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72 GLOSSARY AND ABBREVIATIONS The terms found in this glossary came primarily from the defined as those that experience significant horizontal International Slurry Surfacing Association's 2010 edition of its movements. Inspector's Manual for Slurry Systems. Definitions for terms Cure--The entire process of breaking and set until the final not contained in this reference were imported from various mixture of emulsion and aggregate has lost all moisture sources and are noted by "(author year)" as they occur. resulting from evaporation or dehydration. Curing--A slurry system has "cured" when the asphalt par- ticles have re-combined into a continuous film surround- GLOSSARY ing the aggregates, and the majority of micro-droplets of water have been removed from the mat through evaporation Asphalt Emulsion--Defined by the most common type of system in which the asphalt is the dispersed liquid or the or chemical reaction. At this point the surface is ready for internal phase, and water is the dispersing liquid or the exter- traffic. It should be noted that final cure (total dehydration) nal phase. This is commonly called oil-in-water emulsion. can take periods of from two to four weeks. During asphalt emulsion manufacture, the emulsifying Edge--The point that the aggregate in a slurry system treat- agent promotes emulsification and keeps it stable thereafter. ment ends. Different types of asphalt emulsions are shown in Table 51. Emulsifier (see Surfactant). Adhesion Agents--These substances improve the degree of Emulsified Binder--A liquid mixture of asphalt binder, water, wetting of the aggregate by the binder, thus enhancing the and an emulsifying agent. Emulsions are either anionic adhesion between the binder and aggregate [NCHRP Syn- (negatively charged) or cationic (positively charged). Emul- thesis 340 (2005)]. sions are not as sensitive to moisture, inherently contain Aggregate--A granular material, usually crushed and screened anti-stripping agents, and require much lower application to appropriate gradations, that is used as the cover stone in temperatures than asphalt cements [NCHRP Synthesis 340 a surface treatment [NCHRP Synthesis 340 (2005)]. (2005)]. Binder--A bituminous material that provides a waterproof Emulsion--Defined as a mixture of two immersible liquids, seal and also bonds the cover stone to the pavement [NCHRP one of which is dispersed in the other in the form of very Synthesis 340 (2005)]. fine droplets, usually in the presence of a third component, Bleeding--The upward movement of asphalt through the the surface active agent. surface treatment. Bleeding, also commonly referred to as Flushing--See definition for bleeding. flushing, can be identified by dark patches of asphalt form- Ionic Compatibility--Different types of aggregate are better ing on the surface, most commonly in wheel paths or inter- suited to certain binders as a result of electrostatic charges. sections [NCHRP Synthesis 340 (2005)]. For sufficient adhesion, the binder and aggregate must Breaking--The initial separation of the water from the emul- have opposite charges. sion, which can be detected by a marked color change from Lump Sum Contract--A contract where the contractor is brown to black, and often by the release of fairly clear to required to furnish a single sum for the cost of completing straw-brown water. This characterizes the point when the scope of work described in the plans and specifications. asphalt droplets begin to re-combine. The results in the depo- The contractor assumes the risk that actual quantities exceed sition of the base asphalt on a paved surface and the material contractor-estimated quantities and is not paid extra if they can no longer be hand worked. do [NCHRP Synthesis 340 (2005)]. Colloid--Any fine suspension of finely divided particles in a Macrotexture--Larger irregularities in the road surface continuous medium. (coarse-scale texture) that affects hysteresis. These larger Corrective Maintenance--Maintenance performed once a irregularities are associated with voids between stone par- deficiency occurs in the pavement; that is, loss of friction, ticles. The magnitude of this component will depend on moderate to severe rutting, extensive cracking or raveling. several factors. The initial macrotexture on a pavement Crack Filling--The placement of materials into nonworking surface will be determined by the size, shape, and grada- cracks to substantially reduce infiltration of water and to tion of coarse aggregates used in pavement construction, reinforce the adjacent pavement. Working cracks are defined as well as the particular construction techniques used in as those that experience significant horizontal movements, the placement of the pavement surface layer. Macrotexture generally greater than about 2 mm (0.1 in.). Crack filling is also essential in providing escape channels to water in should be distinguished from crack sealing. the tiresurface interaction, thus reducing hydroplaning Crack Sealing--A maintenance procedure that involves (Noyce et al. 2005). placement of specialized materials into working cracks Micro-Surface Emulsion--Polymer-modified emulsions using unique configurations to reduce the intrusion of incom- with special chemical compositions enable placement pressibles into the crack and to prevent intrusion of water of thick lifts of "slurry." They are normally cationic with into the underlying pavement layers. Working cracks are a low pH.
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73 Microtexture--Irregularities in the surfaces of the stone par- mixing chamber. Spray bars for asphalt emulsion and/or ticles (fine-scale texture) that affect adhesion. These irregu- water/set coat additives are usually mounted in the mixing larities are what make the stone particles feel smooth or chamber near the aggregate feed end. Proportioned ma- harsh to the touch. The magnitude of microtexture depends terials, including aggregates and emulsified asphalts, are on initial roughness on the aggregate surface and the abil- mixed together to yield a uniformly coated mixture. ity of the aggregate to retain this roughness against the Quick Set Emulsion--Emulsions for slurries set by a chem- polishing action of traffic (Noyce et al. 2005). ical reaction between the emulsifier and the aggregate and Modified Binder--Binder modifiers include polymers, latex, a small amount of additives in the slurry. CSS-1h emulsions rubber crumb, and anti-stripping agents. Modifiers have can be formulated as quick-set emulsions. These are nor- proven successful at enhancing flexibility, minimizing mally designated as a CQS-1h. Anionic quick-set emulsions bleeding, increasing aggregate retention, and extending are normally designated QS-1h. the service life of microsurfacing [NCHRP Synthesis 340 Raveling--Also commonly referred to as shelling, it is the loss (2005)]. of aggregate from the surface treatment. Low binder applica- Particle Charge Test--The particle charge test is made to tion rates, inadequate rolling, cool weather construction, and identify cationic emulsions. It is performed by immersing a incompatible binder and aggregate types are common factors positive electrode (anode) and a negative electrode (cathode) that lead to raveling [NCHRP Synthesis 340 (2005)]. into a sample of emulsion and connecting them to a con- RalumacTM--A cold thin surface paving solution consisting trolled direct-current electrical source. At the end of a speci- of a water-based polymer-modified asphalt emulsion, 100% fied time period, the electrodes are observed to determine crushed fine aggregate, mineral filler, water, and additives. which pole has an appreciable layer of asphalt deposited on On asphalt pavements it can be used for sealing, rut filling, it. Cationic emulsions will migrate towards the cathode. and to improve a road's macrotexture. On concrete pave- Pavement Preservation--The sum of all activities undertaken ments it can be used for texturing, noise reduction, and to provide and maintain serviceable roadways. This includes repairing wheel path abrasion channels caused by studded corrective maintenance and preventive maintenance, as tires (Road 2010). well as minor rehabilitation projects (Geiger 2005). Residue From Distillation--The distillation test provides a Pavement Preventive Maintenance--Planned strategy of means of determining the relative proportion of asphalt cost-effective treatments to an existing roadway system and cement and water in the emulsified asphalt. Some grades its appurtenances that preserves the system, retards future of emulsified asphalt also contain an oil distillate and the deterioration, and maintains or improves the functional distillation test provides information on the amount of this condition of the system (without increasing the structural material in the emulsion. Also, the distillation test provides capacity) (Geiger 2005). an asphalt cement residue on which additional tests may Pavement Reconstruction--Construction of the equivalent be made of a new pavement structure that usually involves complete Ring & Bell Softening Point--The term relates a measure removal and replacement of the existing pavement structure of consistency for asphalts. Samples of asphalt loaded including new and/or recycled materials (Geiger 2005). with steel balls are confined in brass rings suspended in a Pavement Rehabilitation--Work undertaken to extend the beaker of water one inch above a metal plate. The liquid is service life of an existing pavement. This includes the heated at the prescribed rate. As the asphalt softens, the restoration, placing an overlay, and/or other work required balls and asphalt gradually sink toward the plate. At the to return an existing roadway to a condition of structural moment the asphalt touches the plate, the temperature of and functional adequacy (Geiger 2005). the water is recorded and this is designated as the Ring & Penetration--An empirical measure of consistency in which Ball Softening Point. a container of asphalt cement is brought to a test tempera- Sand Patch--Also known as the sand circle test, a test for ture of 77°F in a water bath. A needle of prescribed dimen- determining texture depth of a pavement surface (refer to sion, loaded to a weight of 100 grams, is allowed to bear on ASTM E 965) [NCHRP Synthesis 340 (2005)]. the surface of the asphalt cement for 5 seconds. The unit of Set--The point during the breaking process when the asphalt 0.1 mm, which the needle penetrates into the sample, is aggregate mix will no longer track when blotted with white defined as the penetration. paper. (The mix may still be too tender for traffic at this Polymer-Modified Emulsion--These emulsions contain point.) modifiers in the form of finely dispersed polymers. These Set Control Additives--Defined as small amounts of ma- modifiers are blended into the asphalt particles prior to the terials (mineral fillers or chemical) that when added to a manufacturing of the emulsion or mixed with the asphalt slurry/microsurfacing mixture, speed or retard the setting particles during the milling process. Polymers are added to characteristics of that mix. increase strength, reduce temperature susceptibility, and Setting--A point when all asphalt particles have broken and improve adhesion and stability. combined into larger particles. This is observed when the Pug Mill--A chamber in which rotating shafts have paddles material becomes rain safe and will support foot traffic. spaced along their length that are capable of being angled Settlement--The settlement test detects the tendency of to advance or retard the movement of the mix through the asphalt globules to settle during storage of emulsified
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74 asphalt. A prescribed volume of material is allowed to Surface Treatment (AST), is as an application of asphalt stand in a graduated cylinder for a specified number of days. binder and cover aggregate on prepared gravel or crushed Small samples are then taken from the top and bottom stone base [NCHRP Synthesis 340 (2005)]. parts in the cylinder. Each sample is placed in a beaker and Surface Texture--The macroscopic and microscopic char- weighed. The sample is then heated until water evaporates acteristics of the pavement surface. Surface texture depth and the residue is then weighed. The weights obtained is a metric that influences material application rates, design provide the basis for determining the difference, if any, life, skid resistance, and road noise emissions [NCHRP between asphalt cement content in the upper and lower Synthesis 340 (2005)]. portions of the graduated cylinder, thus providing a measure Surfactant (Surface Active Agent)--Any substance that alters of settlement. the energy relationship at interfaces; e.g., organic compounds Sieve Test--The sieve test complements the settlement test displaying surface activity such as detergents, wetting agents, and has a somewhat similar purpose. It is used to determine dispersing agents, and emulsifiers. quantitatively the percentage of asphalt present in the form Uniform Cross Section--The area where the pavement width of relatively large globules. Such globules do not provide is greater than the width of the slurry system treatment placed thin and uniform coatings of asphalt on the aggregate par- and there are no drop-offs greater than 1/2 inch (12 mm). ticles and may or may not be detected by the settlement Unit Price Contract--A construction contact where the con- test. In the sieve test, a representative sample of emulsified tractor furnishes unit prices (i.e., $ per pay unit) for each pay asphalt is poured through a No. 20 sieve. For anionic emul- item in the contract and the contract is awarded to the lowest sions the sieve and retained asphalt are then rinsed with a bidder computed by multiplying the contractor-furnished mild sodium oleate solution and finally with distilled water. unit price with the engineer's estimated quantity for each For cationic emulsions, distilled water is used instead of pay item and extending that to a total bid price. The con- sodium oleate solution. After rinsing, the sieve and asphalt tractor is then paid its unit price for the actual quantities are dried in an oven and the amount of retained asphalt even if exceed the engineer's estimated quantities [NCHRP determined. Synthesis 340 (2005)]. Slow Set Emulsions--Asphalt emulsions that demonstrate Viscosity--The Saybolt Furol viscosity test as described for very stable properties. These emulsions must be stable when asphalt emulsions is used both for the anionic and cationic diluted and also have a high resistance to chemical break- emulsified asphalts to measure and specify consistency down. The ability of the emulsion to mix with cement is an properties. As a matter of testing convenience and also to indication of its suitability for use with an aggregate with achieve suitable testing accuracy, two testing temperatures a high surface area. This type of emulsion for slurries is set [25°C (77°F) and 50°C (122°F)] are used, depending on almost entirely from the evaporation of the water. Typical the viscosity characteristics of the specific type and grade designations are SS-1h (Anionic) and CSS-1h (Cationic). of the emulsified asphalts. Slurry Seal--A mixture of slow setting emulsified asphalt, well-graded fine aggregate, mineral filler, and water. It is ABBREVIATIONS used to fill cracks and seal areas of old pavements, to restore a uniform surface texture, to seal the surface to prevent mois- The following are abbreviations used in the synthesis report: ture and air intrusion into the pavement, and to provide skid BTU British Thermal Units resistance. C Celsius Sprayed Seal--Australian terminology, essentially synony- CO2 Carbon dioxide mous with a chip seal, which refers to the application a cm Centimeter bituminous binder and cover aggregate on various surfaces CM Cubic meter [NCHRP Synthesis 340 (2005)]. CQS-P See Table 51 in chapter eight Stator--The fixed or stationary plate of a colloid mill. Emul- CQS-1H See Table 51 in chapter eight sions are formed when two immiscible liquids are intro- CQS-1HP See Table 51 in chapter eight duced into a cavity with a small clearance between the stator CSS-1 See Table 51 in chapter eight and a high-speed rotor creating high shear forces. CSS-1P See Table 51 in chapter eight Streaking--An aesthetic and construction defect cause by CSS-1H See Table 51 in chapter eight nonuniform application of binder across the lane width. CSS-1HP See Table 51 in chapter eight Streaking leads to a considerable shortening of the life CY Cubic yard expectancy of a surface treatment [NCHRP Synthesis 340 DOT Department of Transportation (U.S. state) (2005)]. F Fahrenheit Stripping--Separation of the binder from the aggregate. FLHD Federal Lands Highway Division Refer to raveling. Ft Foot Surface Texture--The characteristics of the pavement surface G Gram that contribute to both surface friction and noise. gal Gallon Surface Treatment--A surface treatment, commonly referred in. Inch to as a Bituminous Surface Treatment (BST) or Asphalt kg Kilogram
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75 km Kilometer QC/QA Quality control/quality assurance l Liter SBS Styrene butadiene styrene lb Pound SM Square meter MG Megagram SN Skid number MJ Megajoule SS-1 See Table 51 in chapter eight mm Millimeter SS-1H See Table 51 in chapter eight MOT Ministry of Transportation (Canadian province/ NCAT National Center for Asphalt Technology territory) NHI National Highway Institute NO2 Nitrogen dioxide U.S. United States