Tie Bar /Dowel Bar Alignment & Positioning Test MIT-DOWEL-SCAN Overview

MIT-DOWEL-SCAN Tie Bar Alignment & Positioning Test real time mapping with immediate results after testThe MIT-DOWEL-SCAN is a measuring system for the non-destructive and accurate measurement of tie bar / dowel bar position and alignment in concrete pavements, according to ASTM E3013.

The equipment is designed with the accuracy required for dowel bars but most clients use it for both dowel bars and tie bars.

The advantages include:

  • Non-destructive test (NDT) – no need to do coring to measure depth
  • One person operation
  • Measurement can be taken extremely quickly (less than one minute per joint across several lanes)
  • Results are immediately seen on a graphical display on the screen for quality control purposes
  • Positioning and alignment can be checked as soon as a person can walk on it after concrete placement
  • As the results are immediately available, it allows the contractor to take corrective action immediately, making adjustments during the paving process
  • Embedment depths, misalignments & translations are determined precisely, even on rain-drenched surfaces

Tie Bar Misalignment Types

  • Under normal conditions, depths as well as horizontal and vertical misalignments can be determined with an accuracy of ±4 mm and side shifts with an accuracy of ± 8 mm
  • Used to evaluate new and existing joints.
  • Basket joints can be evaluated if the shipping wires are cut.

The MIT-DOWEL-SCAN from MIT Mess- und Prüftechnik GmbH is delivered as a complete system ready to use. The measuring vehicle is equipped with an operating unit, a laser unit, MagnoProof software package, manuals and a solid transportation case.

MIT-DOWEL-SCAN Tie Bar Alignment & Positioning Test Laser Guide

Applications include:

  • Quality Control by Contractors for checking their installation process
  • Highway construction of plain concrete pavements
  • Quality Assurance by Owners for accepting completed facilities
  • Plain Concrete runways, taxiways & ramps at airports
  • Concrete Sea Container storage & staging areas in port facilities
  • Forensic Investigations of failing joints in existing pavements

Properly aligned and embedded dowel bars are vital in jointed plain concrete pavements. Dowel bars are round, smooth, epoxy coated steel bars placed mid‐depth across transverse joints. They allow load transfer whilst allowing the joint to open and they reduce or eliminate faulting and corner cracks. Significantly misaligned dowel bars may lead to joint locking which can cause slabs to crack. Improper placement (embedment) of dowel bars leads to decrease in load transfer efficiency, which can result in faulting and other pavement distresses.

MIT MagnoProof Software for Dowel Bar & Tie Bar Alignment and Pisitioning

Tie bars are deformed, epoxy coated steel bars, typically placed mid‐depth across longitudinal joints or between an edge joint and a curb or shoulder. They are designed to prevent lane separation and differential deflection and reduces transverse cracks by holding the faces of abutting slabs in contact. Although they may provide some minimal amount of load transfer, they are not designed to act as load transfer devices and should not be used as such.

Joints in concrete pavements of highways, airport runways and container areas are exposed to stresses and strains due to traffic and temperature variation. Steel dowel bars, reinforcement bars and tie bars are built into joints, to support the transfer of loads across the joints and to maintain the elevation of adjacent slabs at the joints. The MIT-DOWEL-SCAN is used to determine the number of dowels and tie bars as well as their accurate positions and tolerable displacements, to ensure the long-term performance of the joints.

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