934 EXPERIMENT STATION RECORD. 



AGRICULTURAL ENGINEERING. 



Earthen dams, S. Fortier ( Utah Sta. Bui 46, pp. 56, ph 1, figs. 



^4y This bulletin discusses the character of materials used in earthen 



dams, methods of making a compact embankment and of constructing 

 core walls, the dimensions of reservoir embankments, slope paving, 

 outlet pipes and conduits, waste weirs or overtlows, and State super- 

 vision of dams and reservoirs. The Connecticut and Idaho laws relat- 

 ing to dams and reservoirs are given in an appendix. 



An account is given of experiments at the station to determine the 

 best ])roportion in which to mix gravel, sand, silt, and clay in order to 

 l)roduce the most compact and impervious mass (^' concrete"). In these 

 experiments the size of the particles was determined and also the 

 weight per cubic yard for each grade of soil in its dry state and the 

 percentage by volume of open space. The latter was determined by 

 pouring a given volume of the material from a height of 0,85 ft. into a 

 known volume of water, the volume of water reipiired to till the inter- 

 stices being taken as the percentage by volume of open space. The 

 different mixtures or "concretes" were prepared as follows: 



Formulas for different clay coticri'ies. 



No. 1. 



No. 2. I No. 3. No. 4. 



Ct(b. yds. Cub. yds. i Cub. yds. Cub. yds. 



Gravtl 1.00 ! 



Fine gravel .90 j .90 i 1.00 



Coarse saud .2.5 



Fine sand .56 j ! 



Very fine .sand .27 ] ] 



Medium saud .51 



Clay I .43 ! .58 : 



Silt I .42 .26 



Total 



"When mixture No. 1 -was thoroughly mixed dry aud poured from a height of 0.85 

 ft., its volume was 1.546 cu. yd. When thoroughly mixed aud tamjied dry in oue- 

 tenth of a foot layers, its volume was 1.240 en. yd. Wheu poured slowly into 

 water and mixed, its volume was 1.26 en. yd. When moistened entiticiently to form 

 a stirt" paste and tamped in one-tenth of a foot layers, its volnme was 1.312 cu. yd. 



"When mixture No. 2 was mixed dry and poured from a height of 0.85 ft., its vol- 

 ume was 1.526 cu. yd. When mixed dry and thoroughly tamped, its volume waa 

 1.294 cu. yd. Wheu mixed dry and poured from a height of 0.85 ft. into water, 

 mixed hut not tamped, and the excess of water drained through holes covered with 

 canvas in the hottom of the hex, its volume was 1.256 en. yd. When mixed dry 

 and moistened with 277 cu. yd. water at a temperature of 41= F. into a stiff paste 

 and well tamped, its volume was 1.296 cu. yd. 



"Xo. 3 is identical with No. 2, except that 0.58 cu. yd. of clay is substituted for 0.42 

 cu. yd. silt. When mixture No. 3 was mixed dry and poured from a height of 0.85 

 ft., its volume was 1.604 cu. yd.; when mixed dry and well tamped, 1.324 cu. yd. 

 When mixed dry and poured from a height of 0.85 ft. into water, mixed hut not 

 tampeil, and drained of excess water, its volume was 1.432 cu. yd. after experiment; 

 1.420 cu. yd. after 1 day; 1.360 cu. yd. after 2 days; 1.356 en. yd. after 4 days; 1.324 

 cu. yd. after 15 days. Wheu mixed dry aud moistened with 0.307 on. vd. of water into 



