Hydrated high alumina cement

A hydraulic cement composition is disclosed which utilizes as part of an expansive component novel coated particles of high alumina cement. The particles have a core of substantially unhydrated high alumina cement and an outer layer of hydration products of the core, which outer layer delays the reaction of the particles with other materials in the composition. By varying the nature and relative amounts of the coated particles the amount the cement composition may expand and the setting time of the cement may be varied. The coated particles may be formed by partial hydration, drying and grinding of a mixture of high alumina cement powder alone with water.

SCOPE OF THE INVENTION 
This invention relates to hydraulic cement compositions containing an 
expanding component, more particularly a hydrated high alumina cement. 
BACKGROUND OF THE INVENTION 
Conventional concrete typically comprises Portland cement mixed with 
aggregate such as crushed stone, gravel and sand, and water. Such 
conventional concrete shrinks by as much as 0.05% to 0.1% by volume during 
the curing process. This shrinkage may be a disadvantage in certain 
applications. 
It is known that the disadvantages of shrinkage may be at least partially 
overcome by mixing an expanding component with Portland cement to form an 
expansive cement. The expansive cement when mixed with aggregate and water 
forms an expansive concrete. The expanding component may either compensate 
for shrinkage of the concrete, or cause the concrete to expand during the 
curing process. 
Portland cement is a type of hydraulic cement in the form of finely 
divided, gray powder composed of lime, alumina, silica, and iron oxide as 
in tetracalcium aluminoferrate (4CaO.Al.sub.2 O.sub.3.Fe.sub.2 O.sub.3), 
tricalcium aluminate (3CaO.Al.sub.2 O.sub.3), tricalcium silicate 
(3CaO.SiO.sub.2), and dicalcium silicate (2CaO.SiO.sub.2). These are 
abbreviated, respectively, as C.sub.4 AF, C.sub.3 A, C.sub.3 S, and 
C.sub.2 S. Small amounts of magnesia, sodium, potassium, and sulfur may 
also be present. Hardening typically does not require air and will occur 
under water. 
Portland cement is typically described as being made up of the following 
constituents: 
______________________________________ 
CaO 60-64 wt. % 
SiO.sub.2 18-26 wt. % 
Al.sub.2 O.sub.3 
4-12 wt. % 
Fe.sub.2 O.sub.3 
2-4 wt. % 
MgO 1-4 wt. % 
Other 2 wt. % 
______________________________________ 
Portland cement is analyzed as if it were a mixture of the above oxides. 
However, it is not a simple mixture of these oxides but, rather, a complex 
mixture of aluminosilicates and oxides, some of which are described above. 
As used in this disclosure a reference to a percent by weight alumina does 
not indicate the presence of pure unbonded Al.sub.2 O.sub.3 but rather the 
presence of Al.sub.2 O.sub.3 in this weight percent in the compounds and 
complexes of hydraulic cement. 
The expanding component is typically a mixture comprising high alumina 
cement (hereinafter sometimes referred to as HAC), gypsum and lime as its 
major components, for example in a weight ratio of HAC:gypsum:lime of 
about 22:10:3. HAC, also known as aluminous cement, is well known and 
typically comprises about 30% to 45% alumina by weight, and typically 
contains not more than about 60 to 62 wt. % calcium oxide. It is generally 
known that the formation of ettringite (3CaO.Al.sub.2 
O.sub.3.3CaSO.sub.4.32H.sub.2 O) during the curing process is a source of 
expansive force in expansive cements. 
Some commercially available expansive cements may be identified as for 
example Type K, Type M, and Type S, are based upon portland cements with 
added sulfoaluminate constituents which provide for the formation of 
ettringite. Type K cement contains portland cement, calcium sulfate and 
calcium sulfoaluminate; Type M-portland cement, calcium sulfate and 
calcium aluminate cement; and Type S-a high tricalcium aluminate portland 
cement and calcium sulfate. 
While the mixing of an expanding component and Portland cement to form an 
expansive cement assists in overcoming the disadvantage of volume 
shrinkage, other difficulties arise by reason of the use of expansive 
cements. One serious disadvantage is that concrete made with highly 
expansive cement (hereinafter expansive concrete) tends to set extremely 
quickly, typically having an initial set time of about 10 minutes after 
mixing with water and a final set time of about 20 minutes after mixing 
with water. This rapid setting is at least partially caused by the rapid 
formation of ettringite crystals and other combined hydration products of 
various ingredients. 
Rapid setting is desirable in some applications, such as highway and bridge 
repair, where it is necessary that concrete sets in a short period of time 
into a hard mass with sufficient strength to withstand applied stresses 
and loads. 
However, the extremely rapid setting of expansive concrete containing an 
expansive cement is not always desirable. Under normal circumstances, 
conventional concrete formed for example with Portland cement and not 
containing an expansive component (hereinafter normal concrete) has an 
initial set time of 1 to 2 hours after mixing with water (the start of 
hydration) and a final set time of 6 to 8 hours after mixing with water. 
Such normal concrete may be prepared at a central mixing plant and 
transported some distance to a construction site where, for example, the 
concrete must remain workable until it is placed in a form or cavity. 
It is known to include in both normal and expansive concretes admixtures 
such as retardants and superplasticizers. For example, it is known that 
the set time, both of normal Portland cements and expansive cements, can 
be somewhat extended by the addition of retardants such as sodium citrate 
and carboxymethylcellulose. However, for many applications these 
retardants may not achieve sufficient extension of the set time. As well, 
some of these retardants tend to suppress expansion, even when larger 
amounts of expansive cement are used. Superplasticizers such as that 
available under the trade mark LOMAR D are useful for improving the 
flowability of the concrete at lower water to cement content ratios. 
SUMMARY OF THE INVENTION 
To at least partially overcome these disadvantages of previously known 
devices, the present invention provides an expanding component for an 
expansive cement comprising alumina-bearing particles having an outer 
coating which delays reaction of alumina-bearing materials in the core of 
the particles with other materials. 
An object of the present invention is to provide an alumina-bearing 
material for use in an expanding component of an expansive cement which 
substantially lengthens the set time of the expansive cement. 
Another object is to provide an alumina-bearing material for use in an 
expanding component of an expansive cement which at least partially delays 
the interaction of the alumina-bearing material with other components in 
the expansive cement on hydration of the expansive cement. 
Another object of the present invention is to provide an expansive cement 
in which the set time and degree of expansion can be varied and 
controlled. 
Another object of the present invention is to provide an expansive cement 
in which retardants are not necessarily required to increase the set time. 
Another object of the present invention is to provide an expansive cement 
which may be expansive or shrinkage compensating and which has a set time 
similar to that of ordinary Portland cement. 
The inventor has surprisingly found that alumina-bearing particles having 
an outer coating can be used in the expanding component of expansive 
cements. The use of these particles preferably results in expansive 
cements which have set times approaching those of ordinary Portland 
cement, while retaining a degree of expansion similar to the original 
expansive cement. Furthermore, no retardants are necessarily required to 
extend the set time of expansive cement using preferred forms of this 
material. Therefore, the expansion of the expansive cement need not be 
hindered by retardants. 
The alumina-bearing particles have an inner core which serves as a source 
of substantially unhydrated aluminates of hydraulic cement. An outer 
coating is provided about the inner core which delays reaction between the 
aluminates in the core and other materials in a cement composition. 
Preferably the coating is water penetration resistant as it is believed 
that such a coating on the alumina-bearing material will slow the 
water-aided dispersion of aluminates in the expansive cement paste, which 
is formed by the mixture of water with the expansive cement. Therefore, 
less aluminates are available for the formation of ettringite, thus 
slowing the formation of ettringite. Since the rapid setting of expansive 
cement paste is believed to be at least partially due to rapid formation 
of ettringite and other hydration products, slowing their formation also 
lengthens the set time. 
The inventors have also found that by varying the particle size of the 
alumina-bearing particles, by varying the amount of alumina-bearing 
particles in the expanding component, and by varying the amount of 
expanding component in the expansive cement, both the set time and the 
degree of expansion of the expansive cement paste and expansive concretes 
formed therefrom can be effectively varied and controlled. 
As the inner core is to serve as a source of aluminates it preferably 
comprises substantially unhydrated aluminates of hydraulic cements such as 
tricalcium aluminate and tetracalcium aluminoferrate. Preferably these 
aluminates of hydraulic cement when measured as alumina represent a 
greater weight percent than found in Portland cement preferably greater 
than about 15%, more preferably greater than about 20% or greater than 
about 30% by weight of the material forming the inner core. 
This inner core preferably contains not only such aluminates but also the 
conventional calcium components of hydraulic cement such as tricalcium 
silicate and dicalcium silicate. Preferably the inner core may comprise 
normal high alumina cement, HAC, powder which of course is understood to 
be unhydrated and containing aluminates in an amount representing of at 
least about 30% alumina by weight, as well as other normal calcium 
components of hydraulic cement. 
The outer coating preferably comprises hydration products of the components 
found in hydraulic cements. Preferably, for simplicity of manufacture the 
outer coating may comprise hydration products of the substantially 
unhydrated materials forming the core. Thus in particularly preferred 
particles the core may comprise unhydrated high alumina cement and the 
outer coating may comprise the hydration products of high alumina cement, 
that is a layer of at least partially hydrated high alumina cement 
thereabout. Such preferred particles are hereinafter referred to as 
hydrated high alumina cement or H-HAC. 
A method of forming the partially hydrated alumina-bearing particles 
involves the steps of forming a mixture of water and a finely divided 
powder containing unhydrated aluminates of hydraulic cement, allowing the 
mixture to at least partially set, then particularizing the resultant 
product as by breaking into particles, drying and grinding it into a 
resultant powder. The finely divided input powder of unhydrated aluminate 
preferably is a fine powder of particles having a size and size 
distribution similar to that of conventional hydraulic cements. For 
example, preferably no particles in the input powder are greater than 
about 75 .mu.m, more preferably about 50 .mu.m. Preferably no more than 
about 10 to 15% by weight of the input particles have a size less than 
about 5 .mu.m. The average input particle size by weight is preferably in 
the range of about 10 to 50 .mu.m, more preferably about 20 to 40 .mu.m. 
When the finely divided powder of aluminates is allowed to set, preferably 
without calcium sulfate components or calcium oxide or calcium hydroxide 
present, it is believed that hydration products are first formed as an 
outer layer about the fine powder particles. At about the time of final 
set, the mixture then broken into particles, subsequent drying slows 
further hydration and assists in localizing hydration in an outer layer 
while leaving the inner core substantially unhydrated. Drying may be 
carried out positively as by leaving the particles in an open tray exposed 
to ambiant air for a period of time preferably about 24 hours or by 
heating for a shorter period of time. Drying may also occur merely in the 
course of exposure to air as in processes of crushing followed by grinding 
and/or size classification and separation. 
In the setting process it is believed that the input, fine powder particles 
each comprising a core with a coating thereabout may come to clump 
together into larger clumps and clusters and/or to merge with other 
particles having coatings about one or more cores of substantially 
unhydrated material. The product is therefore mechanically broken by 
crushing and/or grinding to reduce the product to smaller clusters and 
clumps preferably with the maximum size of the resultant powder particles 
about 300 .mu.m, more preferably 150 .mu.m, and preferably with particles 
greater than about 75 .mu.m. 
Preferred H-HAC particles may be prepared by forming a mixture of HAC and 
water and allowing the mixture to at least partially set. This step of 
mixing the HAC with water and letting it set is referred to as 
"prehydration". It is preferred that the mixture be allowed to set for a 
time at least equal to the final set time. The length of time the mixture 
is allowed to set is the "prehydration age". After prehydration the 
mixture is as necessary mechanically broken into particles, dried, ground 
and if desired size classified. 
An expanding component of the present invention is formed by mixing the 
alumina-bearing particles of the present invention with a form of calcium 
sulfate. The calcium sulfate may be anhydrous (CaSO.sub.4), the 
hemihydrate (plaster of Paris, a.k.a "quick set" or "moulding" plaster, 
i.e. CaSO.sub.4.1/2H.sub.2 O) or the dihydrate (gypsum, i.e. Ca.sub.2 
SO.sub.4.2H.sub.2 O). The expanding component also preferably contains 
lime, the major component of which may either be calcium oxide or calcium 
hydroxide. Lime is only optionally added since Portland cement, with which 
the expanding component is mixed, may contain sufficient lime to allow the 
formation of ettringite. 
The ratio of alumina-bearing particles to calcium sulfate in the expanding 
component is preferably from about 0.5:1 to about 4:1 by weight. When lime 
is added, the ratio of alumina-bearing particles to lime is preferably 
from about 4:1 to about 15:1 by weight, more preferably about 8:1. 
An expansive component containing the alumina-bearing particles of the 
present invention may be combined with Portland cement to form an 
expansive cement. Such an expansive cement may either be one which expands 
during the curing process or one which does not expand but compensates for 
shrinkage of the cement during the curing process. 
The preferred weight ratio of Portland cement to expanding component in the 
expansive cement of the present invention is preferably in the range of 
from about 1:1 to about 4:1. More preferably, the ratio of Portland cement 
to expanding component is from about 1.5:1 to about 2:1. 
The expansive cement of the present invention may include a 
super-plasticizer, which improves the workability of concrete considerably 
without seriously affecting the expansion properties adversely. Preferred 
super-plasticizers are condensed naphthalene sulfonates. One such 
super-plasticizer is sold under the trade mark LOMAR-D, which is a 
naphthalene sulfonate condensate powdered superplasticizer. The weight 
ratio of the expanding component to superplasticizer in the expansive 
cement of the present invention is preferably about 10:1 to about 50:1, 
and more preferably 30:1 to 35:1. 
In one aspect, the present invention provides a cement component comprising 
particles, each of said particles comprising: (a) an inner core comprising 
substantially unhydrated aluminates of hydraulic cement with the inner 
core comprising at at least about 30% alumina by weight; and (b) an outer 
coating which resists penetration of water into the inner core. 
In another aspect, the present invention provides a partially hydrated high 
alumina cement powder comprising coated particles, each of said particles 
comprising: (a) an inner core comprising substantially unhydrated 
aluminates of hydraulic cement; and (b) an outer coating comprising 
hydration products of the inner core. 
In yet another aspect, the present invention provides a cement composition, 
comprising: (a) a Portland cement component; and (b) an expanding 
component, comprising: (i) a partially hydrated alumina cement powder 
comprising coated particles, said particles comprising an inner core 
comprising substantially unhydrated aluminates of hydraulic cement and an 
outer coating which delays reaction between the aluminates of the core of 
the particles and other materials in the cement composition; and (ii) a 
calcium sulfate substance selected from anhydrous calcium sulfate, 
hemihydrate calcium sulfate and dihydrate calcium sulfate. 
In yet another aspect, the present invention provides a method for 
preparing a partially hydrated high alumina cement powder, comprising the 
steps of: (a) forming a mixture of water and a finely divided powder of 
substantially unhydrated aluminates of hydraulic cement; (b) allowing the 
mixture of finely divided powder and water to set; (c) mechanically 
breaking the product of step (b) into particles; and (d) at least 
partially drying the particles. 
In yet another aspect, the present invention provides a cement composition 
formed by mixing: (a) a Portland cement component; and (b) an expanding 
component, comprising: (i) a partially hydrated high alumina cement powder 
consisting of coated particles, said particles consisting of an inner core 
consisting of unhydrated high alumina cement and an outer coating 
consisting of hydration products of high alumina cement, said coating 
delaying reaction between the high alumina cement of the core of the 
particles and other materials in the cement composition; and (ii) a 
calcium sulfate substance selected from anhydrous calcium sulfate, 
hemihydrate calcium sulfate and dihydrate calcium sulfate; said partially 
hydrated high alumina cement powder being formed independently and prior 
to mixing with the remainder of the composition. 
In yet another aspect, the present invention provides a cement composition 
formed by mixing: (a) a Portland cement component; (b) a partially 
hydrated high alumina cement powder; (c) a calcium sulfate substance 
selected from anhydrous, hemihydrate and dihydrate calcium sulphate, and 
(d) a calcium oxide substance selected from calcium oxide and calcium 
hydroxide; wherein said partially hydrated high alumina cement powder is 
formed independently and prior to mixing with the remainder of the 
composition by a process of: (i) forming a mixture consisting of water and 
unhydrated high alumina cement, the ratio of high alumina cement to water 
being from about 1:1 to about 4:1; (ii) allowing the mixture of high 
alumina cement and water to set; and (iii) mechanically reducing the 
product of step (ii) into a resultant powder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preparation of H-HAC 
Preferred forms of the alumina-bearing particles of the present invention 
and the "prehydration" process for their preparation are now described. 
In a preferred embodiment of the present invention, HAC powder is partially 
hydrated, mixed with water to form H-HAC and then, as necessary, 
mechanically broken into particles. 
For example, HAC, such as that sold under the trade mark CIMENT FONDU by 
Canada Cement Lafarge Limited, is mixed with water using a water/cement 
weight ratio equal to 0.5. The HAC is prehydrated for a period of from 30 
minutes before final set to about 7 days, during which time it attains a 
hardness ranging from that similar to wet sand to that of a hardened mass. 
The HAC is preferably prehydrated for a period at least equal to the final 
set time. Beyond 24 hours, the length of prehydration age does not seem to 
have any substantial effect on the flow and setting behaviour of the 
expansive cement paste. The most preferred prehydration age is from 4 to 
24 hours. 
After prehydration, the H-HAC is preferably crushed and then preferably 
dried at room temperature for about 24 hours. It is then preferably ground 
into a fine powder having particles ranging in size from about 75 um to 
300 um. Preferred particle size is from 75 um to 150 um. Grinding is not 
required when the H-HAC has been prehydrated for shorter periods of time, 
for example a period of 30 minutes less than final set time. 
The resulting powdered H-HAC may then be combined with calcium sulfate 
(anhydrous, hemihydrate or dihydrate), and preferably also with lime (CaO 
or Ca(OH).sub.2) to form the expanding component. In one preferred 
example, the weight ratio of powdered H-HAC:calcium sulfate 
hemihydrate:hydrated lime in the expanding component is about 9:4:1. 
The expanding component containing H-HAC can be combined with Portland 
cement to form an expansive cement. In one preferred example, the weight 
ratio of Portland cement to expanding component is about 1.5:1. 
Expansive concrete can be formed from the expansive cement of the present 
invention by combining the expansive cement with water and aggregate in 
the same manner as ordinary Portland cement. In one preferred example, the 
weight ratio of expansive cement:stone:sand:water was about 5:8:7:2. 
A small amount of superplasticizer may also be added to expansive concrete 
of the present invention to improve workability and minimize the amount of 
water needed. In one preferred example, the weight ratio of expansive 
cement to superplasticizer was about 130:1. 
HAC cement powder is known to be a finely divided powder of particles, for 
example with an average particle size smaller than about 50 .mu.m. 
Preferably the HAC powder used, as is typical, may have no particles 
greater than about 75 .mu.m, more preferably 50 .mu.m. Preferably no more 
than about 10 to 15% by weight of the particles have a size which is less 
than about 5 .mu.m. The average particle size is preferably in the range 
of about 10 to 50 .mu.m or about 20 to 40 .mu.m. 
The mechanism by which the expanding component containing H-HAC improves 
the setting behaviour of expansive cements is not well understood. 
According to the "Through Solution Theory", discussed in Mehta, "Effect of 
Lime on Hydration of Pastes Containing Gypsum and Calcium Aluminates or 
Calcium Sulfoaluminate", Hour. Amer. Ceramic Soc., Vol. 56, No. 6, 1973, 
p. 315 it is believed that the rate of ettringite formation is 
proportional to the concentration of Al.sup.3+ ions in the concrete pore 
solution. As a result of the prehydration of particles of HAC, a coating 
or cladding of hydration products of HAC is formed on the surface of the 
HAC particles, resulting in the defined H-HAC particles. When the H-HAC 
particles are subsequently used in an expansive cement and mixed with 
water, it is believed that this cladding, on one hand, may resist water 
penetration into the unhydrated cores, and in any event on the other hand 
may reduce the ability of Al.sup.3+ ions to disperse from the cladding. A 
relatively long time period is needed for the reactant Al.sup.3+ ions to 
reach the saturated concentration under which the ettringite is 
crystallized. This slow accumulation of Al.sup.3+ ions from the H-HAC 
particles allows the expansive cement paste to have the desired delayed 
setting behaviour. 
Particle size plays an important role in controlling the degree and rate of 
expansion and the set time of the H-HAC-containing expansive cement. 
Smaller particles have a proportionally higher surface area per unit 
weight than larger particles. This higher surface area is believed to 
either increase the rate of dispersion of Al.sup.3+ particles or increase 
the surface area from which the ettringite grows, or both. Therefore, the 
smaller the particle size, the faster the rate of ettringite formation and 
the shorter the set time. Accordingly, selection of appropriate fineness 
of H-HAC is not only important in controlling the quality of expansive 
cement, but also is a method of adjusting the rate of expansion, the 
ultimate value of expansion, and the set time. 
The length of set time and the degree and rate of expansion may also be 
controlled by adjusting the amount of H-HAC in the expanding component and 
the amount of expanding component in the expansive cement. The higher the 
proportion of expanding component in the expansive cement, the higher the 
degree and rate of expansion and the shorter the set time. 
Tests were conducted to compare expansive cement pastes and concretes 
according to the present invention including H-HAC powders with similar 
expansive cement pastes and concrete, including HAC powders rather than 
H-HAC. 
Commercially available materials were used to prepare sample expansive 
cement pastes and concretes for the tests. These test materials are listed 
below with the name by which they are referred to hereinafter in the 
tables being shown in quotations or brackets: 
1. as ordinary "Portland cement (OPC)", namely ASTM Type 1 or CSA Type 10 
Portland cement; 
2. as the expanding component, a mixture of CIMENT FONDU a high alumina 
cement sold by Canada Cement Lafarge Limited (HAC), quick setting plaster 
being calcium sulfate hemihydrate (quick set plaster) and hydrated 
finishing lime being calcium hydroxide (hydrated lime); 
3. admixtures including the commercial retardant sold under the trade mark 
"DELVO", the retarder "sodium citrate", the superplasticizer sold under 
the trade mark "LOMAR-D", and "fly ash"; 
4. aggregates including sand and crushed limestone (stone) with a maximum 
size of 20 mm; and 
5. water. 
For the tests H-HAC powders were made from CIMENT FONDU (HAC) by the 
following process: 
1. mixing CIMENT FONDU (HAC) with water using a water/cement weight ratio 
of 0.5; 
2. casting it in 100.times.200 mm plastic cylinder mould; 
3. letting the mixture set for one of the designated "prehydration ages"; 
4. after prehydration for the designated prehydration age, as necessary to 
particulize, crushing the H-HAC; 
5. drying the H-HAC at room temperature for 24 hours; 
6. grinding the H-HAC into a fine powder; and 
7. separating it into different sizes by sieving. 
Six representative test H-HAC powders were prepared by this process. These 
six powders are described Table 1 which sets out for each sample the 
"Prehydration Age", the particle size and the sample number of either the 
"cement paste" or "concrete" in which the H-HAC was included. The 
prehydration ages were chosen to be a minimum of 30 minutes before final 
set for powder B; 1.5 hour after final set for powder C; 1 day after 
mixing with water for powders A, E and F; and 7 days after mixing with 
water for powder D. For powder B with a prehydration age of 30 minutes 
before final set there was no crushing or grinding or size separation as 
the resultant H-HAC was a particulate material after removal from the 
mould. For the powder other than sample B, sieving separation was selected 
to provide powders with H-HAC particles in the ranges of either less than 
75 .mu.m, 75 .mu.m to 150 .mu.m or 150-300 .mu.m. 
Cement Paste Samples--EP Series 
Cement paste samples were prepared from the test materials utilizing either 
the preferred H-HAC powders or the Cement Fondue (HAC) powder. The 
composition of fourteen of these cement paste samples are shown in Table 2 
in which each component is indicated by mass in grams. 
Each cement paste sample comprises Portland Cement, an expanding component, 
water and optional admixtures. The expanding component comprises quick set 
plaster and hydrated lime plus either CIMENT FONDU HAC powder or one of 
the H-HAC powders. A small amount of superplasticizer, Lomar D was used in 
each H-HAC cement paste in Table 2 as it was appreciated that larger water 
to cement ratios (w/c) would be needed to achieve preferred workable 
pastes. 
The components of each cement paste were mixed in accordance with the "Type 
of Mixing Process" fully described in Table 5. 
Regarding Table 2, samples EP1, EP2, EP37, EP38, and EP40 to 43 inclusive 
are the HAC cement paste samples prepared with HAC powder. Samples EP49 to 
EP54 inclusive are the H-HAC cement paste samples prepared with the 
various H-HAC powders. 
Cement Pastes--Flowability Tests 
Tests were conducted on the cement pastes of Table 2 to determine the loss 
of flowability with time after adding the expansive components. 
A flow table in accordance with ASTM C-230-68 was used to determine the 
change of flowability of the cement pastes. The method employed did not 
exactly follow this ASTM Standard, because the flow of the cement pastes 
with admixtures usually exceeded the range of the table. In most cases, 
the cement paste flowed by gravity without preforming any drops. The 
results are graphically shown in FIGS. 2 and 4 for HAC cement pastes and 
FIGS. 6 and 8 for H-HAC cement pastes. In FIGS. 2, 4, 6 and 8, the percent 
flow is shown as measured at various times in minutes after adding the 
expansive component to the cement pastes. 
FIGS. 2 and 4 show eight HAC sample cement pastes with a horizontal axis of 
60 minutes and are to be contrasted with FIGS. 6 and 8 showing the H-HAC 
sample cement pastes with a horizontal axis of 200 to 250 minutes. The 
H-HAC sample cements other than EP50 have improved loss of flowability 
compared to the HAC sample cement pastes. H-HAC sample cement paste EP50 
had the shortest prehydration age of 30 minutes before final set and was 
comparable in loss of flowability with single step mixed HAC samples E1 
and E2. FIG. 6 shows that the flow percent increases with prehydration age 
for the H-HAC pastes with the prehydration age increasing from EP50 to 
EP51 to EP49 to EP52. FIG. 8 shows that the flow percent increases for the 
H-HAC pastes with increase in particle size in that H-HAC sample EP53 has 
particles of less than 75 .mu.m; H-HAC sample EP49 has particles of 75-150 
.mu.m and H-HAC sample EP54 has particles of 150-300 .mu.m. 
Cement Paste--Initial and Final Set Tests 
Tests were conducted on the cement pastes of Table 2 to determine the 
initial and final setting time by the method of ASTM C 807-89. In this 
test, after flow decreased with time to less than 10%, the paste was 
compacted in a PVC cone, the surface was finished and the initial and 
final setting times were measured in minutes by a Vicat apparatus. The 
results are shown in Table 4. 
All of the H-HAC sample cement pastes E49 and E51 to E54 had substantially 
greater initial and final set times than the HAC sample cement pastes EP40 
to EP43, with the exception of H-HAC sample cement paste EP50. H-HAC 
sample cement paste EP50 had a prehydration age of less than the final set 
time. H-HAC sample cement paste EP51 had the next lowest set times and was 
the sample with the next lowest prehydration age of 1.5 hours after final 
set. A comparison of H-HAC samples EP49, EP53 and EP54, each of which had 
prehydration ages of 1 day and with H-HAC sample EP52 having a 
prehydration age of 7 days suggests that after 24 hours, the prehydration 
age of H-HAC cement paste does not appear to have a substantial effect on 
the setting behaviour of the paste. 
Cement Paste--Free Expansion Tests 
Tests were conducted on the cement pastes of Table 2 to determine the free 
expansion with time. In these tests, when the flow of the paste had 
decreased to less than 10%, two expansion specimens were cast in steel 
prism moulds to produce 25.times.25.times.125 mm (1.times.1.times.5 
inches) specimens with expansion studs at the ends providing a gauge 
length of (125 mm/5 in.). The specimens were cured initially in a sealed 
plastic box under the relative humidity of 100% and temperatures of about 
23.+-.3.degree. C. (74.+-.5.degree. F.). Some specimens were demoulded 
after 24 hours and others just after final setting. Initial lengths of the 
specimens were measured immediately after demoulding. After 24 hours 
drying in the sealed boxes, the specimens were set in water. The expansion 
was read once a day until the specimens cracked or the lengths of the 
specimens became constant. 
The results are shown in FIGS. 3, 5, 7 and 9 as graphs showing free 
expansion as a percentage of the initial lengths versus the number of days 
after mixing with water. The term "break" shown in FIGS. 3, 5, 7 and 9 is 
used at the end of an expansion curve to indicate the specimen is cracked 
to the extent that further measurements would not be meaningful. 
The expansion of the H-HAC cement pastes are shown in FIGS. 7 and 9 to be 
somewhat comparable with the expansion of the HAC cement pastes EP1 
without any admixtures. HAC cement paste EP1 without any adjunctives had 
the greatest expansion. HAC cement pastes EP37, EP38, EP40 and EP41 had 
low expansion which is believed to be due to the presence of substantial 
admixtures. 
The effects of prehydration age of the H-HAC powders on flow and free 
expansion of the H-HAC cement paste samples are shown in FIGS. 6 and 7. 
The initial and final set times of H-HAC cement paste samples are compared 
with HAC cement paste samples in Table 4. The H-HAC particle size in H-HAC 
cement paste samples EP49, EP51 and EP52 varied between 75 .mu.m and 150 
.mu.m. The results suggest that a prehydration age at least equal to final 
set time is preferred to achieve satisfactory flow characteristics of the 
H-HAC cement pastes. Beyond 24 hours, the prehydration age of H-HAC does 
not seem to have substantial effect on the flow and setting behaviour of 
the H-HAC cement pastes. Even with prehydration age of 1.5 hours longer 
than final set, initial and final set times of approximately 6 hours were 
recorded for the H-HAC paste samples. The effect of prehydration age of 
H-HAC on free expansion of the H-HAC cement paste is minimal as shown in 
FIG. 7. Compared to HAC-type expansive cement pastes as shown in FIGS. 3 
and 5 the expansion characteristics of H-HAC cement pastes as shown in 
FIGS. 7 and 9 are significantly better with respect to the total expansion 
and the delay in expansion. Since the use of admixtures in the H-HAC 
cement paste samples is minimal, the loss of measurable expansion is 
believed to have been minimized. 
The effects of particle size of the H-HAC powders on flowability and 
expansion of the H-HAC cement pastes are shown in FIGS. 8 and 9. The 
prehydration age of H-HAC in HHAC cement pastes EP49, EP53 and EP54 was 24 
hours. As expected, reduced particle size results in faster initial 
reaction. Reduced particle size of H-HAC gave the H-HAC cement pastes a 
lower flow, a larger flow loss with time and a faster set. When the 
particle size decreased from 75-150 .mu.m to less than 75 .mu.m, the 
expansion of the H-HAC cement paste developed earlier. The ultimate amount 
of expansion was, however, very similar with both H-HAC samples EP53 and 
EP49. With an increase in the particle size from 75-150 for EP49 to 
150-300 .mu.m for EP54, the development of expansion was greatly delayed 
and, as well, the ultimate expansion appears to have been reduced. For the 
H-HAC cement pastes under consideration, a particle size of H-HAC in the 
range of 75-150 .mu.m appears to be preferred. 
Concrete Samples--E Series 
Concrete samples were prepared from the test materials utilizing either the 
prepared H-HAC powders of Table 1a or the CIMENT FONDU (HAC). The 
composition and mixing processes of five concrete samples are shown in the 
Table 3 of which expansive concrete sample E11 is made with H-HAC by one 
stage mixing and samples E6 to E9 inclusive are made with CIMENT FONDU 
(HAC) by various mixing processes indicated and fully defined in Table 5. 
For H-HAC cement sample E11, a small amount of a superplasticizer LOMAR D 
was used as it was appreciated that larger water to cement ratios (W/C) 
would be needed otherwise to achieve preferably workable concrete. 
Concrete Sample--Slump Test 
Slump values were measured for H-HAC cement sample E11 over two hours as 
shown in FIG. 10. The behaviour of sample E11 was very similar to that of 
normal Portland cement concrete including similar amounts of 
superplasticizers. For sample E11, initial slump of approximately 160 mm 
(6.2 inches) maintained for about 30 minutes and at 60 minutes the slump 
was still about 100 mm (4 inches). 
Concrete Samples--Compressive Strength and Friction Stress Tests 
To simulate the actual stress state with three dimensional restraint, a set 
of steel tube moulds for casting and curing expansive cement 
pastes/concrete was designed, as shown in FIG. 1. The lateral expansion of 
expansive concrete was restrained by the steel tube 1 and the longitudinal 
expansion was restrained by two steel end plates 2 tightly held in place 
by three 8 mm diameter threaded rods 3. The tube 1 has a 100 mm inner 
diameter and 200 mm length with a 6 mm thick wall. Twenty holes 4 of 5 mm 
diameter were made symmetrically in four columns to allow supply of water 
during hydration. The expansive concrete was cured in the mould in air at 
100% relative humidity and about 25.degree. C. for 24 hours after casting 
and then placed in 23.degree. C. water. At designated ages, steel plates 2 
were removed and the expansive concrete cylinder was squeezed out using a 
universal testing machine. During the demoulding process the friction 
stress between the expansive concrete and the inside of the steel tube 
could be measured from the maximum load required to remove the expansive 
concrete cylinder from the tube. The compressive strength was obtained 
from testing the squeezed-out specimens. 
FIG. 11 illustrates the development of compressive strength of the 
expansive concrete samples over a period of 90 days. The strength of HAC 
concrete samples E6 and E7, both containing no fly ash, was the highest 
mainly because of the lower water:cement ratio used. The addition of fly 
ash and a higher proportion of water to HAC concrete samples E8 and E9 to 
improve workability of the concrete resulted in a reduction in strength. 
FIG. 11 shows the compressive strength for unconfined expansive concrete. 
In actual field conditions, expansive concrete is typically confined 
laterally when subjected to axial stress and will, therefore, display much 
higher strength. 
The H-HAC concrete sample E11 displayed lower strength than comparable HAC 
sample E6 at an early age, but at later stages the two concretes had 
similar strength values. Compared to normal concrete made merely with 
normal Portland cement, the strength development of all the expansive 
concrete samples shown in FIG. 11 is delayed by several days. This effect 
is pronounced in H-HAC concrete sample E11. 
FIG. 15 shows the frictional stress in MPa as measured at different times 
for each concrete sample. H-HAC concrete sample E11 had friction stresses 
comparably as large to those for HAC cement sample E6 without admixtures. 
Concrete Samples--Free Expansion Tests 
Expansive concrete was cast in PVC cylinder moulds 100 mm in diameter, 200 
mm long with 3 mm thick walls with expansion studs embedded at the ends. 
After curing for 24 hours in moist air, the specimens were demoulded. The 
original length of a specimen was obtained by averaging four measured 
lengths of concrete cylinder on symmetric sides. The initial length 
including two targets was measured immediately after demoulding, and then 
specimens were cured in water. The length changes were determined daily. 
The changes in linear free expansion with time of samples E6, E8 and E11 
are shown in FIG. 12. The addition of fly ash to HAC sample E8 delayed 
expansion by about 2 days over HAC sample E6. However, the total free 
expansion of HAC samples E6 and E8 are comparable. 
As shown in FIG. 12, the H-HAC concrete sample E11 had a delayed 
development of expansion by about 9 to 10 days. The rate of expansion of 
H-HAC concrete sample E11 at about 12 days is similar to that of HAC 
concrete sample E6 at about 3 days. The total measured free expansion of 
H-HAC concrete sample E11 was slightly higher than that of HAC samples E6 
and E8. However, it should be noted that, due to extensive cracking of the 
specimens, the free expansion measurements do not necessarily reflect the 
true quantitative effects of different parameters. 
Concrete Samples--Two Dimensional Restrained Expansion Tests 
The expansive concrete specimens for two dimensional restrained expansion 
tests were cast in PVC tubes with 3 mm thick walls, 120 mm long and 100 mm 
inner diameter. Two expansion studs were installed in the centre at the 
ends. The initial length of a specimen was obtained by averaging four 
measured lengths of concrete cylinder on symmetric sides including tow 
targets after one-day of moist curing. Then the specimens with PVC tube 
moulds were stored in 23.degree. C. water. The length changes were 
determined daily. In this test, the restraint was applied to the expansive 
concrete from the wall of PVC tube in the lateral direction. In the 
longitudinal direction the only restraint could have come from the 
friction between concrete and the PVC walls. 
FIG. 13 shows the results of this test as the percent restrained expansion 
versus time in days. H-HAC concrete sample E11 had expansion closest to 
that of HAC sample E6 without admixtures. 
Concrete Samples--Expansion Pressure Tests 
A test mould for measuring this parameter was designed similar to that 
shown in FIG. 1. A thin walled steel tube was used to provide lateral 
restraint and two end steel plates tightly installed by three 8 mm 
diameter threaded rods acted as longitudinal restraint. The expansive 
concrete specimen inside the tube was 150 mm in diameter and 300 mm long. 
The wall thickness of the tube was 3 mm. Several strain gauges were 
installed to measure the changes in lateral and longitudinal strains 
during concrete expansion. Each rod contained one strain gauge in the 
axial direction. The outer surface of each tube was instrumented with 
three strain gauges, one in the axial direction and two in the 
circumferential direction. The holes in the steel tubes were made for easy 
flow of water as mentioned above for the strength test specimens. One hour 
after casting the expansive concrete, initial strain readings were taken. 
The specimens were cured in air at 100% relative humidity and 25.degree. 
C. for 24 hours, and then placed in 23.degree. C. water. Readings were 
recorded every day for each specimen. 
The test results are shown in FIG. 14 plotting the lateral expansion 
pressure in MPa versus time in days. Again H-HAC concrete sample E11 was 
comparable to HAC concrete sample E6 without admixtures. 
Reference is made again to FIGS. 13, 14 and 15 respectively showing the 
variation with age of longitudinal expansion, the lateral expansion 
pressure, and the friction stress of the expansive concrete samples. HAC 
concrete sample E6 displayed the most expansion, the largest expansive 
pressure and the largest friction stress. The addition of admixtures to 
HAC concrete sample E7 greatly reduced its expansive potential, as is 
apparent in all three parameters measured in FIGS. 13 to 15. A comparison 
of HAC concrete samples E7 and E8 shows that an increase in the water to 
cement ratio and perhaps addition of fly ash reduce the expansive 
potential of the concrete. 
It is obvious from FIGS. 13 to 15 that the gain in workability due to 
admixtures in the HAC expansive concrete is obtained at the expense of 
expansive potential. By comparing HAC concrete samples E8 and E9, it is 
apparent that increasing the amount of expanding component compensates 
somewhat for the loss of restrained expansion and friction stress without 
significant adverse effects on strength and workability, but the 
development of lateral expansion pressure is not improved. 
FIGS. 13 to 15 show that H-HAC concrete sample E11 of the present invention 
compared quite favourably with HAC concrete sample E6. Although the 
restrained expansion of H-HAC concrete E11 is somewhat lower than that of 
HAC concrete E6, expansion pressure and friction stress in E6 and E11 are 
of reasonably similar magnitudes. Delay in the development of expansive 
pressure in H-HAC concrete E11 due to the use of H-HAC is beneficial in 
some applications, such as in drilled shafts. 
Cement Pastes--M Series 
Additional cement paste samples were prepared from the test materials 
utilizing either the preferred H-HAC powder A of Table 1 or the CIMENT 
FONDU (HAC) powder. The composition of five additional cement paste 
samples are shown in Table 6 in which each component is indicated by mass. 
In Table 6, Samples M-1, M-2 and M-3 are HAC cement paste samples while 
samples M-4 and M-5 are H-HAC cement paste samples. 
Fresh Paste Samples 
To measure the hydration process of expansive cement paste samples of Table 
6 in the fresh state, two grams of solid materials were mixed continuously 
and uniformly with their relative proportion of water or water-admixture 
solution in a glass beaker at 23.degree. C. The hydration periods were 
fixed at 1, 3, 5, 10, 20, 30 and 60 minutes. At the designated time, the 
hydration of the fresh paste was terminated by adding 30 ml of propanol, 
and then the samples were filtered in a funnel with qualitative filter 
paper (grade 601-25). After washing the sample by propanol three times on 
the filter paper, the remnant on the paper was dried in a vacuum 
dessicator with a negative pressure of 100 kPa for 48 hours. Then the 
sample was ground together in an agate mortar with 100% CaF.sub.2 as an 
internal standard. 
X-ray diffraction patterns of the five expansive fresh paste samples M-1 to 
M-5 during hydration in first 60 minutes are presented for each sample, 
respectively in FIGS. 16 to 20 and at three later ages in FIGS. 21 to 23, 
as measured with an X-ray diffractometer using Copper Kx radiation. In 
FIGS. 16 to 23, A represents Al.sub.2 O.sub.3, B represents 
CaSO.sub.4.1/2H.sub.2 O, CH represents Ca(OH).sub.2, G represents gypsum, 
SA represents calcium sulphoaluminate, C.sub.2 S represents 2CaO.SiO.sub.2 
and C.sub.3 S represents 3CaO.SiO.sub.2. Calculated from these FIGS. 21 to 
23, the relative intensities of three designated minerals, Gypsum (G), 
Hemihydrate (B) and calcium sulphoaluminate (SA), are presented in FIGS. 
24 to 28, respectively for each respective cement paste sample and in 
FIGS. 29 to 31 for each respective mineral. Calcium sulphoaluminate (SA) 
is used here to designate the combination of monosulphoaluminate 
(3CaO.Al.sub.2 O.sub.3.CaSO.sub.4.12H.sub.2 O) and ettringite 
(3CaO.Al.sub.2 O.sub.3.3CaSO.sub.4.32H.sub.2 O). With hydration, the 
intensities of SA obviously increased. In samples with admixtures the 
increase in SA intensities at an early age was larger than in the sample 
without admixtures. In HAC cement samples M-1, M-2 and M-3, the 
hemihydrate peak diminished expeditiously and disappeared before 60 
minutes with corresponding increase of gypsum peak. In the H-HAC cement 
samples M-4 and M-5, the hydration rate seemed very slow. Hemihydrate 
existed in the pastes for 24 hours and the intensity of SA was quite small 
in first 60 minutes even with admixture. With the increase of SA 
formation, gypsum was greatly consumed, which resulted in the decrease of 
gypsum's relative intensity at later ages as seen in FIGS. 29 to 31. Since 
the same content of plaster (hemihydrate) was used in all the mixtures, 
the relatively lower gypsum intensity mostly corresponded with a high rate 
of SA formation. The peak shift from 9.90.degree. to 9.05.degree. 2.theta. 
as hydration proceeded showed the composition change of calcium 
sulphoaluminate from monosulphoaluminate to ettringite. The patterns of 
cement pastes with admixtures exhibited a distinct background hump due to 
amorphous phase in the range of from 8.degree. to 25.degree. 2.theta. as 
seen in FIGS. 16 to 20 indicating acceleration of the hydration rate. 
As seen in FIG. 21 in the X-ray diffraction analyses of expansive cement 
pastes after one day, it was obvious that the sulphoaluminate peak of the 
HAC cement pastes M-2 and M-3 with admixtures was higher than that of the 
HAC cement paste M-1 without admixtures, but no obvious difference could 
be found between the two samples M-2 and M-3 with different mixing 
processes. In the H-HAC cement paste samples M-4 and M-5, the SA peaks 
were much lower than that in the HAC type expansive cement, indicating a 
reduced rate of SA formation. 
As seen in FIG. 22 at 3 days, the X-ray diffraction pattern of expansive 
cement pastes were similar to those at 1 day. But the relative intensities 
of designated minerals (SA, G or B) in different expansive cement pastes 
became somewhat similar. 
As seen in FIG. 23 at 28 days, the five expansive cement pastes were not 
discernably different even in the intensity of each peak. The major 
hydration products were ettringite and calcium hydroxide while some 
unhydrated clinker phase such as C.sub.3 S and C.sub.2 S were also noted. 
However no characteristic peaks representing the hydration products of 
HAC, such as 3CaO.Al.sub.2 O.sub.3.6H.sub.2 O could be detected. 
Hardened Paste Specimens 
To explore the microstructure of expansive cement paste, hardened specimens 
were prepared from the paste samples of Table 6 under conditions 
simulating those in real drilled shafts. Cylindrical specimens 26 mm in 
diameter and 50 mm high were cast in small steel tube moulds with 2 mm 
thick walls. Two 8 mm thick steel plates were placed at bogh ends of the 
steel mould and tightly screwed together using three 6 mm diameter 
threaded rods. At each end of the mould, there were two holes (3 mm in 
diameter each) for water supply during hydration. In the first 24 hours, 
the specimens were cured in air at 100% RH and 23.degree. C., and then 
stored in 23.degree. C., tap water. During the entire curing process, the 
specimens were subjected to three dimensional restraint. At designated 
ages, the threaded rods were removed and the steel moulds were cut 
longitudinally to obtain the paste cylinder specimens. The procedure was 
followed to avoid damage to the cement pastes during demoulding. Hardened 
paste from the central section of the specimen was then taken and crushed 
into 3-10 mm diameter particles. The hardened pastes were immersed in 
propanol for 24 hours to terminate hydration and then dried in a vacuum 
dessicator at a negative pressure of 100 kPa for 48 hours. The hardened 
pastes were then ground and sieved into three grades: particles with 
diameter of about 10 mm were chosen for scanning electron microscopy; 
particles with diameter of about 2-3 mm were favoured for porosimeter 
tests; and the rest of the material was ground together with 100% 
CaF.sub.2 as an internal standard for X-ray diffraction tests. 
A scanning electron microscope was used to evaluate the crystal growth and 
compare the expansion cracks existing in the hardened specimens of the 
cement paste of Table 6 with different admixtures and curing ages. Under 
the particular restraint conditions in the steel mould, the widths of 
cracks varied from 10 um to 30 um and they increased with an increase in 
age at early ages, but then decreased dramatically at 28 days. The surface 
texture of the 28-day specimens was dense and most remaining micro cracks 
were closed. At early ages, they were quite porous and the cracks extended 
through the sample. 
At early ages, average crack widths of the HAC cement pastes M-2 and M-3 
with admixtures were larger than those in HAC pastes M-1 without 
admixtures. While in the H-HAC expansive cement pastes M-4 and M-5 the 
crack widths were only about one-fifth of those in the HAC cement paste 
M-1, M-2 and M-3. At 28 days, the surface morphology of paste M-5 was 
totally different from those at early ages. Only traces of sulphoaluminate 
crystals could be found in some isolated areas. 
The morphologies of SA in pastes at different ages were also studied with 
the scanning electron microscope. In the HAC cement paste M-1 without 
admixtures large size SA crystals (about 15-60 um long and 6 um in 
diameter) were commonly found. But in the HAC cement pastes M-2 and M-3 
with admixtures, only small needle-shaped SA crystals existed in clusters, 
which these smaller crystals being about 3-5 .mu.m long and 1 um in 
diameter. Although in the HHAC cement pastes M-4 and M-5 some SA crystals 
located in pores or cracks were large, about 10-20 .mu.m long and 2 um in 
diameter, most other crystals were still smaller than those observed in 
the HAC cement pastes M-2 and M-3 with admixtures. 
At early ages, most of the SA crystals appeared as conglomerations 
irregularly interlocked with each other, and those in the pores or cracks 
grew from solid side surfaces into the open space. At 28 days, ettringite 
could not easily be detected or identified because of the extreme dense 
structure of the hardened paste. Occasionally, some small clusters of 
ettringite could be found in the pores or some weak areas. 
Cumulative pore size distribution curves of the expansive cement pastes 
hardened specimens were measured using a mercury intrusion porosimeter 
with a contact angle assumed to be 140.degree.. The results are shown in 
FIG. 32. With hydration, cumulative pore volumes at all sizes decreased in 
all the pastes. At 28 days, the volume of pores larger than 400 A tended 
to be zero. This indicated that hydration products had filled in the 
pores. The total pore volume of H-HAC cement paste M-4 and M-5 was 
slightly higher than that of HAC cement pastes M-1, M-2 and M-3. 
FIGS. 33 to 35 show the differential pore size distribution curves at 
different ages for expansive cement pastes. The most probable pore sizes 
(MPPS) of these samples at one-day (FIG. 33) were in the range of 600 
A.degree. to 3000 A.degree.. The HAC pastes M-1 and M-2 without admixture 
had the same MPPS of 3000 A.degree.. As a result of using admixtures, the 
MPPS shifted to smaller sizes. At 3 days of hydration (FIG. 34) the MPPS 
range for these samples was between 300 A.degree. and 900 A.degree.. The 
effect of admixtures on the character of distribution curves was the same 
as that at one day. 
FIG. 35 demonstrates differential pore size distributions of 28-day pastes. 
The MPPS were very low, from 80 A.degree. to 160 A.degree.. The MPPS of 
the H-HAC cement pastes M-4 and M-5 was larger than that of HAC cement 
pastes M-1, M-2 and M-3. This large reduction in pore volume is not common 
in normal cement pastes even incorporating silica fume, indicating that 
when restrained, expansive cements at later ages could have an extremely 
dense structure and high strength. 
TABLE 1 
______________________________________ 
Design of H-HAC Powders 
H-HAC Particle Size 
Prehydration 
Cement Paste or 
Powder um Age Concrete Sample 
______________________________________ 
A 75-150 1 day EP 49, E 11, M-4, M-5 
B No grinding 
30 min. before 
EP 50 
needed final set 
C 75-150 1.5 hr. after 
EP 51 
final set 
D 75-150 7 days EP 52 
E 75 1 day EP 53 
F 150-300 1 day EP 54 
______________________________________ 
TABLE 2 
__________________________________________________________________________ 
Mix Design of Expansive Cement Paste Samples 
Units: Mass 
H-HAC 
Speci- 
Type of Cement Particle Quick 
men Mixing 
Portland 
Fondu Size Pre-hydration 
Set Hydrated Sodium 
Lomar 
Fly 
No. Process 
Cement 
(HAC) 
Content 
of (.mu.m) 
Age Platter 
Lime Water 
Delvo 
Citrate 
D Ash 
__________________________________________________________________________ 
EP1 MPD-I 
480 200 -- -- -- 96 24 320 -- -- -- -- 
EP2 MPD-I 
480 200 -- -- -- 96 24 320 4 -- -- -- 
EP37 
MPD-I 
400 250 -- -- -- 120 30 320 2.4 -- 12 -- 
EP38 
MPD-I 
400 250 -- -- -- 120 30 320 -- 0.3 12 -- 
EP40 
MPD-I 
400 250 -- -- -- 120 30 368 -- 0.3 12 120 
EP41 
MPD-II 
400 250 -- -- -- 120 30 368 -- 0.3 12 120 
EP42 
MPD-III 
400 250 -- -- -- 120 30 368 -- 0.3 12 120 
EP43 
MPD-IV 
400 250 -- -- -- 120 30 368 -- 0.3 12 120 
EP49 
MPD-I 
480 -- 200 75-150 
1 day 96 24 320 -- -- 6 -- 
EP50 
MPD-I 
480 -- 200 No 30 min. before 
96 24 320 -- -- 6 -- 
grinding 
final set 
needed 
EP51 
MPD-I 
480 -- 200 75-150 
1.5 hr. after 
96 24 320 -- -- 6 -- 
final set 
EP52 
MPD-I 
480 -- 200 75-150 
7 days 96 24 320 -- -- 6 -- 
EP53 
MPD-I 
480 -- 200 &lt;75 1 day 96 24 320 -- -- 6 -- 
EP54 
MPD-I 
480 -- 200 150-300 
1 day 96 24 320 -- -- 6 -- 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
Proportions of Expansive Concrete Samples 
Speci- Type of Cement Mould- 
Hyd- 
men Type of 
Mixing Portland 
Fondu ing rated Sodium Fly 
No. Concrete 
Process 
OPC/EC 
Cement 
(HAC) 
H-HAC 
Plaster 
lime 
Water 
W/C 
Stone 
Sand 
Citrate 
Lomar 
Ash 
__________________________________________________________________________ 
E6 HAC one-stage 
60/40 
306 128 -- 61 15 217 0.43 
902 
742 
-- -- -- 
E7 HAC two-stage 
60/40 
306 128 -- 61 15 217 0.43 
902 
742 
0.19 
7.6 -- 
E8 HAC two-stage 
60/40 
306 128 -- 61 15 316 0.54 
756 
524 
0.19 
7.6 76 
E9 HAC two-stage 
50/50 
260 163 -- 78 19 300 0.50 
772 
534 
0.20 
7.8 79 
E11 H-HAC 
one-stage 
60/40 
306 -- 128 61 15 217 0.43 
902 
742 
-- 3.8 -- 
__________________________________________________________________________ 
TABLE 4 
______________________________________ 
Initial and Final Set of Cement Paste Samples 
Initial Set 
Final Set 
Sample (minutes) 
(minutes) 
______________________________________ 
EP 40 65 78 
EP 41 67 72 
EP 42 130 210 
EP 43 155 230 
EP 49 480 510 
EP 50 27 31 
EP 51 348 378 
EP 52 486 516 
EP 53 426 486 
EP 54 510 540 
______________________________________ 
TABLE 5 
______________________________________ 
Design of Special Mixing Processes 
Type of Mixing 
Processes Procedures of Mixing 
______________________________________ 
MPD-I Mix all the cementitious materials (and aggregates, 
(one stage mixing 
if any) in the mixer for 3 minutes. Add the water with 
process) dissolved retarder and superplasticizer and mix 
for 3 minutes. 
MPD-II Mix Portland cement plaster and water with dissolved 
(two-stage mixing 
retarder and superplasticizer in the mixer for 3 
process) minutes; Wait for 5 minutes; Add the rest of the 
materials (Ciment Fondu, Lime and fly ash) with the 
previously mixed paste for 3 minutes. 
MPD-III Mix Portland cement, fly ash, plaster and water with 
(two-stage mixing 
dissolved retarder in the mixer for 3 minutes; 
process) Wait for 5 minutes; Add the rest of the materials 
(Ciment Fondu, Lime and superplasticizer) with the 
previously mixed paste for 3 minutes. 
MPD-IV Mix Portland cement, fly ash and water with dissolved 
(two-stage mixing 
retarder (and aggregates, if any) in the mixer 
process) for 3 minutes; Wait for 5 minutes; Mix the 
expansive components and superplasticizer with 
the previously mixed paste for 3 minutes. 
______________________________________ 
TABLE 6 
__________________________________________________________________________ 
Proportions of Expansive Cement Paste Samples 
Units: mass 
Expansive Components 
S-Bearing 
Ordinary Material Admixture 
Portland Al-bearing Material 
Quick Set 
Hydrated Sodium Type of Mix 
Sample 
Cement 
HAC H-HAC 
Plaster 
Lime Lomar-D 
Citrate 
Water 
Process 
__________________________________________________________________________ 
M-1 0.6 0.25 
-- 0.12 0.03 -- -- 0.43 
MPD-I 
One-stage 
M-2 0.6 0.25 
-- 0.12 0.03 0.015 
0.000375 
0.43 
MPD-I 
One-stage 
M-3 0.6 0.25 
-- 0.12 0.03 0.015 
0.000375 
0.43 
MPD-IV 
Two-stage 
M-4 0.6 -- 0.25 0.12 0.03 -- -- 0.43 
MPD-I 
One-stage 
M-5 0.6 -- 0.25 0.12 0.03 0.0075 
-- 0.43 
MPD-I 
One-stage 
__________________________________________________________________________ 
The expansive cement of the present invention is particularly useful in 
highly expansive concrete compositions for use in drilled shafts (bored 
piles). Bored piles are used to support foundations of structures such as 
buildings and bridges when the soil is unsuitable for supporting stresses 
transmitted by the foundation. 
Expansive concrete compositions having a free expansion of about 4% can be 
used for bored piles. These expansive concretes produce a stronger bond 
between the shaft concrete and the surrounding soil, (ie. higher "skin 
friction"), thus enabling the shaft-soil system to carry a higher load. 
Settlement is also reduced due to the increased load transferred to the 
soil by the sides of the shaft. 
In tests conducted by Sheikh et al., "Expansive Concrete Drilled Shafts", 
Canadian Journal of Civil Engineering, Vol. 12, No. 2, 1985, pp. 382-395, 
it was determined that the use of expansive concrete increased skin 
friction by 25-50% and reduced settlement by about 50% in shafts built in 
over consolidated clay. 
Although the invention has been described in connection with certain 
preferred embodiments, it is not intended that it be limited thereto. 
Rather, it is intended that the invention cover all alternate 
compositions, equivalents, and embodiments as may be within the scope of 
the following claims.