metals of different chemical composition, methods of installation, maintenance, climatic conditions, etc., are being thoroughly studied.
This study has already brought about improved methods or culvert construction and maintenance which will materially increase the life of metal culverts, thus amply justifying the cost of the investigation.
3. Admixture Tests.
Extensive laboratory and field investigations are being conducted to ascertain the effect of various percentage admixtures of silica dust. pumicite, talc, and diatomaceous earths.
Advantages claimed for admixtures are improved workability and strength of concrete.
4. Reinforcement in Concrete Pavements. Several test sections have been constructed and are now under observation.
5. Impact Tests for Rock and Gravel.
Studies are being made to devise an improved method of determining the quality of coarse aggregate for pavement construction.
6. Studies of Hydration and Causes for Disintegration of Cement Concrete.
This investigation is being conducted by our chemical department and is of particular importance in connection with concrete dam construction.
7. Expansion Joint Materials. There is need of an efficient and durable expansion joint. Progress is being made in this direction.
8. Development of a Quirk Hardening Concrete.
There is frequent need of opening concrete pavement to traffic at an early period after construction. Investigation is being made of the different special brands of cement on the market for this purpose and also relative to methods of using standard local brands for the same purpose.
9. Studies of Light Oil Mix Surfaces.
Studies are being made relative to the best design of an oil mix as regards grading, oil content, etc.
The successful application of this relatively cheap method of construction has made possible the early improvement of many miles of desert road at a low cost.
10. Stability Tests of Asphaltic Concrete Mixtures.
A great deal of thought at the present time is being given to the design of asphaltic concrete mixtures and the devising of methods of making accelerated laboratory tests which will determine the probable stability of such mixtures. Properly designed asphaltic mixtures should give many more years of service without excessive maintenance as compared with improperly designed mixes.
11. Development of Accelerated rated Tests for Determining Quality and Durability of Traffic Line Lacquers.
Work done to date has resulted in specifications for a high grade of traffic line lacquer with a resultant material saving in renewal costs.
12. Development of Equipment for Measuring the Relative Coefficient of Friction in Bridge Expansion Plates Due to Differences in Finish and Character of Metal
Considerable progress is being made in this work. There is promise of development of procedure which will result in an ultimate saving both in original construction and subsequent maintenance and reconstruction costs.
13. Non-Corrosive Coatings for Steel Bridge Members.
An investigation is being made of the value of the various so called noncorrosive metal paints on the market. These tests are being made under adverse field conditions in a location close to the sea.
14. Fillers for Asphaltic Concrete.
Lime rock dust or Portland cement have, in the last, been specified as fillers in asphalt mixtures. Investigation is being made relative to the merits of other commercial fillers with a possibility of saving in construction costs.
15. Miscellaneous Investigations and Studies of a Relatively Minor Nature Which Are Vnder Wag Mag lie Mentioned as follows:
(a) Comparative strengths of different brands of California cements.
(b) Field tests for determination of adverse soils.
(c) Strain gauge design and studies.
(d) Development of method for analysis of graphite paint pigments. (continued on p.27)
