12 
General. 
Grading. 
General. 
Fineness. 
Methods of 
Testing. 
BULLETIN 704, U. S. DEPARTMENT OF AGRICULTURE. 
SAND FOR SHEET-ASPHALT WEARING COURSE. 
The sand shall be composed of sound, durable, angular stone particles, 
free from a coating of clay or loam. 
When tested by means of laboratory sieves the sand shall meet the 
following requirements: 
Per cent. 
Passing AlO-MESH SIC VG so 265 ste os ae ae aa a 100 
Total passing 10-mesh and retained on 40-mesh sieve_______ 2 atom 0 
Passing 10-mesh and retained on 20-mesh sieve____________ DETOm ails 
Passing 20-mesh and retained on 30-mesh sieve_____._._.-__.__ 5 to 15 
Passing 30-mesh and retained on 40-mesh sievye_________ 3 1K 2S 
Passing 40-mesh and retained on 50-mesh sieve____________ 5 to 30 
Passing 50-mesh and retained on 80-mesh sieve____________ 5 to 40 
Total passing 80-mesh and retained on 200-mesh sieve______ 20 to 40 
Passing 80-mesh and retained on 100-mesh sieye___________ 6 to 20 
Passing 100-mesh and retained on 200-mesh sieve__________ A OM OMee ss 
Passing ?200-meéesh! ‘Sie Ves= = = ea eee ee ree Be ph eee 0 to 5 
MINERAL FILLER FOR SHEET-ASPHALT WEARING COURSE. 
The mineral filler shall consist of limestone dust, dolomite dust, 
Portland cement, or natural cement. It shall be free from foreign or 
other objectionable material. 
When tested by means of laboratory sieves, the mineral filler shall 
meet the following requirements : 
Per cent. 
Ba SSIMS: (SO OSMVEST IST VC ae Ra la gat eT ge 100 
Total passing 200-mesh sieve, not less than _~_________________--_ 65 
Tests of the physical properties of the rock and of the size, mechani- 
cal analysis, or grading of broken stone, sand, and mineral filler shall be 
made in accordance with the following methods: 
1. Toughness, U. S. Department cf Agriculture Bulletin 347, p. 15. 
2. Size of broken stone, U. S. Department of Agriculture Bulletin 555, 
Dp. 32: 
38. Mechanical analysis or grading of sand and mineral filler, U. S. 
Department of Agriculture Bulletin 555, p. 33. 
This specification is intended to cover the mineral constituents 
and rough grading of the mineral aggregate of a binder course 
and the sand and mineral filler for a sheet-asphalt wearing course. 
The gradings are essentialiy those included in Specifications for 
Shect Asphalt Paving adopted by the American Society of Munici- 
pal Improvements in 1915. The aggregate for binder course will 
carry from 4 to 7 per cent bitumen. It should be laid upon a con- 
crete base so as to produce a thickness after compaction of about 
14 inches. 
In order to secure the specified sand grading for the wearing 
course it may be necessary to combine two or more sands in pre- 
determined proportions. The surface mixture should be com- 
posed of sand, mineral filler, and asphalt cement. It should carry 
from 6 to 20 per cent filler and from 93 to 134 per cent bitumen. 
It should be laid upon the binder course so as to produce a com- 
pacted wearing course 14 or 2 inches thick as desired. Mainte- 
nance of the wearing course should consist only in patching with 
sheet asphalt topping until it is necessary to replace the entire 
course, 
