MICHIGAN 



DETROIT, MICH., FEBRUARY, 1911. 



Michigan State Good Roads Association 



P. T. COLGROVE, Hastings, President. N. P. HULL, Diamondale, Vjce-President. 



THOMAS SATTLER, Jackson, Secretary and Treasurer. 



SPECIFICATIONS FOR 



ASPHALT PAVEMENTS 



[E. M. Perdue in Municipal Engineering.] 



For a number of years I have made the 

 study of asphalt pavment a sepcialty. In 

 every way I have advocated a closer specifica- 

 tion, strict municipal supervision, and the abol- 

 ition of the five or ten year maintenance. It 

 is obvious that for these reasons I could have 

 no part in standardizing specifications. 



A technical chemical and constructing engi- 

 neer would gather from the "Standard Speci- 

 fication," adopted by the Organization for 

 Standardizing Paving Specifications, that the 

 asphalt paving industry was in its infancy, 

 that it had no standards, that it was still a 

 matter of experiment and it was laregly guess 

 work. The facts are that the physical con- 

 stitunts of asphilt pavements are as actually 

 determined as the chemical composition of 

 Portland cement; they can vary within as nar- 

 row limits, and can be as satisfactorily and 

 accurately filled by the contractor. 



Asphalt pavement is one of the best of pave- 

 ments. It can be laid on streets of the heaviest 

 traffic so as to need no repair for a period of 

 ten years and at the same time be smooth, 

 clean and sanitary. Yet municipal engineers 

 lave permitted having contracts to influence 

 them to write a wide-open specification and 

 so cloud the real points of value with chemi- 

 cal analyses until the so-called asphalt pave- 

 ment disintegrates in two years and has be- 

 come unpopular. 



Three pages of your edition of the Standard 

 Specification (5, 6, and 7) are devoted to a 

 confusing, illogical and wholly unprofitable 

 nixture of requirements of derivation, phy- 

 -ical and chemical properties, specific gravity, 

 latural asphalts and the products of distil- 

 itiorr. What difference does it make whether 

 in asphalt comes from Trinidad Lake or the 

 Isle of Trinidad, the Province of Bermudez, 

 Cuba, Utah, Kentucky or Oklahoma, or is the 

 product of the distillation of an asphaltic, 

 iemi-asphaltic or paraffin petroleum; has or 



ha; not a particular ductility, viscosity, pene- 

 tration and flash point; is soluble to a par- 

 ticular percentage in carbon disulfid naptha; 

 has a fixed residue of a given percentage on 

 ignition? These requiremnts only serve to 

 make the specifications abstruse, difficult, be- 

 yond the comprehension of the average en- 

 giner and impossible to the public. 



The only considerations of value to the 

 municipality and to the abutting property 

 owner are the combinations of asphalt and 

 flux, commonly called asphaltic cement or A. 

 C., have the proper ductility, viscosity and 

 penetration to insure a good pavement. These 

 are all the physical and not clerical proper- 

 ties. Given proper ductility, viscosity and 

 penetration, and the solubilities, residues, or- 

 gin and derivation will take care of them- 

 selves. The requirement cumbers the specifi- 

 cation, their determination is a useless ex- 

 pense and labor. 



A large part of pages 9 and 10 is devoted 

 to the "binder course." Now, there are three 

 good reasons for laying binder. 



1. It incrases the cost of the pavement to 

 the property owner. 



2. It requires more work. 



3. It promotes the rapid disintegration of 

 the surface. As a matter of scientific engine- 

 ering, especially as applied to the principles of 

 viscous pavements, the binder course is ob- 

 solete. It is a relic of the early days of the 

 industry. It should never be laid. 



The 'mixes" of concrete aggregates and the 

 aggregates of macadam, bitulithic, Hassam 

 and asphalt pavements depend on the theory 

 of bonding density. This rule applies with 

 greater strictness where the bonding material 

 is bituminous. The set of the limes is the 

 chemical process of hydration. It is rigid and 

 absolute. The set of the bitumens is physi- 

 cal and viscous and depends upon tempera- 

 ture. Therefore, to make a rigid pavement, 

 the stability must be in the mineral aggre- 

 gate and not in the cementing material. For 

 this reason, the sand grading is the Most im- 

 portant feature of the mix. 



The sand and lime dust can be graded so 

 Continued on'Page'6 



THE LAKE STATES FOREST 



FIRE CONFERENCE 



The Lake States Forest Fire Conference 

 held in St. Paul, December 6 and 7, is now a 

 matter of history. The significance of this 

 meeting is far-reaching and the potent influ- 

 ence than emanated from it will go a long 

 way in bringing about rational forest fire leg- 

 islation in the Lake States. 



In point of attendance, unanimity of interest 

 and sentiment, in the variety of interests rep- 

 resented, in seriousness and enthusiasm, this 

 meeting stands alone as the most important 

 of its kind ever held. If this meeting has ac- 

 complished nothing else, it has brought be- 

 fore the American people the fact that, at 

 Itast in the Lake States, the forestry, lumber 

 and railroad interests are unanimous in the 

 matter of forest fire protection by co-operation 

 and each stands ready to aid as far as possible 

 in the abatement of the fire evil. 



The Conference was not a popular conser- 

 vation meeting calculated chiefly to further 

 political ends but was a meeting of hard 

 headed business men, practical foresters, state 

 and national, lumbermen, railroad men, fire 

 insurance men, governors and legislative com- 

 mittee men, and by others whose business 

 compels them to consider the forest fire 

 problem in the Lake States. 



The following resolutions embody the 

 sentiment of this conference and were passed 

 unanimously. 



Resolutions. 



Resolved, That we recommend to the legis- 

 lature of our states: 



First, that the forest fire protection of each 

 state and such other branches of state work as 

 may be deemed best to combine with it, be 

 placed under the control of a non-partisan 

 commission empowered, as fully as possible 

 under the constitution of the different states, 

 to carry on the work, and under civil service 

 rules. Such commission should represent all 

 the interests involved as far as possible, and 

 we recommend that such commission place 

 the work in charge of a chief forester, who 

 should be a professional graduate forester, and 



