Committees responsible for this British Standard

The preparation of this British Standard was entrusted by the Cement, Gypsum, Aggregates and Quarry Products Standards Committee (CAB/-) to Technical Committee CAB/2, upon which the following bodies were represented:

Aggregate Concrete Block Association

Association of Consulting Engineers

Association of Consulting Scientists

Association of Lightweight Aggregate Manufacturers

Brick Development Association

British Aggregate Construction Materials Industries

British Cement Association

British Ceramic Research Ltd.

British Civil Engineering Test Equipment Manufacturers’ Association

British Geological Sciences

British Precast Concrete Federation Ltd.

British Ready Mixed Concrete Association

British Steel Industry

Building Employers’ Confederation

Calcium Silicate Brick Association Limited

Chartered Institute of Building

Concrete Society

County Surveyor’s Society

Department of the Environment (Building Research Establishment)

Department of the Environment (Property Services Agency)

Department of Transport

Department of Transport (Transport and Road Research Laboratory)

Electricity Supply Industry in England and Wales

Federation of Civil Engineering Contractors

Institute of Concrete Technology

Institution of Civil Engineers

Institution of Highways and Transportation

Institution of Structural Engineers

Institution of Water and Environmental Management (IWEM)

Mortar Producers’ Association Limited

Sand and Gravel Association Limited

Society of Chemical Industry

This British Standard, having been prepared under the direction of the Cement, Gypsum, Aggregates and Quarry Products Standards Committee, was published under the authority of the Board of BSI and comes into effect on 31 August 1989

The following BSI references relate to the work on this standard:

Committee reference CAB/2 Draft for comment 85/13372 DC

Foreword

This Section of BS 812, prepared under the direction of the Cement, Gypsum, Aggregates and Quarry Products Standards Committee, is a revision of 7.2 of BS 812‑1:1975 which is withdrawn. BS 812‑2 and BS 812‑3 are also being revised and as each of the tests, or collection of related tests, is revised, it is intended to issue it as a separate Part or Section of this standard.

In the case of the test for the determination of clay, silt and dust in fine or coarse aggregate, major changes have been made to the procedures described in BS 812‑1:1975. The decantation method for determining the amount of material passing a 75 µm test sieve complying with BS 410 is no longer included, as a procedure for determining this fraction is included in BS 812‑103.1, originally published as BS 812‑103. The field settling test has also been omitted because of difficulties in interpreting the results. This Section of BS 812 therefore deals only with a revision of the sedimentation test of 7.2.3 of BS 812‑1:1975. Although the general principles of the method have been retained, more detail has been included and the procedure has been brought into line with the procedure for sedimentation described in BS 1377.

The terms “clay, silt and dust” which were used in the previous edition of BS 812 have not been retained as they have never been properly defined; the particles are classified solely on the basis of their equivalent particle diameters. The classification is thus solely one of particle size and gives no indication of the composition of the particles or whether or not their presence is likely to be deleterious. It should not therefore be used for this purpose.

It is intended that other British Standards should call up BS 812 test methods as the basis of compliance. Nevertheless it is not intended that all aggregates should be subjected regularly to all the listed tests. Requirements in other British Standard specifications will refer only to the relevant test methods.

Some of the tests in other Parts of this standard are of limited application and advice on the use of simpler tests is given, for example, when they can be used for a preliminary sorting of aggregates to see whether more expensive testing is justified.

Reference should be made to BS 812‑102 for general guidance on testing aggregates, precision of test methods and variance arising from sampling errors.

A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application.

Compliance with a British Standard does not of itself confer immunity from legal obligations.

Summary of pages

This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover.

This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.

1 Scope

This Section of BS 812 describes a gravimetric method, based on sedimentation, for the determination of the proportion of material finer than 20 µm in particle size in aggregates.

This method is not suitable for particles larger than 20 µm because of their short settling times.

NOTE 1 Methods for determination of particle size distribution of an aggregate down to the passing 75 µm fraction are described in BS 812‑103.1. If the proportion of material between 20 µm and 75 µm is required, this may be calculated from the results of the determination carried out in accordance with this Section and BS 812‑103.1.

NOTE 2 The titles of the publications referred to in this standard are listed on the inside back cover.

2 Definitions

3 Principle

4 Sampling

5 Apparatus

5.1

5.2

5.3

5.4

5.5

5.6

5.7

5.8

5.9

5.10

5.11

5.12

5.13

6 Reagents

6.1

6.2

7 Preparation of test portion

7.1

7.2

8 Procedure

8.1 Calibration of sampling pipette

8.2 Preparation of suspensions

8.3 Sedimentation and gravimetric procedures

9 Calculation and expression of results

9.1

9.2

9.3

10 Precision

10.1

10.2

10.3

10.4

10.5

11 Test report

Publications referred to

BS 812-103.2:1989

Testing aggregates. Method for determination of particle size distribution - Sedimentation test

Current

Published:

31 Aug 1989