Laboratory of Special tests
Our technicians and engineers act upon the request of construction companies, project owners, designers (design offices, project managers) and experts to define the composition of an existing roadway, analyze the pathology of a structure and propose technical solutions.
The missions carried out by our teams cover all types of works and all types of structures
Installations
Platforms and aeronautical areas (Landing runway, Parking, Taxiway, Ramp, etc)
Linear infrastructure (road, highway)
Types of pavements
Flexible pavements
Semi-Flexible pavements
Inverse pavements
Rigid pavements
Whatever the project, LTPS has the resources to carry out all tests, analyses, studies and controls required from the preliminary diagnosis to the proposal of solutions for the repair and reinforcement of the structures
The design missions that we carry out also include the design of new pavements
Insitu tests
Deflection tests
Characterization uniformity
Skid Resistance
PAVEMENT SURVEYING
PAVEMENT SURVEYING USING HWD
HWD description
The HWD (Heavy Weight Deflectometer) generates, through a falling weight on a plate in contact with the road, an impulse type load, in order to simulate an aircraft or vehicle wheel passage on the road. The response of the road to this stress (surface deflections) is measured by means of geophones while a force sensor integrated into the loading plate allow monitoring the force applied to the road during the test
Scope of application
HWD can be used for flexible, semi-rigid or rigid road and aeronautical pavements, during inspection, approval, reinforcement studies and studies monitoring the behavior over time of new reinforcement techniques
LTPS made available two different deflection measuring devices, namely
- Deflectometer branded DYNATEST
- Deflectometer branded PRIMAX
This device is used to
- Carry out relative comparison of pavements based on deflection indices
- Determine the structural capacity of pavements
- Determine the elastic moduli of the material layers using back calculations
- Calculate deformations and stresses in the pavements
- Evaluate the structural integrity of rigid pavements (load transfer to cracks and joints)
- Determine lifespan and rehabilitation
- Determine the PCR (Pavement Classification Ratio) for airfields
Rigid pavement (airfield runway)
Flexible pavement (airfield runway)
Flexible pavement (road)
Surveying using Road Surface Profiler
Description
Uniformity is measured using a Dynatest RSP 5051 laser inertial profiler device attached using metal supports to the front of the vehicle.
The device consists of two laser probes and two accelerometers and a distance measuring instrument (DMI) attached to the rear wheel of the vehicle
Laser probe
Accelerometer
Distance Measuring Instrument
Scope of application
The RSP Profiler device is designed to control the flatness of road and aeronautical pavements in the control, approval and even reinforcement studies stages
The data obtained are recorded as longitudinal profiles, and with the IMPLAX processing software it is possible to calculate the flatness index or comfort or rolling IRI "International Roughness Index" and with the ProFAA processing software it is possible to calculate the BBI "Boeing Bump Index"
Automatic Skid Resistance
The IMAG is an automatic skid resistance measuring device, designed by the Civil Aviation Technical Service, developed in partnership with “Aéroports de Paris”. Patented in 1991, the IMAG is now used operationally at several French airports: Roissy-Charles de Gaulle, Orly, Strasbourg, Metz-Nancy-Lorraine and Europort-Vatry. On these platforms, the IMAG is commonly used operationally during the winter season to measure the quality of runway surface skid and to inform pilots about the operating conditions of the runway.
Figure. 02 : Schéma de principe (source VECTRA)
Technical characteristics :
- 3-wheel trailer towed by a motor vehicle
- Support chassis with 2 load-bearing wheels equipped with speed sensor (measurement of speed and distance)
- Measuring frame articulated on the supporting frame including a measuring wheel
- equipped with a smooth AIPCR tire
- Dimensions: 165R15
- Inflation pressure: 150 kPa
- Load on the measuring wheel: 180 daN
- Braking of the measuring wheel of the moving device, according to a constant slip rate of 15%
- Continuous measurement of horizontal tractive force, braking torque and dynamic wheel load
- Processing of the measurement signal and conversion in the form of two friction coefficients: pure friction coefficient (linked to the quality of the surface only) and a drag friction coefficient (linked to the presence of the “contaminant” on the road surface).
- Measuring speed up to 130 km/h.
- Usual speeds: 40, 65 and 95 km/h
Expertise
Combining in situ measurements with laboratory tests allows our teams to define the pathology that can affect a road structure regardless of its type
Following the investigations, we are able to model the existing road surface and propose restoration solutions accordingly
Studies
- Assessment of pavement bearing capacity (PCR)
- Expert study of road and airport pavements
- Approval of airport runways
- Uniformity Control
- Skid resistance
- ……
Design
We have all the software necessary for mechanical dimensioning calculations (ALIZE, ELMOD, PRIMAX))