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Durability of Building Materials, 4, 2, pp. 137-149, 1986-12
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Dependence of the durability of mortars on sand/cement ratio and
micro-silica (silica fume) addition
Feldman, R. F.
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Ser
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N21d National Research Conmil national no.
k454
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CouC 0
ncil Canada de recherche8 Canada
BZDG Institute for lnstitut de
. -
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Research in recherche enConstruction construction
Dependence of the Durabilify
of Mortars on Sand/ Cement
'Ratio and Micro-Silica
(Silica Fume) Addition
by R.F. FeldmanReprinted from
Durability of Building Materials Vol. 4, No. 2, December 1986 p. 137-149
(IRC Paper No. 1454)
N R C
-
CtSTlI R C
L I B R A R Y
JUL 24
l987
~ I B L I O T H ~ Q U E IR C
CN--
ICIST Price $3.50 NRCC 27642On a prepare des mortiers contenant 0 et 10 X de silice fine
dans des rapports eau/(ciment
+
silice fine) de 0,60 et 0,70*Les rapports sablelciment etaient de 0, 0,5, 1,0, 1,5, 1,8, 2,0, 2,25 et 3,O. Les resultats montrent qu'il se produit une forte augmentation de la resistance au gel dans le cas des
6chantillons contenant 10 % de silice fine et dont le rapport
(sable)/(ciment
+
silice fine) est>
2,25 dans un rapport e/(c+
sf) de 0,60, la plus grande resistance Btant obtenueavec un rapport sable/(ciment
+
silice fine) de 3,O.L'augmentation de la resistance au gel a 6t6 attribuee 3 la
formation de pores dans la gamme 97 000-875 nm 3 l'interface
Durability o f Building Matenak, 4 (1986) 137-149
Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
DEPENDENCE OF THE DURABILITY OF MORTARS ON SANDICEMENT RATIO AND MICRO-SILICA (SILICA FUME) ADDITION
R.F. FELDMAN
Institute for Research in Construction, National Research Council of Canada, Ottawa, Ontario K I A OR6 (Canada)
(Received June 20,1986; accepted June 24,1986) Keywords
Mortar Mechanisms/ Freezing- thawing Cements causes of failure
Waste- recovered
ABSTRACT
Feldman, R.F., 1986. Dependence of the durability of mortars on sand/cement ratio and microsilica (silica fume) addition. Durability o f Building Materials, 4: 137-149. Cement mortars containing 0% and 10% silica fume were prepared with a water/ (cement + silica fume) ratio of 0.60 and 0.70. Sandlcement ratios of 0, 0.5, 1.0, 1.5, 1.8, 2.0, 2.25 and 3.0 were used. Results indicate a large increase in frost resistance for specimens with 10% silica fume plus (sand)/(cement + silica fume) ratio of >2.25 at w/ ( C + sf) of 0.60, with the greatest resistance for a sand/(cement + silica fume) ratio of 3.0. The improved frost resistance was attributed t o the formation of pores in the 97,000-875 nm range at the sand--cement interface.
INTRODUCTION
The addition of condensed silica fume, a by-product of the ferro-silicon industry, t o cement mortars and pastes alters the microstructure of the hydration product (Feldman and Huang, 1984, 1985; Huang and Feldman, 1985a, b; Traetteberg, 1980). I t has been shown that the microstructural changes that occur in pastes are magnified in mortars, and it was concluded that the sand-cement interface plays a large role in these changes (Huang
and. ~ e l d m a n , 1985a, b).
Work with mortar containing 10% silica fume and a sandlcement ratio of 2.25 has shown that freeze--thaw resistance is greatly improved by adding silica fume (Huang and Feldman, 1985a, b); this improvement was attributed t o a large increase in the volume of pores in the 97,000-875
nm range. Further work has shown that pores in this range increase with the sand/cement ratio, and that a portion of these pores is relatively in- accessible t o mercury (Feldman et al., 1986).
I t has been suggested (Huang and Feldman, 1985a, b) that the 97,000-- 875 nm diameter pores that exist at the sand--cement interface provide protection against freeze-thaw action, in the same manner as does air entrainment, and that a uniform distribution of various amounts of sand can control the spacing of these pores. Consequently, frost resistance greater than that obtained previously for mortars with a sand/cement ratio of 2.25 may be obtainable with higher sand/cement ratios (Feldman, 1986). This work investigates whether further improvements in frost resistance can be obtained by varying the sandlcement ratio both with and without silica-fume addition.
EXPERIMENTAL
Type I portland cement with a C3A content of 11.82% and a silica fume containing 95.2% Si02, 1.56% carbon, 0.27%K20 and 0.10% Na20, whose surface area was 21,000 m2/kg was used. Ottawa silica sand meeting the ASTM C 109 specification was used for mortar with sandlbinder ratios of 0.0, 0.5, 1.0, 1.5, 1.8, 2.0, 2.25 and 3.0. Binder in the mortar contained either 0% or 10% silica fume. Mixes were prepared at w/(c + sf) of 0.60 and 0.70 (w = water, c = cement, sf = silica fume). Two mixes at w/(c + sf) of 0.70 were also prepared, both with a sandlcement ratio of 3.0; one mix contained 0%, and the other 10% silica fume. No water-reducing or air-entraining admixtures were used.
The mixing procedure is described in a previous paper (Feldman, 1986). The cement and silica fume were placed first into the mixing bowl and mixed together with water for 30 seconds at a slow speed before the sand was added. All the sand was then added and mixing continued at slow speed for 30 seconds. The mixer was stopped and then mixing was immediately continued at medium speed for 30 seconds after which the mix was allowed t o stand for 1% minutes. Mixing was then completed by a further one- minute of mixing at medium speed.
Properties determined
The specimens were 1 mm thick dried by vacuum for approximately 1 5 h at room temperature and final heating for 24 h at 100°C. Pore-size distributions was determined for all mixes after 28 days of curing time using Hg porosimetry at a maximum pressure of 414 MPa. The mercury was removed by heating the specimens at 105°C in vacuum for several weeks until their weight returned t o the original value (Feldman, 1984). Mercury was reintruded into all the mixes containing silica fume and into the mix prepared at w/(c
+
sf) of 0.7 with a sand/cement ratio of 3.0,with and without silica fume. Previous work (Huang and Feldman, 1985a, b; Feldman, 1984) has shown how pore structure partly derived from pozzolanic reactions form relatively coarse but discontinuous pore structures. The extent of this can be detected by mercury reintrusion experiments.
Freeze-thaw resistance was determined by measuring the residual ex- - pansion of four specimens from each mix; measurements were made on specimens that had been cured for 1 4 days. The mortars were made in the form of 25.4 X 25.4 X 127 mm prisms, outfitted with steel studs.
- The freeze--thaw cycle consisted of: freezing in air and thawing in water
(-18°C t o +5"C), two cycles in 24 h, according to ASTM standard test method C-666, Procedure B (ASTM, 1979a).
Freeze-thaw resistance also monitored on selected samples by measuring weight loss during exposure t o freeze-thaw cycles.
RESULTS
Pore distribution
Drying procedures may affect pore-size distribution. Also, specimen size is very important. Direct observation by optical microscopy by other workers (Hwang and Young, 1984) on specimens less than 2 mm thick showed that although some microcracks may form on the surface at the beginning of drying, only a small volume is affected and these cracks close up later. Other workers (Marsh and Day, 1985) have compared various techniques of drying, including solvent replacement and oven drying, and shown that major differences occur mainly in the pore radius <35 nm.
The pore-distribution results obtained from mercury intrusion meas- urements are presented in histogram form in Figs 1. and 2. These results have been presented in a different form in a previous paper (Feldman, 1986). The pore volume was divided arbitrarily into four increments of pore diameter: 97,000-875, 875-175, 175-17.5 and 17.5-2.9 nm. Figure
1 contains the results for sandlcement ratios of 0.0, 0.5,'l.O and 1.5 with distributions for 0% silica-fume, 10% silica-fume and reintruded 10% silica- fume mixtures, for each sandlcement ratio. Similar results for sandlcement ratios of 1.8,2.0,2.25 and 3.0 are presented in Fig. 2.
The results in Figs. 1 and 2 show that adding silica fume increases the volume of pores in the 97,000-875 nm range (as well as in the 17.5-2.9 nm range) and that this effect increases with the sandlcement ratio. In addition, the distribution obtained on reintruding the 10% silica-fume mixtures is similar t o the distribution for specimens containing no silica fume except that in the former the volume of pores in the range 97,000-875
I nm is larger. The pore volume in this range of pore diameter increased
again between the first and second intrusions. Figure 3 shows the change in volume, after the first and second mercury intrusions, of pores in the 97,000-875 nm pore-diameter range as a function of sandlcement ratio.
S l l l C A n l M 04 SILICA FUME 10% REINTRUDED SANDICEMENT = 1.5 2 0 r
-
; 10 + 5 = 0:
5 I1 R 3 g s E E d d d d m , , , F 2 3 2 6- -
m ; a d SANDICEMENT = 0.5h
SANDICEMENT = 0hh
0. " % " " "g s E $
0 0 - m d d d d d d d d # # , , m , , , Z X 3 6 3 2 2 6 6 - m ti d d ; t i 6 - - mFig. 1. Histograms of poresize distribution of cement ratio = 0-1.5.
S I L I C A FUME 0 % S I L I C A FUME 10% REINTRUDED 7 0 - SANDICEMENT = 3.0
mortars (vol/vol paste portion).
- - > 5
-
--
ii;
0dL
; 1 0 - - Crl5;dL
5 o 0I:;
W
g $ s E
d d d d SANDICEMENT = 2.25 SANDICEMENT = 2.0DL
SANDICEMENT = 1.8L
R " o h 2 2 0 0 - m d d d m -Fig. 2. Histrograms of poresize distribution of mortars (vol/vol paste portion). Sand/
I I 14 - 91 - 0.875 x 10' "in F I R S T I N T R U S I O N - 12 - -9 9 1 - 0 . 8 1 5 x 10' nm S E C O N D I N T R U S I O N 1 0 4 - S A N D I C E M E N 1 R A T I O
Fig. 3. .Pore volume (vol/vol paste portion) after first and second intrusions in pore range 97,000-875 nm for mortars containing 10% silica fume.
The difference between the two curves is a measure of the accessibility of a portion of the pore structure t o mercury intrusion, while the increase in pore volume with the sand/cement ratio possibly relates t o the inter- action of silica fume at the sand-matrix interface with Ca(OH), (Huang and Feldman, 1985a, b). Both factors are important with regard t o the freeze-thaw resistance of these mixes. In the absence of silica fume, the pore volume in this poresize range attained a value of only 4.0% at a sand/ cement ratio of 3.0 (Fig. 2).
Residual expansion with freeze-thaw exposure
Measurements of the expansion that occurred after the various mixes cured for 1 4 days were subjected t o freezing and thawing cycles are presented in Fig. 4. Specimens made from paste (sand/cement ratio = 0) and mortars having 0.5, 1.0, 1.5, 1.8 and 2.0 sandlcement ratios, with and without silica fume, expanded readily. However, specimens having sand/cement ratios of 0.5 and 1.0 without silica fume were not tested. Generally, adding silica fume to mortars with sandlcement ratio G2.0 reduced the residual expansion only marginally. However, at sand/cement ratios of 2.25 and 3.0 significant reductions were noted. Without the silica fume there was a minor reduction in expansion when the sandlcement ratios increased between values of 1.5 and 2.0 and expansion actually increased at a value of 2.25; at a value of 3.0, residual expansion of 0.02% was exceeded after 210 freeze-thaw cycles. However, with the addition of silica fume, at a sandlcement ratio of 2.25, residual expansion of 0.02% was exceeded after as much as 400 cycles; at a sandtcement ratio of 3.0, an expansion of only 0.009% was measured after 554 cycles.
F R E E Z E - T H A W C Y C L E S
Fig. 4. Residual length change as a function of freeze--thaw cycles for mortars of sand/ cement ratio 0-3.0 containing 0% and 10% silica fume.
TABLE 1
Summary of measurements of residual length change due t o exposure t o freeze-thaw cycles
Cycles producing
Specimen residual % Epansion
expansion Ultimate Ultimate per 100 cycles Sand/ Silica % expansion no. cycles ( x 100)
cement fume 0.1% 0.2% w/(c + s f ) = 0.60 3.0 0% 3.0 10% 2.25 0% 2.25 10% 2.0 0% 2.0 10% 1.8 0% 1.8 10% 1.5 0% 1.5 10% 1.0 0% 1.0 10% 0.5 0% 0.5 10% 0.0 0% 0.0 10% w / ( c + sf) = 0.70 3.0 0% 3.0 10%
in Table 1. The last column gives the average expansion expressed as per cent
residual expansion per 100 freeze-thaw cycles X 100. Values were very high
for specimens both with and without silica fume until the sandlcement ratio
is greater than 2.0 (w/(c
+
sf) = 0.60). The per cent expansion per 100freeze--thaw cycles X 100 for the specimen with a sandlcement ratio of 2.25
.
and containing 10% silica fume was 0.26, and 102.5 without silica fume.The corresponding values for the specimens with a sandlcement ratio of 3.0 were 0.16 and 0.68, respectively.
1 The mixes prepared at w/(c
+
sf) of 0.7 with a sandlcement ratio of3.0 displayed a different behaviour; the per cent expansions per 100 cycles
X 100 were 0.64 and 7.72 for the mixtures containing 0% and 10% silica
fume, respectively; in this case, the expansion for the specimen without silica fume was lower than for the one with silica fume.
These results are shown in histogram form in Figs. 5 and 6. It is clearly
shown in Fig. 5 how very large decreases in expansion due t o freeze-thaw cycles occur with 10% silica-fume addition a t sandlcement ratios of 2.25
and 3.0 and w/(c
+
sf) of 0.60. Increasing the sandlcement ratio from 2.25t o 3.0 also decreases the expansion but not t o so marked an extent.
The number of freeze-thaw cycles needed t o produce 0.1% residual
expansion for the same specimens are shown in Fig. 6. The arrows signify
S I L I C A F U M E C O N T E N T , %
3.0 2.25 2.0 1.8 1.5 1.0 0.5 0 3.0
S A N D I C E M E N T R A T I O
Fig. 5 . Histograms comparing length change due to exposure to freeze-thaw cycles for mortars containing 0% and 10% silica fume.
S I L I C A FUME C O N T E N T . %
3.0 2.25 2.0 1.8 1.5 1.0 0.5 0 3.0 S A N D I C E M E N T R A T I O
Fig. 6 . Histograms comparing number of freeze-thaw cycles producing 0.1% residual expansion for mortars containing 0% and 10% silica fume.
that the specimens had undergone the indicated number of cycles without attaining 0.1% residual expansion. The seemingly anomalous improvement
in the specimens prepared a t w/(c
+
sf) = 0.70 is shown here.Weight loss with freeze-thaw exposure
The results of weight-loss measurements due t o freeze--thaw exposure
are presented in Table 2. The results for mortars made at w/(c + sf) of
0.60 with a sand/cement ratio of 1.8 and 2.0 were similar t o those where the residual length change was measured, in that both indicated rapid, severe deterioration; this was true for mortars with and without silica fume. The mortar with a sand/cement ratio of 3.0 and 10% silica fume showed no weight loss even after 548 freeze-thaw cycles, confirming the result of the residual-length-change measurement; the same mortar without the silica fume displayed large and rapid weight loss on all specimens tested, contrary to the result from the residual-length-change measurement. The relative conditions of these two mortars are shown in Fig. 7.
The mortars prepared at w/(c
+
sf) = 0.70 with a sand/cement ratioof 3.0 also showed a weight loss that differed from residual-length-change measurements. The mortar containing 10% silica fume lost weight at a slower rate than the mortar without silica fume, although both samples deteriorated rapidly.
TABLE 2
Summary of measurements of weight loss due t o exposure t o freeze-thaw cycles
Cycles producing
Specimen weight loss % Weight loss
Ultimate Ultimate per 100 cycles
' Sand/ Silica 0.5% 2.0% % weight loss no. cycles ( x 100)
, cement fume W/(C + s f ) = 0.60 3.0 0% 3.0 10% 2.0 0% 2.0 10% 1.8 0% 1.8 10% w/(c + s f ) = 0.70 3.0 0% 3.0 10%
Fig. 7. Mortar bars of 3.0 sandlcement ratio, w/(c + sf) = 0.60, containing 0% (upper bar) and 10% silica fume (lower bar) after exposure t o freeze-thaw cycles.
The weight-loss results are shown in histogram form in Figs. 8 and 9.
I t is shown clearly in Fig. 8 (indicated by the arrow) that whereas there
is no weight loss for the specimen prepared at w/(c + sf) of 0.6 with 10%
silica fume and sand/cement ratio of 3.0, the other specimens, including
those at w/(c + sf) of 0.7, experience considerable weight loss per 100
freeze-thaw cycles. The number of freeze-thaw cycles producing 0.5%
W l l c + s f ) = 0. 7 0
S I L I C A FUME CONTENT. % 10 0 10 0 10 0 10 0 SANDICEMENT RATIO 3.0 2.0 1.8 3.0
Fig. 8. Histograms comparing weight loss due to exposure to freeze--thaw cycles for mortars containing 0% and 10% silica fume.
S I L I C A FUME CONTENT, % 10 0 10 0 10 0 10 0 SANDICEMENT RATIO 3.0 2.0 1.8 3.0
Fig. 9. Histograms comparing number of freeze-thaw cycles producing 0.5% weight
loss for mortars containing 0% and 10% silica fume.
w/(c + sf) of 0.6 and containing 10% silica fume at a sand/cement ratio
of 3.0 is the most durable, experiencing no weight loss after almost 600 cycles.
DISCUSSION
Several factors must be considered in creating a frost-resistant mortar or concrete; the accepted method for obtaining frost resistance is to entrain
air bubbles (about 6-8% of the volume of the concrete) into the concrete
during mixing, using a suitable admixture (ASTM, 197913). I t is generally agreed that the bubbles be larger than 1 0 pm in size and the distance between them be less than 0.2 mm t o provide frost resistance. The bubbles do not usually become saturated with water, but if they do, the concrete will lose
.
its ability t o resist frost action. Thus, the relative accessibility of the bubblest o water migrating from the outside must be low.
Work by Litvan and Sereda (1978) has shown that these "bubbles"
-
can also be introduced by adding porous particles to the plastic concretemixture. These porous particles can be made from a variety of materials which include commercially fired clay bricks, diatomaceous earth, and vermiculite; by varying the size and porosity of the particle, one can control the volume and spacing of the pores. Litvan (1983) also concluded more recently that pores in the range 2,000 t o 300 nm are most effective in providing resistance t o frost action.
Results of the present work show that pores in the range 97,000-875 nm are formed in a cement paste when sand is added. As the sandlcement ratio increases, the volume of pores in this range increases. Incorporating silica fume into the mix increases the volume of these pores further (Huang and Feldman, 1985a, b; Feldman, 1986), suggesting that they are probably formed at the sand--cement interface, and that their volume and spacing can be controlled.
Only the mixes having sandlcement ratios of 2.25 or 3.0 a t 0.6 w/(c + sf) and containing 10% silica fume have proven t o be frost resistant. This is due not only t o the volume and number of pores in the 97,000-875 nm range, but also t o the spacing of these pores. The greater the sand con- tent, the closer the sand grains are t o each other, and thus the closer the pores are to each other. I t can be shown by simple calculation that at a sand/ cement ratio of 2.25 the sand grains are on average 0.1 mm apart (Huang and Feldman, 1985a, b). The mortar prepared with a sand/cement ratio
of 3.0, w/(c + sf) of 0.6 without silica fume, shows a lower expansion
on freezing and thawing compared with mortars having lower sand con- tents although a high rate of weight loss occurs. This phenomenon may
be due not only t o an increase in pore volume in the 97,000--875 nm
range, but also t o an increase in restraint t o length change due t o the higher fractional volume of sand (Beaudoin and MacInnes, 1975).
Adding silica fume greatly decreases the permeability of mortars and concretes (Huang and Feldman, 1985a, b; Markestad, 1977) (due t o in- creased discontinuity of pores), and a portion of the pores in the 97,000- 875 nm range is relatively inaccessible even to mercury intrusion. This property is probably partly responsible for the improved frost resistance of mixes containing 10% silica fume with sandlcement ratios of 2.25 and
3.0, and w/(c + sf) of 0.60. However, the mortar made at w/(c + sf) of
0.70 with a sand/cement ratio of 3.0 and silica fume, although possessing a large volume of pores in the 97,000--875 nm range, is not durable. This
lack of durability, shown by both length- and weight-change measurements, is probably due t o the fact that the pores are too accessible to water (high permeability of paste a t 0.7 w/(c
+
sf); Powers e t al., 1954), resulting in saturation. On the other hand, previous results have shown that a specimen made with 30% silica fume and a sandlcement ratio of 2.25 at w/(c + sf) of 0.45 is too impermeable, and that excess mixing water trapped in the-
pores results in frost damage.CONCLUSIONS
(1) Frost resistance is increased at w/(c + sf) of 0.6 by the addition of 10% silica fume t o mortar when the sandlcement ratio is 2.25 or greater. Below this sandlcernent ratio, frost resistance is not improved by the addition of silica fume.
(2) Improved frost resistance as a result of an increase in the sandlcement ratio is attributed to pores of the range 97,000-875 nm formed a t sand-matrix interfaces.
(3) Improved frost resistance is attributed t o spacing of sand particles in the paste matrix allowing close spacing of pores at the interfaces of sand particles.
(4) Relative inaccessibility of pores t o water contributes to frost resistance; this can be provided by the impermeable structure formed in the presence of silica fume and w/(c + sf) below 0.7.
The above conclusions are based on work done on mortars and apply only t o those mixes using sand meeting ASTM C 109. Freezing-thawing tests reported here were according t o test method ASTM C 666, Procedure B.
ACKNOWLEDGEMENT
The author thanks G.W. Chan for his work in helping t o perform the experiments, and Dr. G.G. Litvan for many fruitful discussions. This paper is a contribution from the Division of Building Research, National Research Council of Canada.
REFERENCES
I
ASTM, 1979a. Standard test method for resistance of concrete to rapid freezing and thawing (ASTM C666-77). 1979 Annual Book of ASTM Standards, Part 14. American Society for Testing and Materials, Philadelphia, pp. 383-388.
ASTM, 197913. Standard recommended practice for microscopal determination of air-void content and parameters of the air-void system in hardened concrete (ASTM C457-71). 1979 Annual Book of ASTM Standards, Part 14. American Society for Testing and Materials, Philadelphia, pp. ,269-284.
Beaudoin, J.J. and MacInnis, C., 1975. Dimensional changes of hydrated portland cement mortar due to slow cooling and warming. American Concrete Institute SP 47-3, Detroit, MI, pp. 67-77.
Feldman, R.F., 1984. Pore structure damage in blended cements caused by mercury intrusion. J. Amer. Ceram. Soc., 67(1): 30-33.
Feldman, R.F., 1986. The effect of sand--cement ratio and silica fume on the micro- structure of mortars. Cem. Concr. Res., 16(1): 31-39.
Feldman, R.F. and Huang Cheng-yi, 1984. Microstructural properties of blended cement mortars and their relation t o durability. RILEM Seminar on the Durability of Concrete Structures under Normal Outdoor Exposure. Institut fur Baustoffkunde und Material- prufung, Universitat Hannover, Hannover, F.R.G., March.
Feldman, R.F. and Huang Cheng-yi, 1985. Properties of portland cement silica fume pastes: I. Porosity and surface properties. Cem. Concr. Res., 15(5): 765-774.
Huang Cheng-yi and Feldman, R.F., 1985a. Dependence of frost resistance on the pore structure of mortar containing silica fume. Proc. Amer. Concr. Inst., 82: 740-743. Huang Cheng-yi and Feldman, R.F., 198513. Influence of silica fume o n the microstructure
development of cement mortar. Cem. Concr. Res., 15(2): 285-294.
Hwang, C.L. and Young, J.F., 1984. Drying shrinkage of portland cement pastes. I.
Microcracking during drying. Cem. Concr. Res., 14(4): 585-594.
Litvan, J.J., 1983. Air entrainment in the presence of superplasticizers. Proc. Amer. Concr. Inst., 80(4): 326-331.
Litvan, G.G. and Sereda, P.J., 1978. Particulate admixture for enhanced freeze--thaw resistance of concrete. Cem. Concr. Res., 8(1): 53-56.
Markestad, A.M., 1977. An investigation of concrete in regard t o permeability problems and factors influencing the results of permeability tests. Report STF 65A 77027, Norwegian Institute of Technology, NTH, Trondheim, Norway, 278 pp.
Marsh, B.K. and Day, R.L., 1985. Some difficulties in the assessment of pore structure of high performance blended cement pastes. In: Very High Strength Cement-Based Materials. Mat. Res. Soc. Symp., 42: 113-122.
Powers, T.C., Copeland, L.E., Hayes, J.C. and Mann, H.M., 1954. Permeability of port- land cement paste. Proc. Amer. Concr. Inst., 51: 285-298.
Traetteberg, A., 1980. Frost action of blended cement with silica dust. Durability of Building Materials and Components. (ASTM STP 691). American Society for Testing and Materials, Philidelphia, pp. 536-548.
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Ce document e s t d i s t r i b u g sous forme de t i r 8 - 3 - p a r t p a r l l I n s t i t u t de r e c h e r c h e e n c o n s t r u c t i o n . On peut o b t e n i r une l i s t e d e s p u b l i c a t i o n s de 1 ' I n s t i t u t p o r t a n t s u r l e s t e c h n i q u e s ou l e s r e c h e r c h e s e n m a t i e r e d e bbtiment e n B c r i v a n t
