12 Questions
What is the purpose of a prime coat?
To fill the surface voids and protect the subbase from weather
What is the main source of natural asphalt?
Natural Deposits
What is emulsified asphalt?
A suspension of small asphalt cement globules in water
What is the color of asphalt?
Dark brown to black
What is asphalt binder?
The principal binding agent in HMA, including asphalt cement and any material added to modify its properties
What is cutback asphalt?
A combination of asphalt cement and petroleum solvent
What is the primary function of tack coat?
To promote bonding between HMA pavement lifts
What is the term used to describe the study of deformation and flow of matter?
Rheology
What happens to asphalt cement when heated?
It gives off vapor
What is the purpose of an emulsifying agent in emulsified asphalt?
To assist in the suspension of small asphalt cement globules in water
What is the characteristic of asphalt cement used in HMA paving?
It is highly pure
What is the basis of penetration grading?
The depth a standard needle will penetrate an asphalt binder sample when placed under a 100 g load for 5 seconds
Study Notes
Asphalt Characteristics
- Asphalt is a dark brown to black, highly viscous, hydrocarbon produced from petroleum distillation residue
Sources of Asphalt
- Natural Deposits: Trinidad Asphalt lakes
- Petroleum Refinery
- Bituminous Materials
Types of Asphalt
- Asphalt Cement: prepared for use in hot-mix asphalt (HMA) and other paving applications
- Asphalt Binder: the principal binding agent in HMA, including asphalt cement and any added materials to modify its properties
Cutback Asphalt
- A combination of asphalt cement and petroleum solvent
- Classified into three types:
- Rapid Curing (RC)
- Medium Curing (MC)
- Slow Curing (SC)
Emulsified Asphalt
- A suspension of small asphalt cement globules in water, assisted by an emulsifying agent (such as soap)
- Classified into three types:
- Rapid Setting (RS)
- Medium Setting (MS)
- Slow Setting (SS)
- Can be anionic (negatively charged) or cationic (positively charged)
Foamed Asphalt
- Formed by combining hot asphalt binder with small amounts of cold water
Prime Coats
- A sprayed application of cutback or emulsion asphalt applied to the surface of untreated subgrade or base layers
- Purpose: to fill surface voids and protect the subbase from weather
Asphalt Properties
- Asphalt: a dark brown to black, highly viscous, hydrocarbon produced from petroleum distillation residue
- Asphalt Cement: prepared for use in hot-mix asphalt (HMA) and other paving applications
- Asphalt Binder: principal binding agent in HMA, including asphalt cement and materials added to modify its properties
Types of Asphalt
- Cutback Asphalt: combination of asphalt cement and petroleum solvent
- Emulsified Asphalt: suspension of small asphalt cement globules in water, assisted by an emulsifying agent
- Foamed Asphalt: formed by combining hot asphalt binder with small amounts of cold water
Asphalt Applications
- Prime Coat: sprayed application of cutback or emulsion asphalt to untreated subgrade or base layers
- Tack Coat: thin bituminous liquid asphalt, emulsion, or cutback layer applied between HMA pavement lifts to promote bonding
Asphalt Characteristics
- Durability: measure of how asphalt binder physical properties change over time (age hardening)
- Rheology: study of deformation and flow of matter
- Volatility: asphalt cement volatilizes (gives off vapor) when heated
- Purity: asphalt cement should consist of almost pure bitumen
Asphalt Grading Systems
- Penetration Grading: based on the depth a standard needle will penetrate an asphalt binder sample
- Viscosity Grading: measures penetration and an asphalt binder's viscosity at 140°F and 275°F
- Superpave Performance Grading (PG) System: uses a common battery of tests to determine an asphalt binder's performance at specific temperatures dependent on climatic conditions
Asphalt Mix Design
- HMA Mix Design: process of determining what aggregate to use, what asphalt binder to use, and the optimum combination of these two ingredients
- Job Mix Formula: recommended mixture, including aggregate gradation and asphalt binder type
Learn about the characteristics and sources of asphalt, a viscous hydrocarbon produced from petroleum distillation residue. Understand natural deposits, petroleum refinery, and bituminous materials.
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