Basics of the IBO® Hollow Thread Bar Micro Pile

The IBO® Hollow Thread Bar Micro Pile is a problem solver. It has a lot of beneficial functions, including that it works well in several different soil types and isn’t affected by groundwater levels. IBO stands for Grout Injection Boring, which uses grout to fill a hollow steel bore. Using IBO to construct micro piling can create stable walls in sensitive or fragile environments, where precision is essential.

This product has gradually gained acceptance among engineers since it’s development in 1985 because it performs well and results in high-quality outcomes while preserving the soil. Hollow bars reinforce steel to transmit compression and tension.


Installation Techniques

Drill rigs have to meet specific parameters to work with the Hollow Thread Bar Micro Pile. Rigs made by TEI need to meet specific standards.

  1. The rotary or rotary-percussion drill needs to have a top hammer sized for various bars.
  2. The rotation needs to be 160 mph and left-turning for hollow bars up to 52 millimeters with left-hand threads.
  3. Right-hand threads and larger bars need hydraulic drills instead.

A threaded drill bit and flushing head will pump the grout out through the drill bit.


Other Necessary Equipment

Hollow bars are used as drill rods and are subjected to high force, so it’s important that the steel in the bars be very fine grain. The thread should also be designed to transfer loads through the couplings every 10 feet. Additional equipment that is necessary includes button drill bits, clay and sand bits, cross-cut bits for gravel and sandstone, and carbide cross-cut bits for various other rocks.

Other equipment that may be needed for use in hollow thread bar micro piling includes an excavator, grout mixer, grout pump and high-speed, high-shear mixer. To achieve optimal results, it’s effective to use two mixers. One mixer should be used for thinner flushing grout, and the other mixer is for the final grout. A double-plunger pump is also helpful.


The Details of Micro Piling

Micro piling creates strong reinforcement in construction. An IBO micro pile comprises a hollow bar, final grout, flushing grout with cement mix, and ground improvement.

Testing is conducted for hollow bar micro piles in the same way as for standard micro piles. No special testing techniques are necessary.

Monitoring can be done with vibrating wire strain gauges. Strain gauges are installed on a fiberglass rod, which is then pushed into a hollow bar. The test results are displayed on a calibration loading response chart.

Using a hollow thread bar micro pile can be instrumental in the technical and economic success of your next project.


Contact TEI Rock Drills at 1-800-777-3745 for inquiries or information on rock drill components and services.