SAMPLING AND TESTING HIGHWAY MATERIALS. 
27 
except when the percentage of total solids is large, or the water 
appears to give abnormal tests in other respects. 
5. A comparison of the given water with a water of known 
satisfactory quality can he obtained by making standard sound- 
ness, time-of-setting, and 1 : 3 mortar-strength tests with standard 
sand, using the same cement of standard quality with each water. 
(Suggested limits for the last-named test are as follows: Any 
indication of unsoundness, marked change in time of setting, or 
a variation of more than 10 per cent in strength from results 
obtained with mixtures containing the water of satisfactory 
quality, shall be sufficient cause for rejection of the water under 
test.) 
SPECIFICATIONS AND TESTS FOR PORTLAND CEMENT. 
(A. S. T. M. 
slightly modified.) 
standard specifications, serial designation C 9-21, 
SPECIFICATIONS. 
1. Portland cement is the product obtained by finely pulverizing 
clinker produced by calcining to incipient fusion an intimate and 
properly proportioned mixture of argillaceous and calcareous ma- 
terials, with no additions subsequent to calcination excepting 
water and calcined or uncalcined gypsum. 
I. CHEMICAL PROPERTIES. 
2. The following limits shall not be exceeded: 
Per cent. 
Loss on ignition 4. 00 
Insoluble residue .85 
Sulphuric anhydride (S0 3 ) 2.00 
Magnesia (MgO) 5.00 
II. PHYSICAL PROPERTIES. 
3. The specific gravity of cement shall be not less than 3.10 (3.07 
for white Portland cement). Should the test of cement as re- 
ceived fall below this requirement, a second test may be made 
upon an ignited sample. The specific gravity test will not be made 
unless specifically ordered. 
4. The residue on a standard No. 200 sieve shall not exceed 22 
per cent by weight. 
5. A pat of neat cement shall remain firm and hard, and show no 
signs of distortion, cracking, checking, or disintegration in the 
steam test for soundness. 
6. The cement shall not develop initial set in less than 45 min- 
utes when the Vicat needle is used or 60 minutes when the Gill- 
more needle is used. Final set shall be attained within 10 hours. 
7. The average tensile strength in pounds per square inch of 
not less than three standard mortar briquets (see section 50) 
composed of 1 part cement and 3 parts standard sand, by weight, 
shall be equal to or higher than the following : 
Chemical 
properties. 
Physical 
properties. 
Age at 
test. 
Storage of briquets. 
Tensile 
strength per 
square inch. 
Days. 
28 
1 day in moist air, 6 days in water 
Pounds. 
200 
300 
8. The average tensile strength of standard mortar at 28 days 
shall be higher than the strength at 7 days. 
