Study of Volta River Aggregate Samples

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Technical Note (National Research Council of Canada. Division of Building Research), 1957-05-01

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Swenson, E. G.

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NOT FOR PUBLICATION

DIVISION OF BUILDING RESEARCH

NOTlE

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_{1HI N ][ CAlL}

NATIONAL RESEARCH COUNCIL OF CANADA

,

PREPARED BY _{E.G. Swenson} CHECKED BY .R.F.L. APPROVED BY R.F.L.

PREPARED FOR Sir William Halcrow and

Partners.

DA.TE May 1957

SUBJECT Study of Volta River Aggregate Samples

Four samples of stone and sand were submitted to the Division of Building Research for determination of alkali

reactivity. These are designated in the accompanying table as A, B, C and D.

Two tests were carried out ,as .described below but it has not yet been possible to obtain a detailed petrographic

evaluation as to the presence or absence of constituents known to be deleteriously reactive with high alkali cements.

The chemical test, ASTM Designation C289-54T, is "a method for determining the potential reactivity of aggregates

and their potentiality for producing abnormal expansion in concrete when used with high alkali cementll

• The reSUlts of this test for the four samples submitted are shown in the accompanying table, which also shows comparison data for a

highly alkali-reactive material and a non-reactive material, both used as control samples. These data should be interpreted on the basis of the generally accepted criterion.*

The data, thus evaluated, indicate that the two

arkose quartzite rock materials (C and D in the table) are both potentially capable of producing abnormal expansion in concrete when used with high alkali cements. This test is not considered conclusive by itself, however, and the results obtained should be compared with those from physical and petrographic tests. The two sands may be considered, on the basis of this test, to be not ､･ｬ･ｴ･ｲｩｯｵｳｾｹ reactive when used with high alkali cements.

The standard mortar bar test, ASTM Designation C227-52T "is intended to determine the potential expansive alkali .

reactivity of cement aggregate combinations". The four aggre-gates submitted produced negative results in this test. ThA mortar bar test is generally considered to provide more reliable

information than the chemical,test as to the probability of alkali-aggregate reaction in the field.

·lio See R.C. Mielenz, K.T. Greene, and E.J. Benton; "Chemical Test

for Reactivity of Aggregates with Cement Alkalis; Chemical

Processes in Cement-Aggregate Reaction", Proc.

Am.

44,

•

It is expected that a detailed petrographic evaluation will be carried out shortly to supplement the results of the

above tests.

On the basis of these two tests, and without benefit of petrographic evaluation, it can be tentatively concluded

that the two sands are not deleteriously reactive to high alkali cements, and that the two stone materials ｾｲ･ not entirely free from suspicion.

..

Ｎｾ

3

!,ABLE SHOWING SILICA. RELEASE (Sc) AND REDUCTION

IN

Aggregate Sample Sc

roM/I

roM/I

Sand, from east channel near

line

99

32.8

Sand, from west channel near line

99.

coarse fractions.

29.3

Sandstone, (Arkose Quartzite) from Quarry No.3, taken from rockpile after blasting. From

power house site.

42.8

Quartzite from Power house site, Quarry No.1. _{Takeiltrom rock}

pile after blasting. 62.0

Reference Materials

Sand-gravel sample known to be very reactive to high alkali cements.

Sand sample known to be innocuous.

33.5

As a rough guide to those who want a general idea as to the interpretation of data in the quick chemical te st, if the Rc value exceeds the Sc value, and the latter is not unduly high (as for aggregates A and B in the above table), the

material being tested is probably innocuous. If, however, the Rc value is lower than the Sc value, and the latter is sufficiently large (as for

aggregates C and D in the table) the material may be suspect.