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CZU 624.131.431

ROMANIAN STANDARD STAS 1913/1-82

Classification index G 23

Replacing:STAS 1913/1-73

Previous editions:

1961, 1973, 1981

FOUNDATION GROUNDDETERMINATION OF MOISTURE CONTENT

Teren de fundare

DETERMINAREA UMIDITATII

Terrain de fondation

DETERMINATION DE LHUMIDITE Validation date:1982-08-01

1. GENERAL

1.1 Scope

This standard establishes the methods for laboratory and site determination of soils moisture content that formthe foundation ground.

The methods apply to all the classified and identified soils according to STAS 1243-74. The soils which

include frequent gypsum impregnations, iron or limestone hydrates, and also the ones which contain more than 5%organic matters, will be mentioned in the analysis report.

1.2 Moisture content means water mass wasted on a soil sample by desiccation at 105 2oC, reported to its driedmass. The result is expressed in percents.

For the soils which include frequent gypsum impregnations or more than 5% organic substances, the

desiccation takes place at the temperature of 80oC.

2. LABORATORY DETERMINATION OF MOISTURE

2.1 Principle of method

The method consists in the determination of the water mass wasted by a known soil quantity, by desiccation inthe thermo-adjustable oven till constant mass, at the temperature of 105 2oC.

2.2 Sampling

The determination of moisture content will be done on a sample or on three samples whose total mass will beof:

- for cohesive soil, approximately 75 g;- for fine sand approximately 100 g;- for coarse, medium sand approximately 200 g;- for gravel with sand approximately 500 g;

- for gravel approximately 1 kg;-

for boulder 2....6 kg.

ASOCIAIA DE STANDARDIZARE DIN ROMNIA (ASRO),Adresa potal: str. Mendeleev 21-25, 70168, Bucureti 1, Direcia General: Tel.: +40 1 211.32.96; Fax: +40 1 210.08.33,

Direcia Standardizare: Tel. : +40 1 310.43.08; +40 1 310.43.09, Fax: +40 1 315.58.70,Direcia Publicaii: Serv. Vnzri/Abonamente: Tel: +40 1 212.77.25, +40 1 212.79.20, +40 1 212.77.23, +40 1 312.94.88 ;

Fax : +40 1 210.25.14, +40 1 212.76.20

ASRO Entire or partial multiplication or use of this standard in any kind of publications and by any means (electronically, mechanically,photocopy, micromedia etc.) is strictly forbidden without a prior written consent of ASRO

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STAS 1913/1-82 2

The material quantity necessary for one determination depends on its nature and on the accuracy of the used

balance, according to table 1.

Table 1

Balance accuracy Material quantity

0,01 g 20100 g

0,1 g 100500 g

1 g > 500 g

2.3 Equipment

- Covered containers, glass bottles, clock glasses with clamp, thin capsules from chrome-plated brass;

- Technical balance with weighting accuracy in accordance with table 1.

- Thermo-adjustable oven, with the possibility of adjusting the temperature at 105 2oC, with free aeration

device.

- Exsiccator with plate, having as dehydrating substance the calcium chloride technical anhydrous or the

granulated fine-pored silica gel 4.....7 mm, anhydrous, indicated especially in the case of the heavy loamsoils.

NOTE: - The fine-pored silica gelwashed with a solution of 15% of hydrated cobalt chloride (CoCl2* 6H2O)and then dried is used as indicator of the moisture degree of the dehydrator; this one is placed in a small

crystallizer (30 mm) in the dehydrator mass from the exsiccator, at sight. The color of this indicator is navyblue when the dehydrator is used, becoming pink when the dehydrator needs to be regenerated. The

regeneration of the silica gel is done by desiccation in the oven at 130oC for 24 h, together with the indicator.

The regeneration of the calcium chloride is done at 200oC for 24 h, together with the indicator.

2.4 Operating mode

The covered containers are numbered, desiccated at 105 2oC, cooled and then calibrated. Their tare mc is

periodicallychecked.

The container with the test material is closed immediately after sampling and is determined its mass mu.

Then the sample container is opened and is desiccated in the oven, at the temperature of 105oC, which shouldbe maintained constantly with a deviation of 2

oC. During desiccation, the aerating device of the oven will be

maintained open.

The samples larger than 25 g will be crumbled before desiccated in the oven.

The material should be desiccated in the oven till constant mass.

The minimum desiccation period, for the quantities provided at section 2.2 is of:

6 h for sands;

10 h for sandy soils;

16 h for argillaceous soils;

24 h for heavy loams;

24 h for soils that include frequent gypsum impregnations, desiccated at 80oC.

This minimum period is not valid in the case when in the oven are soils with different granularity.

During desiccation, one should not introduce in the oven a new lot of wet test pieces, in order not to increasethe moisture of those in desiccation.

After desiccation, the container is closed and is determined the container mass md with the dried test piece.

The results of the weightings mu, md, mcare entered in a report according to the one from annex A.

In the case when it is necessary the check of reaching the constant mass, the containers with test pieces areintroduced in the oven at 105 2oC for 2 h, in the same conditions as above, after what is checked the dried mass.

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2.5 Expression of results

The moisture is calculated on the basis of the values mu, md, mc, resulted from weighting, with the relation:

W% = 100cd

du

mm

mm

where

mu wet material mass + the container tare, in g;md dried material mass + the container tare, in g;mc the container tare, in g.If determination was done on three samples (section 2.2), the moisture is the arithmetic average of those three

partial values obtained if these ones do not differ among them with more than 2% (percents of moisture); in oppositecase the determination is repeated.

When dealing with non-cohesive soils, stratified soils or soils with frequent inter layers (ferruginous, sandy,argillaceous), and also soils including frequent gypsum or organic matters impregnations, which carry moisturedeviations higher than the ones provided above, the arithmetic average of the partial determinations is done under theconditions achieved from the test, entering at the same time the note in the analysis report.

3. SITE DETERMINATION OF MOISTURE

3.1 Methanol burning method

3.1.1 Principle of method

The method consists in the determination of the water mass wasted by a known quantity of soil by methanol

burning, till constant mass.This method applies to all the soils except the coarse soils (gravels a.s.o.).

3.1.2 Sampling

3.1.2.1 The sampling will be in accordance with section 2.2.3.1.2.2 The material quantity necessary for a determination depends on the soils nature according to section 2.2.

For prevalent sandy soils only one sample of approximately 150 g can be used.When dealing with cohesive soils three parallel samples of approximately 25 g. are used.

3.1.3 Equipment

- Capsules, preferably metallic and chrome-plated, numbered and calibrated, having 10 cm.- Steel flexible spatula.- Asbestos plate of 30 x 30 cm, minimum thickness of 4 mm, or any other support, non-combustible, non-

adherent and with low thermal conductibility.- Technical balance Cl II with cursor, maximum load of 100 g, with the division value in cg, or adequate

balance according to section 2.3.- Exsiccator with adequate dehydrator, according to section 2.3.

3.1.4 Reagents

- Pure methanol.NOTE: - When using the methanol will take in consideration the security rules.

3.1.5 Operating mode

The big samples divide in smaller samples, adequate to the capsules capacity.Never burn more than 50 g of soil.The test material capsule is weight immediately after the sampling.a quantity of methanol which should cover the crumbled soil test piece by means of the spatula is added.

The material capsule is placed on the asbestos plate and is set on fire. During burning, the soil in stirred withthe spatula.

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The burnings take place successively, the number of burnings being in accordance with table 2; after every

burning the capsule is placed to chill in an exsiccator with adequate dehydrator.

Table 2

Soil categoriesNumber ofburnings

Sand with gravel, sand, powder sand,

sandy powder, powder

2

Argillaceous sand, argillaceous powder,loam, powder clay

3

Clay, heavy clay 4

After the final cooling the weighing is done as quickly as possible.The facts obtained are entered in the report according to the one from annex A.

3.1.6 Expression of resultsThe moisture content is calculated according to section 2.5.The difference admissible of the method from section 2 is of 1%.

3.2 Flame burning method

3.2.1 Principle of method

The method consists in the determination of the water mass wasted by a known quantity of soil by drying on ametallic tray, set above a flame; the heat will be moderated, so that the tray should not turn red.

This method applies to the coarse soils (gravels .a.s.o) and to the slightly cohesive soils.

3.2.2 Sampling

A representative soil quantity is taken for the determination of moisture content, according to section 2.2.Not less than three specimens shall be sampled.

3.2.3 Equipment

- Un-emailed metallic tray or pan.- Heating source: gas oven, electric plate a.s.o.- Iron spoon, spatula.- Balance (weighting device), according to table 1.

3.2.4 Operating mode

The soil is closed in a thin layer on the metallic tray and is heated moderately, stirring continuously. In order to

ensure a drying of the material as uniformly as possible, the material tray will be introduced in a sand bath.The heating continues till the soils drying at constant mass, respectively till by approaching a piece of cold

and dried glass to the surface of the heated soil, the glass does not steam out, or by introducing pieces of white paper inthe material, the paper becomes brownish.

The facts obtained are entered in the report according to annex A.

3.2.5 Expression of results

The moisture content is calculated according to section 2.5.The difference admissible of the method from section 2 is of 2,5%.

3.3 Radiometric method

According to STAS 1242/9-76.

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STAS 1913/1-825

ANNEX A

MOISTURE

LABORATORY Order.........................................

Site.............................................Sampling.....................................Sample no..................................Depth...........................................

Test pieceDetermination course

1 2 3

Container no.

Wet sample mass + tare mu (g)

Dry sample mass + tare md (g)

Tare mc (g)

m - m (g)u d

m - m c (g)d

W = 100cd

du

mm

mm

(%)

Results average

Description of material.................................................

Date..................................

Elaborated by.....................................

Elaborated by: Ministry of Agriculture and FoodIndustry Institute of studies and designs for landimprovementProject coordinator: geologist Maria Badica

geologist Irena ContineanuFinal elaboration: Romanian Standards InstituteDepartment of constructions, materials of constructionand forest economy

Eng. Magda Ionescu

Collaborators:- Central Institute of investigation, design and building

line- Institute of constructions Bucharest Faculty of

constructions- Institute of investigations in constructions and economy

of constructions- Institute of technological investigation and design of

engineering enterprises