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Examination of some index test procedures for peat
NATIONAL RESEARCH COUNCIL CANADA
DIVISION O F BUILDING RESEARCH
AN EXAMINATION O F SOME INDEX T E S T PROCEDURES FOR P E A T by
ANALYZED
I. C. M a c F a r l a n e and C. M. Allen I n t e r n a l R e p o r t No. 3 1 4 of t h e Division of Building R e s e a r c h OTTAWA J u n e 1965PREFACE
Laboratory engineering t e s t s on peat a r e a relatively recent development. Unlike m i n e r a l soils, which have an accepted quantitative classification system, peat soils have yet t o be c l a s s i f i e d in an acceptable quantitative manner. A few b a s i c index t e s t s , however, have become the common denominator in describing samples of peat tested in the laboratory. These t e s t s a r e water content, organic content, and specific gravity.
Engineers have, in general, applied t o peats t h e s a m e t e s t p r o c e d u r e s and techniques used f o r m i n e r a l soils, despite some doubt that such p r o c e d u r e s and techniques w e r e applicable without some modification. Consequently, a study was undertaken by t h e Division of Building R e s e a r c h t o investigate modifications t o t e s t p r o c e d u r e s for t h e s e t h r e e basic t e s t s , with the aim of developing a m o r e satisfact0r.y procedure for testing peats than h a s been used in the past. This study was c a r r i e d out during the s u m m e r of 1962 by the junior author, a s u m m e r student with the Division, under the direction of the senior author, a r e s e a r c h officer with the Division. The projected t e s t p r o g r a m was a lengthy one and consequently was not completed in the one s u m m e r ; this r e p o r t i s a r e c o r d of the p r o g r e s s that was made in that interval. It i s anticipated that this project will be continued.
Ottawa June 1965
Robert F. Legget Dir ect or
T A B L E O F CONTENTS DESCRIPTION O F P R O J E C T DESCRIPTION O F S A M P L E S WATER CONTENT G e n e r a l L i t e r a t u r e R e v i e w of Methodology T e s t P r o c e d u r e s R e s u l t s and O b s e r v a t i o n s C o n c l u s i o n s ORGANIC CONTENT G e n e r a l Review of Methodology T e s t P r o c e d u r e R e s u l t s and O b s e r v a t i o n s C o n c l u s i o n s
S P E C I F I C GRAVITY O F SOIL SOLIDS G e n e r a l
L i t e r a t u r e R e v i e w of Methodology T e s t P r o c e d u r e s
R e s u l t s C o n c l u s i o n s
G E N E R A L CONCLUSIONS AND RECOMMENDATIONS R E F E R E N C E S Appendix A C a l i b r a t i o n of Ov.en Appendix B D e t e r m i n a t i o n of W a t e r i n P e a t not L i b e r a t e d D u r i n g Oven D r y i n g Appendix C S u g g e s t e d T e n t a t i v e P r o c e d u r e f o r W a t e r Content T e s t s f o r P e a t Appendix D S u g g e s t e d T e n t a t i v e P r o c e d u r e f o r O r g a n i c and A s h Content T e s t s f o r P e a t P a g e 1 1 2 2 4 Appendix E S u g g e s t e d T e n t a t i v e P r o c e d u r e f o r D e t e r m i n i n g t h e S p e c i f i c G r a v i t y of P e a t
AN EXAMINATION O F SOME INDEX TEST PROCEDURES FOR P E A T
by I. C. M a c F a r l a n e and C.M. Allen DESCRIPTION O F P R O J E C T At t h e p r e s e n t t i m e no s a t i s f a c t o r y quantitative method of c l a s s i f y i n g p e a t s i s a v a i l a b l e ; t h o s e qualitative m e t h o d s t h a t a r e a v a i l a b l e a r e not n e c e s s a r i l y u n i v e r s a l l y accepted. C e r t a i n l a b o r a t o r y i n d e x t e s t s t o a s s i s t i n d e s c r i b i n g p e a t s , however, have now b e c o m e f a i r l y common. T h e s e include w a t e r content t e s t s , o r g a n i c ( o r a s h ) content t e s t s , and s p e c i f i c g r a v i t y of s o i l s o l i d s , a s w e l l a s
-
t o a l e s s e r d e g r e e-
acidity, p e r m e a b i l i t y , and void r a t i o . T h i s b a s i c i n f o r m a t i o n p r o v i d e s a background of i n f o r m a t i o n on p e a t and f o r m s a b a s i s f o r c o m p a r i s o n of engineering t e s t s s u c h a s c o m p r e s s i o n c h a r a c t e r i s t i c s , s h e a r s t r e n g t h , etc.In g e n e r a l , t h e engineering p r a c t i c e h a s been t o apply t o p e a t s t h e s t a n d a r d s o i l m e c h a n i c s t e s t i n g p r o c e d u r e s and t e c h n i q u e s u s e d f o r i n o r g a n i c s o i l s . Difficulties s o m e t i m e s a r i s e , however, when t h e s e s t a n d a r d t e s t p r o c e d u r e s a r e applied b e c a u s e of t h e c o m p l e x n a t u r e of p e a t with i t s high w a t e r and o r g a n i c content. Consequently, modifications a r e often m a d e t o t h e s e p r o c e d u r e s and t h e r e s u l t i n g l a c k of u n i f o r m i t y of t e s t m e t l ~ o d s h a s m a d e i t difficult t o c o m p a r e r e s u l t s of t e s t s on v a r i o u s p e a t s .
T h i s u n c e r t a i n t y led t o t h e c a r r y i n g out, by t h e
Division of Building R e s e a r c h , of a n i n v e s t i g a t i o n into t e s t p r o c e d u r e s f o r t h e t h r e e b a s i c index t e s t s ; w a t e r content, o r g a n i c content, and s p e c i f i c g r a v i t y of soil. solids. T h e a i m w a s t o a s c e r t a i n f r o m a study of t h e l i t e r a t u r e and by e x p e r i m e n t a t i o n t h e m o s t s a t i s f a c t o r y p r o c e d u r e s f o r d e t e r m i n i n g t h e s e t h r e e c h a r a c t e r i s t i c s .
DESCRIPTION O F SAMPLES
Two t y p e s of p e a t s a m p l e w e r e u s e d
-
one of a v e r y f i b r o u s n a t u r e , t h e other m o r e decomposed ( o r a m o r p h o u s - g r a n u l a r ) . T h e f o r m e r w a s obtained f r o m t h e M e r Bleue P e a t Bog n e a r Ottawa, in a n a r e a c l a s s i f i e d a s EBI m u s k e g (11) with C a t e g o r y l o p e a t (woodyp a r t i c l e s held i n non-woody, fine f i b r o u s
eat).
T h e decomposed p e a t s a m p l e w a s obtained f r o m a s m a l l muskeg a r e a , which is c r o s s e d b y t h e T r a n s -Canada Highway, n e a r Rockland, Ontario. C l a s s i f i c a t i o n of t h e o r i g i n a l vegetation i s now difficult, but it was p r o b a b l y FI. T h e p e a t i s C a t e g o r y 3: a m o r p h o u s - g r a n u l a r with non-woody fine f i b r e s .In t h e l a b o r a t o r y , t h e p e a t s a m p l e s w e r e thoroughly r e m o u l d e d with a kitchen hand-mixer. T h e r e m o u l d e d s a m p l e s w e r e then s t o r e d in c o v e r e d p l a s t i c p a i l s in a humid r o o m ( r e l a t i v e humidity
90 p e r cent, t e m p e r a t u r e 55" F). By using r e m o u l d e d s a m p l e s , i t was hoped t o e l i m i n a t e t h e v a r i a t i o n s i n h e r e n t i n u n d i s t u r b e d peat s a m p l e s , and t h u s be a b l e t o achieve r e p r o d u c i b i l i t y of r e s u l t s .
WATER CONTENT G e n e r a l
In s o i l m e c h a n i c s terminology, "water cont entl' o r " m o i s t u r e content'' is defined a s "the l o s s in weight e x p r e s s e d a s a p e r c e n t a g e of t h e d r y m a t e r i a l when t h e s o i l is d r i e d t o a constant weight at 105" t o 110°C" ( I ) ,
P e a t h a s a g r e a t c a p a c i t y f o r taking up and holding w a t e r ; i n t h i s r e s p e c t it a c t s somewhat like a sponge. T h i s affinity f o r w a t e r is one of t h e m o s t i m p o r t a n t c h a r a c t e r i s t i c s of t h e m a t e r i a l and i s p a r t l y r e s p o n s i b l e f o r t h e wide v a r i a t i o n i n p h y s i c a l and
m e c h a n i c a l p r o p e r t i e s of peat. T h e quantity of w a t e r h e l d i n peat v a r i e s considerably, being l e s s f o r t h e m o r e decomposed ( a m o r p h o u s - g r a n u l a r ) t y p e s than f o r t h e m o r e f i b r o u s types. In i t s n a t u r a l condition and below t h e w a t e r table, peat u s u a l l y contains sufficient w a t e r t o
s a t u r a t e t h e vegetable m a t t e r . It i s evident, t h e r e f o r e , t h a t t h e w a t e r content of a peat s a m p l e i s a m o s t significant p h y s i c a l c h a r a c t e r i s t i c , and i t is i m p o r t a n t t h a t e v e r y effort should b e m a d e t o obtain a s a c c u r a t e a d e t e r m i n a t i o n a s p o s s i b l e in t h e l a b o r a t o r y . T h i s p r e s u p p o s e s , of c o u r s e , that t h e s a m p l e i s t r u l y r e p r e s e n t a t i v e of field conditions, which i n i t s e l f is e x t r e m e l y difficult t o obtain f o r p e a t s . That is a s e p a r a t e p r o b l e m , however, and is not within t h e s c o p e of t h i s discussion.
T h e drying c h a r a c t e r i s t i c s of peat a r e dependent on t h e c h e m i c a l and p h y s i c a l m a n n e r i n which w a t e r i s h e l d by t h e p e a t substance. T h e r e have been s e v e r a l c l a s s i f i c a t i o n s of peat m o i s t u r e content although none s e e m s t o o f f e r a completely s a t i s f a c t o r y
explanation of t h e behaviour of p e a t drying. The following a r e t h e m a i n c l a s s i f i c a t i o n s (5) :
(1) Ostwald8s classification:
i) Water of occlusion held in l a r g e p o r e s over 1 m m in diameter. ii) Capillary water held within and between c a p i l l a r y walls.
iii) Colloidally bound water held by s e v e r a l colloidal chemical compounds such a s humins, humic acid, pectin, lignin, etc. iv) Osmotically bound water, within undecomposed plant cells.
v) Chemically bound water, a s water of crystallization. (2) Dumansky8s classification:
i) F r e e water in 2 f o r m s
-
that in c a p i l l a r i e s with a diameterof between 0. 1 and 1 0 ' ~ cm and that held in p o r e s and c a p i l l a r i e s with a diam. from 1 0 ' ~ t o l o e 7 c k .
ii) Physically bound water in l a y e r s of oriented water molecules bordering, t h e solid phase, the denser layer lying next t o t h e p a r t i c l e s u r f a c e and the l e s s dense and l e s s well oriented l a y e r s lying outside these. This might be described a s adsorbed water.
iii) Osmotically held water in undecayed plant cells.
iv) Chemically bound water, analagous t o water of crystallization. ( 3 ) Stabnikosf's classification:
Mechanically held water which i s e a s i l y removed by p r e s s u r e .
ii) Colloidally bound water (a) water which i s lost i n a i r of 100 p e r cent humidity.
(b) adsorbed water which i s retained in a i r of 100 p e r cent humidity. In the oven-drying p r o c e s s f o r peat, i t i s not fully understood p r e c i s e l y which types of water a r e f r e e d and which a r e not.
Consequently, t o p e r m i t a complete explanation of the drying c h a r a c t e r i s t i c s of peat, considerable r e s e a r c h i s s t i l l n e c e s s a r y on the manner by which water i s held in peat.
L i t e r a t u r e Review of Methodology
In general, the methud f o r determining t h e water content of peat h a s been the s a m e a s that for determining the water content of m i n e r a l soils. Anderson ( 2 ) determined water content by drying a sample of peat for 2 4 h r in an oven a t 110°C. F e u s t e l and B y e r s
(6)
placed an a i r d r y sample in a 105°C oven for 48 h r , and Hanrahan (8) dried peat samples t o constant weight at 107°C. Smith et a1 ( 1 3) dried peat at 105°C. Colley (3) used an oven t e m p e r a t u r e of 110°C and a drying t i m e of 14 hr. Stanek (1 4) obtained m o i s t u r e content by drying peat f o r 48 h r in an oven at 108" C. R i s i et a1 (1 2) used a drying t i m e of 48 h r f o r l a r g e 200 -gm samples and 24 h r for s m a l l , 10 -gm samples, a t a t e m p e r a t u r e of 105°C in both c a s e s .
On the other hand, Ackroyd (1) suggests that t h e s e t e m p e r a t u r e s may be too high f o r organic s o i l s and recommends a lower t e m p e r a t u r e of about 60" C t o prevent oxidation of the organic m a t t e r . This was the drying t e m p e r a t u r e utilized by Miyakawa for Japanese p e a t s (10). Goodman (7), however, used a drying t e m p e r a t u r e of 85°C.
T e s t P r o c e d u r e s
The oven used for the water content t e s t was a F i s h e r Senior F o r c e d Draft Isotemp model. It was calibrated initially a s
described in Appendix A. The r a n g e of t e m p e r a t u r e s used was 75°C to 1 20°C, increasing i n i n c r e m e n t s of 5 degrees.
In the humid room, peat samples of the p a r t i c u l a r type t o be t e s t e d w e r e placed in twelve s m a l l aluminum t a r e s , 55. 45 cu c m in size, and w e r e weighed. The s a m p l e s w e r e then placed in the oven and dried a t the specified t e m p e r a t u r e . After 4 h r t h e s a m p l e s w e r e removed f r o m the oven, cooled in a desiccator and weighed. They w e r e then replaced in the oven, heated for 2 m o r e h r , removed and reweighed. This cycle was repeated a t 2-hr i n t e r v a l s until a n e a r constant weight was reached. Samples w e r e then weighed at 1 -hr i n t e r v a l s until
constant weight was attained. To s e r v e a s a standard, samples of peat w e r e a l s o a i r dried t o a constant weight in a constant t e m p e r a t u r e room (temp. z 20°C).
Water content (per cent d r y weight) was calculated f r o m the for mula: water content
W = W w x 1 0 0 W
d s where W
=
weight of waterW
R e s u l t s and O b s e r v a t i o n s
A s u m m a r y of t h e r e s u l t s obtained for both t h e f i b r o u s and t h e a m o r p h o u s - g r a n u l a r p e a t s i s given in T a b l e s I and 11. It will be noted t h a t t h e r e s u l t s a r e not c o m p l e t e f o r t h e a m o r p h o u s - g r a n u l a r p e a t ; t h i s w a s due t o t i m e limitations. F i g u r e 1 i n d i c a t e s t h e v a r i a t i o n in w a t e r content with drying t e m p e r a t u r e , and F i g u r e 2 shows t h e
v a r i a t i o n in drying t i m e with t e m p e r a t u r e f o r t h e two p e a t types. T a b l e s I and I1 a l s o show t h e c a l c u l a t e d t o t a l w a t e r content, b a s e d on wet weight, and including t h e w a t e r l i b e r a t e d during drying a s w e l l a s w a t e r not l i b e r a t e d during t h e n o r m a l oven-drying p r o c e s s but which is d e t e r m i n e d f r o m t h e d i f f e r e n c e between t h e two m e t h o d s of o r g a n i c content d e t e r m i n a t i o n and c o n f i r m e d b y t h e
distillation p r o c e s s d e s c r i b e d in Appendix B.
T h e d i f f e r e n c e between t h e w a t e r content ( b a s e d on d r y weight) of t h e f i b r o u s p e a t d r i e d a t 20°C and t h a t d r i e d a t high
t e m p e r a t u r e s c a n b e a t t r i b u t e d both t o t h e i n c r e a s i n g oxidation of t h e o r g a n i c m a t e r i a l a s well a s t o t h e i n c r e a s i n g amount of w a t e r t h a t i s l i b e r a t e d . . T h e d r y weight i s , t h e r e f o r e , a function of t h e
t e m p e r a t u r e of d r y i n g ; consequently t h e v a l u e s of w a t e r content, b a s e d on d r y weight, a r e a l s o a function of t h e drying t e m p e r a t u r e . A
t e n t a t i v e p r o c e d u r e f o r m e a s u r i n g t h e m o i s t u r e content of p e a t a s a p e r c e n t a g e of t h e d r y weight is given in Appendix C.
It w a s o b s e r v e d , u s i n g a magnifying g l a s s , t h a t t h e r e was no evidence of c h a r r i n g of t h e f i b r o u s p e a t s a m p l e s a t t e m p e r a t u r e s l e s s than about 85°C. F o r t e m p e r a t u r e s g r e a t e r than t h i s , however, c h a r r i n g b e c a m e i n c r e a s i n g l y evident and above 9 5 ° C t h i s w a s sufficient t o noticeably affect t h e o r g a n i c content r e s u l t s . It w a s a l s o o b s e r v e d that, f o r a l l drying t e m p e r a t u r e s above 75"C, m o r e t h a n
90
p e r c e n t of t h e u l t i m a t e weight l o s s o c c u r r e d within t h e f i r s t 2 4 h r . T h i s is shown in F i g u r e 3 f o r a f i b r o u s peatmsample d r i e d a t 85°C.Conclusions
(1) It a p p e a r s evident t h a t t h e t e m p e r a t u r e of drying f o r t h e w a t e r content d e t e r m i n a t i o n of p e a t should n e v e r exceed 95" C and t h a t
p r e f e r a b l y t h e t e m p e r a t u r e should not exceed 8 5 ° C . T h e t e s t p r o g r a m t o t h i s s t a g e did not e s t a b l i s h t h e optimum t e m p e r a t u r e of drying, but i t s u g g e s t e d that i t should p e r h a p s b e even a s low a s 6 0 ° C ; however, f u r t h e r t e s t s m u s t b e c a r r i e d out t o c o n f i r m t h i s .
(2) T h e oven-dried weight of p e a t i s ' a function of t h e drying t e m p e r a t u r e and i s t h e r e f o r e not a constant value. Consequently, t o r e p o r t t h e w a t e r content a s a p e r c e n t a g e of t h e d r y weight i n t r o d u c e s s o m e e r r o r , which i n c r e a s e s a s t h e drying t e m p e r a t u r e i n c r e a s e s . It would doubtless b e m o r e a p p r o p r i a t e t o e x p r e s s w a t e r content of p e a t s a s a p e r c e n t a g e of t h e t o t a l wet weight. However, t h i s would p r o b a b l y i n t r o d u c e c o n s i d e r a b l e confusion b e c a u s e of t h e e s t a b l i s h e d s o i l m e c h a n i c s p r a c t i c e of e x p r e s s i n g w a t e r content a s p e r cent of t h e d r y weight.
F o r low t e m p e r a t u r e s of drying, such a s a t 60°C, t h e e r r o r i n t r o d u c e d by t h e s t a n d a r d p r o c e d u r e would be s u f f i c i e n t l y low t o b e ignored. In a n y c a s e , t h e t e m p e r a t u r e of drying should be r e c o r d e d for all t e s t s . ( 3 ) T h e drying t i m e for p e a t s a m p l e s d r i e d at about 6 0 ° C will b e s u b s t a n t i a l l y g r e a t e r than f o r s t a n d a r d t e s t s on i n o r g a n i c s o i l s and t h i s e x t r a t i m e of drying m u s t b e c o n s i d e r e d in any p r o p o s e d t e s t p r o g r a m . ORGANIC CONTENT -- G e n e r a l
T h e "organic content1' of a s o i l is t h e weight of t h e o r g a n i c m a t e r i a l p r e s e n t in a s a m p l e , e x p r e s s e d a s a p e r c e n t a g e of t h e d r y weight. In peat, t h e o r g a n i c m a t e r i a l i s g e n e r a l l y combustible, c a r b o n a c e o u s m a t t e r , while t h e m i n e r a1 constituent
-
whether p a r t of t h e plant's growth o r e x t r a n e o u s m a t t e r-
is incombustible and a s h forming. T h e o r g a n i c content of p e a t h a s a c o n s i d e r a b l e effect on i t s p h y s i c a l and m e c h a n i c a l p r o p e r t i e s . In general, t h e g r e a t e r t h e o r g a n i c content t h e g r e a t e r t h e w a t e r content, void r a t i o , and c o m p r e s s i b i l i t y of t h e peat." P e r cent ash1' is t h a t p r o p o r t i o n of t h e d r y weight of t h e peat which r e m a i n s a f t e r a s a m p l e h a s been ignited.
Review of Methodoloev
Much of t h e a v a i l a b l e l i t e r a t u r e r e f e r s t o t h e d e t e r m i n a t i o n of t h e o r g a n i c m a t t e r content of p r e d o m i n a n t l y i n o r g a n i c s o i l s . Naturally, t h e s e methods a r e not always e n t i r e l y applicable t o p u r e peat s o i l s ,
with t h e p o s s i b l e exception of t h e l o s s -on-ignition method and t h e dichr o m a t e -oxidation method. Most s o i l m e c h a n i c s i n v e s t i g a t o r s who have wished t o d e t e r m i n e t h e o r g a n i c content of peat have u s e d t h e l o s s -on-ignition method. No s p e c i f i c t e m p e r a t u r e of ignition is u n i v e r s a l l y accepted, however, although it r a n g e s between 600" C and 900°C. T h i s p r o c e d u r e a c t u a l l y d e t e r m i n e s t h e a s h content and t h e
o r g a n i c content i s t h e n c o n s i d e r e d t o a b e t h e difference between 100 p e r cent of t h e d r y weight and p e r cent ash.
T h e dichromate-oxidation method is u s e d t o d e t e r m i n e t h e p e r cent o r g a n i c c a r b o n in a s o i l and t h i s i s multiplied by a f a c t o r of 1.724 t o c o n v e r t i t t o p e r cent o r g a n i c m a t t e r . T h i s i s b a s e d on t h e a s s u m p t i o n that s o i l o r g a n i c m a t t e r contains 58 p e r cent o r g a n i c
c a r b o n on t h e a v e r a g e . T h e Schollenber g e r -Allis on v o l u m e t r i c method (9) of d e t e r m i n i n g o r g a n i c c a r b o n i s only one of s e v e r a l a v a i l a b l e
chernical m e t h o d s but w a s s e l e c t e d b e c a u s e of i t s a c c u r a c y with high c a r b o n s o i l s and i t s s i m p l i c i t y both in a p p a r a t u s and i n method. The Walkley-Block method i s m o r e rapid, but is not s u i t a b l e f o r high c a r b o n s o i l s s u c h a s peat. With t h e Schollenber g e r -Allison method t h e amount of equipment and c h e m i c a l s r e q u i r e d is s m a l l and e a s i l y obtainable. T h e method involves only weighing, volume m e a s u r e m e n t , heating and t i t r a t i o n . I t s m a i n disadvantage is t h a t i t t a k e s a b e t t e r p a r t of a day t o do two t e s t s on a p a r t i c u l a r sample.
T h e p e r o x i d e oxidation method i s u n s a t i s f a c t o r y for p e a t s a s i t h a s only a l i m i t e d e f f e c t on r o o t s and f i b r e s . T h e sulphur dioxide method was c o n s i d e r e d t o b e t o o e l a b o r a t e i n equipment and method t o be s u i t a b l e f o r m o s t s o i l m e c h a n i c s l a b o r a t o r i e s . T h e d r y combustion method f o r d e t e r m i n i n g t h e p e r cent c a r b o n is p r o b a b l y t h e m o s t a c c u r a t e method but once again t h e equipment r e q u i r e d is quite elaborate. T h i s is equally t r u e f o r d e t e r m i n i n g p e r cent o r g a n i c m a t t e r by c a l o r i m e t r i c a n a l y s i s and by m e a n s of a photo - e l e c t r i c c a l o r i m e t e r . T e s t P r o c e d u r e
F o r t h e l o s s -on-ignition method, about 5 t o 10 gm of p e a t d r i e d a t 7 5 ° C w e r e p l a c e d i n c r u c i b l e s which w e r e then placed i n t o a muffle furnace. Initially, a t e s t s e r i e s w a s c a r r i e d out i n which t h e t e m p e r a t u r e of t h e muffle f u r n a c e w a s v a r i e d f r o m 500°C t o 900°C. The length of t i m e t o complete combustion was noted. Combustion was c o n s i d e r e d t o b e c o m p l e t e when all t h e b l a c k had d i s a p p e a r e d , leaving only a whitish g r e y ash. A f t e r combustion t h e c r u c i b l e s w e r e r e m o v e d f r o m t h e f u r n a c e , c o v e r e d and allowed t o cool. T h e a s h content is t h e n d e t e r m i n e d on t h e b a s i s of t.lie d r y weight of t h e peat. F u r t h e r t e s t s w e r e then c a r r i e d out on f i b r o u s
p e a t s a m p l e s oven d r i e d a t t e m p e r a t u r e s of 8 0 ° C t o 105"C, and a m o r p h o u s - g r a n u l a r p e a t s a m p l e s d r i e d a t t e m p e r a t u r e s of 100" and 105"C, with t h e m u f f l e f u r n a c e s e t a t 800°C.
In t h e Schollenber g e r -Allis on volurn e t r i c method, about 0. 1 t o 0.2 gm of finely ground peat ( d r i e d at v a r i o u s t e m p e r a t u r e s ) w a s mixed with an e x c c s s of p o t a s s i u m d i c h r o m a t e and h e a t e d with
c o n c e n t r a t e d s u l p h u r i c acid under controlled conditions. The c h r o m i c acid in e x c e s s of that r e q u i r e d t o oxidize organic c a r b o n was t i t r a t e d
a g a i n s t s t a n d a r d f e r r o u s a m m o n i u m sulphate solution, using diphenylamine a s a n indicator. T o t a l o r g a n i c c a r b o n i s g c r ~ e r a l l y c a l c u l a t e d on t h e
a s s u m p t i o n that t h e oxidation was at l e a s t 87 p e r cent complete. F o r high c a r b o n s o i l s , s u c h as peat, howcver, t h e p e r c e n t a g e of oxidation b e c o m e s i n c r e a s i n g l y h i g h e r s o t h a t ail a p p r o p r i a t e c o r r e c t i o n m u s t be m a d e t o t h e g e n e r a l l y a s s u m e d 87 p e r cent value. A c o r r e c t i o n c u r v e i s shown in F i g u r e D-1. T h i s t e s t was c a r r i e d out on t h e f i b r o u s peat s a m p l e s d r i e d a t t e m p e r a t u r e s of 75°C t o 105" C and a m o r p h o u . ~ -granul.ar peat s a m p l e s dried a t 100 and 105°C. T h r e e t e s t s w e r e c a r r i e d out on
e a c h s a m p l e and an a v e r a g e value obtained. R e s u l t s and O b s e r v a t i o n s
( a ) F i b r o u s P e a t
T a b l e I11 shows the organic content t e s t r e s u l t s on f i b r o u s peat s a m p l e s , obtained by t h e S c h o l l e n b e r g e r -Allison and t h e loss-on-ignition methods. It i s o b s e r v e d t h a t t h e r e i s a s u b s t a n t i a l difference between the r e s u l t s of t h e two methods, t h e difference g e n e r a l l y d e c r e a s i n g with i n c r e a s e in drying t e m p e r a t u r e up t o 9 0 ° C a f t e r which i t behaves r a t h e r e r r a t i c a l l y . It was a s s u m e d t h a t a t l e a s t p a r t of t h i s difference was due t o w a t e r i n t h e peat, which had not been driven off during t h e oven drying period. T o c o n f i r m t h i s assumption, a distillation a p p a r a t u s was s e t up, a s d e s c r i b e d in Appendix B, t o d e t e r m i n e t h e p e r cent w a t e r r e m a i n i n g in a n oven-
dried peat sample. T i m e did not p e r m i t a sufficient n u m b e r of t e s t s t o be c a r r i e d out t o conclusively show t h a t t h e difference in t h e r e s u l t s was w a t e r ; however, t h e few t e s t s that w e r e c a r r i e d out showed a r e m a r k a b l e s i m i l a r i t y in t h e amount of w a t e r r e m o v e d f r o m a "dried" p e a t s a m p l e by t h e distillation p r o c e s s , t o t h e difference in o r g a n i c
content r e s u l t s f o r t h e two t e s t methods on t h e s a m e peat s a m p l e . As t h e t e m p e r a t u r e of drying i n c r e a s e s , t h e amount of w a t e r d r i v e n off a l s o i n c r e a s e s , a s does t h e amount of o r g a n i c
m a t e r i a l oxidized. F r o m T a b l e I11 i t c a n be s e e n t h a t t h e p e r cent o r g a n i c m a t t e r by t h e S c h o l l e n b e r g e r -Allison method i n c r e a s e s with t e m p e r a t u r e f o r s a m p l e s d r i e d within t h e r a n g e of 2 0 ° C t o 9 0 ° C .
It would a p p e a r that for s a m p l e s d r i e d a t t e m p e r a t u r e s g r e a t e r than 90" C t h e oxidation of t h e organic m a t t e r begins t o have a g r e a t e r effect than t h e i n c r e a s e in t h e w a t e r l i b e r a t e d which p o s s i b l y a c c o u n t s f o r t h e p e c u l i a r r e s u l t s o b s e r v e d between t h e s a m p l e s d r i e d a t 9 5 ° C t o t h o s e d r i e d a t 105°C.
Amorphous - g r a n u l a r P e a t
T e s t s s i m i l a r t o t h o s e c a r r i e d out on f i b r o u s p e a t s a m p l e s w e r e conducted on only two of t h e a m o r p h o u s - g r a n u l a r peat s a m p l e s due t o t i m e limitations. One s a m p l e had been d r i e d a t 1 0 0 ° C &nd t h e other s a m p l e a t 105"C, Thus, r e s u l t s m a y not be too r e l i a b l e , p a r t i c u l a r l y i n d e t e r m i n i n g t h e w a t e r not l i b e r a t e d during drying, b e c a u s e of
c o n s i d e r a b l e oxidation of t h e o r g a n i c m a t e r i a l a t such high t e m p e r a t u r e s . T h e difference between t h e r e s u l t s of t h e two d i f f e r e n t m e t h o d s is,
f o r t h e m o s t p a r t , w a t e r with s o m e e l e m e n t a r y carbon.
T a b l e IV shows t h a t the difference between t h e two methods f o r t h e p e a t s a m p l e d r i e d a t 105" C i s g r e a t e r than t h e difference between t h e two methods f o r t h e s a m p l e d r i e d a t 100°C. T h i s i n d i c a t e s t h a t c o n s i d e r a b l y m o r e o r g a n i c m a t t e r is burned a t 1 0 5 ° C t h a n a t 100°C.
Conclusions
(1) T h e l o s s -on-ignition method of d e t e r m i n i n g t h e p e r cent o r g a n i c m a t t e r of peat i s a t b e s t only a n approximation which c a n be f r o m 5 t o
15 p e r cent i n e r r o r . It can, however, b e u s e d t o find t h e p e r cent a s h with a r e a s o n a b l e d e g r e e of a c c u r a c y .
( 2 ) T h e S c h o l l e n b e r g e r -Allison v o l u m e t r i c method of d e t e r m i n i n g t h e
p e r cent organic m a t t e r is r e a s o n a b l y a c c u r a t e f o r p e a t soils. The a p p a r a t u s involved is e a s i l y obtained and t h e method i s not too difficult. T h e only disadvantage i s that i t t a k e s f r o m 4 t o 5 h r t o c o m p l e t e t h r e e t e s t s on one s a m p l e .
( 3 ) By p e r f o r m i n g both t h e S c h o l l e n b e r g e r -Allison v o l u m e t r i c method f o r d e t e r m i n i n g t h e p e r cent o r g a n i c m a t t e r and t h e l o s s -on-ignition method f o r d e t e r m i n i n g t h e p e r cent a s h , one c a n d e t e r m i n e t h e w a t e r i n t h e d r i e d p e a t s a m p l e which h a s not been l i b e r a t e d during t h e oven- drying period.
(4) T h e Schollenber g e r -Allison v o l u ~ e t r i c method f o r d e t e r m i n i n g t h e p e r c e n t o r g a n i c m a t t e r m a y not b e v e r y r e l i a b l e f o r p e a t s a m p l e s which h a v e been oven d r i e d at t e m p e r a t u r e s g r e a t e r t h a n 90°C.
(5) With t h e 10s s -on -ignition method f o r d e t e r m i n i n g a s h content, a t e m p e r a t u r e of 700" C t o 8 0 0 ° C should be u s e d and t h e amount of s a m p l e
should be about 5 gm.
S P E C I F I C GRAVITY O F SOIL SOLIDS G e n e r a l
T h e s p e c i f i c g r a v i t y of s o i l s o l i d s is t h e r a t i o of t h e d e n s i t y of t h e s o i l s o l i d s t o t h a t of w a t e r and depends on t h e o r g a n i c and i n o r g a n i c content of t h e s o i l sample. T h e s t a n d a r d p r o c e d u r e f o r m o s t s o i l s i s t h e w a t e r d i s p l a c e m e n t method u s i n g a 500-ml f l a s k o r a 50 - m l d e n s i t y bottle. F o r peat, h o w e v e r , t h e w a t e r d i s p l a c e m e n t method p r e s e n t s difficulties a s s o m e of t h e p a r t i c l e s of d r i e d p e a t w i l l float on t h e w a t e r . A s t r o n g a r g u m e n t a g a i n s t t h e u s e of w a t e r in s p e c i f i c g r a v i t y t e s t s for p e a t is given i n a p a p e r by W i n t e r k o r n (15). He
points out t h a t t h e w a t e r r e p l a c e m e n t method does not give t r u e v a l u e s f o r t h e s p e c i f i c g r a v i t y of s o i l p a r t i c l e s , e s p e c i a l l y i f t h e y a r e of c l a y a n d c o l l o i d a l s i z e . He explains t h a t t h i s i s due t o t h e c o m p r e s s i o n of a d s o r b e d w a t e r f i l m s by t h e a c t i o n of exchangeable c a t i o n s and t h a t by using w a t e r t h e s p e c i f i c g r a v i t i e s a r e found t o b e too high. It is
s u g g e s t e d t h a t i n s t e a d of w a t e r , a good wetting agent which does not f o r m e i t h e r c o m p r e s s e d o r expanded a b s o r p t i o n f i l m s s u c h a s
decahydr onaphthalene (decalin) o r t e t r ahydr onaphthalene ( t e t r a l i n ) should b e used. L i t e r a t u r e Review of Methodology In t h e d e t e r m i n a t i o n of p r o p e r t i e s of s o m e p e a t s in n o r t h e r n Ontario, W. S t a n e k (1 4) u s e d k e r o s e n e for t h e s p e c i f i c g r a v i t y d e t e r m i n a t i o n s . Other i n v e s t i g a t o r s u s e d t h e w a t e r d i s p l a c e m e n t method f o r s p e c i f i c g r a v i t y d e t e r m i n a t i o n s f o r p e a t (6, 7). S t i l l other s , however, s u g g e s t e d finding t h e p r o p o r t i o n of s o i l s o l i d s and woody m a t e r i a l and computing t h e c o m p o s i t e s p e c i f i c g r a v i t y by u s i n g specific g r a v i t y of t h e two components. Cook ( 4 ) s u g g e s t s v a l u e s
of specific g r a v i t y for e a c h component of 2.70 f o r t h e m i n e r a l s o i l and 1. 50 for t h e woody component.
In h i s s t u d i e s of J a p a n e s e p e a t s , Dr. Miyakawa (10) p r o p o s e s t h e following f o r m u l a : w h e r e N =. i g n i t i o n - l o s s - r a t i o
G
=
a v e r a g e s p e c i f i c g r a v i t y of m i n e r a l constituent s of p e a t ( C o n s i d e r e d t o b e 2.6)G
=
a v e r a g e s p e c i f i c g r a v i t y of o r g a n i c c o n s t i t u e n t of p e a t ( C o n s i d e r e d t o be 1.2). T h e l i t e r a t u r e r e v i e w i n d i c a t e d t h a t t h e liquid d i s p l a c e m e n t method would p r o v i d e t h e m o s t s a t i s f a c t o r y s p e c i f i c g r a v i t y r e s u l t f o r p e a t ; i t w a s n e c e s s a r y , t h e r e f o r e , t o d e t e r m i n e what liquid t o u s e f o r t h e wetting agent. T e s t P r o c e d u r e s S p e c i f i c g r a v i t y t e s t s w e r e c a r r i e d out on t h e d r i e d p e a t s a m p l e s r e s u l t i n g f r o m t h e w a t e r content t e s t s . P r i o r t o s p e c i f i c g r a v i t y d e t e r m i n a t i o n s , t h e s e d r i e d s a m p l e s w e r e p u l v e r i z e d with a p e s t l e and m o r t a r . On e a c h of t h e s a m p l e s , d r i e d a t 75"C, 8 0 ° , 85", 9 0 ° , 95", 100°, 105", and l l O 0 C , t h r e e d i f f e r e n t s e r i e s of s p e c i f i c g r a v i t y t e s t s w e r e c a r r i e d out. T h e f i r s t s e r i e s of t e s t s w a s t h e w a t e r d i s p l a c e m e n t method, u s i n g d i s t i l l e d w a t e r . Two t e s t s w e r e r u n with 500-ml f l a s k s in t h e u s u a l m a n n e r . T h e second s e r i e s of t e s t s w a s c a r r i e d out u s i n g d e - a i r e d , f i l t e r e d k e r o s e n e a s a wetting agent. T h r e e of t h e s e t e s t s w e r e c a r r i e d out u s i n g t h e 50-ml d e n s i t y b o t t l e s and t h e p r o c e d u r e followed i s a s t a n d a r d k e r o s e n e s p e c i f i c g r a v i t y t e s t a s outlined i n Ackroyd (1). Instead of u s i n g a constant t e m p e r a t u r e bath of 25"C, however, e x p e r i m e n t s w e r e c o n d u c t e d i n a c o n s t a n tt e m p e r a t u r e r o o m with a t e m p e r a t u r e of 20. 0 ° C
f
0, 5". T h e t h i r d s e r i e s of t e s t s w a s c a r r i e d out u s i n g t e t r a h y d r o n a p h t h a l e n e ( t e t r a l i n ) a s a wetting agent. T h e p r o c e d u r e followed w a s t h e s a m e a s f o rR e s u l t s
T a b l e s V and V I show t h e s p e c i f i c g r a v i t y r e s u l t s using t h e t h r e e wetting agents: w a t e r , t e t r a l i n and k e r o s e n e . It is s e e n t h a t the r e s u l t s f o r k e r o s e n e and t e t r a l i n a r e v e r y close, w h e r e a s t h e r e s u l t s f o r t h e w a t e r a r e c o n s i s t e n t l y higher than f o r t h e o t h e r two. T h e t e m p e r a t u r e at which t h e p e a t h a d been oven d r i e d had no d i s c e r n i b l e effect on t h e s p e c i f i c g r a v i t y r e s u l t , e i t h e r f o r t h e f i b r o u s or a m o r p h o u s - g r a n u l a r Feats.
If k e r o s e n e i s a s s u m e d t o give t h e c o r r e c t value of s p e c i f i c gravity, t h e n t h e a v e r a g e e r r o r using w a t e r a s a wetting agent i s 5.8 p e r cent for f i b r o u s p e a t and 10 p e r cent f o r a m o r p h o u s - g r a n u l a r peat, and t h e a v e r a g e e r r o r using t e t r a l i n is 0. 7 p e r cent f o r f i b r o u s peat. T h e r e i s l i t t l e evident d i f f e r e n c e between t h e u s e
of t e t r a l i n and k e r o s e n e , although t h e l a t t e r h a s one advantage i n t h a t it is t h e m o r e e a s i l y available.
It i s i n t e r e s t i n g t o r o m p a r e t h e r e s u l t s of v a r i o u s methods of d e t e r m i n i n g s p e c i f i c g r a v i t y of one p a r t i c u l a r p e a t
sample. A s a m p l e w a s s e l e c t e d , with an ignition l o s s of 96. 8 p e r cent (ignition-loss r a t i o
=
0. 968), t h e t r u e o r g a n i c content w a s 89. 15 p e r cent (i. e. a s s u m e d ignition-loss r a t i o=
0. 8915). Miyakawa's f o r m u l a was applied f i r s t u s i n g Cook's c o n s t a n t s of 2 . 7 and 1. 5 and t h e n Miyakawa's c o n s t a n t s of 2.6 and 1.2. T h e r e s u l t s w e r e a s follows:Liquid Displacement Method ( w a t e r ) 1. 46 Liquid Displacement Method ( k e r o s e n e ) 1. 40 F o r m u l a : Cook (10s s -on-ignition t e s t ) 1. 5 2 Cook ( c h e m i c a l t e s t ) 1.575 Miyakawa (10s s -on -ignition t e s t ) 1.22 Miyakawa ( c h e m i c a l t e s t ) 1. 27
T h e value of 1. 40 f o r t h e s p e c i f i c g r a v i t y is c o n s i d e r e d t o be c l o s e s t t o t h e t r u e value.
Conclusions
(1) T h e liquid d i s p l a c e m e n t method is t h e m o s t a p p r o p r i a t e method of d e t e r m i n i n g s p e c i f i c g r a v i t y of s o i l s o l i d s f o r p e a t s .
2 ) Water should not be u s e d a s a wetting agent f o r p e a t s . Difficulty is e x p e r i e n c e d in getting t h e p e a t t o m i x with t h e w a t e r d u r i n g t h e t e s t , and t h e r e s u l t s m a y b e in e r r o r on t h e high s i d e by a s m u c h a s 10 p e r c ent.
( 3 ) E i t h e r k e r o s e n e o r t e t r a h y d r o n a p h t h a l e n e ( t e t r a l i n ) is s u i t a b l e for u s e a s a wetting agent in t h e liquid d i s p l a c e m e n t method. One advantage of t e t r a l i n is t h a t i t s s p e c i f i c g r a v i t y v a r i e s l e s s with cha.nge in t e m p e r a t u r e than d o e s k e r o s e n e . On the o t h e r hand, one disadvantage of t e t r a l i n is that i t s s p e c i f i c g r a v i t y i s c l o s e t o t h a t of
w a t e r , and s m a l l p e a t p a r t i c l e s h a v e a t e n d e n c y t o float. T h e a d v a n t a g e s of k e r o s e n e a r e i t s low s p e c i f i c g r a v i t y , c o m p a r e d t o w a t e r , and i t s availability. In g e n e r a l , t h e r e f o r e , i t will b e expedient t o u s e k e r o s e n e . (4) T h e t e m p e r a t u r e of d r y i n g had l i t t l e o r no e f f e c t on t h e s p e c i f i c g r a v i t y r e s u l t s of peat.
GENERAL CONCLUSIONS AND RECOMMENDATIONS
(1) T h e w a t e r content of p e a t b a s e d on d r y weight i s a function of t h e t e m p e r a t u r e of drying s i n c e t h e weigllt loss i n c r e a s e s with i n c r e a s e d t e m p e r a t u r e s . Water content, when e x p r e s s e d a s a p e r c e n t a g e of t h e t o t a l weight, i n t r o d u c e s l e s s p e r c e n t a g e of e r r o r for p e a t s d r i e d a t high t e m p e r a t u r e s . Although t h e r e i s s o m e a r g u m e n t , t h e r e f o r e , f o r e x p r e s s i n g m o i s t u r e content of p e a t a s a p e r c e n t a g e of t h e t o t a l weight (wet w t . ) r a t h e r than of d r y weight, for p e a t s d r i e d a t low t e m p e r a t u r e s t h e e r r o r i n t r o d u c e d by t h e s t a n d a r d p r o c e d u r e is not g r e a t .
(2) T h e h i g h e r t h e d r y i n g t e m p e r a t u r e , t h e g r e a t e r t h e amount of w a t e r d r i v e n off, and t h e g r e a t e r t h e amount of o r g a n i c m a t e r i a l oxidized. F o r t h e f i b r o u s p e a t at t e m p e r a t u r e s above 9 0 ° C o r g a n i c t e s t r e s u l t s b e c o m e e r r a t i c and c h a r r i n g b e c o m e s a p p a r e n t . F o r a c c u r a t e r e s u l t s , t h e r e f o r e , t h e d r y i n g t e m p e r a t u r e should be m u c h lower t h a n f o r i n o r g a n i c s o i l s . T h i s t e s t p r o g r a m did not e s t a b l i s h t h e optimum t e m p e r a t u r e of drying, but i t i s s u g g e s t e d t h a t i t should b e no h i g h e r t h a n 85"C, and p o s s i b l y even a s low a s 6 0 ° C (140°F). T h e t e m p e r a t u r e of drying should b e noted f o r a l l w a t e r content t e s t r e s u l t s .
( 3 ) T h e a s h content of peat i s f a i r l y s i m p l y d e t e r m i n e d by t h e l o a s -on- ignition method. Organic content can be d e t e r m i n e d by t h e d i c h r o m a t e - oxidation method d e s c r i b e d i n Appendix D which, however, i s quite a lengthy p r o c e d u r e (most of a day f o r t h r e e determinations). Differences in o r g a n i c content r e s u l t s obtained by t h e two methods a r e a s c r i b e d t o w a t e r s t i l l r e m a i n i n g in t h e p e a t a f t e r it h a s been oven dried.
(4) T h e liquid d i s p l a c e m e n t method f o r d e t e r m i n i n g t h e s p e c i f i c g r a v i t y of s o i l s o l i d s i s t h e m o s t a p p r o p r i a t e method f o r p e a t s , with t h e u s e of k e r o s e n e recommended. T h e t e m p e r a t u r e of drying had no d i s c e r n i b l e effect on t h e s p e c i f i c g r a v i t y r e s u l t s .
(5) T h e t e s t p r o g r a m should b e continued t o include t e s t s in t h e t e m p e r a t u r e r a n g e of 50" t o 75°C f o r both types of peat. In addition, other peat t y p e s should be t e s t e d t o check t h e g e n e r a l application of t h e drying phenomena.
( 6 ) T h e t e s t p r o g r a m should a l s o be continued t o c o m p l e t e t h e r a n g e of t e s t s for t h e a m o r p h o u s - g r a n u l a r p e a t i n t h e t e m p e r a t u r e r a n g e of 75" t o 110°C.
R E F E R E N C E S
1. Ackroyd, T. N. W. L a b o r a t o r y T e s t i n g in S o i l E n g i n e e r i n g . S o i l M e c h a n i c s L i m i t e d , London, 1957, 233p.
2. A n d e r s o n , K. 0. Muskeg S t u d i e s i n A l b e r t a . Highway R e s e a r c h B o a r d , B u l l e t i n 316, Washington, D, C.
,
M a r c h 1962, p. 23 -31. 3. Colley, B. E. C o n s t r u c t i o n of Highways o v e r P e a t and MuckA r e a s . A m e r i c a n Highways, Vol. 29, No. 1, J a n u a r y 1950, p. 3-6.
4. Cook, P. M. C o n s o l i d a t i o n C h a r a c t e r i s t i c s of O r g a n i c S o i l s . P r o c e e d i n g s , Ninth C a n a d i a n S o i l M e c h a n i c s C o n f e r e n c e , National R e s e a r c h Council, A s s o c i a t e C o m m i t t e e on S o i l and Snow M e c h a n i c s , T e c h n i c a l M e m o r a n d u m 41, Ottawa, 1956, p. 82-87.
5. Dalton, J. A i r D r y i n g of P e a t . P r o c e e d i n g s , I n t e r n a t i o n a l P e a t Symposium. P u b l i s h e d b y B o r d n a Mona, Dublin 1954, S e c t i o n C3.
6. F e u s t e l , I. C. and H. G. B y e r s . T h e P h y s i c a l and C h e m i c a l C h a r a c t e r i s t i c s of C e r t a i n A m e r i c a n P e a t P r o f i l e s . U. S. Dept. of A g r i c u l t u r e , Tech. Bull. 214, N o v e m b e r 1930, 26p. 7. Goodman, L. J. and C , N. Lee. L a b o r a t o r y and F i e l d D a t a on
E n g i n e e r i n g C h a r a c t e r i s t i c s of S o m e P e a t Soils. P r o c e e d i n g s , Eighth M u s k e g R e s e a r c h C o n f e r e n c e , N a t i o n a l R e s e a r c h Council, A s s o c i a t e C o m m i t t e e on S o i l and Snow M e c h a n i c s , T e c h n i c a l M e m o r a n d u m 74, Ottawa, 1962, p. 107-129.
8. H a n r a h a n , E , T. T h e M e c h a n i c a l P r o p e r t i e s of P e a t w i t h S p e c i a l R e f e r e n c e t o Road C o n s t r u c t i o n . Bull. Inst. of C i v i l E n g i n e e r s o f I r e l a n d , Vol. 78, No. 5, A p r i l 1 9 5 2 , p. 179-215.
9. Metson, A. J. Methods of C h e m i c a l A n a l y s i s f o r S o i l S u r v e y S a m p l e s . New Zealaud Dept. of S c i e n t i f i c a n d I n d u s t r i a l R e s e a r c h , S o i l B u r e a u , Bull. 12, 1956. 10. Miyakawa, I. S o i l E n g i n e e r i n g R e s e a r c h on P e a t y Alluvia. R e p o r t s 1 t o 3. C i v i l E n g i n e e r i n g R e s e a r c h I n s t i t u t e , I-lokkaido Development B u r e a u , J a p a n , Bull. 20, J a n u a r y 1959, 88p. ( t r a n s l a t i o n a v a i l a b l e a s NRC T e c h n i c a l T r a n s l a t i o n 100 1, Ottawa, 1962).
11. Radforth, N. W. A Suggested C l a s s i f i c a t i o n of Muskeg f o r t h e Engineer. E n g i n e e r i n g J o u r n a l , Vol. 3 5, No. 1 1, November 1952, p. 1199-1210.
12. R i s i , J. et al. A C h e m i c a l Study of t h e P e a t s of Quebec. Quebec
-
Dept. of Mines, L a b o r a t o r i e s Branch. 10 p a r t s : 5 r e p o r t s : P R 234 (1950), P R 281 (1953) P R 282 (1953).
13. Smith, D. G . et al. C h e m i c a l Composition of t h e P e a t Bogs of t h e M a r i t i m e P r o v i n c e s . Canadian J o u r n a l of Soil Science, Vol. 38, August 1958, p. 120-127.
14. Stanek, W. The P r o p e r t i e s of C e r t a i n P e a t s in N o r t h e r n Ontario. Unpublished T h e s i s , U n i v e r s i t y of Toronto, Dept. of F o r e s t r y , A p r i l 1961.
15. Winterkorn, H. F. D i s c u s s i o n of F a c t o r s Affecting Specific G r a v i t y Values i n t h e P r o p o s e d Method of T e s t for Soils. A. S. T. M. Bulletin No. 126, J a n u a r y 1944.
T A B L E I
FIBROUS
P E A TI Y
=
7'0
w a t e r content, b a s e d on d r y weight.157
=
Yo w a t e r c o n t e n t , b a s e d on t o t a l weight (i. e. w e t weight).W D r y i n g T e m p . T. ( " C ) 20" 75" 8 0 " 8 5 " 9 0 " 95" 100" 105" 1 1 0 " 115" 12OC -
ifT
=
% w a t e r not l i b e r a t e d d u r i n g drying. C a l c u l a t e d f r o m o r g a n i c and a s h c o n t e n t t e s t r e s u l t s ,x
D i f f e r e n c e(70)
f r o m WD a t 2 0 ° C 0 6. 30 11.02 11.40 14. 50 14.75 20.10 22. 30 25.80 28.20 29.20 -i
'
'I:=
5
t o t a l w z t e r content, b a s e d on w e t weight, a n d i n c l u d i n g w a t e r l i b e r a t e d d u r i n g d r y i n g and w a t e r not l i b e r a t e d d u r i n g drying.I T i m e t o Const. Weight ( h r ) 1170 5 6 5 0 45 4 2 3 9 3 7 3 3 2 6 25 2 2 W a t e r Cont. W~
(%
Wet Wt. ) 91.39 91.83 9 2 . 1 5 92.29 92.37 92. 39 9 2 . 7 0 9 2 . 8 2 93.01 9 3 . 1 3 93.19 -- - W a t e r Cont. W~(%
D r y Wt. ) 1057.72 1124. 45 1174, 20 1197.89 1210.67 1213.68 1270. 2 4 1293.10 1330.89 1355.93 1367. 59 D i f f e r e n c e (To) f r o m Ww at 2 0 ° C 0 0. 48 0. 8 3 0.98 1. 07 1 . 0 9 1. 43 1.57 1.77 1.90 1. 97 - W a t e r Not ~ i b ~ ~ ~ ~ ~ d W~(%
D r y Wt. ) 11.91 10. 68 9 . 1 1 8. 17 7. 19 9.00 7. 66 8. 29-
-
-
- C a l c u l a t e d T o t a l W a t e r C o n t e n t ( W T ) = W+
W~ W W~+ m
(%
Wet Wt. ) 92. 42 9 2 . 7 0 92.86 9 2 . 9 2 9 2 . 9 2 93.08 93.26 93. 41-
-
-
T A B L E I1 AMORPHOUS -GRANULAR P E A T
-
D r y i n g T e m p , T. ( " C ) 100" 1 0 5 " 1 1 0 " 115" 1 2 0 " T i m e t o C o n s t . W e i g h t ( H r ) 3 1 26
26
2 4 22 W a t e r C o n t . W d(7%
D r y Wt. ) 665.81 675.44 679.76 682.62 677.57 M o i s t , C o n t . W (70 W% Wt. ) 8 6 . 9 4 87.10 87.18 87.22 8 7 . 1 4 W a t e r N o t L i b e r a t e d W ( % ~ r " v t . ) 7. 0 5 8. 20-
-
-
C a l c u l a t e d T o t a l W a t e r ( W ) T W N = + W W~ +loo(7%
W e t Wt. ) 87.87 8 8 - 1 6-
-
-
T A B L E I11
ORGANIC CONTENT T E S T RESULTS ON FIBROUS P E A T S A M P L E S
T A B L E I V
ORGANIC CONTENT T E S T RESULTS ON AMORPHOUS-GRANULAR P E A T S A M P L E S + D i f f e r e n c e i n T w o Methods,
70
11.91 1 0 . 6 8 9 . 1 1 8. 17 7. 1 9 9 . 0 0 7. 66 8 . 2 9 4 Oven D r y i n g T e m p e r a t u r e , " C # 2 0 7 5 8 0 8 5 90 9 5 1 0 0 1 0 5 O/o O r g a n i c M a t t e r Oven-Dr ying T e m p e r a t u r e , " C 1 0 0 1 0 5 L o s s -on -Ignition Method 9 6 . 9 1 9 6 . 4 4 96.59 9 6 . 5 9 96.59 9 6 . 5 9 9 6 . 8 1 9 6 . 7 5 S c h o l l e n b e r g e r-
A l l i s on Method 85.00 8 5 . 7 6 87. 48 88. 42 8 9 . 4 0 87. 59 8 8 . 1 5 88. 46 D i f f e r e n c e i n Two Methods,70
7 . 0 5 l o . 09%
O r g a n i c M a t t e r L o s s -on -Ignition Method 75.06 73.70 S c h o l l e n b e r g e r-
A l l i s o n Method 68.01 6 3 . 6 1T A B L E V FIBROUS P E A T S T A B L E V I AMORPHOUS -GRANULAR P E A T T e m p . of D r y i n g , " C 7 5 8 0 8 5 9 0 9 5 1 0 0 w A v e r a g e S p e c i f i c G r a v i t y T e m p . of Drying, " C 1 0 0 1 0 5 1 1 0 A v e r a g e : K e r o s e n e (G ) K 1.39 1. 38 1.37 1.35 1.39 1. 40 1. 38 S p e c i f i c G r a v i t y W a t e r ( G W ) 1.45 1. 49 1. 46 1. 48 1. 46 1. 46 1. 47 T e t r a l i n (GT) 1. 38 1. 38 1.37 1. 40 1.43 1. 40 1.39 GW-G K 0. 17 0. 1 8 0. 1 3 0. 1 6 K e r o s e n e (G ) K 1. 59 1. 60 1. 6 1 1. 6 0 GW-G T 0.07 0 . 1 1 0.09 0 . 0 8 0. 07 0. 0 6 0. 0 8 W a t e r (GW) 1.76 1.78 1 . 7 4 1.76 GW-G K 0. 0 6 0.11 0.09 0. 1 3 0. 07 0.06 0. 09 G ~ - G ~ -0.01 0 0 0. 0 5 0. 0 4 0 0 . 0 1
20
40
60
80
100
120
D r y i n g Temperature, "C
-
-
Fibrous, per cent d r y weight
-
-
-
-
-
-
Amorphous-Granular, per cent wet weight
\,,./m-m- a\
-
-
,,10-0-0,
/-04
Amorphous-Granular, per cent d r y weight
-
-
FIGURE
1
VAR
I
AT1 ON OF WATER CONTENT WITH DRY
I
NG
TEMPERATURE
8 4 ' 3 0 9 9 - 1Temperature,
"C
FIGURE 2
0
10
20
30
40
5 0
Time of Drying,
hr
FIGURE
3
LOSS OF WEIGHT W I T H DRY l N G FOR F I BROUS PEAT SAMPLE AT 85
"C
APPENDIX A
CALIBRATION OF OVEN
T h e oven used in t h i s t e s t s e r i e s was a F i s h e r F o r c e d Draft oven, Model No. 2733, with 3 shelves. A t h e r m o m e t e r was i n s e r t e d through a s m a l l hole in t h e top of t h e oven and r e c o r d e d the nominal oven t e m p e r a t u r e . Calibration of t h e oven was n e c e s s a r y t o d e t e r m i n e the a c t u a l t e m p e r a t u r e on each shelf at a given t e m p e r a t u r e r e a d i n g on t h e t h e r m o m e t e r .
F o u r thermocouples w e r e m a d e up f r o m copper and constantan w i r e s . One thermocouple was suspended f r o m t h e ceiling of t h e oven, about one-half in. f r o m t h e t h e r m o m e t e r bulb and at about the s a m e elevation. The other t h r e e t h e r m o c o u p l e s w e r e suspended f r o m t h e bottom of t h e top, middle and bottom shelves, such t h a t they would r e c o r d the t e m p e r a t u r e s half way between each shelf and between t h e bottom shelf and t h e floor of t h e oven. T h e w i r e s w e r e led through the hole in the top of t h e oven and t o a potentiometer and i c e bath.
T h e oven was s e t at approximately 85°C and t h e t e m p e r a t u r e s between t h e shelves calculated f r o m t h e thermocouple readings. T h e oven t e m p e r a t u r e was then r a i s e d in 5°C i n c r e m e n t s t o 125°C; the thermocouple readings w e r e taken in each c a s e .
F i g u r e A-1 i s a graph of t h e t e m p e r a t u r e r e a d i n g s on t h e t h e r m o m e t e r plotted against the t e m p e r a t u r e r e a d i n g s f r o m t h e
thermocouples. F r o m t h i s family of c u r v e s , it i s p o s s i b l e t o find t h e p r e c i s e oven t e m p e r a t u r e on each shelf for a given t h e r m o m e t e r reading, up t o 1 3O0C, when the oven i s empty. With s a m p l e s in t h e oven, a f u r t h e r variation between t e m p e r a t u r e s a s r e c o r d e d by t h e t h e r m o m e t e r and a c t u a l t e m p e r a t u r e s was noted. Consequently, t h e thermocouples w e r e u s e d throughout t h e water content t e s t s e r i e s .
aJ
-
!?
loo
0 E L-
-
-
-
-
-
-
-
-
-
-
o
Above Top Shelf
-
Below Top Shelf
0
Below Middle Shelf
-
a
Below Bottom Shelf
-
80
90
100
110
120
130
Thermometer Reading, " C
FIGURE A-1
APPENDIX B
DETERMINATION O F WATER IN P E A T NOT LIBERATED DURING OVEN DRYING
T h e a p p a r a t u s i s s e t up a s i l l u s t r a t e d in F i g u r e B-1. B e f o r e t h e p e a t s a m p l e i s t e s t e d , a blank d e t e r m i n a t i o n m u s t b e made. Nitrogen g a s i s p e r m i t t e d t o p a s s through t h e s y s t e m in such a m a n n e r t h a t a f a i r l y even s t r e a m of n i t r o g e n bubbles p a s s e s through t h e
s u l p h u r i c acid. The n i t r o g e n i s t h u s "dried" by being p a s s e d through t h e s u l p h u r i c acid and t h e c a l c i u m c h l o r i d e i n t h e drying tube. T h e v a r i a c i s s e t t o about 30 volts. T h e g a s e s p a s s t h r o u g h t h e a b s o r p t i o n bulb which h a s been p r e v i o u s l y weighed. After s e v e r a l h o u r s t h e a b s o r p t i o n bulb i s a g a i n weighed and t h e weight i n c r e a s e i s t h e c o r r e c t i o n f a c t o r .
About 1 gm of t h e p e a t i s p l a c e d i n t h e f l a s k and t h e above p r o c e d u r e i s r e p e a t e d . T h e i n c r e a s e in weight of t h e a b s o r p t i o n tube, l e s s t h e c o r r e c t i o n f a c t o r , i s t h e weight of t h e w a t e r given off. T h e n i t r o g e n a c t s a s a c a r r i e r f o r t h e g a s e s a s w e l l a s p r e v e n t i n g t h e peat s a m p l e s f r o m oxidizing. R e s u l t of t e s t on f i b r o u s n e a t s a m ~ l e d r i e d at 9 0 ° C and ground t o p a s s through a K 100 s i e v e : Blank d e t e r m i n a t i o n : c o r r e c t i o n f a c t o r
=
0.007 Water d e t e r m i n a t i o n : weight of s o i l u s e d=
1. 136 gm weight of w a t e r f r o m g a s i f i c a t i o n = 0. 0 8 4 g m70
w a t e r = 7. 470Ash
-
3. 40Jo ( l o s s -on-ignition)O r g a n i c m a t t e r
=
89. 4% (Schollenber g e r -Allison)Water
=:
7. 4%APPENDIX C
SUGGESTED TENTATIVE PROCEDURE
FOR WATER CONTENT TESTS FOR P E A T Scope
T h i s p r o c e d u r e d e s c r i b e s a method of m e a s u r i n g t h e m o i s t u r e content of peat, a s a percentage of t h e d r y weight.
(i) Drying oven with a thermostatically-controlled t e m p e r a t u r e of 80 t o 85°C.
(ii) T a r e s with tight fitting lids. (iii) Balance, a c c u r a t e t o 0. 01 gm.
(iv) Desiccator. Sample
The s a m p l e should be t r u l y r e p r e s e n t a t i v e of field conditions, and should be s t o r e d i n a humid r o o m until r e a d y for use. P r o c e d u r e
1. P l a c e a sample of t h e peat in a clean d r y t a r e and r e p l a c e t h e lid. 2. Determine t h e weight of t h e peat s a m p l e t o the n e a r e s t 0. 01 gm. 3. Remove the lid and place the t a r e and contents in t h e oven, heated
t o a t e m p e r a t u r e of 80 t o 85°C.
4. D r y t h e peat to constant weight, which will be of.the o r d e r of 45 h r for a sample weighing 125 gm.
5. After drying, r e m o v e t h e t a r e and s a m p l e f r o m t h e oven and p l a c e in a desiccator t o cool t o r o o m t e m p e r a t u r e . Replace lid on t h e t a r e .
Calculations
The moisture content of the peat (per cent dry weight) i s calculated from the formula:
where W
=
weight of water driven offW
APPENDIX D
SUGGESTED TENTATIVE PROCEDURE FOR ORGANIC AND ASH CONTENT TESTS FOR PEAT
A. ORGANIC CONTENT
-
DICHROMATE-OXIDATION METHODThe dichromate-oxidation method of determining the organic content involves treatment of t h e peat sample with chromic acid in hot sulphuric acid, then quantitatively determining, by t i t r ating against a standard £ e r r ous ammonium sulphate solution, t h e excess chromic acid that r e m a i n s after oxidation of the carbon. Total organic carbon i s generally calculated on t h e assumption that the oxidation i s 87 p e r cent complete; f o r carbon values above 10 per cent, a s in peat, the oxidation i n c r e a s e s with an i n c r e a s e in
organic carbon and an appropriate correction must be made. A correction curve i s shown in F i g u r e D-1.
Apparatus and Reagents
(i) Drying oven with thermostatically-contr olled t e m p e r a t u r e of 80" t o 85°C.
(ii) Balance, a c c u r a t e t o 0.001 gm. (iii) Graduated measuring cylinders.
(iv) Five 500-ml. volumetric flasks. (v) 2 b u r e t t e s .
(vi) Thermometer, range 80 t o 200°C. (vii) Glass s t i r r i n g rod.
(viii) 5 p y r e x glass t e s t tubes. (ix) 3 s m a l l beakers.
(x) Rubber -covered pestle and m o r t a r . (xi) Bunsen burner.
(xii) Potassium dichromate (A. R. Grade, finely powdered, dried at 105°C and bottled)
(xiii) 0. 4 N (normal) p o t a s s i u m d i c h r o m a t e solution, m a d e by dissolving 19. 61 6 gm p o t a s s i u m dichr omate s a l t in distilled w a t e r and m a d e up t o 1 litre.
(xiv) 0. 4 N ( n o r m a l ) f e r r o u s ammonium sulphate solution, m a d e by dissolving 15.70 gm of f e r r o u s ammonium sulphate (A. R. Grade) i n 80 m l of distilled w a t e r containing 2 m l concentrated sulphuric acid and diluting t o 100 ml.
(xv) Concentrated sulphuric acid.
(xvi) D i ~ h e n y l a m i n e indicator. 0. 5 gm of diphenylamine dissolved i n 100 m l concentrated sulphuric acid and t h e solution c a r e f u l l y poured into 20 m l cold distilled water.
(xvii) Sodium fluoride.
N. B. Quantity of r e a g e n t s used a p p l i e s only t o p e a t s w h e r e organic carbon i s
> 46
p e r cent.A r e p r e s e n t a t i v e s a m p l e of t h e soil, oven dried, is broken up with a p e s t l e and m o r t a r . By p a s s i n g through a
#
100 sieve, and by quartering, the s a m p l e i s reduced t o about 0.1 gm.P r o c e d u r e
1. Accurately weigh 1.177 gm of p o t a s s i u m d i c h r o m a t e and t r a n s f e r t o a p y r e x t e s t tube.
2. Carefully weigh t o n e a r e s t 0. 001 gm the finely-ground peat s a m p l e i n a s m a l l beaker and t r a n s f e r t o t h e t e s t tube. Add a few drops of w a t e r t o slightly dampen the peat.
3. Add 20 m l concentrated sulphuric acid. T h i s m a y f i r s t b e put in t h e beaker and u s e d t o wash out a n y s t r a y peat p a r t i c l e s into t h e t e s t tube.
4. P l a c e t h e t e s t tube i n a c l a m p and incline t o a 45" angle.
5. Heat the solution over a f l a m e until a t e m p e r a t u r e of 150
" G
is attained in 90 t o 120 sec. S t i r throughout the heating p e r i o d witha t h e r m o m e t e r . Heating too r a p i d l y and over 155°C m u s t b e avoided.
6.
After r e a c h i n g 15O0C, r e m o v e thedflame and allow t h e t h e r m o m e t e r t o cool i n t h e solution f o r 20 t o 30 see. R i n s e t h e t h e r m o m e t e r in t h e t u b e with a few m l of c o n c e n t r a t e d s u l p h u r i c acid.7. Allow t h e t u b e and contents t o cool f o r 5 m i n i n a i r and t h e n plunge t h e t u b e into running t a p w a t e r u n t i l thoroughly cooled.
8. P o u r and thoroughly r i n s e t h e contents of t h e tube into 100 t o 200 m l of distilled w a t e r in a 500-ml v o l u m e t r i c f l a s k .
N. B. When t h e contents of t h e t e s t tube a r e p o u r e d into t h e f l a s k of w a t e r , i f a b l u i s h - g r e y solution i s obtained i n s t e a d of a g r e e n one, t h i s i s a n indication that insufficient d i c h r o m a t e h a s been used. (See R e f e r e n c e 9 f o r a p p r o p r i a t e quantities).
9.
B r i n g t h e t o t a l volume i n t h e f l a s k up t o 300 t o 350 m l and add 0. 5 m lof t h e diphenylamine indicator.
10. Repeat s t e p s 1 t o 9 two additional t i m e s .
11. A c c u r a t e l y weigh 0.3922 gm of p o t a s s i u m d i c h r o m a t e and t r a n s f e r t o a t e s t tube.
12. Add 10 m l c o n c e n t r a t e d s u l p h u r i c a c i d t o t h e t e s t tube.
13. Heat and c o o l t h e t e s t t u b e and contents a s d e s c r i b e d i n s t e p s 4 t o 7 above.
N. B. F o r c o n s i s t e n t r e s u l t s , s t a n d a r d i z a t i o n of t h e heating and cooling p r o c e s s i s a b s o l u t e l y e s sential.
14. P o u r t h e contents of t h e t e s t tube into 100 t o 200 m l d i s t i l l e d w a t e r in a 500-ml v o l u m e t r i c flask.
15. B r i n g t h e t o t a l volume up t o 300 t o 350 m l with d i s t i l l e d w a t e r and add 0. 5 m l diphenylamine indicator.
16. R e p e a t s t e p s 11 t o 15 a s i t i s n e c e s s a r y t o r u n two blank d e t e r m i n a t i o n s in o r d e r t o s t a n d a r d i z e t h e f e r r o u s a m m o n i u m s u l p h a t e solution.
T h e r e a r e now five 500-ml v o l u m e t r i c f l a s k s e a c h containing 300 t o 350 m l of solution. T h e 0. 4 N equivalent of p o t a s s i u m d i c h r o m a t e taken f o r t h e two solutions u s e d f o r t h e blank d e t e r m i n a t i o n s i s 20 ml. T h e 0. 4 N equivalent of p o t a s s i u m d i c h r o m a t e t a k e n for t h e solution containing t h e p e a t s a m p l e is 60 m l b e f o r e oxidation t a k e s place.
