The Bridgeport evening farmer., 1916-09-11

is not used in either Sheet Asphalt or Topeka"
 The reason for the use of flush coat in Bitulithic construction is on account of the coarse aggregate used, It is impossible to secure a smooth surface or one that will not have void spaces in the surface which admit water which freezes and disintegrates the pavement. The flush coat is a necessity in trc case of pavements which have pervious surfaces, but is not necessity in the case of sheet asphalt or Topeka, which do not have the inherent" weaknesses of pave ments of coarse aggregate. The Bos- ton specifications provide for a flush coat for Topeka. The coat also acts to form a film of asphalt and fine ma terial over the large stones of the ag- gresete and so prevent direct contact between the iron tires of carts and the stone, and the consequent crushing of the latter.
 In this connection the attention of the Commission is called to three sam- rles, showing the manner in which the various types of pavements under discussion wear in service on streets:
 Sample No. 1 is a sample of Ritu- lithic. containing comparatively large stones. Particular notice should be taken Of the fact that some of these stones have evidently been crushed by the iron tires of carts carrying heavy loads. When one of the large stones of Bitulithic is crushed it makes a large hole in the pavement compared with the same action on either Topeka or sheet asphalt pavement, and spot from which disintegration spreads very rapidly.
 Sample No. 2 is sample of To- peka. Close examination will show that the same operation of crushing has taken place as in the Bitulithic As the stones in the Topeka, however, are smaller the effect is not so appa- rent.
 Sample No. is a sample of sheet asphalt The crushing effect is not apparent to the naked eye, but under a microscope the same effect will be shown in the grains of sand composing the aggregate. The wear, however, is inf1nitesimal as compared with Bitu- lithic and small as compared with To- peka.
 | paper read by MT. Francis P. Smith before the American Society of Muni- cipal Improvements at the 1915 con- vention. This report may be found on page 120 of the Proceedings of that convention. Partial quotations from this paper were made by an engineer of the paving service before the City Council at meeting some weeks ago, ( %y,@ ;,,%0 1 t~ as paving material. Unfortunately for the complete information of the Council, the engineer did not quote statements more pertinent to the mat ter than those he did quote, particu- larly the summary, as follows:
 Coarse aggregate (hot mixtures) (Bitulithic is in this class) suitable for light and medium traffic only.
 Topeka mixture, suitable for light and medium traffic.
 Sheet asphalt suitable for light, medium and heavy traffic.
 18th. Heavier machinery, which is more, expensive in first cost and in cost of operation, is required for prop erly manufacturing and laying Bitu- lithic Pavement than is required for either Sheet Asphalt or Topeka"
 The weight of machinery required entirely depends on the capacity of the plant, plant having a large ca pacity being necessarily heavier than a plant of smaller capacity For the same capacity there is no appreciable difference in the cost of the plants, in fact the same plant is applicable to the preparation of either class of pave ment.
 18th. Only the best gradesN of ma terials of all kinds are used in Bitu- lithic construction" etc.
 No dispute is made regarding this statement. Neither is there any req son why equally good material should not be secured for sheet asphalt or Topeka mixture under proper inspec- ton.
 "7th. We have large organiza- ton of experts in the bituminous pa- wing industry which is available to cities that purchase Bitulithic Pave ment." etc.
 This statement applies equally well to the larger organizations laying any kind of bituminous pavements, and the matter of care is one that can be adequately provided for in the guar anty provisions of the contract for any class of pavement.
 The remainder of the letter of June 2 does not seem to contain statements of special importance. Proceeding to the letter of June. 1l2.
 Notwithstanding the somewhat heated denial by the representative of the Warren Brothers Company of the correctness of my estimate of 64 cents per square yard as the approximate cost of Bitulithic or Topeka two inch es thick, including labor, materials, and plant investment, the amount is approximately correct. In fact it is correct within much narrower limits of accuracy than the usual approxi- mate estimate. There is no myste- rious or unusually expensive ingre- dient in Bitulithic. It is composed of materials easily obtainable in the op- en market. Asphalt, stone, sand, lime stone dust or Portland cement can be bought by any contractor at standard prices, and the correctness of the costs of the operations of laying will be tes- tified to by any disinterested contrac- tor acquainted with such work
 As regards the costs of pavements one, two or three inches in thickness, Bituhthic, as far as I know, is never laid of one-inch thickness and Tope- ka and sheet asphalt only in rare in- stances. The cost, however, of Tope- kn and Bitulithic is approximately proportional to the thickness As be- tween two and three inches the cost