IC Terminology and Glossary

Absolute Compaction Testing (ACT): This method offers the absolute values of the achieved compaction for the operator of the compaction equipment, which can be attached to the compaction equipment.

Accelerometer: It is used to measure the relative motion of the drum with respect to the compactor frame, which is subsequently empirically related to the modulus of the compacted layer. It is a vibratory system of compactor, the roller drum rotates an angle and moves a horizontal distance back and forth after the drum is lift up the pavement surface, then it is compacted downward on pavements. Generally the accelerometer is used to measure the relative motion of the drum with respect to the compactor frame, which is subsequently empirically related to the modulus of the compacted layer. This result provide the necessary information to control the compaction efforts by adjusting a number parameters such as vibration direction (vertical, horizontal, or any angles between), and the ground speed of the compactor.

Acceptance Criteria: It is the criteria to accept the rolling effect, which is related to the material property and pavement performance such as modulus and density.

Acceptance Quality Characteristic (AQC): It is a parameter that affects pavement performance under the contractor control and is measured during or after construction, such as density or elastic modulus.

Bearing Capacity (BC): It is the capacity of soil to support the loads applied to the ground in geotechnical engineering; the ultimate BC is the theoretical maximum pressure which can be supported without failure; while allowable BC is the ultimate BC divided by a factor of safety.BC is the maximum average contact pressure between the foundation and the soil which will not produce shear failure in the soil. The bearing capacity of soil is an important consideration in construction projects. Dams, bridge abutments, and temporary support structures during construction are all examples of structures that can be supported by underlying soil.

Cold Mix Asphalt (CMA): Cold mix is a combination of unheated mineral aggregates and emulsified asphalt binders which can be plant-mixed or mixed-on-location. Cold mix asphalt is used for temporary patching.

Compaction Control Value (CCV): For the Caterpillar IC system, the use of CCV is an extension of the value Geodynamic CMV (compaction meter value). For the Sakai IC system, the use of CCV is based on Sakai’s own implementation.  Both methods are based on the amplitudes at different vibration frequencies to determine CCV.

Compaction Documentation System (CDS): It is the ultimate tool for CCC. It presents all relevant and necessary information to the roller driver for assisting in achieving the optimum performance of compaction job.

Compaction Efficiency: The compaction efforts spent in a specified time and resource to reach the targeted compaction value, such as density and modulus.

Compaction Efforts: They are referred to the compaction parameters primarily including the compaction frequency, amplitude, and forward (rolling) speed.

Compaction Energy Index (CEI): It is used to study changes in compaction effort, and cohesion and adhesion of binders were measured. Superpave gyratory compactor (SGC) is used to decide the resistance of mixture to densification, in which a compaction energy index (CEI) was determined.

Compaction Meter Value (CMV): It is a measurement of compaction level, developed by Geodynamik in the 1970s. It is defined as the ratio of the second harmonic of the vertical drum acceleration amplitude divided by the 1st harmonic of the vertical drum acceleration amplitude multiplied by a constant c (i.e. 300). The reported CMV is the average of a number of 2-cycle calculations.

Compaction Meter: It is a device instrumented in the compaction rollers to measures material density, layer bounce and determines material stiffness or modulus.

Compaction Uniformity: The comparison of material properties at different spots, such including material modulus and density.

Comprehensive Testing: In the IC, the system tests multi variables including material modulus, density, temperature, etc.

Construction Quality Index (CQI): It provides a practical tool for evaluation of construction quality of individual components.

Continuous Compaction Control (CCC): It is based on roller integrated meters that continuously measure the roller acceleration and calculate a compaction meter value from the acceleration signal. These meter values give the operator information to avoid under or over compaction.

DCP Penetration Index: It is an index for characterizing soil strength using the dynamic cone penetrometer (DCP) device. It is typically has a unit of mm/blow and inversely related to penetration resistance (i.e. soil strength).

Directed Exciter: It is an exciter mechanism that usually causes the drum to move vertically. In some instances, the direction of movement can be changed through a 90-degree arc from vertical to horizontal.

Double Drum Vibratory (DDV): It uses double drums that can obtain different measurements, especially suitable for the tender mixture that still requires a minimum density or maximum air void to be satisfied. A DDV roller can be used though it obtains different measurements. However, for tender mixes with high fluidity, the roller patterns should be alerted to achieve mixture density in the upper temperature zone before the mix starts to move and shove. HMA mixtures that have tender characteristics still have to be compacted to a minimum level of density or a maximum level of air void content. Accordingly, the double-drum vibratory rollers have been used to address this problem. The DDV roller should be kept close behind the paver in order to execute its breakdown effect immediately when the mixture is still hot.

Double Jump: A condition in which the drum skips every other impact, because it has acquired so much energy that it begins to move upward during a vibratory cycle before hitting the ground.

Drum Amplitude: Drum amplitude primarily controls the penetration depth of vibratory compaction forces, generally lower amplitudes are used for thinner pavements while higher amplitudes are used for thicker pavements.

Drum Impact Spacing: The optimum drum impact spacing can be determined by narrowing or widening based on the drum diameter as well as compaction experience.

Dynamic Cone Penetrometer (DCP): It is a device used to measure material shear strength, and. it provides the stability characteristic of compacted soil. The test involves dropping an 8-kg hammer 575 mm and measuring the penetration rate of a 20-mm diameter cone.

Dynamic Modulus: It is the ratio of stress to strain under vibratory conditions from either free or forced vibration tests, in shear, compression, or elongation of viscoelastic materials.

Dynamic Roller: It is a type of roller in parallel with static roller; it applies vibrating mechanism or oscillating mechanism by combing static and dynamic loads to execute compaction efforts and achieve the target density during compaction. See also static roller.

Elastic modulus: It is also called modulus of elasticity, is the mathematical description of an object or substance’s tendency to be deformed elastically (i.e. non-permanently) when a force is applied to it. The elastic modulus of an object is defined as the slope of its stress-strain curve in the elastic deformation region:

Energy method: It is one method used by the compaction meter; it uses larger rolling resistance and induces lower stiffness than other methods.

Exciter Mechanism: The system of rotating eccentric weights within a roller’s drum that causes the drum to move in an off-center motion.

Falling Weight Deflectometer (FWD): It is a non-destructive test device used to measure the deflections of pavement layers when applying dynamic loads to the pavement surface.

Feedback Control: The vibratory system adjusts the compaction efforts including vibration frequency, amplitude, and forward speed based on the measured material properties such as modulus or stiffness, and density.

Global Information System (GIS): It is a system for capturing, storing, analyzing and managing data and associated attributes which are spatially referenced to the Earth. In a more generic sense, GIS is a tool that allows users to create interactive queries (user created searches), analyze the spatial information, edit data, maps, and present the results of all these operations.

Global Positioning System (GPS): It is the only fully functional global navigation satellite system (GNSS). Utilizing a constellation of at least 24 medium Earth orbit satellites that transmit precise microwave signals, the system enables a GPS receiver to determine its location, speed, direction, and time.

GPS-Based Mapping: It performs data acquisition functions and displays real-time position and compaction values using GPS with controlling accuracy capabilities, in which the roller width is divided into series divisions. A operator interface is equipped within the operators field of view and performs data acquisition functions as well as displaying real-time position and compaction values .The system uses a GPS with controlling accuracy capabilities (e.g. ±10mm in the horizontal plane and ±20 mm in the vertical plane). The roller width is divided into series divisions (e.g. 30 cm) for mapping roller coverage. Post processing and visualization of data can be performed by the software.

Ground-penetrating radar (GPR): It is a non-destruction testing equipment used to measure the material density in construction.

Hot Mix Asphalt (HMA): It is an asphalt mixture compacted in a temperature ranged from 275-3250F. See also WMA and CMA.

Infrared Inspection System: It is a device equipped with roller to measure the pavement surface temperatures using the infrared technology.

Intelligent Compaction (IC): A compaction system that contains (1) continuous assessment of mechanistic compacted material properties (e.g., stiffness, modulus) through roller vibration monitoring; (2) on-the-fly modification (feedback control) of vibration amplitude and frequency; and (3) integrated global positioning system (GPS) to provide a complete GPS-based record of the compaction site.

Intelligent Compaction Measurement Value (ICMV): It is a generic term for IC roller-integrated measurement value.

Intelligent Soil Compaction (ISC): IC system for soil is different from that for asphalt mixtures due to their different material and structural properties.

Light Weight Deflectometer (LWD): It is a portable, non-destructive test device used to measure pavement deflections by applying a dynamic load to the pavement surface.

Linear Voltage Displacement Transducer (LVDT): It is a device used to measure the displacement of samples, which has been used at both the laboratory test, and the in-situ test.

Low Shear Viscosity (LSV): It is a procedure developed under the NCHRP 9-10 to establish the mixing and compaction temperatures at laboratory by using low shear viscosity as the index. It was found that modified asphalts are difficult to be compacted primarily due to their high shear viscosity at low-shear rate, and a procedure to determine compaction temperature by using low shear viscosity was developed.

Machine Drive Power (MDP): It relates to the soil properties controlling drum sinkage, uses the concepts of rolling resistance and sinkage to determine the stresses acting on the drum and the energy necessary to overcome the resistance to motion.

Measured Value (MV): It is the measured value by rollers, including vibration frequency, amplitudes, rolling speed, time interval, and rolling distance.

Mechanistic-Empirical (ME) Design: It is a pavement design method. Typically, it determines the pavement response of stress and strain using the mechanistic method such as multi-layered program or finite element program, and predicts the pavement performance including rutting and cracking using the empirical method correlating to response.

Minimum Index Density: It is the minimum-index dry density/unit weight of cohesiveless, free-draining soils, which can be determined by following the ASTM 04254-00 (2006) specification.

Modulus: Modulus may refer to elastic modulus, Young’s modulus, and dynamic modulus to describe the material properties.

Newtonian Asphalt: Asphalt’s shear stress is linearly proportionally to the shear strain rate, especially for neat asphalt at high temperature.

Non-Newtonian Asphalt: Asphalt’s shear stress is not linearly proportionally to the shear strain rate, and asphalt performs viscoelastic and viscoelasticplastic behavior, such as for the polymer modified asphalt and/or asphalt at room or low temperature.

Nuclear Density: It is an in-situ pavement material density measured by using the nuclear density gauge, which has been widely used as an effective non-destructive method. However, it has the potential risk for operators and public due to its nuclear radiation.

Oscillatory Compaction: It uses a dual, opposed and eccentric weights rotating in the same direction around the drum axis to produce a rocking motion, “massaging” the HMA. This rocking motion induces a horizontal shear force in addition to the downward compressive force by roller weight. It is more applicable to the lower temperature compactions.

Oscillatory Exciter: An exciter mechanism that causes the drum to rock fore and aft on the surface.

Performance Specifications: It is acceptance specifications that can be categorized into: End-Result Specifications, Performance-related Specifications, and Performance-based Specifications Warranty Specifications.

Plate Load Tests (PLT): The test methods are used to estimate the bearing capacity of a soil under field loading conditions for a specific loading plate and depth of embedment but also for load tests of soil and flexible pavement components for use in evaluation and design of airport and highway pavements.

Quality Assurance (QA): It is an activity of providing evidence and confidence that a product or service will satisfy the given requirements for quality. Typically, field spot tests such as modulus and density are measured and the quality is determined using the statistical method to assure construction quality.

Relative Compaction Testing (RCT): It provides relative values such as the index values for two successive passes with the same compaction equipment. These values are achieved as an attachment for any rollers, called “compactometer”.

Resilient Modulus: An elastic modulus of materials (soil, gravel and granular, asphalt), representing the material’s capability to recover after releasing loading. The test for soil and aggregates can be determined according to AASHTO T-307 (1999)

Resonance Meter Value (RMV): It is similar to CMV discussed above, defined as the ratio of the sub-harmonic drum acceleration to the first harmonic drum acceleration.

Risk: It explained as “the possibility of suffering harm or loss danger”. In IC system, it primarily refers to the over compaction or under compaction. IC has the potential ability to reduce risk probability through its monitoring and feed-back control in real-time.

Roller Vibrator Amplitude: A measure of the drum’s movement, in thousandths of an inch, from its centered position. A drum that moves (or vibrates) vertically will travel as far above the surface as it does below the surface. In this instance, amplitude is usually reported as half the total travel.

Roller Vibrator Frequency: The rotational speed of the exciter mechanism, typically measured in vibrations per minute (vpm).

Roller-Integrated Measurement: The equipped roller can measure the modulus/stiffness and density of pavement materials, which can be used to compare with the laboratory tested results for quality assurance (QA), and predict the pavement performance using the mechanistic-empirical method that is similar to the method used by AASHTO 2002.

Rotary Exciter: An exciter mechanism that causes the drum to move off-center in a circular or elliptical motion.

Shear Rate: It has been regarded the primary issue and it is controlled for achieving targeted volumetric properties of mixture regardless of binder type and rheology property during construction.

Spot Testing: It includes the tests of material density and modulus at the chosen spots, which is used for quality assurance. Such as using the static plate load test and the falling weight deflectometer (FWD) test to measure modulus, the nuclear gauge and the water balloon and sand replacement test to measure the material density, drilled cores and radiometric sounds test to measure the asphalt concrete density, and the non-destructive pavement quality indicator test without nuclear to test the asphalt concrete density. However, all of them have the limitations, and the operator needs to wait hours or days for the available results.

Static Roller: It is a type of roller in parallel with dynamic; it applies a downward static load to achieve the target density during compaction. See also dynamic roller.

Stiffness: It is the resistance of an elastic body to deflection or deformation by an applied force. It has been widely used as a measure of material property with a unit of KN/m for soil during construction or QA/QC.

Target Density: The objective value of material density set in the IC system for controlling and adjusting the compaction efforts.

Targeted Modulus: The objective value of material modulus set in the IC system for controlling and adjusting the compaction efforts.

Variomatic: It has two rotary exciters with two unbalanced weight counter rotating. The oscillation is directed and has automatically controlled and varied amplitude at both horizontal and vertical directions.

Vibration Frequency: It is the vibration speed of roller drum’s lifting off and compaction on pavement surface. It is one of the primary compaction efforts to be controlled for achieving target density or modulus in the general or intelligent compaction. Along with drum diameter, it is a control factor to determine the appropriate rolling speed for the breakdown compaction.

Vibratory Amplitude: It is the height of roller drum’s lift from pavement surface during vibratory compaction.

Vibratory Compaction: It is one of the primary three compaction technologies, in which the drum is lifted off and forced downward on the surface, and roller weight, vibratory frequency and amplitude are the keys to affect compaction effect. The forward speed and vibratory efforts can be adjusted in the IC.

Vibratory Roller: It is a kind of roller, and its drum lifts pavement surface and forces downward with a frequency during compaction.

Vibratory System: It is one important component of IC and tired together with accelerometer by using an onboard computer. It continuously adjusts amplitude and frequency based on compaction meter’s input such as material density and modulus or stiffness.

Warm Mix Asphalt (WMA): It is an asphalt mixture compacted in an intermediate temperature of 250-2750F. It has been used more for dense wearing course, but still meets the HMA standards and uses the existing HMA plants.

Young’s Modulus: In solid mechanics, it is a measure of material stiffness. It is a tensile modulus and can be experimentally determined from the slope of a stress-strain curve created during tensile tests conducted on a sample of the material.