DUST PREVENTION AND ROAD PRESERVATION, 1916. 21 
Fairfax County. This road had been reconstructed and surfaced 
with gravel only a few months before the experimental surface treat= 
ment was undertaken. The principal features of the road may be 
- described briefly as follows: 
Milena bIMOntOAdss Je sae sees aco na aciasls ee aisieisiacitcad ass sie aa 24 feet. 
antnwidhh of otavel suriaces <2 02s -s\44 5-2-2 esis eee eee 16 feet. | 
Compacted depth of gravel (2 courses having respective depths of 
Samigiomnehes iss seoecgjiet ysl Pyne eters Sask as kieScles sacl. 8 inches. 
Sr RompieeneTOn ga se ces Sh 9S OEY SB ho i i RS hae cits 4 inch to 1 foot. 
eG GReIANTI TI OTAMC 98 2525S oo ceo ae on ve Bam Sore orks = Se ee enee ee 5 per cent. 
Pe SRC ON GMOS =e sesae Soon os seit c Saya els «nisin eas selnsicin sa Favorable. 
Gravel for use in the original construction was obtained from the 
county pit, located about 500 feet south of station 0+00 at Gum 
Spring, and the Walker pit, located about 100 feet east of station 
92+50. The gravel from the county pit was used from station 
0+00 to station 48+00, while that from the Walker pit was used 
from station 48+00 to the south end of the road. The mechanical 
analysis for the material from each pit is shown in Tables 25 and 26. 
TABLE 25.— Mechanical analysis of sand-clay gravel from Walker pit, Fairfax County, Va. 
Per cent | Per cent 
Per cent 
Totals retained. Passing— Retained on— of | cfCoarse| of fine 
sample. | ®88Te- | agere- 
gate. gate. 
Per cent. 
3-inch screen......-------- 6.5 || 1-inch sereen....| #-inch sereen.... 6.5 OO Ley tal (i aa a 
PeITICMSCRERMe sear cic in = 5) 15.9 || 3-inch sereen-...| 4-inch screen... 9.4 3059) | Gece aoanis 
34-inch screen.....--------- 30.4 || 4-inch screen... .| +-inch screen... 14.5 ARIE ees acceie 
10-mesh sieve 40.6 || 4-nch screen. ...| 10-mesh sieve.... IMP) |ossssceaac 14.7 
20-mesh sieve 45.5 || 10-mesh sieve....| 20-mesh sieve.... BO) See ssecsee 7.0 
30-mesh Sieve...........-- 59.2 || 20-mesh sieve....| 30-mesh sieve.... ae ye eee 19.7 
40-mesh sieve.........-.-- 77.2 || 30-mesh sieve....| 40-mesh sieve.... ASEON ee eU eee 25.9 
50-mesh sieve.....-...---- 85.3 || 40-mesh sieve....| 50-mesh sieve.... Se LM ak Fa ae 11.6 
80-mesh sieve.........-.-- 88.4 || 50-mesh sieve....| 80-mesh sieve.... i lig a Me a cea 4.5 
100-mesh sieve..-.....-.-- 88.9 || 80-mesh sieve....| 100-mesh sieve -. Alay ee See af 
200-mesh sieve-.-.....---- 89.6 || 100-mesh sieve ..| 200-mesh sieve .. ea (el traps edd 1.0 
200-mesh sleve ..}.............--..-- LOS4 3 iso tees 14.9 
100.0 100.0 100.0 
TABLE 26.— Mechanical analysis of sand-clay gravel from county pit. 
Per cent | Per cent 
Per cent 
Totals retained. Passing— Retained on— of coarse | of fine 
sample. | 288"e- | agere- 
gate. gate. 
Per cent. 
i-inch sereen......:.--..-. 4.8 || 14-inch sereen...] 1-inch screen.... 4.8 SI Gr Mee ane. 
2-inch sereen.....-..-..--- 15.6 || 1-inch screen....| 3-inch screen.... 10.8 nL 87) i Seales 
z-inch screen-.....-.---.-- 34.6 || inch screen....| 4-inch screen.... 19.0 34:0) |e eee 
4-inch screen............-- 55.9 || 4-inch screen....| 4-inchsereen....}“ 21.3 Oe) Bl | eet 
10-mesh Sieve.......-.-.-- 69.9 || 4-inch sereen....| 10-mesh sieve.... EEN RGeeasaane 31.7 
20-mesh Sieve...........-- 74.5 || 10-mesh sieve....| 20-mesh sieve.... 456M goa 10.4 
30-mesh sieve............. 80.3 || 20-mesh sieve....| 30-mesh sieve.... Ee) epee 13.2 
40-mesh sieve...........-- 86.5 || 30-mesh Sieve....| 40-mesh sieve.... GER a se 14.1 
50-mesh sieve.....-.....-. 88.6 || 40-mesh sSieve....| 50-mesh sieve.... Dit Coe e ern 4.8 
80-mesh sieve.......-...-- 91.1 || 50-mesh sieve....| 80-mesh Sieve.... 2 Oi ea ee 5.7 
100-mesh sieve............ 92.0 || 80-mesh sieve....| 100-mesh sieve .. Eales arth As 2.0 
200-mesh sieve............ 93.7 || 100-mesh sieve ..| 200-mesh sieve .. Ne ee aCe 2.9 
200-mesh'SI@VO tL.) ooo. ccceceeseeree Gee eases 15.2 
100.0 100.0 100.0 
