ISBN 978-0-626-25308-0
SANS 3001-GR20:2010
Edition 1.1
SOUTH AFRICAN NATIONAL STANDARD
Civil engineering test methods
Part GR20: Determination of the moisture
content by oven-drying
Published by SABS Standards Division
1 Dr Lategan Road Groenkloof
Private Bag X191 Pretoria 0001
Tel: +27 12 428 7911 Fax: +27 12 344 1568
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© SABS
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Table of changes
Change No.
Date
Scope
Amdt 1
2010
Amended to update the introduction.
Acknowledgement
The SABS Standards Division wishes to acknowledge the valuable assistance of the Committee of
Transport Officials (COTO), and the South African National Roads Agency Limited (SANRAL).
Foreword
This South African standard was approved by National Committee SABS SC 59E, Construction
standards – Pavement materials testing, in accordance with procedures of the SABS Standards
Division, in compliance with annex 3 of the WTO/TBT agreement.
This document was published in December 2010.
This document supersedes SANS 3001-GR20: 2008 (edition 1).
A vertical line in the margin shows where the text has been technically modified by amendment
No. 1.
SANS 3001 consists of various parts under the general title Civil engineering test methods.
Parts GR of the SANS 3001 series contain methods for testing gravel, sand and soil.
This oven-dry procedure is the reference method for the SANS 3001 series of standards.
Introduction
This part of SANS 3001 was originally developed and used by agricultural research workers and
has been in use in South Africa for over 60 years as part of other methods published in
TMH1, Standard methods of testing road construction materials.
Water is present in most naturally occurring materials. The amount of water present has a
significant effect on the behaviour of road construction materials.
The data of the moisture content of a fraction of material taken from a test sample is used in a
range of other field and laboratory tests. The data may be used as a guide for classification, as a
control criterion for compaction and in the determination of the dry density of a material.
The oven-dry procedure is the reference method in standard laboratory practice.
Apparatus dimensions that are critical to the outcome of the method or procedure given are given
with a tolerance. All other dimensions are nominal and should be considered fit for purpose.
Existing apparatus that complies with the requirements of TMH1 may be used in this part of
SANS 3001 until the apparatus is no longer fit for purpose.
Amdt 1
This test method is classified as Group: A, Rating: 2, Activity: AG or GR, in accordance with the
requirements of the South African Construction Education and Training Authority (CETA).
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SANS 3001-GR20:2010
Edition 1.1
Contents
Page
Acknowledgement
Foreword
Introduction
1 Scope .....................................................................................................................................
3
2 Normative references .............................................................................................................
3
3 Definitions ..............................................................................................................................
3
4 Apparatus ...............................................................................................................................
4
5 Sampling ................................................................................................................................
4
6 Procedure ...............................................................................................................................
5
7 Calculations ............................................................................................................................
6
8 Test report ..............................................................................................................................
8
Bibliography ..............................................................................................................................
9
1
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SANS 3001-GR20:2010
Edition 1.1
Civil engineering test methods
Part GR20:
Determination of the moisture content by oven-drying
1 Scope
This part of SANS 3001 describes a method for determining the moisture content of test samples
taken from gravel, sand or soil, by drying in an oven to a constant mass.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of the
referenced document (including any amendments) applies. Information on currently valid national
and international standards can be obtained from the SABS Standards Division.
SANS 1649 (SABS 1649), Non-automatic self-indicating, and semi-self-indicating weighing
instruments.
SANS 3001-PR1, Civil engineering test methods – Part PR1: Determination of uncertainty of
measurement, repeatability, reproducibility and bias.
3 Definitions
For the purposes of this document, the following definitions apply.
3.1
constant mass
less than 0,1 % change in mass after two successive (more than 1 h) periods of drying
3.2
oven-dry
dried in an oven at a temperature of 105 ºC to 110 ºC
3.3
liquid limit
LL
empirically established moisture content at the boundary between the liquid and the plastic states
3
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3.4
plastic limit
PL
empirically established moisture content at the boundary between the plastic and semi-solid states
3.5
plasticity index
PI
difference between the liquid limit and the plastic limit
3.6
seal
place in a container with the lid closed so that moisture cannot escape
3.7
soil
natural particles of silt and clay size
4 Apparatus
4.1 Two electronic balances, of the fine measurement type complying with SANS 1649, with one
having a capacity of 5 kg and reading to of 0,1 g, and one having a capacity of 100 g and reading to
0,01 g.
4.2 Drying oven, that is capable of maintaining a temperature range of 105 ºC to 110 ºC with
continuous draft.
WARNING: Under no circumstances shall the microwave oven be used.
4.3 Moisture content containers each of which is, pre-weighed, air-tight and identified (such as a
weighing bottle or corrosion-resistant tin), with a capacity of at least 30 mL, with a stopper or lid that
will prevent the loss of moisture.
4.4 Non-corrodible containers each of which is, numbered, and of at least 10 L capacity with an
airtight lid for field samples.
4.5 Non-corrodible, square, flat-bottomed pans, of width suitable for oven drying and of size
capable of containing the mass of the sample for use in the intended test.
4.6 Brush, with hard nylon bristles not more than 25 mm long.
4.7 Oven gloves.
5 Sampling
5.1 General
Moisture content test samples are taken in several tests and at different stages during the tests.
Test samples will therefore vary depending on the particular national standard method used.
5.2 Laboratory sampling
5.2.1 Take small samples (50 g or less), from materials used for the determination of, for example,
the plasticity index (PI).
4
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5.2.2 Take large samples (greater than 50 g), from material used for the determination of, for
example, the maximum dry density test and the California Bearing Ratio (CBR) test.
5.3 Field sampling
Take large samples (greater than 50 g) in the field and seal them immediately in pre-weighed
(mass = CFm), identified, moisture content containers.
6 Procedure
6.1 Oven temperature
6.1.1 Normal operation
Set the oven to operate at a temperature of between 105 °C and 110 °C.
NOTE Certain soils contain gypsum that on heating loses water of crystallization as well as free or unbound
water. The moisture content determined by this method will be affected by approximately 0,2 % for each 1 % of
gypsum.
6.1.2 Material containing gypsum
If gypsum is present, or if its presence is suspected, the moisture content samples are dried at an
oven temperature of not more than 80 °C and possibly for a longer time than for normal samples.
NOTE When a small quantity of soil is heated on a metal plate to approximately 150 °C, the presence of
gypsum can be identified. Grains of gypsum will turn white within a few minutes, whereas most other mineral
grains remain unchanged in colour.
6.2 Small laboratory samples (see 5.2.1)
6.2.1 Determine the mass (CM) of the sample container (see 4.3 and 4.4) to the nearest 0,01 g.
6.2.2 Place the moist material in the container and seal it. Weigh and record the mass (CM + MW)
to the nearest 0,01 g. (MW is the mass of the moist material.)
6.2.3 Place the open container with the moist material in the oven and dry to a constant mass.
NOTE Time required for drying will vary depending on the material type and the mass of material. Normally
drying overnight will be sufficient, but larger samples will require a longer drying time.
6.2.4 When the material has dried to a constant mass, seal the container and allow to cool.
6.2.5 Weigh the container with the dry material and record the mass (CM + Md) to the nearest
0,01 g. (Where Md is the mass of the dried material.)
6.3 Large laboratory samples (see 5.2.2) and field samples (see 5.3)
6.3.1 In the case of a field sample, first determine the mass of the container (CFM) and then the
mass of the container plus the field sample (CFM + MW), to the nearest 0,1 g.
6.3.2 In the laboratory, determine the mass of a clean dry pan and record the mass (CP) to the
nearest 0,1 g.
6.3.3 Place the moist sample in the pan. See that all fines are transferred by using a brush or
rinsing with water. Determine and record the mass (CP + MW) to the nearest 0,1 g.
5
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6.3.4 Break up the material and spread evenly across the base of the pan.
6.3.5 Place the pan with the moist material in the oven and dry to a constant mass.
NOTE Time required for drying will vary depending on the material type and the mass of material. Normally
drying overnight will be sufficient, but larger samples will require a longer drying time.
CAUTION: To allow free air circulation around the moist material and to avoid contamination
from the pans, do not stack the pans.
6.3.6 After the material has dried to a constant mass remove the pan from the oven and allow to
cool.
6.3.7 Determine and record the mass of the dry material and pan (CP + Md), to the nearest 0,1 g.
NOTE For the field samples, weighing as described in 6.3.3 is not necessary, as MW is the mass of the moist
field sample, calculated from (CFM + MW) and CFM is the mass of the container.
7 Calculations
7.1 Moisture content
7.1.1 Calculate the small laboratory sample percentage (%) moisture content to two decimal
places as follows:
MW = (CM + MW) – CM
Md = (CM + Md) – CM
W=
(M w − M d )
× 100
Md
where
MW
is the mass of the moist material, expressed in grams;
CM
is the mass of the moisture content container, expressed in grams;
Md
is the mass of the dry material, expressed in grams;
W
is the percentage moisture content.
7.1.2 Calculate the large laboratory sample percentage moisture content to two decimal places as
follows:
MW = (CP+ MW) – CP
Md = (CP + Md) – CP
W=
(M w − M d )
× 100
Md
where
CP
is the mass of the pan, expressed in grams.
6
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7.1.3 Calculate the field sample percentage moisture content to two decimal places as follows:
MW = (CFM + MW) – CFM
Md = (CP + Md) – CP
W=
(M w − M d )
× 100
Md
where
CFM is the mass of the field container, expressed in grams.
7.2 Uncertainty of the test method
Use the typical sigma, σ, and E values given below for large samples (double-sided limit) for the
statistical analysis of the uncertainty of the test results, in accordance with SANS 3001-PR1.
σ (X) = C × F
E(X) = (C – 0,03)F
From table 1 select the value for C.
Table 1 — Typical material properties to assist in choosing a value for C
1
2
3
Type
% passing 2 mm sieve
Factor
C
Course
< 20
0,37
Medium
20 to 35
0,30
Fine
> 35
0,25
Determine the value of X from the typical material properties given in table 2.
Table 2 — Typical material properties to assist in choosing a value for X
1
2
3
4
5
Typical material properties
O.M.C.
%
Range
Plasticity
index
Mica
content
%
6
X-value
Water
absorption
%
0–5
<7
None
<1
1
5 – 10
7 – 12
5 – 10
1 – 1,5
2
10 – 15
12 – 20
10 – 25
1,5 – 2,5
3
15 – 20
> 20
> 25
> 2,5
4
> 20
> 20
> 25
> 2,5
5
After determining a value for X, select a value for F from table 3.
7
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Table 3 — Values of X for choosing F
1
2
3
4
5
6
Values
X
1
2
3
4
5
F
1,0
1,7
3,0
5,0
8,3
NOTE Uncertainty values are provided for large samples only. Small samples are predominantly those taken
for Atterberg Limit and linear shrinkage testing and their uncertainty values are covered in the relevant test
methods.
8 Test report
Report the moisture content obtained as the percentage mass fraction of moisture content to one
decimal place.
8
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Bibliography
ASTM D 2216, Standard test methods for laboratory determination of water (moisture) content of
soil and rock by mass.
BS 1377-2, Methods of test for soils for civil engineering purposes – Part 2: Classification tests.
TMH1, Standard methods of testing road construction materials.
© SABS
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