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INDUSTRIAL A N D ENGINEERING CHEMISTRY
6-“Antifreeze Solutions for Auto Radiators,’’ I n d . Eng. Chem., News Edition, 4, 1 (January 20, 1926); see also 4, 5 (May 20, 1926). 7-Rudnick, “A Series of Tests of Metals Held in Couples in Solutions of CaCh,” Chem. Met. Eng., 20, 394 (1919). 8-LaU‘all, “Glucose as a Preventive of Automobile Radiator Freezing,” A m . J. Pharm., 94, 97 (1922); J . SOC.Chem. I n d . , 41, 206A (1922). 9-Shaw and Robertson, “Honey a s Antifreeze for Automobile Radiators,” Can. Chem. Met., 8, 63; Chem. Met. E n g . , SO, 473; C. A . , 18, 1370 (1924). IC&-Lane, “Freezing Points of Glycerol and Its Aqueous Solutions,” I n d . E n s . Chem., 17, 924 (1925); J. SOC.Chem. I n d . , 44, 826B (1925). 11-Kaestner, “Winter Operation of Gasoline Engines,” Can. Eng., 51, 132 (1926). l2-“Government Bureau of Standards Tests Antifreezing Solutions,” Automobile J . , 26 (October, 1918). 13--“4ntifreeze Solutions f o r Automobile Radiators,” J. Soc. Automotive Eng., 3, 285 (1918). 14--Ikert, “Antifreeze Solutions,” Motor Age, 1 8 (November 7 , 1918). I F ‘ A u t o m o b i l e Makers Recommend Glycerine,” Soap, 1, 13 (December, 1925). 16-Cummings, “Antifreeze Solutions and Compounds,” J. SOL.Automotive E n g . , 19, 93, 247 (1926). 17-Hibbert, “Liquid Composition,” U. S. Patent 1,213,368; C. A , , 11, 877 (1917).
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lS-Lewis, “Antifreezing Compounds,” U. S. Patent 1,282,249; C. A , , 13, 169 (1919). 1%-Reusz, “Antifreezing Solution,” U. S. Patent 1,319,178; 0.picial Ga?. U . S. Pat. Ofice, 267,377 (1919). l h s t e i n h a r t , “Low-Freezing Point Composition,” U. S. Patent 1,436,828; O,ficial Gaz. U.S. Pal 0-ffice, 304, (4) 669 (1922). 21-Pederson, “Noncorroding Antifreeze Solution,” U. S. Patent 1,405,320; C. A , , 16, 1138 (1922). 22--Dubois, “Antifreeze Cooling and Refrigerating Solution,” U S . Patent 1,442,330; C. A , , 17, 1115 (1923). 23-Sperr, “Antifreeze Composition,” U. S. Patent 1,473,327; Oficial Gaz. U.S. Pat. O.fice, 316, (1) 175 (1923). 24--Wright, “Noncorroding Antifreeze Composition,” C . S. Patent 1,626,998; OAcial Gaa. U . S. Pat. OAce, 358, (1) 160 (1927). 25-Crofoot, “Antifreezing Solution,” U. S. Patent 1,581,179; C. A , , 20, 1892 (1926). 26-Wagner, “Antifreezing Solution,“ U. S. Patent, 1,598,464; C. A , , 20, 3544 (1926). 27-Schultheiss, “Antifreezing Mixture,” U. S. Patent 1,605,377; O f i c i a l Gaz. U . S. Pat. O,pice, 352, (1) 177 (1926). 28-Gillespie, Clifford and Sam, “Antifreezing Solutions,” Canadian Patent 200,674; C. A , , 14, 2401 (1920). 2+Quenby, A. G. H . and H. F., “Nonfreezing Solutions,” British P a t e n t 166,209; C. A , , 16, 803 (1922).
Highway Construction By Charles M. Upham’ HIGHWAY RESEARCHBOARDO F THE DIVISIONOF ENGINEERING A N D I N D U S T R I A L RESEARCH, NATIONAL RESEARCH COUNCIL, WASHINGTON,D. C
H
IGHWAY construction is one of the oldest arts; yet it is only recently that it has made any great strides or development. When analyzed and properly regarded from a true economic standpoint, it is quite evident that the greatest economic strides are yet to come, Road construction is a t present largely confined to the physical manipulation of materials, some of which may be products of chemical manufacture. The only chemistry used is in the production of some of these materials and materials entering into the manufacture of road-building equipment. Materials of Construction
When we think of chemically manufactured materials used in road construction we immediately recall cement, asphalt, tar, brick, and steel. Other materials, however, such as lime, hydrated lime, calcium chloride, sodium silicate, lignosulfate liquors, and a few others, form a very small percentage of road-building materials. PORTLAND CEMENT-MUch credit is due the chemist for the development of Portland cement. There is probably no other manufactured material that is so widely used in the highway industry. Its characteristics permit it to be used not only for road pavement but for bridges and other structures which form a part of the highway. The invention of Portland cement is relatively recent and its development is still in progress. Chemists are continually increasing its strength, and a t present much research is being undertaken both to improve this product as to strength and to extend its field of usefulness. Recently quick-hardening cements have been placed upon the market. BSPHALT-T~~original asphalt pavements were undoubtedly constructed from rock asphalt taken from mines, which consisted of either limestone or sandstone impregnated with bitumen. Although the demand for this type of pavement became great, the cost was very high, and the road builder conceived the idea of making artificially an asphalt pavement from sand and asphalt cement which would have in general the properties of rock asphalts. Some of the earlier 1
Director of the Highway Research Board, Washington, D. C.
asphalts used in the preparation of asphalt pavement were what are known as natural asphalts, but before it was possible to mix these with the sand it was necessary to change them to the proper consistency. This was done by fluxing with lighter bitumens, generally obtained from crude oil. Therefore, the chemist directed the manufacture of an asphaltic cement consisting of a fluxed natural asphalt that might be incorporated with sand to form a satisfactory paving material. Again the demand became so great that it was found economic to produce other materials that could be incorporated with sand to form a satisfactory pavement. The chemist once more physically and chemically manipulated crude oil and secured an asphalt residuum which could be used as a cement to supply necessary binding qualities. Thus it is seen that the asphalts as manufactured under the guidance of the chemical engineer form one of the main ingredients in road construction. There have been many attempts to blow asphalts and treat them with various chemical compounds, such as Sulfur and sulfates, but a t present most of the asphalt cement used in road construction is made from what is known as “straightrun” material and is a product of blending asphalt of various consistencies to secure one that will have high binding value and be affected as little as possible by temperature changes. TAR-Tar was undoubtedly one of the first materials ever used in road construction. There are various kinds of tar, but those most used in highway work are cold-gas tar and water-gas tar. The preparation of tars for road work consists of the dehydration and blending of various tars to secure consistency that will be as little as possible affected by the normal air temperature and have high binding values and, under certain conditions, high penetrating values. Tars have certain characteristics similar to asphalt, but others that are decidedly different. The work of the chemist has been mainly in blending the different tars to secure proper consistencies and in determining just how many more valuable products may be taken from tar and still have it a satisfactory binding medium for pavement surfaces. Today most tars that are used me “straight-run” tars
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
and are not chemically prepared except as by-products of other manufactured materials. Tars are widely used in the highway industry. The demand is so great that all the tar produced is utilized. BRrcI(-Brick was also used in the very early days of road construction. There are records indicating that certain roads in the early days of Babylon were constructed of brick. The early brick, however, did not resemble the brick manufactured a t the present time, but consisted chiefly of the clay baked in the sun, sometimes subjected to pressure. Later this clay was fused by lire until the bricks more nearly resembled those of the present-day manufacture. The present art of road-brick manufacture is undoubtedly the immediate product of the chemist, for constantly the demand has been to produce a brick that is tough and hard-one that will resist abrasion and have no absorptive properties. Brick as manufactured today is made from selected shales and clay, carefully fused until the final product greatly resembles a rock of igneous nature. While there are constantly slight changes and improvements in the blending and treatment of clays, most of the present changes in brick manufacture are physical rather than chemical. STEEL-Every one is familiar with the great strides that have been made in the improvement of steel as a direct effort of the chemical engineer. Steel has played an important part in the road industry, not only in the construction of bridges and reenforcement of roads, but in the manufacture of road equipment. The great strength obtained in road equippent and the hardnew obtained in the blades and cutting edges of earth-moving machinery are examples of the great contribution of the chemist to this branch of the highway industry. LIME-dthough lime and hydrated lime have been used for many years in the highway industry, they are not among the more important materials used in road construction. A few roads have been built of lime mortar and a large number of structures have also used this material. Hydrated lime in small quantities has been used as an admixture in concrete, but this practice has not proved popular and probably will never be universally adopted. There is some evidence, however, of lime becoming more extensively used in the road industry. CALCIUM CHLoRIDE-calcium chloride has recently been utilized as an accelerator in concrete. It has also been used as a dust palliative, as it absorbs moisture from the atmosphere and keeps the surface of the road moist. It is prepared in a way that makes it easy to handle and effective in use and is fast claiming the attention of engineers in the curing of concrete. No doubt this material will be used more and more in the highway industry. SODIUM SILIcAm-Several attempts have been made to use sodium silicate in roadways. Owing to its solubility in water, it has not been generally satisfactory, although in regions where there is little rain it acts as a good binding medium and no doubt could be successfullyused. However, the amount of sodium silicate used is very limited. A problem for the chemist would be to secure some way to make sodium silicate insoluble after it is used and once set up in a road surface. LIGNOBULFAT~ LIQuoRs-There have always been attempts to utilize the lignosulfate liquors in road construction, and under certain conditions in the manufacture of certain road binders they have been successful. The road binder is made by evaporating these liquors until they become sticky and have a binding value. This product is also not entirely satisfactory as a road binder, however, for it is soluble in water a t all times and under all normal conditions. Here again is an opportunity for the ehemist to improve a road-
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building material by finding some way to make the lignosulfate liquor insoluble. Chemical Problems Awaiting Solution Although the highway industry has made great strides because of the chemically prepared materials furnished by the chemical engineer, and although the development has extended over a long period, the chemical engineer in the highway industry will be remembered for what he is going t o do rather than what he has already done. Beyond the preparation of materials the chemical engineer has taken little active part in road construction and probably this is one of the reasons why no greater advance has been made. Up to the present time most of the research that has been undertaken has been physical. The highway industry should be truly grateful for Portland cement as manufactured today, still there is much work left for the chemist on this product. The development of a high early-strength cement a t a reasonable expense will overcome many of the present dficulties in the use of concrete in the highways. Other problems for the chemist are the preparation of an asphalt and tar that will be little affected by temperature changes and the production of a bitumen that will not be greatly changed over a long period of time. Five hundred thousand miles of primary roads of the country are fast being covered by pavements that can meet the demands of present-day traffic; but they are being constructed and maintained a t great cost. Besides this primary system nearly three million miles of road are left to be improved. The traffic on this large mileage of unimproved road does not justify the construction of expensive pavements such as are being laid on the primary routes. Therefore, a low-cost pavement that will satisfactorily take care of a reasonable amount of traffic must be provided. Already considerable work has been done. Physical research has been undertaken. The Highway Research Board has a committee working on this problem continuously, but progress reports indicate that the maximum progress at this time is the development of a road made of suitable local natural material protected with some bituminous binder. In some places local material is satisfactory for road construction but usually the preponderance of clays makes the material unfit for any suitable road use. One of the most deleterious materials of road construction is clay, especially when in excessive quantities. Clay lends itself to many classifications but because it is highly absorptive and difficult to drain, and of low bearing value when wet, it is one of the expensive and dif6cult factors in road construction. Certain clays up to 15 or 20 per cent in a roadway can be handled satisfactorily, but frequently the percentage of clay greatly exceeds this figure and in such places it is difficult to construct a low-cost or standard-type pavement. The chemist can render no greater service than to discover a method for treating clay in such a way as to make it more nearly resemble the sands. It is very desirable to change its nature so that it can be drained, and reduce to a minimum the volumetric changes when subjected to various amounts of moisture and increase the bearing value under moist condition, thus making it into a material that can be shaped and maintained by road machines. Such a discovery would be welcomed by all states in the Union and could immediately be utilized on that large mileage of unimproved roads which must take care of a large percentage of our present-day traffic and which in a very short time will serve as primary roads of the country. Such a discovery would almost immediately create savings that would mount into the millions of dollars and thereby change the whole art of road building.
