One of the missions of the INDOT Research and Development Division is to perform specialized testing on behalf of the department. The Research and Development Special Testing Programs provide savings and benefits to its customers. INDOT Districts, major programs (e.g. Major Moves, Pavement Preservation Program) and INDOT offices benefit from INDOT R&D Specialized Testing Program as decision tools. The Special Testing Program provides INDOT with data driven decision for both network and project levels testing. This web site serves the Special Testing Program requestors to submit and review special testing requests.

Pavement Structure Evaluation Program

Pavement structure evaluation program incorporates non-destructive deflection testing of pavement to evaluate the structural capacity of in-situ pavements. Falling Weight Deflectometer (FWD) testing is utilized by INDOT in pavement scoping, pavement design, pavement investigation, and budgeting for contracts. Use of the newly adopted MEPD guidelines, which depend upon FWD data, has resulted in confirmed material savings of more than $10M annually. Use of FWD data allows INDOT to apply science rather than speculation in its under-sealing contracts. This has resulted in additional savings and helps to stretch scarce construction dollars. FWD testing consists of dropping a weight of known amount onto the surface of the pavement and measuring the deflection at different radial distances. The most effective way to evaluate the structural condition of a pavement is by using FWD deflections to back-calculate layer modulus. Structural integrity of pavement is typically determined by comparing the current modulus to the design modulus. If the measured current modulus is less than the design modulus, then the pavement has deteriorated and is losing its structural integrity. FWD testing can also measure the load transfer efficiency (LTE) between concrete slabs. An LTE value of less than 60% indicates the onset of pavement deterioration. FWD testing can provide accurate identification of voids in the pavement substructure that need undersealed during rehabilitation treatments.

Pavement Friction Testing Program

Pavement skid resistance or friction is a critical factor in providing safe conditions for vehicles traveling on roads. Sufficient pavement friction provides drivers the ability to control and maneuver their vehicles safely in both the longitudinal and lateral directions, especially in wet weather. INDOT has been conducting annual network pavement friction inventory testing since 1975. The current INDOT pavement test program includes special pavement friction testing, warranty pavement friction testing, and annual inventory network pavement friction testing. The ultimate goals of INDOT pavement friction test program are to identify potentially slippery pavements and bridge decks, evaluate new high friction aggregates/mixes, and provide safe roads in wet weather. Currently, the INDOT pavement friction test program covers all interstates pavement and bridge decks and one third of US and State routes each year. The test data and analysis results have been used in forensic investigation, pavement preservation programming, polish resistant aggregate evaluation, pavement resurfacing programming, and Joint Transportation Research Program (JTRP) research studies

Specialized Bridge Testing Program

Periodical bridge inspection of about 6000 bridges is a major task conducted by INDOT bridge engineers and inspectors. Bridge inspection technology has advanced significantly in the last number of years from conventional visual inspection toward more advanced nondestructive testing, NDT, supporting bridge preservation management and more rational decision making processes in maintenance, rehabilitation and replacement.

INDOT Research and Development has established a specialized testing program for non destructive testing (NDT) of bridge decks. Testing capabilities include;

  • Half-cell potential measurement,
  • Chloride ion concentration analysis,
  • Impulse-response test,
  • Infrared thermograph testing, and
  • Ground Penetrating Radar, GPR, testing.

These tests provide characterization and investigation of existing corrosion activities, future corrosion potentials, and delamination mapping.

Half-cell potential testing measures the electrical potential of reinforcement in concrete structures for detecting the potential corrosion activities in the reinforcement bars at the time of measurement.

GPR is a high resolution geophysical technique that utilizes electromagnetic radar waves to locate and map rebar condition in concrete. GRP testing shows the presence and extent of corrosion activities between the embedded steel and its surrounding concrete. The use of the half-cell test and GPR on the concrete structures is for classifying its overall condition at the time of testing and for prioritizing rehabilitation decisions of bridge decks.

Chloride concentration analysis can be used to determine whether chloride concentrations in the bridge deck are high enough to initiate corrosion of the reinforcing steel. Chloride concentration in the deck is of concern because high concentration of chloride ions in the bridge deck accelerates corrosion of the reinforcing steel in the bridge deck. This test can be used to determine the potential corrosion activities on the bridge decks and to aid in prioritizing bridge deck overlay decisions.

The impulse-response test, infrared thermograph, and sounding methods are used to evaluate concrete structures for delamination. The impulse response test is one of the dynamic response evaluation methods for detecting delamination based on given impact pulse or sound wave. Infrared thermograph detects delamination of concrete based on temperature variation on the surface.

The bridge deck testing protocol and criteria will be determined by both the requestor (Engineer/Inspector) and INDOT Research and Development Bridge Structure Engineer.

Pavement Smoothness Testing Program

Pavement smoothness is the factor of pavement performance that the motoring public notices most. Currently the office of Research and Development has the ability to collect road profiles with a class 1 inertial profiler when requested. The international roughness index (IRI) will be calculated from the measured profiles and provided to the requestor giving the requestor a quantitative measure of the smoothness of a road section. Furthermore, the locations of areas of localized roughness (bumps) can be identified. Simulations of smoothness improvement by diamond grinding may also be provided if requested and warranted.

Ground Penetrating Radar Testing Program

Ground penetrating radar (GPR) is a versatile geophysical tool that can be utilized to provide nondestructive pavement forensic analysis, and locate buried targets. Currently, the Office of Research and Development has equipment necessary for collecting both air launched and ground coupled GPR data when requested. Some of applications of GPR include.

  • Pavement thickness evaluation
  • Bridge deck corrosion evaluation
  • Location of dowel bars/rebar and other conductive reinforcement
  • Location of voids at ridged pavement support interface (concrete pavement)
  • Location of large voids
  • Location of underground storage tanks (UST)
  • Location of pavement under drain outlets
  • Mapping of changes in the dielectric constant at pavement interfaces

Accelerated Pavement Testing Program

The Accelerated Pavement Testing Program is a program to evaluate the ability of pavement mixtures to resist permanent deformation or rutting using half of a standard truck axle in combination with speed and temperature control. Using this approach, in an environmentally controlled facility, the effects of 25 million Equivalent Single Axle Loads (ESALs) can be compressed into just a few days. This represents the effect of several years of in-service pavement traffic. The goal is to efficiently use the facility to evaluate the quality of pavement mixtures and materials to achieve a longer design life when constructed in the field. This in turn results in less traffic congestion due to pavement reconstruction, and therefore minimizes the life-cycle cost of the pavement and the users-costs to the traveling public. This program, consequently, results in significant cost-savings by improving the quality, durability, and performance of Indiana's pavements.

The INDOT/JTRP Research Program has attracted interest in accelerated pavement testing as Indiana has one of the few functional Accelerated Pavement Testers (APTs) in the nation. In addition to bringing research funds from other transportation departments and industry into Indiana to address shared research needs, visitors from more than 18 countries and 30 states have toured the APT facility. Since it opened in 1991, more than 5 million load passes have been made on various mix designs, drastically reducing the time it takes to determine their effectiveness

  • The Accelerated Pavement Testing (APT) facility is used to quickly tested pavements and mix designs
  • Dollars and years that used to be spent in constructing and monitoring full scale test roads are currently being saved by employing this facility
  • The facility is an example of successful partnering between INDOT, Purdue University (Civil Engineering, Mechanical Engineering and Electrical Engineering Technology Schools) and Industry
  • The APT facility is located at the INDOT Office of Research and Development and is housed in a 2,000 square feet, environmentally controlled building
  • The Accelerated Pavement Testing Program is guided by established Performance Measures, testing protocols and calibration requirements