CEMENT and CONCRETE RESEARCH. Vol. 14, pp. 887-890, 1984. Printed in the USA. 0008-8846/84 $3.00+00. Pergamon Press, Ltd.

THE GLASS IN LOW-CALCIUM FLY ASH

Bryant Mather Structures Laboratory

U.S. Army Engineer Waterways Experiment Stat ion P.O. Box 631

Vicksburg, Miss iss ipp i 39180 USA

(Refereed) (Received March 7, 1984)

Among the 16 mater ia ls studied in the Corps. of Engineers inves t iga t ion of pozzolans and slags (Mather, 1958) were four f l y ashes, a l l co l lected in the eastern part of the United States, a l l from power plants burning bituminous coal. They were designated AD-3 (Chicago) AD-7 (De t ro i t ) , AD-8 (Phi ladelphia) and AD-9 (Bal t imore). The CaO, by chemicai ana lys is , was between 2.3 and 5.3 percent. Mather (1958) gave some data on these including the fo l lowing:

AD-3 AD-7 AD-8 AD-9

SiO 2 47.2 47.4 38.2 44.9

AI203 19.5 34.0 25.7 34.0

Fe203 18.2 9.0 16.3 6.5

CaO 5.3 2.3 3.9 2.3

Loss on Ign i t i on 0.8 3.9 12.2 7.9

Carbon 0.43 3.17 11.13 7.22

Finer than 75-um sieve 95.5 92.8 93.6 85.1

Finer than 45-~m sieve 93.5 81.7 85.8 81.5

The values for s i l i c a content p lo t ted in Fig. 2, recalculated omit t ing the carbon and Fe203, are 58.0, 54.0, 52.6, and 52.0 respect ive ly . Some quartz was noted but did not make up as much as 3% by mass of any sample based e i ther on microscope or XRD evaluat ion.

The discussions by Diamond (1983, 1984) and Idorn (1984) on the glass in f l y ash suggested that data on the glass in these four ashes might desi rably be recorded. These data are taken from a manuscript report prepared by Katharine Mather from data developed by D.M. Hausen and A.D. Buck.

Transparent i so t rop ic par t i c les were recorded as glass. Glass content was determined as weighted average by p a r t i c l e counts in s ieve-s ize groups.

Most of the glass par t i c les are spheres in the 1-20 ~m range. The index of re f ract ion of the colored glass was higher than that of the color less glass

887

I~ II

z ~

X

"~ '':

F

" ~

''- ~-

> ¢::~

'~ -.-.."

~ ~

1, 8

~"i o

~

~o ~@

.

~-. =

I ~

[i- °

"~ ~5

~ ~

-~

.,~

... ~

~ I

,~.~ ~

I '

~ F

.... ~

- ~ -.

a~

~ ~

~ ~

, ,

~ ~

~ ~

-- ....

~ ~

~

~ ~

o g

~ ~

m~

~

~ •

~ ~

~ .~

~

~ ~

~ ~

o

-~

~

~ ~

~

~ ~

0-~

~ ~

~ ~

~*

~

~ ~

~ -~

~ •

~.

~

~ ~

~ ~

~ ~

~ ~

~ ,~

~

" ~

~ m

~

~

~

~

,, ~

~

"~ ~

.

Z:: ,

~ ~

~ ~

~ -o

~

e,

~

' ~

=~

:

~ ~

~ ~

~o

"

I~ ~

~ ,

.~-

-~

*

~ ~ .~

, ,. ~~~-* ~

.... _~ ~~

~ ~

~ ~

~ ~

.,,[ .

~ -~

, ~

'~

~ '

, ~

o ,~

o ~

o ,~

~ ~

~ o

~ o

~ ~

~ o

~ o

~ ~

~Q

m

~

~ °

'~ o

~ ~

m

~ -

-

~ ,

i ,

' ,

, ~

~ ~

' i

~ ~

~ ~

~ ,

~ ,

~ I

~ .

..

..

..

.

~ ~

7~

'~ )

~

t ~ ~

Vol. 14, No. 6 889 GLASS, LOW CALCIUM FLY ASH, ANALYSES

~ - - I I ~ ~ ~ , 4.~~ E~O

"- AI)-42 I ~ w~e~. ~-~ __ ~ . , r~,oe i~ ~ e ~ r ~ ~ I ~ o L ~ ~ "" ~ o~ ~ - ~ ,, ~ S S ~ 7o ~o-. ~ . ~ ~ , ~ ~ .

~ - / ~ - ~, . ~ o b ~ e ~ d ~ ~ ~ ' ~ A~-~o~ ' ~

~ ~ ", ~ , ~ . ~ I ~ ] ,. ~ ~ ~ )

~ ~ "" ~ ~ ~ ~ ~ ' .X ~ - ~

~, ~ A D - 7 ~ FLY A~R ~ . . . . ~ ~ ' ~ ~o-9 ~ : ~ . . . . ~ ~ ~ . , ~ ~ ~ ~ .~ m ~ ' ~

~ ~ ~ ~ . ~ ~

~ ~ ~ l ~ ~ .~ - f~$ -d ~ s ~ l e ~ c ~ n

~ ~ ~ , ~ . o . , ~ B~sT ~ ~ ~ - ~ ~ ~ Rc-~m6

1 ~ ~ . ~ ~.~o i. s ~ ~.6o ~.~S 1.7o

~ . ~ . o( £,£~a,&~ ~ ~ ~ p~4,~

FIG. 2

A simple inverse l i n e a r r e l a t i o n s h i p has been found to e x i s t between s i l i c a content and mean index of r e f r ac t i on

o f glass por t ion o f g lassy admixtures

AD-3 AD-7 AD-8 AD-9

Glass, % 81 75 51 70

Size range, ~m I - I 0 3-13 4-20 3-14

Mean indes of r e f r a c t i o n 1.546 1.557 1.568 1.565

% glass in

150 to 75-~m s ize 60 55 35 60

s ize f i n e r than 75 ~m 82 76 52 72

but there was a range of ind ices in each case. About I0 percent of the glass pa r t i c l es contained c r y s t a l l i n e i nc l us i ons ; m u l l i t e needles were more common in ye l lowish-green glass of h igher index. The s i l i c a content of the glass can be

890 Vol. 14, No. 6 B. Mather

estimated from the index of refract ion (George, 1924). F i f t y glass part ic les in each of several samples of each f l y ash were recorded as having an index of re- f ract ion above or below that of the immersion medium. The media used had in- dices of from 1.480 to 1.680 in steps of 0.020. The examination was made using white l i gh t at a magnification of 420X. The data are presented in Fig. 1 as histograms. The data as mean and range are indicated in Fig. 2 on which also are shown the index of refract ion of the glass in other materials containing glass used in the study pa r t i a l l y reported by Mather (1958).

References

S. Diamond, Cement and Concrete Research I~3, 459 (1983). S. Diamond, Cement and Concrete Research 14, 146 (1984). W.O. George, J. of Geology 32, 353-372 ( I ~ 4 ) . G.M. Idorn, Cement and Concrete Research 14, 145 (1984).

- -

B. Mather, The Partial Replacement of Cement in Concrete, Am. Soc. Testing Materials, Sp. Tech. Publ. No. 205, Philadelphia, PA, pp. 37-73, 1958.