Mixed gypsumless portland cement

A mixed gypsumless Portland cement of high initial and long-lasting strengths which contains 60-96.7 weight percent gypsumless Portland cement clinker with the specific surface of 350-550 m.sup.2 /kg and 3-40 weight percent of ground latently hydraulic matter, such as granulated blast-furnace slag, light ash, and the like, which two components have been ground in the presence of 0.01-0.1 weight percent of a liquid milling admixture, advantageously with a synthetic surface active matter with wetting properties, and containing 0-20 weight percent of fine amorphous SiO.sub.2 and/or 0.1-3 weight percent sulphonated polyelectrolyte or ligninsulphonate and 0.5-6 weight percent alkaline carbonate, hydrogen carbonate, or alkaline hydroxide.

The invention applies to a mixed cement based on cementation clinker mixed 
with latently hydraulic admixtures. 
It is known in the production of cement to replace a part of the clinker in 
the cement by latently hydraulic matters. These matters include granulated 
blast-furnace slag, pozzolana, and, more frequently, light ash. Actually, 
mixed cements participate in the production of cements--in the world-wide 
measure--quite considerably. More than 90 million tons of matters with 
latently hydraulic admixtures share in the overall production of more than 
280 million tons of mixed cements, and the use of slags and ashes leads to 
the production of more than million tons of cements. (R. Bucchi, "Outlines 
on additions and composite cements of view of industry", Proc. 8 Inter. 
Congress of Cement, Rio de Janeiro 1986, Vol. I, pp. 185-195.) 
A way is also known to enable the better exploitation of the hydraulic 
properties of ground slags via slag-alkaline cements and concretes. V. D. 
Gluchovskij has paid considerable attention to these problems. (See V. D. 
Gluchovskij, Scolochonyje i Scolocnozemelnyje gidravliceskije vjazuscije i 
betony, Kiev 1979, 1982.) In these works, there has been proposed the use 
of alkaline compounds, namely silicates and hydroxides, in considerably 
higher concentrations compared to that applied up to now, e.g., from 5 to 
10 weight percent of the ground slag. 
In USSR Patent 1,046,222 there is mentioned the composition of the binding 
agent containing more than 60 weight percent of slag ground at least to 
the specific surface of 300 m.sup.2 /kg, from 7.5 to 9 weight percent of 
the 20% solution of KOH, and from 22 to 27 weight percent of a solution of 
soda silicate. 
From the Czech author's certificate 224,163, it is known that the binding 
agent based on hydraulically active gypsumless substance containing from 0 
to 40 weight percent of ground cementation clinker with the specific 
surface of from 250 to 700 m.sup.2 /kg, from 100 to 40 weight percent of 
ground latently hydraulic matter, for example, slag, fly ash, and 
pozzolana, with the specific surface of from 300 to 600 m.sup.2 /kg, from 
0 to 20 weight percent of very fine SiO.sub.2 and/or containing milling 
admixtures, such as ligninsulphonates, and further containing batch water, 
synergistically acting mixture of substances containing from 0.2 to 3 
weight percent sulphonated or sulphonmethylated condensate of monovalent 
or multivalent phenols with formaldehyde doped eventually with ferric, 
aluminum, or chromium cations, and from 0.5 to 10 weight percent of 
alkaline metal salt or alkaline earth metal, where the weight percent of 
matters is related to the overall weight of the powder binding agent. 
From the technical literature it is also known to add to Portland cement 
slag ground to the specific surface of more than 500 m.sup.2 /kg (K. Sato, 
E. Konishi, and K. Fukaya, "Properties of very fine blast furnace slag 
prepared by classification", Proc. 8 Inter. Congress of Cement, Rio de 
Janeiro 1986, Vol. 4, p. 239). 
The disadvantage of mixed cements is the slow growth of the initial 
strength. The hydration process is accelerated with the help of some known 
methods, especially through the addition of accelerating substances, for 
example, gypsum, calcium hydroxide, and other alkaline salts. The 
hydration process can also be accelerated in grinding the slag to a higher 
specific surface. In contradistinction to the cementation clinker, slags 
ground beyond the specific surface of 500 m.sup.2 /kg have no practical 
manifestation. 
The mentioned disadvantage has been removed by the mixed gypsumless 
Portland cement according to the present invention. The substance of the 
cement contains from 60 to 96.7 weight percent of gypsumless Portland 
cement clinker with the specific surface of from 350 to 550 m.sup.2 /kg, 
from 3 to 40 weight percent of a ground latently hydraulic matter, for 
example, the granulated ground slag, fly ash, and the like. Both these 
components are ground in the presence of from 0.01 to 0.1 weight percent 
of a liquid milling admixture, advantageously with a synthetic surface 
active substance with wetting properties. The cement further contains from 
0 to 20 weight percent of finely amorphous SiO.sub.2 and/or from 0.1 to 3 
weight percent of sulphonated polyelectrolyte, for example, sulphonated 
polyphenolate or ligninsulphonate, and from 0.5 to 6 weight percent of 
alkaline carbonate or hydroxide. 
Systematic experimental works have proved the possibility of obtaining 
binding agents, based on the mixed cement according to the invention, 
which achieve both high initial and long-lasting strengths. 
Advantageously, use is made of the liquid milling admixture, especially of 
that with wetting properties, in milling the mixed cement and/or its 
different components. High initial strength has been achieved due to the 
elimination of the gypsum replaced by the synergistically acting mixture 
of sulphonated polyelectrolyte, for example, sulphonated polyphenolate or 
ligninsulphonate, and alkaline salt, especially carbonate. The latently 
hydraulic substance has been ground to the specific surface which exceeds 
that of current mixed cements, i.e., to the specific surface in the range 
from 350 to 550 m.sup.2 /kg. 
The invention is exemplified by the following examples which, however, do 
not limit it. All percentage data set forth in the examples and tables are 
weight percents. The weight percents are related to the weight of the 
clinker.

EXAMPLE 1 
From the clinker of the cement works in Prachovice and the granulated 
blast-furnace slag from Trinec, mixed gypsumless cements were prepared and 
ground in the ball mill with the addition of 0.05% cement liquid milling 
admixture. This admixture was the commercial preparation ABESON TEA 
(sodium alkylarylsulphonate or triethanolamide of 
dodecyl-benzoyl-sulphonic acid). The mixed cements were prepared by 
grinding to the specific surface in the range from 420 to 470 m.sup.2 /kg 
in different ratios of the cement to the slag. From the different 
mixtures, mortars were prepared with the cement-water ratio of w=0.31 and 
with the ratio of cement:sand of continuous granulometry=1:3. As 
admixtures, the following were applied: soda and Kortan FN (sodium-ferric 
polyphenolate with the addition of triethanolamine) dissolved in batch 
water. Table 1 shows the cement compositions and achieved properties. 
EXAMPLE 2 
From the clinker of the cement works in Prachovice and the granulated 
blast-furnace slag, mixed cement was prepared with the specific surface of 
530 m.sup.2 /kg. The composition of the cement was the following: clinker 
80% and slag 20%, with 0.05% of the preparation ABESON TEA having been 
applied as the milling admixture. From this cement, pastes were prepared 
with the cement-water ratio w=0.24 of freely liquid consistency. Soda and 
Kortan FN were applied as admixtures in the amounts set forth in Table 2. 
Table 2 also shows the properties of these pastes. 
EXAMPLE 3 
The clinker from the cement works Prachovice was ground with granulated 
blast-furnace slag to give the mixed cement of the specific surface of 460 
m.sup.2 /kg. The content of the slag in the cement amounted to 10%. In the 
homogenizer further admixtures were added to the cement, namely 0.2% of 
Kortan FN and 0.5% of soda. This cement has been worked up as a cement 
with the plastic consistency of w=0.22. The initial setting of this cement 
began after 3 minutes. After 15 minutes from the preparation it reached 
the compression strength of 1.6 MPa, after one hour 2.5 MPa, after two 
hours 4 MPa, after four hours 8 MPa, and after 5 hours 12 MPa. The 
achieved strength after 24 hours equaled 35 MPa. 
The cement for which both the clinker and the slag have been ground 
separately to the specific surface of 450 m.sup.2 /kg and mixed prior to 
further treatment has the same properties in practice. 
EXAMPLE 4 
The clinker from the cement works Prachovice was ground together with the 
blast-furnace slag to form the mixed cement with the specific surface of 
440 m.sup.2 /kg with liquid milling admixture added. Of this mixed cement, 
paste was prepared with w=0.24 of freely liquid consistency and setting 
starting after 50 minutes. The applied admixtures were 0.4% of Kortan FN 
and 1% of soda. The compression strength of the paste was 3.5 MPa after 
two hours after the setting, 10 MPa after 41/2 hours, 55 MPA after 24 
hours, and 89 MPa after twenty-eight days. 
From the same cement a mortar was prepared with w=0.31 of from plastic to 
soft consistency with the use of sand 0-6.3 mm from Halamky. The applied 
admixtures were 0.8% of Kortan PN and 1.9% of soda. The setting of this 
mortar started after 50 minutes. 
TABLE 1 
______________________________________ 
Content Start Compression 
Of Slag Of Strength (MPa) 
In Content of Density Setting 
After After 
Cements 
Admixtures (kg/m.sup.3) 
(min) 24 hours 
3 days 
______________________________________ 
5% Kortan 0.7% + 
2382 105 46.8 53.6 
Soda 1.9% 
10% Kortan 0.7% + 
2402 65 42.6 51.2 
Soda 2% 
15% Kortan 0.7% + 
2382 65 41.1 49.2 
Soda 2.1% 
20% Kortan 0.7% + 
2343 55 39.0 48.0 
Soda 2.2% 
30% Kortan 0.7% + 
2324 40 30.0 40.0 
Soda 2.4% 
0% Kortan 0.6% + 
2324 45 42.0 45.1 
Soda 1.6% 
Comparison Experiment according to the Czech author's 
certificate 244,163 
80% Kortan 0.6% + 
2300 120 3.2 15.1 
Soda 4% 
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TABLE 2 
__________________________________________________________________________ 
Admixtures (%) 
Compression Strength (MPa) After: 
Soda 
Kortan FN 
2 hrs. 
3 hrs. 
5 hrs. 
6 hrs. 
24 hrs. 
7 days 
28 days 
__________________________________________________________________________ 
1 0.4 4.4 6.3 9.4 -- 65.5 
75.0 
98.0 
1 0.5 3.5 4.8 7.0 16.5 
58.5 
72.0 
90.6 
1 0.6 2.5 3.5 5.6 7.1 
60.0 
83.5 
102.4 
1.2 
0.4 4.0 5.3 7.5 -- 58.0 
76.0 
97.6 
1.2 
0.5 3.6 5.3 7.5 -- 59.0 
74.0 
-- 
1.2 
0.6 3.3 3.9 5.8 -- 59.5 
80.5 
-- 
1.4 
0.4 4.3 6.5 11.3 
-- 66.0 
87.5 
-- 
1.4 
0.5 3.5 6.3 8.6 -- 54.0 
71.5 
-- 
1.4 
0.6 2.3 3.6 6.3 -- 61.5 
-- -- 
1.6 
0.4 4.5 7.5 12.0 
-- 60.5 
-- -- 
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