Structural Engineering Blog

Atlanta Louisville Los Angeles Seattle

Field Testing for Reinforced Concrete

concrete restoration atlanta

Want to know the health of your concrete structure?

Want to upgrade your concrete structure but don’t have as-built structural drawings?

Non-destructive and minimally invasive concrete field testing can determine the health of your concrete structure and predict its useful remaining life. It can also determine or verify the reinforcement in your concrete structure. Non-destructive testing can also be used to determine the actual concrete compressive strength which supports as-built analysis and determination of reserve load carrying capacity.

Corrosion is reinforced concrete’s number one enemy. Corrosion is the result of an electrochemical reaction among ferrous metal, water, and oxygen where rust or other corrosion is formed. This rust expands 5 to 7 times its original volume, and there is no stopping it.

Concrete that is very strong in compression is also very weak in tension. As a result, as the rusted rebar expands, the concrete cracks and eventually spalls.

Concrete has a naturally high pH which protects the reinforcing steel from corrosion. However, the presence of chlorides from saltwater and the process of carbonation occurring from oxygen in the atmosphere serve to lower the naturally protective pH.

The resulting atmosphere promotes corrosion and deterioration of the concrete exponentially over time. Corrosion also occurs at a faster rate and is more concealed in prestressed concrete than conventional reinforced concrete due to more surface area of exposed steel.

Initial Non-Destructive Testing (NDT) recommended:

  • Visual Examination: to identify wood and concrete deterioration, efflorescence, and leaks.
  • Probes: to identify soft spots requiring further investigation. Crack gauge to determine crack width and identify which cracks need to be sealed or epoxied (glued) back together.
  • Hammer and Rotary Hammer Testing (sounding): to identify delamination and future spalls on horizontal and vertical concrete surfaces.
  • Electrical Resistivity: to identify the presence of a corrosive environment (corrosion potential) containing chlorides and moisture penetration.
  • Ground Penetrating Radar (GPR): to identify corroded rebar, rebar size, cover, and location. Check for voids behind concrete.
  • Instantaneous Corrosion Rate Measurement: to measure the rate of corrosion to see how active the corrosion is and predict longevity of reinforcing from a known condition.
  • Impulse Echo: to check thickness and detect voids, delamination, and discontinuities of slabs, walls, footings, pile caps, and piles (concrete, steel, or wood), and to measure in situ concrete compressive strength. Pile testing may require minor excavation.

Optional Minimally Invasive Testing:

  • Chloride Ion Content and Depth to predict service life of reinforced concrete.
  • Carbonation Depth: requires cores sprayed with pH indicator solution to predict service life of reinforced concrete.
  • Half-Cell Potential: to locate different intensities of active corrosion.

The IEI Advantage: Concrete Restoration

The engineers at IEI specialize in concrete restoration! We’re happy to walk your facility and let you know of any conditions that require immediate attention and what maintenance activities you can perform now to extend the life of your facility. Since the back of IEI business cards contain a crack gauge, one can easily evaluate cracks within your structure. Give us a call today!

Leave a Comment