﻿UNITED STATES DEPARTMENT OF AGRICULTURE 



DEPARTMENT BULLETIN No. 1132 



Washington, D. C. PROFESSIONAL PAPER March 21, 1923 



THE RESULTS OF PHYSICAL TESTS OF ROAD-BUILDING ROCK FROM 

 1916 TO 1921, INCLUSIVE. 



Prepared in the Bureau of Public Roads. 



CONTENTS. 



Page. 



Introduction 1 



Table 1. — Results of physical tests of road- 

 building rock from 1916 to 1921, inclusive. . 2 



Crushing strength or compression test 46 



Interpretation of results of physical tests 46 



Table 2. — Results of compression tests of rock 



made prior to January 1, 1916 48 



Table 3. — General limiting test values for 

 broken stone 51 



Table 4. — Geographical distribution of rock 

 samples tested from January 1, 1916, to 

 January 1, 1922 52 



INTRODUCTION. 



This bulletin gives the results of tests of all rock made by the 

 Bureau of Public Roads from January 1, 1916, to January 1, 1922, 

 classified alphabetically according to location. It supplements 

 United States Department of Agriculture Bulletin 370, " Results of 

 Physical Tests of Road-Building Rock," and replaces United States 

 Department of Agriculture Bulletin 670, "Results of Tests of Road- 

 Bunding Rock in 1916 and 1917." The results of tests of approxi- 

 mately 5,300 samples are now avilable in the two bulletins, and 

 these tests represent road-building material from practically all parts 

 of the United States and some parts of Canada, Haiti, the Dominican 

 Republic, and Porto Rico. Reference to Table 1, in which the 

 results of tests made subsequent to January 1, 1916, are tabulated, 

 will show that a test of crushing strength has been made on a number 

 of samples, and a column of test results not found in Bulletin No. 370 

 is added thereby. Tests of crushing strength made prior to 1916 

 are recorded in Table 2. This quality of rock is not determined 

 ordinarily when making examinations of their suitability for road 

 building, but it is employed often when considering rock for use as 

 paving blocks or as railroad ballast. A brief description of this test 

 as made by the Bureau of Public Roads is given on page 46. 



19525°— 23— Bull. 1132 1 





