrode forms one half of the cell and the reinforcing steels in the concrete form the other half cell. The behavior of steel in concrete can be characterized by measuring its half-cell potential. The chances of corrosion occurring on the steel in concrete and half-cell potential are directly proportional; the higher the potential, the higher the risk of corrosion occurrence.

PILE INTEGRITY TESTING SERVICES

Integrity test of Pile is a technique that can be used both on cast-in-situ and prefabricated piles, and it is a non-destructive type of testing to check the integrity of the pile shaft. PIT test of Pile is relatively quick and straightforward and enables several piles to be tested in a single working day.

Construction and installation of concrete piles and deep foundations is a challenging task. Problems may occur during the process, which in turn results in defects or anomalies such as: pile formation problems, concrete faults, and reinforcement installation issues. The resulting defects can negatively impact the durability and mechanical performance of the pile. Pile Integrity Tests are a group of non-destructive test methods that are used by geotechnical engineers and contractors to for quality control and quality assurance of deep foundations and piles. This article describes some of the most important NDT methods for evaluating pile integrity.

Concrete piles and drilled shafts are an important category of foundations. Despite their relatively high cost, they become necessary when we want to transfer the loads of a a heavy superstructure (bridge, high rise building, etc.) to the lower layers of soil. In general, Pile Integrity refers to certain characteristics of deep foundations and piles such as:

- Physical Dimensions of Pile (Length or Cross-Section);
- Continuity of Pile (presence of Voids or Major Cracks); and
- Consistency of the Pile Material.

CORE CUTTING SERVICES

A core cut is necessary to:

Examine the roofing system for moisture and determine how much is present.
Determine the types and characteristics of the existing roofing materials.
Complete a thorough roofing survey.
Assess the structural integrity of the roof deck. Metal corrodes. Concrete spalls. It’s important to determine if deck replacement or preparation is needed.
Determine the type of roofing project your contractor will execute. A core cut will reveal whether a recover is possible (is there already two roof systems in place?) or if partial tear-off or a total reroof is necessary..
Core drilling is a type of service in which a drill is used to remove a cylinder of material, called a ‘core.’
This type of concrete cutting is used in many applications, including but not limited to:
Walls, floor slabs, and ceilings for electrical and communication services, cabling, plumbing, or HVAC
Slab and roadway holes for doweling drilling, rebar tie-ins, or drainage
Recessed lighting and fixtures
Sampling and analysis of material.

Most often, core cuts are taken when the building owner or facility manager wants to have work performed on the roof. More information is needed by the roofing contractor before the project can be determined and scope of work planned. This can help develop an accurate estimate and prevent unexpected expenditures due to unforeseen conditions as the project progresses.

SCAN BEFORE YOU CORE.

Penhall uses GPR and digital X-ray technologies to detect hazards in concrete before you cut or core, keeping projects on track and personnel safe