1. Bituminous Materials I. * Terms and Properties of Asphalts 1. Binder: a material used for the purpose of holding solid particles together 2. Bitumen: any of various flammable mixtures of hydrocarbons and other substances, occurring naturally or obtained by distillation from coal or petroleum, etc. Bitumen 3. Asphalt: a general term for certain mixtures of asphaltic cement and mineral matter. 4. Tar: a viscous liquid, black in color, with adhesive properties, obtained by the distillation of coal, wood, shale, peat, bone, etc. 5. Pitch: a solid or semi-solid residue of fractional distillation or partial evaporation of tar results 6. Asphaltic cement: bitumen, a mixture of lake asphalt and bitumen, or lake asphalt and flux oils or pitch or bitumen, with cementing qualities suitable for the manufacture of asphalt pavements. 1 Sunday, November 22, 2015

2. Bituminous Materials *Bitumen isBitumen 1) Viscous and adhesive; 2) in gaseous, liquid, semi-solid, or solid phase; 3) soluble in carbon disulphide; 4) consisting essentially of hydrocarbons and their derivatives; 5) substantially non-volatile and softening gradually when heated; 6) black or brown in color; 7) waterproof; 8) obtained by refinery processes from petroleum, and found as a natural deposit or as a component of naturally occurring asphalt Back 2 Sunday, November 22, 2015

3. Bituminous Materials II. Properties in detail 1. *General : water resistant, weather resistant, and adhesive, relatively cheap, and available in large quantities. 2. Elementary chemical properties 1) exceedingly complex materials chemically: more than 10,000 compounds in tar 2) according to their solubility in a series of solvents, bitumens fall into a. Carbenes( 卡宾、碳烯 ): the fraction insoluble in carbon tetrachloride; b. Asphaltenes( 沥青烯 ): the fraction insoluble in light aliphatic hydrocarbon ( 脂肪族烃 )solvent; c. Maltenes( 马青烯 / 石油质 ): fraction soluble in light aliphatic hydrocarbon solvent. 3 Sunday, November 22, 2015

4. Bituminous Materials 3. Safety in Use 1) When hot enough and air present, most oily substances and tars will burn. a. the flash point (ignition temperature of a binder): the temperature at which vapor given off from its surface will burn in the presence of air and an ignition source; or the lowest temperature at which the vapor of a combustible liquid can be made to ignite momentarily in air. -- great care taken when handling cutback bitumen b. the fire point: the lowest temperature at which a volatile liquid after its vapors have been ignited, will give off vapors at a rate sufficient to sustain combustion. 4 Sunday, November 22, 2015Sunday, November 22, 2015Sunday, November 22, 2015Sunday, November 22, 2015

5. Bituminous Materials 2) In general most bitumen-based products present no health hazard in use except that some emulsions may contain chemicals which can cause allergic reactions with prolonged skin contact. Most seriously and some potentially carcinogenic; 4. Adhesiveness/ Adhesion （粘性 / 着附性） a. materials to be bound should be clean, dry and free from dust -- the binder may not reach dusty or dirty stones; -- If water present, it is difficult for a binder to displace the water and adhere to the stones 5. Stripping of binders （黏合剂的剥离） 1) the stripping of binders by water 2) Tars resist such stripping better than asphalts 5 Sunday, November 22, 2015

6. Bituminous Materials 3) The harder (high viscosity) binders adhere better in the presence of water than soft (low viscosity) binders 6. Viscosity （粘滞度 / 性） 1) The property of a liquid which retards flow 2) If the viscosity is high then flow under load is slow, and vice versa; 3) Bituminous materials are in a wide variety of consistencies, ranging from very hard pitches which shatter when struck to liquids which are free-flowing at ordinary temperatures; 4) All bitumens possess the liquid property of viscosity. 5) In engineering terms viscosity is the ratio of shear stress to the rate of shear strain. 6 Sunday, November 22, 2015

7. Bituminous Materials 6) All bituminous binders become very much softer or of lower viscosity as their temperature increases, and harder or of higher viscosity as their temperature falls; 7) The rate of viscous flow decreases with time. 7. Stiffness （劲度） 1) At low temperatures, and in particular for short duration of loading, many binders show elastic properties, deforming under load and recovering on the removal of load. 8. Thixotropy( 触变性、摇溶现象 ) 1) the property whereby a fairly still material becomes much more fluid when vibrated or agitated, marked in blown or oxidized bitumens, 7 Sunday, November 22, 2015Sunday, November 22, 2015Sunday, November 22, 2015Sunday, November 22, 2015

8. Bituminous Materials 9. Softening point （软化点） 1) “Soft” is defined in terms of a particular piece of apparatus, and the test is called the ring and ball test. 2) In this test a sample of the hot binder is poured into a brass ring and allowed to cool, so that a flat disc of binder is enclosed in the ring. The ring is fitted to an opening on a metal carrier and immersed in water at 5 °C. A steel ball 9.53 mm in diameter is placed centrally at the top of the disc of binder using a centering dragged downwards by the weight of the ball- bearing and the softening point is defined as the temperature of the water at the instant when the binder just touches a plate placed 25 mm below the ring. 8 Sunday, November 22, 2015

9. Bituminous Materials 10. Temperature susceptibility （易感性） 1) For a fairly wide range of temperature a graph of log viscosity against temperature gives approximately straight-line plots. 2) Tars are slightly more susceptible to changes in temperature than bitumens; again the consistency of oxidized bitumens alters less with changes in temperature than that of either tars or bitumens. 11. Penetration index 1) At their softening points all bitumens had the same penetration of approximately 800. 2) penetration index (PI): the linear relationship between log penetration and temperature 9 Sunday, November 22, 2015