Download - - 106 - Sample 2 5 1800 ®2 - MOLE
- 106 -
y/.BIiS (Continu cd)
Sample
Grouping
Step
Oxide
Considered
Intercept
Regression
Coefficient
Standard Error
of Regr’r.sion
Coefficient
Calculaisd t
Values
slag ce:-3hts s t k c t h a n slag cements stronger than
1800 N x 10,;/ai2 - UEIGirr 5: 1800 N x 10V®2 - MOLE £
1 2 5 4
C S A M
1138 1700 2011 162743
Calculated F
Value
Significant Val
ues for 999$ Prob.
Standard Error
of Estimate
-17.3 -16.7
0.7
27.1 26.6 27.0
rv .1 21.4
19.8
13.7 •’-3.4 18.5
1.32 0.73
.0.05
1.98 1.93 1.^6
3. SO 2.92 ',*Ro
3.75 3.75 3.75
14.15 1^.15
269.1 271.6 293.3
Multiple
Correlation
Coefficient
-1?.2 -21.2 -1626
-8 .1 -16.10
-1601
24.0 22.5 21.0 -1588
• & .;:r *> '>n
. .f •- 4*{i‘v
14.5 17.8 1504
19.5 1510 1501
12.2 12.0 12.9 1508
1.19 1.19 1.03
0.41 1.07
1.07
1.97 1.87 1.63 1.05
?.88 2.70 1.74 1.61
3,.75 3.75 3.75 3.75
14.15 14.15 H.15 1***15
269.3 274.7 294.7 304.9
0.47 0.49 0.44 0.46
0.47 0.51 0.45
i due to '11 condition of data
. Step could not be completed due
a regression equation docnot provide sufficient inform .tion to Tot
ulate fi alip composition
The results of the 10.RA merely confirm the findings of the pre
vious .section: no satisfactory linear relationship exists between slag
composition and hydraulic properties.
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�here
F = ionic field strength
Z a valency of the iou
r = ionic radius.
Thus the ionic field strength is a measure of the tendency of the ion
to co-ordinate itself with neighbouring oxygen atoms. Ionic field
(28)strengths for the oxides in question are :
F = 7r2
Si*" - 23.3
Al*5 - 12.0
<4.7
Ca4-2 - 2.04.
Thus it can be seen th t the cationic strength of network formers
iB high, that of network modifiers, low, and intermediate oxides possess
an intermediate ionic field strength. Those ions of an intermediate
nature, can, to a limited extent, replace Si"* ions in the tetrahedral
arrangement of the (SiO,,)-** "building block." «hile modifying oxides can
only be situated between the (SiO,,)-'* tetrshedra. Al’3 ions, for ex
ample, because of their intermediate ior.ic field strength con assume
either a modifying or foming role in th. silicate structure. When re
placing Si*** in the basic silica tetrahedra, Al*5 assumes four-fold co
ordination provided other cations ore present to provide electrical
neutrality, while as « modifier it has six-fold coordination.
A. other oxides are mixed with the main network former, silica,
. certain amount of Juggling occur, with regard to th, spatial ..range-
'/he^eas r*ire has each silicon ion
ment of the anions and cations, . 2
__ the addition of a email eaount of a net-
bonded with four oxyt.en '•* *
« breakage i" t’ne dual bonding of the
work modifier, say CaO, causes a breakage
• two silicon ions,
bridging oxygen ions to two sj.
unbonded oxygensingly bonded or
ron-bridging
doubly bonded
or bridging
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between composition nd liquiduG temperature do not exist over extended
compositional areas except at the corners wher the composition consists
of essentially one oxide, "veil in particular phase fields, varying
slopes ore present preluding straight-line functions from existing.
If the comparatively simple mechanism of liquifaction (hence liq
uidus temperature) fails to exhibit linear functions with composition,
there should bp little reason to hope for widespread correlation be
tween hydraulic activity (a rather complex mechanism depending upon
several external factors such as fineness, temperature, amount of ac
tivation, etc.) and composition. Thus although a few conclusions can
be made concerning the statistical analysis, these confirm the leason-
ing that the hydration of clogs is much too complex a reaction to be
governed by relatively simple relationships.
1+.3 Kelationnhir- 0tv-'?r mhnn Compositional
The previous sections point out that only limited relationships
„ i . t between exposition and stren5th. It was therefor, decided to
assess the strength c*hilitod b, a slaB on soco crit.ri. other then ooc-
position, -nd to deter,!.. if . =enninef.l rolstionship could be derived.
The criteria chosen » the total co.hinod voter of hydration.
Th. non-evaporable water is a »«a=ur« of the deeree of hydration
i„ s cement paste. Thus if two id.nticl c e n t p>stes are allowed to
hydrate for a period of ti.e, the one contain^ the noot nnn-
CVBporoble water would bo the -ore c»plete,y reacted hence the stronger.
1». 3 .1 Sample r.election
, L 51 that silica and lime are generally theIt was shown (Scction «».2) that
. . i n a slag cement in regard to stren ;th.
most important constituents in a slag
for the measurement of the non-evaporable water were
Thus samples chosen fo
. ti n cirht samples of the dried 28-day test based or this consideration. - W
c 12 C-13, C-1J*, and c“15 based on acylinders were chosen. These were
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conntant silica m d alumina l.,vel, C-2 and 0-2*1 based on a const: nt
C/M ratio and alumina level, and B-13 anC D-13 based on constar.t.
r itio r xlicj 1 >vel. I'heae sanples form a rough three-dinensional
cross with sample C-13 as the centre pcint. Such an arrangement of
samples includes compressive strengths between 8:0 and 2270 N x 1 o V m 2 .
If a relationship between the combined water and strength exists,
the stronger slag cements should have a greater amount of combined
water. The non-evaporable water contained in a dried cement paste can
bo attributed to two sources: (1) combined water of hydration and (2)
water fixed in Ca(0H)- durir.g hydration. Particularly in the synthetic
slags tnder investigation where 15 per cent CaCOH)^ was intentionally
added as activator the amount of water contained in unreacted acti
vator must be determined and applied as a correction to the total com
bined water in the sample.
k. 3.2 The mo-gravimetric Analysis
_3
Ground samples of the over»-dried cement weighing 1 x 10 kg were
placeu in a Stanton thcrmo-gravimetric analyzer (TGA) and heeted from
room temperature (nominally to at a rate of per ain-
ute under rtmcspheric conditions. A typical first derivative curve
( A W / A T ) resulting from this test is shown as Figure 20. The peak
that occurs at about 35 minutes (approximately is attributed to
the loss of combined water of hydration. The peak oceurlng subsequently
at 70 - 100 minutes (^50 - was taken as the loss of weight from
the dissociation of height loss from the dissociation of CaCOj
(if any) was included in the weight loss of calcium hydroxide.
• u nf each sample, the weight loss attributed
The total weight loss ol eacn oaayj. ,
. r„(Cv) and, by difference, the weight of com-
to the dissociation of CalO.Ug ana’ J
bined water . « shown in Table XI. The th.or.tic.1 ~ou»« of Ca<0H>2
i„ each ample wan ecpotcd and «1~ **“• « •
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k lU & f i .1
^•3«5 X-ray Diffraction Analysis
In addition to the TUA work, the sanples were subjected to X-ray
’iffraction analysis using the Fhilipa goniometer scanner. It waa hoped
th -t the presence of unrenctod calcium hydroxide or hydraticn products
could be detected. Only the filler sand (pure SiO^) could be identified,
and all peaks recorded were associated with the Si02-
h.J.k Discussion of Results of Non-ev.- porable Vfater Tests
Only 25 per cent of the original solid mort'-ir constituents wero
reactive, the remainder being inert filler sand. In oi'der to determine
the percentage combined water of each sample, the sample weight loss
must be applied to only the reactive portion. Thus a combined water
loss of 20 x 10”' kg for the entire sample yields eight per cent com
bined water for the ~.re slag. These computed values of per cent com
bined water are shown in Table XI.
During the hydration process CatOH)^ is liberated by the reaction,
the amount of which cannot be determined. Nor can the amount of CaCOH^
re-reacted be determined ence the computed amount of CaiOHjg remaining
in the sample after hydration includes the amount provided by the hy
dration reaction as well as that added as an activator.
The total weight losses of the simples were so n u l l than
five per cent) that the accuracy of the TGA work is questionable. There
appears to he no definite relationship between th. combined water or the
amount of unrencted hydrovid, and strength. Even though the
two strongest slags contained the highest per cent of combined water,
the weakest sln8 contained a greater amount th* other, stronger slags.
than that exhibited between strength
This trend is no more significant
and composition.
Increased production of iron, steel, and ferro-alloys hats produced
large quantifies of blag from tr.ese operations. Tlvs composition of
these slags f-lls generally into the quaternary system
CaO which, depending upon other considerations, may ratskc them suitable
for the cement industry. Formerly the composition of slag to be uaed
for cement was rigidly controlled so th it the effects of line and nag-
nesia unsoundness (the cause of which v/as net clear) would not be ex
perienced. Kecent work h:\s shown the causes of unsoundness and methods
to eliminate it have been proposed has expanded
the composition range of slags suitable for use as cement.
In nddition to composition, other characteristics may affect a
sing's behaviour as a cement. These include the crystallizing poten
tial, presence of foreign material not belonging to the quaternary cys-
tem, fineness, amount of activaMon, and other factors. Although sr je
investigations h*ve been made into high-alumin* and high-magnesia slags
fo use as cement, the entire range of slags available for use as ce
ment has not been investigated. this in nind, 101 slag compositions
were selected for the purpose of investigating their hydraulic proper
ties. The compositions of these slags are shown in Table II.
Of interest was the quenching behaviour of the slag samples. If
they could not be successfully quenched to form a glass, their
cation .. . cement would be hindered. Th. Uquidu. temperature of oil
th. samples was determined s, that .11 could be quench.d from the same
temperature above the liquidus temperature. The dc„ree of order that
exists in . liquid dependent upon th ■ temperature of th.
above itr li,uidus temperature. Th, liquidus temperature. as determined
are given in Table IV.
Author Coale R D Name of thesis Cementitious properties of Metallurgical slags 1971
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