Building Construction Handbook, Eighth Edition

Site Soil Tests ~ these tests are designed to evaluate the density
or shear strength of soils and are very valuable since they do not
disturb the soil under test. Three such tests are the standard
penetration test, the vane test and the unconfined compression
test all of which are fully described in BS 1377; Methods of test
for soils for civil engineering purposes.

Standard Penetration Test ~ this test measures the resistance of a
soil to the penetration of a split spoon or split barrel sampler driven
into the bottom of a bore hole. The sampler is driven into the soil to a
depth of 150mm by a falling standard weight of 65kg falling through a
distance of 760mm. The sampler is then driven into the soil a further
300mm and the number of blows counted up to a maximum of 50 blows.
This test establishes the relative density of the soil.

TYPICAL RESULTS

Non-cohesive soils:-

Cohesive soils:-

The results of this test in terms of

number of blows and amounts of

penetration will need expert

interpretation.

No. of Blows Relative Density

0 to 4 very loose

4 to 10 loose

10 to 30 medium

30 to 50 dense

(^50) + very dense
No. of Blows Relative Density
0 to 2 very soft
2 to 4 soft
4 to 8 medium
8 to 15 stiff
15 to 30 very stiff
(^30) + hard
Soil Assessment and Testing