Effect of temperature on brick suction

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Journal of Testing and Evaluation, 10, 3, pp. 81-82, 1982-05

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Effect of temperature on brick suction

Davison, J. I.

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EFFECT OF TEMPERATURE ON BRICK SUCTION

by J.I. Davison

Reprinted from

American Society for Testing and Materials Journacrl of Testing and Evaluation

Vol.

10,

No.

3,

May

19EEa

DBR Paper No. 1054

Division of Building Research

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SOMMAIRE On a e f f e c t u e une b r e v e e t u d e d e l ' e f f e t d e l a t e m p e r a t u r e s u r l ' a b s o r p t i o n d e s b r i q u e s e t notamment s u r l e t a u x i n i t i a l d ' a b s o r p t i o n , f a c t e u r q u i s e r t B d e t e r m i n e r l a q u a n t i t e d ' e a u du m o r t i e r a b s o r b e e p a r l e s b r i q u e s a d j a c e n t e s . C e t t e c o n s i d e r a t i o n e s t i m p o r t a n t e pour l a c o n s t r u c t i o n p a r temps f r o i d s l o r s q u e l a q u a n t i t ' e d ' e a u e x t r a i t e du m o r t i e r permet d e d e t e r m i n e r l ' e s p a c e r e s t a n t pour les f o r c e s d ' e x p a n s i o n q u i a g i s s e n t s i l ' e a u r e s i d u e l l e g S l e B un s t a d e avancd. L'Ctude p o r t e s u r l e s b r i q u e s e x t r u d e e s e n a r g i l e e t e n s c h i s t e , e n a r g i l e s'echee e t compress&, s i l i c o - c a l c a i r e s , e t e n b e t o n c h o i s i e s s p e c i a l e m e n t pour l e u r s d i f f ' e r e n t e s v a l e u r s d u t a u x i n i t i a l d ' a b s o r p t i o n . L e s v a l e u r s o n t 5 t 6 d6terminBes B 20, 10, -1.5, e t -lO°C a v e c d e l ' e a u B 20°C, e t B 20°C a v e c d e l ' e a u 2 10°C. Les r d s u l t a t s i n d i q u e n t une l e g e r e d i m i n u t i o n du t a u x a v e c l e s t e m p e r a t u r e s d d c r o i s s a n t e s pour l e s b r i q u e s B f a i b l e a b s o r p t i o n e t une d i m i n u t i o n p l u s n e t t e pour l e s b r i q u e s B f o r t e a b s o r p t i o n ( b r i q u e s e x t r u d e e s e t b r i q u e s e n a r g i l e s e c h e e e t compress'ee) 3 d e s t e m p e r a t u r e s i n f ' e r i e u r e s B 0°C. On e n c o n c l u t q u e l e s b r i q u e s d e v a i e n t 3 t r e Zi d e s t e m p e r a t u r e s s u p e r i e u r e s 3 O°C pour o b t e n i r une r e d u c t i o n maximale d e l ' h u m i d i t ' e du m o r t i e r pendant l a c o n s t r u c t i o n e n h i v e r .

Authwlzsd Rsprint Imm

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Testlng and EvaliWJon, May 1982 CoW*l%lt

A m d a n Soekty for Testing mnd Mmtdmk 1916 Ram S-, Philadelphia, Pa. 19103

1982

J. I.

Davison

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Effect of Temperature on Brick

Suction

REFERENCE: Davison, J. I., "EffscC of TcmperrtPrc oa Brick Suc- fined as the amount of water absorbed in 1 min by 193.55 cm2 (30

tba," lournal of Testing and Ewluation. JTEVA. Vol. 10. No. 3, May _{in.2) of bedding surface when a dry brick is immersed to a depth of} 1982, pp. 81-82.

3.175 mm ('/a in.) in water. This is considered to be a good indica-

ABSTRACT: A brief study has been carried out on the effect of tem- perature on brick suction or initial rate of absorption (IRA), which is a factor in determining the amount of water extracted from mortar placed between bricks. This is important during cold weather construction when the amount of water extracted determines the pore space avail- able for expansive forces if the remaining water freezes at an early age. The study included extruded clay and shale, dry-press clay, sand- lime, and concRte bricks selected to include a range of control IRA (suction) values. Values were determined at 20, 10,

-

1.5, and - 10°C with water at 20°C and at 20°C with water at 10°C.

Results indicate a small reduction in suction with dropping temperature for low absorption bricks and a substantial drop for high absomtion extruded and dm-~ress clav bricks at temueratures below

tion of the ability of the brick to extract water from mortar when there is contact between the two in a masonry wall. IRA was deter- mined, using procedures contained in Canadian Standards Associ- ation Methods of Sampling and Testing Brick (CSA A82.21, on a sampling of 33 bricks, including shale and clay extruded, clay dry- press, concrete, and sand-lime units, successively at temperature levels of 20, 10,

-

1.5, and -10°C with water at 20°C and at a temperature of 20°C with water at 10°C. Between tests the bricks were redried for 72 h at 1 10°C, then cooled, sealed in polyethylene, and left in the cooling chamber overnight.

O°C. it is concluded that brick: should

be

at temperatuks above 0°C to ensure maximum potential for reducing the moisture content of mortar during winter construction.

Brick Temperature KEYWORDS: bricks, clays, shales, concretes, sand-lime, extruding,

dry pressing, initial rate of absorption, suction, cold weather masonry Suction values for bricks at temperatures of 4-20 and

-

10°C construction with a water temperature of 20°C, are shown graphically in Figs. 1

to 3. Average values (g/193.55 cm2 [g/30 in.2] per minute) are One of the condiions, identified in Scandinavian studies [1.2], given in Table 1. Increased suction at the low temperature is in- that enables plastic masonry mortars to survive early freezing is dicated for the extruded shale and concrete bricks. Their low suc- that "the moisture content should be reduced to 6 percent by the tion values coupled with possible experimental error suggest that suction of the masonry units" before freezing occurs. This is based the increase is not significant. There was a definite reduction in on data by Sneck et al [I] showing the virtual elimination of freez- suction at the low temperature for the other three p u p s , the ing expansions in plastic mortar in which the moisture content has

been reduced to the 6% level. These findings have been substan- tiated by the author [3] under ideal ambient laboratory conditions

in which mortar moisture content levels were reduced under the in- fluence of the suction of dry masonry units (bricks). Problems in reaching the low 6% level have prompted questions regarding the probability of achieving similar reductions under the less than ideal condiions gf winter construction, where bricks may contain some moisture and may be laid up in freezing temperatures. The moisture problem has been addressed by one of the cardinal rules for traditional cold weather masonry construction, the requirement that bricks must be dry. This paper reports the results of a brief study of the effect of temperat- on brick suction.

Suction was determined by initial rate of absorption (IRA), de-

This paper is a contribution from the Division of Building Research. Na- tional Research Council of Canada, and is published with the approval of

the Director of the Division.

'Research officer (retired). National Research Council of Canada, Divi- sion of Building Research, 1411 Oxford St., Halifax B3H 321 Canada. Member of ASTM.

el982 by t h e American Society for Testing a n d Materials

81

1 .

20 10 - 1 a -10 BRICK TEMPERATURE, OC

FIG. l-Extruded clay and shale bricks. g/30 in.2 per min = v193.55

82 JOURNAL OF TESTING AND EVALUATION

TABLE 2-Average suction d u e s (gl193.55 cm2 [ g / N in.2] per minute) for bricks (+20°C) at two water temperatures.

Bricka +20°C

+

10°C Shale, extruded ( 6 ) 1.6 2.1 Clay, extruded ( 12) 11.3 8.6 Clay, dry-pres ( 7 ) 64.0 61.7 C o n m e ( 2 ) 2.0 2.2 Sand-lime (6) 23.0 19.9

"Number of specimens in parentheses.

largest in the high absorption clay dry-press bricks (Fig. 2) where the average loss was more than 50% of the control value. Suction loss in the clay extruded bricks was greatest in samples with the highest control values (Fig. 1). Losses for the sand-lime bricks (Fig. 3) were not as substantial as those for comparable clay bricks. 2 0 10 - 1 I -10

BRICK TEMPERATURE, OC

Water Temperature

FIG. 2-Dry-press cloy bricks. g/30 in. per min = g/J93.55 cm2 per min.

I a 1

20 10 -I J -10

BRICK TEMPERATURE, OC

FIG. 3-Sand-lime and concrete bricks, g/30 in.2 per min = g493.55 cm2 per min.

TABLE 1-Average suction d u e s (g/J93.55 cm2 [g/30 in.2] per minute)

for bricks at temperatures of +20 and - JO°C with a water temperature

o j

mOc.

Shale, extruded (6) 1.6 2.1 Clay, extruded (12) 11.3 8.6 Clay, dry-press (7) 64.0 31.5 Concrete ( 2 ) 2.0 2.2 Sand-lime ( 6 ) 23.0 19.9

"Number of specimens in parentheses.

Average suction values (g/193.55 cm2 [g/30 in.2] per minute) for bricks (+20°C) at two water temperatures are given in Table 2. There was a minor increase in suction values for low absorption

shale and concrete bricks at the low water temperature, with small decreases in clay extruded, dry-press, and sand-lime bricks. Al- though the trend towards lower suction values with dropping water temperature appears to be similar to that for dropping brick temperature, no determinations were made at lower temperatures because it was unlikely that there would be serious reductions when water temperature dropped from

+lo

to O°C and because water below O°C would not, in any case, be used in cold weather masonry construction.

It is possible that IRA values may vary when individual units are successively tested under the same temperature conditions. Al- though the results at each data point were not checked against values for a control unit at 20°C, in water at 20°C, the results are considered significant.

Suction values for clay and sand-lime bricks decline as the tem- perature of the bricks drops. The decline is significant in extruded and dry-press clay bricks with high suction values and is most sub- stantial when brick temperatures drop below O°C. This suggests that bricks should be at temperatures above O°C to ensure max; imum potential for reducing the moisture content in plastic mor- tars during cold weather masonry construction.

[I] Sneck, T., Koski, L., Oinonen. H., Svendsen, S., Waldum, A., DUhr- kop, H., and Helander, E., "Winter Masonry." Publication 1. Build- ing Technology and Community Development, Technical Research Center of Finland, Helsinki, 1972.

[ 2 ] Sneck, T., "Winter Masonry Construction," in Proceedings of the

First Canadian Masonry Symposium. University of Calgary, Calgary,

Alberta, Canada. 1976, pp. 238-246.

[ 3 ] Davison, J . I . , "Volume Change Due to Freezing in Masonry Mortar," presented at Symposium on Masonry: Materials, Roperties and Per- formance, sponsored by American Society for Testing and Materials, Philadelphia, Dec. 1980.

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