Method for producing a storable mortar

A method for controlling the setting of a cementitious composition of matter, the present invention allows mixing of a mortar and retention thereof for a prolonged period of time before use, the mortar setting at least as rapidly as normally when applied to brick, block, or the like during the period of retention. The method involves the addition of an effective amount of saccharide polymers having a size of from three glucose units to on the order of 25 glucose units to a cementitious mixture, the additive optionally including air entrainment agents and similar agents such as have been previously used in the formulation of mortars. The method further involves entraining air in the mortar mixture to a particular degree which allows control of the setting rate of the mortar mixture when evaporation from the mixture is controlled. The invention further provides cementitious compositions of matter capable of being stored in a plastic state for a prolonged period of time, the composition setting at least as rapidly as normally when applied to brick, block, or the like.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to cementitious compositions which set on admixture 
with water and particularly to a method for controlling the temporal 
interval between mixture of the compositions with water and the setting 
thereof. 
2. Description of the Prior Art 
Mortar compositions have long been used for construction purposes, those 
mortar compositions presently in use usually containing portland cement 
and aggregates which harden on addition of water. Portland cement 
compositions are hydraulic in nature, that is, such compositions are 
capable of hardening under water or when not in the presence of air. On 
addition of water to hydraulic cement compositions, a process known as 
"hydraulic hydration" occurs, the composition hardening as a result of 
this hydration. According to present practices, additive compositions are 
known which are primarily used to strengthen hydraulic cement 
compositions. Additive compostions are also known which retard or 
accelerate the setting of hydraulic cement compositions. However, 
retarding compositions have not been greatly effective due to the 
unpredictability of their behavior, certain cement compositions being 
completely inhibited from hydration when such additive compositions are 
utilized. It has not been possible, therefore, according to prior art 
practices to controllably retard the setting of mortar compositions, 
particularly hydraulic cement compositions, in a manner which allows 
holding of mortar in a plastic, workable state for any extended period of 
time and still retain the capability of immediate setting of the mortar 
when the mortar is actually used at some time during this holding period. 
Additives previously used in the formulation of mortar include agents which 
act to strengthen the mortar, entrain air in the mortar, plasticize the 
mortar, color the mortar, and vary setting times of mortars. As disclosed 
by Kelly et al in U.S. Pat. No. 3,432,317, saccharide polymers inter alia 
are added to cementitious materials in order to strengthen the hardened 
mortar. The saccharide polymers so disclosed provide a strengthening 
function without retarding the setting rate of the mortar according to the 
invention disclosed by Kelly et al. It is noted in the aforesaid patent 
that sugars, such as the glucosaccharides of the patent, are retarders of 
cement hydration and are unpredictable in use. Therefore, the teachings of 
Kelly et al do not provide an additive for or a method for controlling the 
setting of a cementitious material, particularly a hydraulic cement, which 
allows a hydraulic mortar to be formed and held for an extended period of 
time. 
In U.S. Pat. No. 3,432,316, Kelly et al disclose the addition of extracts 
or portions of the tobacco plant to hydraulic cement in order to increase 
the strength of the concrete formed thereby and to cause a degree of 
retardation of hardening of the cement. Kelly et al do not disclose a 
method for maintaining a hydraulic mortar mixture in a plastic, workable 
condition for an extended period of time. Kelly et al further do not 
disclose a method for utilizing a mortar mixture which has been or can be 
maintained in a plastic, workable condition for an extended period of time 
and which can be used at any time during this extended period of time with 
the mortar mixture setting up as rapidly or more rapidly than normally on 
application of said mortar mixture to brick, block, or the like. 
SUMMARY OF THE INVENTION 
The present invention particularly provides a method for suspending the 
hydraulic hydration of hydraulic cementitious mixtures, such as of 
portland cement and the aggregate and additives normally mixed therewith. 
The present method comprises the admixture with cementitious mixtures, 
particularly hydraulic cementitious mixtures, of an additive comprised of 
glucosaccharide polymers preferably having a size of three glucose units 
to approximately 25 glucose units. The hydraulic cementitious mixtures 
thus formed, which mixtures may contain pozzolanic materials, such as fly 
ash, coloring agents, air entraining agents, and the like, can be stored 
in sealed containers and be thus held in a plastic, workable condition for 
a period of approximately 72 hours. The invention further teaches that 
this stored mixture can be used at any time during the storage period with 
the result that the mixture sets as rapidly or more rapidly than normally 
when applied to block, brick, and the like. Therefore, the invention 
enables a user of mortar to purchase or make up at one time a sufficient 
amount of mortar needed for a time period of up to three full days. The 
mortar needed for most jobs can thus be purchased, delivered, and/or made 
up at one time, thereby introducing desirable economies into the marketing 
and use situations surrounding the utilization of mortar. Further, mortar 
sufficient for use over an extended time period can be made up at a 
central facility and delivered to job sites in quantities sufficient for 
two to three days usage, the quality of mortar made under such 
circumstances being controlled more readily than is possible for mortar 
made up at a job site. 
The present invention, therefore, makes possible the single delivery of 
quantities of pre-mixed mortar formulated under relatively precise quality 
control conditions, which quantities are sufficient for multiple day usage 
and which can be used at any time during a storage period of up to three 
days. The hydraulic hydration action of the stored mortar is suspended 
according to the invention until such time as the mortar is actually used 
and applied to brick, block, and the like, in a normal manner. When used, 
the mortar immediately begins normal setting and strength development, 
some mortars hardening to a given strength even more quickly than when 
used normally. Thus, a user of the mortar according to the invention can 
maintain a single delivery of mortar in a usable plastic state for an 
extended period of time and retain normal workability, consistency, 
setting rate, and strength development. 
Application of mortar formulated according to the invention to brick, 
block, and the like, initiates hydraulic hydration of the mortar due to 
absorption of moisture from the mortar not only by the atmosphere but also 
by the brick and block itself. Therefore, the present invention teaches 
the retardation of setting of mortar for an extended period of time which 
is at least of the order of 72 hours under sealed conditions whereby 
moisture evaporation from the mortar is minimized, the mortar remaining in 
a workable, plastic condition. Further, the invention teaches the 
immediate setting and attainment of normal strength when applied to brick, 
block, and the like, on use of the mortar at any time during the storage 
period. 
The present invention further teaches the entrainment of air in a mortar 
having the storage and use characteristics referred to herein, air being 
entrained in the mortar in percentages greater than normal in order to 
assist in the attainment of the aforesaid storage and use characteristics 
of the mortar. Air entrained in the mortars according to the invention is 
within a percentage range by volume of the mortar of 12% to 35%, the 
higher percentage amounts being particularly suited to attainment of the 
storage and use characteristics according to the invention. 
It is, therefore, an object of the present invention to provide a method 
for controlling the setting of a cementitious composition of matter, the 
present method particularly allowing the mixture of a mortar and retention 
thereof for a prolonged period of time before use, the mortar setting at 
least as rapidly as normally when applied to brick, block, or the like, at 
any time during the period of retention. 
It is another object of the invention to provide a method comprising the 
addition of an effective amount of saccharide polymers having a size of 
from three glucose units to on the order of 25 glucose units to a 
hydraulic cementitious mixture and subsequently storing the mortar under 
conditions which prevent evaporation of moisture from the mortar, the 
mortar then being capable of usage at any time during a prolonged storage 
period without loss of desirable setting and strength development 
characteristics. 
It is a further object of the invention to provide a method for suspending 
the hydration of hydraulic cementitious mixtures, such as of portland 
cement and the aggregates and additives normally admised therewith, the 
present method comprising admixture with the mortar of glucosaccharide 
polymers, entrainment of relatively large quantities by volume of air in 
the mortar, and the prevention of moisture evaporation from the mortar 
until the time of actual use, such as by storage of the mortar is sealed 
containers. 
Other objects and advantages of the invention will become more readily 
apparent in light of the following detailed description of the preferred 
embodiments of the invention. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In a preferred practice of the present invention, a mortar which can be 
stored and maintained in a plastic workable state for an extended period 
of time is mixed at a central location for delivery to job sites. The 
mortar formulated according to the invention is containerized at the 
mixing location, the mortar being maintained in sealed containers for 
storage at the job sites. In this fashion, quality control of the mortar 
produced according to the invention is improved due to the fact that the 
mortar is mixed at a central location rather than on the individual job 
sites. The teachings of the present invention allows such mixing at a 
central location since the mortar according to the invention can be stored 
for a period of 72 hours or more without loss of workability. Therefore, 
relatively lower quality small batches of mortar need not be continually 
mixed at job sites so that only enough mortar necessary for use over a 
short future time period is provided. According to the present invention, 
quantities of mortar sufficient for use over a two to three day time 
period can be centrally mixed with control of the quality thereof and then 
stored at job sites without loss of workability. Due to mixing of the 
mortar at a central location, there is no need to provide water at job 
sites or to provide sand stockpiles and quantities of bagged cementitious 
materials which need to be covered and protected against the elements. The 
present invention further allows the use of pozzolanic materials, 
particularly fly ash, which allows an increase in the strength of the 
mortar. 
The present method particularly comprises the admixture with a hydraulic 
mortar mix of cement, aggregate, and sufficient water to effect hydraulic 
setting of the cement mix with an additive comprising saccharide polymers 
having a size of from three glucose units to on the order of 25 glucose 
units. Saccharide polymers useful in the practice of the present invention 
are described in U.S. Pat. No. 3,432,317, the disclosure of this patent 
being incorporated hereinto by reference. When using additives according 
to the aforesaid patent, it is to be understood that lesser amounts of 
glucosaccharides are normally used when more rapid hardening of the 
cementitious mixture is desired, more glucosaccharides being used when 
retardation is desired. Similarly, lesser amounts of chlorides or other 
desiccants are to be used when retardation of the setting of a 
cementitious mixture is desired, a greater amount of said substances being 
used when it is desired for the mixture to harden more rapidly. 
The present invention particularly contemplates the usage of additive 
mixtures disclosed in the aforesaid patent which include as the primary 
constituent the glucosaccharides so disclosed, the glucosaccharides being 
particularly present in the mixtures according to the invention in 
quantities greater than those quantities disclosed in the aforesaid 
patent. 
The present method provides a hydraulic mortar mixture which can be used at 
any time during the prolonged storage period as aforesaid, the mortar 
immediately setting and developing usual strength characteristics as soon 
as the mortar is applied to brick, block, and other similar building 
materials. Accordingly, the use of the present invention does not result 
in a delay in setting time or strength development as is the case with 
prior retardation compositions and methods. It is a teaching of the 
invention that the normal hydraulic hydration process which occurs in the 
otherwise retarded settability of the present mortar mixtures is 
accelerated by absorption of moisture by the building materials to which 
the mortar is applied. Accordingly, the mortar immediately begins setting 
at least as rapidly as it normally would if the mortar had not been 
formulated with an additive according to the invention which allows 
storage of the mortar for a prolonged period of time. Further, the normal 
strength development of the mortar is not affected by the process of the 
invention. 
As can be appreciated by the disclosure provided herein, the present 
invention provides a method of suspending the hydraulic hydration action 
of mortar mixtures, the invention allowing either immediate use of the 
mortar or use after a prolonged storage period. While the glucosaccharides 
essentially disclosed in the aforesaid patent are utilized as the additive 
according to the present method which acts to accomplish the unexpected 
results and advantages of the present invention, it is to be noted that 
there is no teaching in the aforesaid patent which would lead one of 
ordinary skill in the art to the conclusion that such additives would be 
useful to produce the results and advantages provided by the present 
invention, there particularly being no indication in the aforesaid patent 
that the prevention of moisture evaporation from mortars formulated 
according to the invention would prevent setting of such mortars for 
prolonged periods of time. 
The methods of the present invention particularly relate to formulation of 
mortars which contain as one constituent thereof hydraulic cements such as 
portland cement, such cements typically being comprised of finely divided 
gray powder composed of lime, alumina, silica and iron oxide as 
tetracalcium aluminoferrate, tricalcium aluminate, tricalcium silicate, 
and dicalcium silicate. Such cements typically also comprise small amounts 
of magnesia, sodium, potassium and sulphur. Portland cement when provided 
with water for hydration will harden under water, air not being required 
for hardening of such mixtures. Sand and other substantially inert 
aggregate material is usually added to portland cement as a diluent. Other 
additives, such as coloring additives, air entrainment agents, and the 
like can also be added to portland cement in a known fashion and can be 
used in the practice of the present invention. 
It is particularly to be noted that air entrainment agents can be added to 
the mortar compositions formed according to the present methods, such air 
entrainment agents being well-known in the art. Exemplary of such agents 
is the proprietary material known commercially as Vinsol Resin, a product 
of the Hercules Powder Company, which is a hard, brittle, dark-colored, 
thermoplastic resin derived from pine wood, and containing phenol, 
aldehyde, and ether groups. This product in supplied in lump, flake, and 
pulverized forms, and as a stable emulsion. Other air entrainment agents 
are commercially available and are well-known in the art. Such air 
entrainment agents can be used according to the invention to increase the 
volumetric quantity of air entrained within mortars according to the 
present invention when the volumetric quantity of air entrained within the 
mixtures are to be increased over the quantities provided by the admixture 
into the mortar of the glucosaccharide additives according to the 
invention. While mortars useful according to the invention can be 
formulated with a quantity of entrained air as low as 12% of the volume of 
the mortar, it is preferred that the quantity of air entrained be 
equivalent to 20 to 30% of the volume of the mortars. This greatly 
increased quantity of air entrained according to the present invention 
facilitates use of the mortars according to the invention to provide the 
results and advantages referred to herein. The volumetric quantity of 
entrained air according to the invention can be greater than 30%, a 
quantity of 40% being within a desired range. When the volumetric quantity 
of entrained air in mortars formulated according to the present invention 
is to be increased over and above that amount of air entrained by 
admixture of the glucosaccharide additives, commercially available air 
entrainment agents may be used in a known fashion to increase the 
volumetric quantity of air entrained in the mortar. 
The present invention particularly provides for the use of pozzolanic 
materials, particularly fly ash, in the mortar mixtures formulated 
according to the invention. Generally, pozzolanic materials are 
pulverulent siliceous or siliceous and aluminous substances which react 
chemically with lime and moisture at ordinary temperature to form a 
cementitious material. According to the present invention, pozzolanic 
materials, particularly fly ash which comprises the noncombustible ash 
carried out of a bed of solid fuel by draft, are utilized with hydraulic 
cement, such as portland cement, and without the addition of slaked lime 
to form a mortar mixture of substantial strength and which has the storage 
and setting characteristics referred to herein. Accordingly, while the 
portland cements useful according to the invention may contain lime which 
is not hydrated, hydrated lime is not added to the mortar mixtures 
according to the invention, it being thereby possible to eliminate the 
whiting efflorescence on the surface of mortars which typically contain 
hydrated lime. Further, it is known that concrete/mortar aggregates in 
certain geographical locations contain a water soluble calcium content 
which is present in sufficient quantity which, when combined with portland 
cement and water, accelerates the hydraulic hydration action thereof to a 
point that such aggregates are undesirable for use. By utilizing the 
glucosaccharide additives according to the teachings of the present 
invention in percentages at the upper portion of the desired range 
according to the present invention, such adverse conditions can be 
controlled and such aggregates can then be used without the undesirable 
characteristics previously encountered in their use. 
Accordingly, it is to be seen that the different characteristics of 
portland cements and the different characteristics of aggregates which 
occur in different geographic locations can be overcome through the 
practice of the present invention such that adverse setting times do not 
occur under such conditions. By varying the quantity of additives 
according to the present invention, these differing characteristics of 
portland cements and aggregates can be controlled in order to produce a 
desired settability of mortars formed from such materials. In particular, 
these materials having different characteristics can be controllably 
suspended in a mortar mix in a desired plastic state of workability for 
periods of at least 72 hours, the mortar being capable of use at any time 
during this prolonged period as aforesaid. 
Mortar formed according to the present invention has as the primary 
ingredients thereof standard cementitious materials which conform to 
certain American Society Testing Material Standards. In particular, the 
following materials are of particular use: 
(1) Portland Cement of Types I, II and III ASTM Designation C-150; 
(2) Portland Blast Furnace Slag Cement of Types IS, IS(MS), IS-A and 
IS-A(MS), ASTM Designation C-595 for blended hydraulic cement; 
(3) Fly ash and raw or calcined natural pozzolans according to ASTM 
Designation C-618; and, 
(4) Masonry cement type II, ASTM Designation C-91 for masonry cement. 
Aggregates useful in the formation of standard mortars, ASTM Designation 
C-144, are also useful according to the present invention. Water which is 
used in the formation of the present mortars should be clean and potable. 
Methods used for measuring materials useful in mortars according to the 
invention should be such that the specified proportions of the mortar 
materials can be controlled and accurately maintained according to ASTM 
Designation C-94. It is to be further understand that mortars formulated 
to the present invention are mixed and delivered to a job site in 
conformation to the requirements of the National Ready-Mix Concrete 
Association. The mortars formulated according to the invention are 
particularly to be stored in containers of suitable size and which are 
capable of being sealed from ambient until the mortar is to be used. 
Mortar proportioning in the practice of the present invention should also 
conform with ASTM Designations C-476, particularly Table I thereof. The 
ASTM Designations referred to herein are further incorporated hereinto by 
reference. 
The additive particularly useful according to the present invention 
comprises saccharide polymers are described in U.S. Pat. No. 3,432,317, 
each said saccharide polymer being composed of glucose units and having a 
size of from three glucose units to on the order of 25 glucose units. It 
is preferred that a larger proportion of the saccharide polymers have from 
three glucose units to on the order of 10 glucose units in the polymer 
structure. The amount of the glucosaccharide polymeric additives mixed 
with the cementitious materials according to the present invention to 
produce a mortar having the characteristics described herein typically 
various between two and 20 ounces of the additive for each 100 pounds of 
cement employed in the mortar. A range of six to eight ounces of the 
additive is preferred for most cement materials, particularly most 
portland cement materials. Utilization of the glucosaccharide additives 
according to the invention enables sufficient air to be entrained in the 
mortar mixture to facilitate development of the characteristics particular 
to the invention, that is, the production of a desired retardation with 
maintenance of a desired workability of the mortar and the accomplishment 
of an immediate setting and strength development of the mortars on 
application thereof to brick, block, stucco, gunite, and other building 
materials. In order to produce an air entrainment factor in the mortar 
mixtures according to the invention, air entrainment agents of known 
composition can be added to the mortar mixtures in order to increase the 
air entrainment factor to between 12 and 35%, particularly 18 to 27% of 
the volume of the mortar mixture. Water evaporation within the present 
mortar mixtures can be retarded in a manner additional to storage of the 
mortar within said sealed containers, particularly by the addition of 
resins, such as methyl cellulose and hydroxyethyl cellulose. 
A mortar formulated according to the present invention using 6.6 ounces of 
the glucosaccharide additive material as described hereinabove per 100 
pounds of portland cement produced case test samples having the following 
strength given in pounds per square inch, the mortar from which the test 
samples were cast containing 0.0768 units of absolute volume of portland 
cement and 0.0523 units of absolute volume of fly ash mixed with masonry 
sand and water: 
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Test Results Reported in Pounds per Square Inch 
Time In 
Suspension 
7-Day Results 
28-Day Results 
28-Day Results 
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24 Hours 2570 psi 3760 psi 3920 psi 
48 Hours 2705 psi 3860 psi 3910 psi 
72 Hours 2810 psi 3845 psi 3830 psi 
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Examples of particular mortar mixtures according to the present invention 
are provided hereinafter, it being understood that such examples are 
exemplary only and are not limiting of the invention as described herein. 
In each of the following examples, each unit of cement indicated as 
"Sacks" is a 94 pound unit. The saccharide additive employed in the 
examples essentially comprises glucosaccharide polymers as described 
hereinabove.