Geotechnical and Materials Engineering Standards for Bridge ...
Geotechnical and Materials Engineering Standards for Bridge ...
Geotechnical and Materials Engineering Standards for Bridge ...
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TABLE 3.4<br />
CLASSIFICATION OF ROCK WITH REGARD TO STRENGTH<br />
Strength FLe ld Range of unconfined<br />
Grade identif lcation compressive strcngth<br />
Classification method (MPa)<br />
RO Extremely Idented by thumbnail < 1<br />
weak<br />
R1 Very weak Crumbles under firm<br />
blows of geological<br />
hammar; can be peeled<br />
with a pocket knife<br />
R2 Wcak rock Can be peeled by a pocket<br />
R3 Medium<br />
strong<br />
R4 Strong<br />
knife with difficulty;<br />
shallow indentations made<br />
by a firm blow with point<br />
of geological hammer<br />
Cannot bc scraped or<br />
peeled with a pocket knife;<br />
specimen can be fractured<br />
with a single firm blow<br />
of geological hammer<br />
Specimen requires more<br />
than one blow of gealo~ical<br />
hammer to fracture<br />
R5 Very Specimen requires many<br />
strong blows of geological<br />
hammer to fracture<br />
R6 Extremely Speclmencanonlybe<br />
strong chipped by the geological<br />
hammer<br />
(From Canadian Foundation Manual)
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