WO2001044358A1

WO2001044358A1 - Organic-mineral modifier for cementitious systems

Info

Publication number: WO2001044358A1
Application number: PCT/US1999/030186
Authority: WO
Inventors: Shahviran Teimurogly Babeav; Jaime Moreno; Augusto Eberhardt; Rafael Shahviran Babeav
Original assignee: Bbf & M Chemicals Corp
Current assignee: Bbf & M Chemicals Corp
Priority date: 1999-12-17
Filing date: 1999-12-17
Publication date: 2001-06-21
Anticipated expiration: 2002-06-17
Also published as: AU2590400A

Abstract

For use in cementitious systems, a modifier is disclosed comprising a solid polydispersed organic-mineral composition consisting essentially of a water reducing component, a mixture of water-soluble organic and inorganic salts and a mineral base. The water reducing component comprises an organic polymer with low adsorbent activity. The mineral base comprises a mixture of two or more active mineral substances with specific surface areas of no less than 1500 cm2/gm and a high adsorbent capacity with respect to water. The water reducing component preferably comprises a homopolymer obtained by a polymerization regulated by formaldehyde mixed with formalin with a mineral starting system followed by adding a regulator for the degree of polymerization. The solid polydispersed organic-mineral composition is obtained without using external heating sources.

Description

ORGANIC-MINERAL MODIFIER FOR CEMENTITIOUS SYSTEMS

The new invention presented here belongs to a group of industrial construction materials and can be used in the fabrication of clinker, cement, concrete and/or other construction materials based on portland cement and its variations. It is used particularly to increase the fragmentation degree of cement when grinding clinker with different types of calcium sulphate and mineral additives. It can also be used to increase the strength of cement and/or to increase the hourly production of the mill, to improve the workability of mortars and concretes, and to increase the density and strength of cementitious systems at all ages.

To improve the above-mentioned characteristics of cementitious systems, various specially synthesized modifiers are used, consisting of organic polymers and/or their combinations with mineral substances of different quantitative compositions. Generally such polymers are the result of a polycondensation of two or more components differentiated mainly by their chemical structure. As a result of a progressive interaction of moπomeric molecules of the initial components, water soluble polymers with regular structures are formed and low molecular weight by-products ( water, for example) are separated.

Modifiers based on sulfonated products, derived from the copolycondensation of melamine with formaldehyde [1] or of melamine and urea (carbamide) with formaldehyde [2] are well-known. Such modifiers have high plasticizing and water reducing capacities in comparison with all cementitious systems; they do not incorporate air into mortars and concretes and do not reduce concrete strength with a constant water/cement ratio.

These modifiers have several disadvantages. The most significant disadvantage is the tendency for spontaneous polymerization during the synthesis process or during storage, due to the action of solar light or high temperature (above 25° C). Because of this disadvantage, the fabrication of dry modifier is complicated and when used as modifiers in cement grinding, the efficiency is radically lowered. Such modifiers are fabricated with expensive raw materials and are allocated In high percentages (in concrete 0.4 -0.8% of cement weight and in grinding cement 1.2 - 2.5% of clinker weigh) thus reducing the area of application in the construction materials industry.

The existing product most similar to this invention is the control modifier based on the poly-condensation of formaldehyde with naphthalene sulfonate [3]. This aforementioned copolymer has a high plasticizing and water reducing effect in cementitious systems. It can be mixed with active mineral additives (for example, micro silica) [4] or be converted to a dry form. The dry form of this modifier has been used in the production of composite cements (modified), has high strength at all ages and develops rapid strength during the onset of hardening [5].

The disadvantage of such a polymer as a modifier for cementitious systems is the ability to incorporate 2-4 % of air, thus producing a decrease in mortar and concrete strengths during early stages. Very aggressive substances and high temperatures are necessary for the synthesis of such modifiers, resulting in ecological problems during industrial production.

High temperature is necessary during the fabrication of the dry form of the copolymer or its composites containing micro silica. The authors of this invention have corroborated experimentally that if the critical temperature (120 - 130° C) is slightly exceeded, a thermal destruction of polymeric molecules of the modifier is observed with an alteration of its molecular mass distribution (MMD). As the efficiency of such modifier is obtained only with a high content of the polymeric fraction and with a given MMD, the aforementioned disadvantages lead to an irreversible reduction in the efficiency of the modifier.

The high efficiency of modifiers based on polymers of formaldehyde with naphthalene sulfonate in cementitious systems is produced by a chemisorption of the polymer in a hydrated πeo-genesis (using an aqueous solution of modifier) or in the active center of the solid phases (during inter-grinding of clinker, calcium sulphate, mineral additives and dry modifier) with an interaction of sulphuric groups with basic fragments (containing CaO) on the surfaces of the clinker minerals. The blockade of such active surfaces requires relatively high doses of modifier 0.5 to 1.0 % of cement mass when using aqueous solutions, and 1.75 - 2.00 % of clinker in the fabrication of modified cement [6J.

With the new product, the goal is to obtain a chemical composition of the modifier without incorporating air and without a reduction in the hardening kinetics of cementitious systems while having a high water reducing effect in pastes, mortars, and concretes; improving the particle distribution of cement; and increasing the density and strength of cementitious systems at all ages.

Such a goal is obtained by using as a modifier a solid poly-dispersed organic-mineral composition consisting of a water reducing component based on an organic polymer with low adsorbent activity, in a mixture of mineral and organic water soluble salts and a mineral base of two or more active mineral substances with a specific surface no lower than 1500 cm 2/gr. and with a high capacity for water adsorption.

The organic polymer used is a homopolymer obtained by means of a controlled polymerization of formaldehyde with formalin (aqueous solution of formaldehyde) and a mineral starting system, adding a regulator for the degree of polymerization. The solid poly-dispersed organic-mineral composition is obtained without using external sources of heat. The mass proportions of the organic-mineral modifier components are as follows:

Homopolymer 10 - 16%

Water soluble salts 22 - 33%

Mineral base 44 - 66%

Water 2 - 7%

The homopolymer used is the product obtained from the aldollic condensation of formaldehyde in the presence of an starting system assuring a pH in the medium of no less than 11.5 at a temperature of 42 - 85" C in thermodynamic equilibrium conditions obtained by adding the starting system to the monomers.

The product of the aldollic condensation of formaldehyde under thermodynamic equilibrium conditions in the presence of a starting system containing hydroxyl and nitrate ions Is also used as a polymer.

The product of the homopolymerization of formaldehyde under conditions of kinetic equilibrium obtained by adding formalin to the starting system can also be used as a polymer.

The following is used as a starting system: a mixture of one or more earth-alkaline metal oxides (MeO) and nitrates of mono or di-valence metals [M(N0₃)x], where x = 1 - 2; the mass proportion of the components MeO: M(N03)x = 1 : 3 to 1 : 5 or the mixture of the corresponding hydroxides with the aforementioned nitrates; the proportion of components is Me(OH)₂ :M(Nθ3)x =1 : 2.5 to 1 : 4.

Another starting system used is a mixture of one or more nitrates of earth alkaline metals with alkali MOH (M = Li+, Na+ or K+) in a proportion of 1 : 0.4 to 1 : 1.

An additional starting system which can be used is a suspension of calcium hydroxide obtained by mixing water with quicklime or hydrated lime.

Industrial calcium nitrate can be used as the nitrate component in the starting system

Mineral acids forming soluble salts with calcium ions (such as percloric, perbromic, nitric or metaphosphoric acids) are used as regulators for the degree of polymerization.

Individual carboxylic acid, its derivatives oxi, halures or amino, with an ionization constant of k₍>10^"12, or the mixture of two or more of the aforementioned acids can also be used as regulators for the degree of polymerization.

Water soluble salts used are composites which form part of the starting system and the products of their chemical interaction.

Known hardening accelerators and retardants are used as water soluble salts also.

The mineral base of the solid polydispersed organic-mineral composition is a mixture of calcium hydroxide with one or more anhydrous mineral substances containing active components with respect to clinker minerals and having a high adsorbent water capacity, for example, fly ash, calcium carbonate, micro silica, granulated blast furnace slag, volcanic ash, natural or artificial pozzolan, kaolin, clay and others.

The mineral base of the solid polydispersed organic-mineral composition consists of mixtures of the above- mentioned components with a specific surface of no less than 4500 cm²/gr.

The organic portion of the solid polydispersed organic-mineral composition used to modify materials based on white cement consists of the leuco form of the homopolymer formed at a temperature no higher than 70° C.

The intermediate product, which is the aqueous solution of the organic-mineral composition formed after adding the regulator for the degree of polymerization, is also used as a modifier.

The principle of the technical solution proposed is that the organic-mineral modifier is formed by three components in an optimal proportion: the water reducing organic homopolymer which does not have a high adsorbent activity and does not include air; the mixture of water soluble salts which regulates the kinetics of the formation of the structures and the hardening; and the mineral base which carries the first two components, compacts the structure of the cementitious systems, and provides crystallization centers of the hydrated neogenesis.

The innovational aspects of this technical solution consist of:

- The use of the formaldehyde homopolymer as the water reducing component.

- The application of the starting system for the control of the directional selectivity of the process, subsequently using the starting system and the products of its transformation as the regulators of the formation processes of the structure and hardening of the cementitious materials. - The utilization of the mineral base with high water adsorbing capacity to obtain the solid polydispersed organic-mineral composition (modifier) with no application of heat sources.

As is normal with modifiers for cementitious systems, the function of the water reducing component is accomplished by the copolymers of a polycondensation type, based on formaldehyde and sulfonates derived from aromatic hydrocarbons (melamine, naphthalene, anthracene and others). As a consequence of a bimolecular attraction of the structure [difference of polarity between the base (aromatic hydrocarbon radical) and the functional group (sulfonic group)], there is considerable surface activity within the limits of the condensed phases and they are easily adsorbed in the hydrated neogenesis if introduced in the cementitious systems with water or in the active centers of clinker grains during grinding of the components (intergrinding). The formation of such adsorbent layers requires a higher modifier consumption in order to obtain the required technical effect and is accompanied by a retardation of the hardening process during the early phases of hydration of the cement paste.

When using the proposed modifier, which is based solely on formaldehyde, such polarity difference between the hydrocarbon base and functional groups does not exist, so the aforementioned homopolymer does not have significant surface activity in the cementitious systems.

In tests conducted by the authors, the adsorbent activity (Aύ with relation to the clinker minerals of the copolymer based on naphthalene sulfonate and formaldehyde is 10 , for the homopolymer based on formaldehyde, it is A < 10 .

Depending upon the condition of the synthesis based on formaldehyde, polymers of the polycondensation or of the polymerization type can be obtained; the first does not have the characteristics needed for its utilization in the composition of the modifier. The use of the above-mentioned starting system in the proposed invention allows us to control the synthesis of the polymer, assuring sufficient homogeneity and high quality of the final product . The composition of the starting system is chosen in such a way that the products of its chemical transformations can be used with maximum profitability as regulators of the formation process of structures and hardness of the cement systems.

Also new is the use of the combination of special substances which forms an optimum mineral compound with a high water absoφtion capacity as a mineral base to obtain the solid organic-mineral polydispersed modifier without the use of complimentary sources of heat. This technical solution concurrently allows:

- Avoidance of thermal-destruction of the organic polymer.

- Prevention of the deactivation of the surfaces of the mineral components.

- Creation of optimum conditions for the uniform distribution of the modifier in cement systems, for the transference of mineral components, and for the transference of active organic hydro-solubles.

The experiments, conducted by this work's authors, showed that with this method of obtaining the modifier, its mineral base is not an inert agent, but contributes to the of the structure and creates many active centers, around which, during the hardening process, the formation and the consequential consolidation of the cement systems' crystallized structures occurs.

The principle of this invention can be seen more clearly in the manufacturing examples which follow.

EXAMPLE 1

The composition of the solid organic-mineral polydispersed composition shown here was used as a water reducing modifier under laboratory conditions in order to increase cement strength through a combined grinding of clinker, gypsum with two molecules of water, and the aforementioned modifier in a single-chamber mill, 60 cm. in length and 50 cm. in diameter. The chamber load of 263 kg of cylpebs consisted of 79 kg (30%) with dimensions (diameter and length) of 14 x 22mm and 184 kg (70%) of 16 x 25mm.

The relative mass of the cement components used is as follows:

Clinker: 95%

Gypsum with two molecules of water: 5%

The percentage of solid modifiers refers to the cement mass and are indicated in Table 1.

The modifiers which were used were the solid organic-mineral polydispersed composition, as proposed, and the control modifier, which is the dry product of the polycondensation of naphthalene sulfonate with formaldehyde in the mixture with sodium sulfate, obtained by drying its aqueous solution at a temperature of 120-140° C.

The portland cement clinker composition used was: c_λs = 64-68 % c₂s = 7-10 %

C₄AF = 10-12 %

K₂0 = 0.85 %

Na₂ = 0.6 %

LSF = 0.98 - 1.02 %

The modified cements that were obtained were tested in cement and sand mortars having the same consistency as the control sand mortar without modifier (Table 1, Line 7).

The comparative data in Table 1 show a noticeable increase in cement strength in the early ages as well as in the ages prescribed in the codes when the proposed modifier with the proposed composition is used (Lines 1-4), when compared with cement containing the control modifier (Lines 5 and 6) and cement without modifier (Line 7).

TABLE 1

Using the solid polydispersed organic-mineral composition from the proposed modifier composition in doses (with reference to the organic fraction of the modifier) below 0.6% and above 1.2%, the results obtained with respect to strength of the cement samples are higher than the strength values of the control-modifier samples.

EXAMPLE 2

The solid polydispersed organic-mineral composition was used as in Example 1. As a water reducing component, the homopolymer containing a carbon chain was used, which was obtained in the controlled polymerization of formaldehyde when formalin was added to the mineral starting system. In order to obtain the homopolymer with the desired value of adsorbent activity, a reactor was added at the end of the synthesis process to regulate the degree of polymerization which diminished the pH of the reactive mass to a value of between 6.0 and 8.2 . The solid organic-mineral modifier was used in the joint grind with the portland cement clinker and calcium sulfate with two molecules of water (gypsum) in conditions analogous to Example 1. In order to obtain modified cements, the setting times of normal consistency cement pastes were determined, as were the compression strengths of the samples of sand and cement mortars from the earlier stages and those specified by the codes. From the results shown In Table 2, it can be deduced that the use of the modifier with the organic polymer, synthesized without the polymerization degree regulator, produced a considerably prolonged setting time for normal consistency cement paste and a noticeable delay in the standard cement and sand mortar strength development in the earlier stages of the test (Table 2, Line 1).

The employment of the polymerization degree regulator in an optimum quantity permits the obtaiπment of the organic portion of the solid polydispersed organic-mineral composition with the required value of adsorbent activity (Table 2, Line 2); and the cement modified by this modifier shows normal setting times and high strengths in all of the tests performed. TABLE 2

EXAMPLE 3

The solid polydispersed organic-mineral composition was used as in Example 2. In the "A" variant, the solid polydispersed organic-mineral composition was obtained without heat utilization, solely by applying a mineral base with a high water-adsorbent capacity; and In the "B" variant, it was obtained by means of a drying temperature of 130 -135° C. The results displayed in Table 3 show that the application of a complimentary heat source initiates a reduction in the modifier's water reduction capacity, which would be followed by a deterioration of strength in the samples studied (Table 3, Line 2).

TABLE 3

* After mixing together all the components of the organic-mineral modifier, the temperature increased spontaneously,

EXAMPLE 4

The solid polydispersed organic-mineral modifier was used as in Example 2. The proportion of modifier ingredients, the test results with normal consistency cement paste and a standard mortar, and the employment of modifiers of different compositions are shown In Table 4.

TABLE 4

From the data in Table 4 it can be deduced that the use of modifiers in which the ingredients are within the indicated limits results in: (a) the reduction of water content in pastes of normal consistency from 29 to 37 %, and (b) the increase of the initial strength to 56%, as an average, and strength at 28 days to about 67% (Table 4, Lines 1-4) in comparison with the cement paste and control mortar (Line 5, Table 4).

If the solid polydispersed organic-mineral composition is used with a homopolymer with a formaldehyde content below 10%, it is not possible to obtain a cement paste with normal consistency and with a water content below 23%, and consequently, with a standard mortar strength at the standard test time ( 28 days) above 77 N/mm .

If we increase the homopolymer content in the composition to more than 14%, the hardening process in the early stages is noticeably delayed.

The higher water level content restrictions (humidity) of the solid polydispersed organic-mineral composition is related to the fact that the aforementioned existence level (Table 4, Line 3) complicates grinding conditions and makes uniform distribution of the modifier on the surface of the material to be ground difficult. The lower value of the water content level (Table 4, Line 1) is related to the fact that if its quantity is reduced, the spontaneous heat increase (resulting upon mixing together all the organic-mineral modifier ingredients) will surpass 100°C, resulting in the thermo-destruction of the organic-polymer.

The optimum water soluble salt content recommended for the proposed invention (22-31%), is based on the fact that below the inferior limit there is a delay in the setting and hardening process in the modified cements, and above the higher level, the initial setting time would not be within code and standard requirements.

The superior and inferior limits of the mineral base in the solid polydispersed organic-mineral composition are related to the circumstance that in the first case (less than 40 %) a uniform distribution of the modifier components is not obtained on the surface of the material to be ground; in the second case (more than 66 %) a decrease in the water reducing effect of the modifier is observed.

EXAMPLE 5

The solid polydispersed organic-mineral composition was used as in Example 4. The homopolymer obtained through the aldolic condensation of formaldehyde was used as the modifier's water reducting component . To assure the directional selectivity of the homopolymer synthesis process, a hyperalkaline mineral starting system was used which assured a pH of the reactive mass of less of than 11.5. The polymer synthesis was made in balanced thermodynamic conditions that were obtained by adding the monomer starting system (formaldehyde aqueous solution) at a temperature of between 42° to 85° C. The synthesis conditions of the water's organic reducing component and the solid organic-mineral composition's influence over the water content in the cement paste of normal consistency are indicated in Table 5.

TABLE 5

* Value of the water content in cement paste of normal consistency, without modifier.

As deduced from the data in Table 5, using the solid organic-mineral composition that contains the homopolymer and is synthesized at a temperature interval of 42 to 85° C with a pH reactive mass of no less than 11.5, a reduction of 30-33% of water content in normal consistency cement paste is achieved (Table 5, Line 4). If the modifier's organic portion is synthesized with a low pH value (Table 5, Line 3) or with values without temperature limits (Table 5, Lines 2 and 7), in the combined grinding of portland clinker, calcium sulfate (gypsum), and the organic-mineral modifier, a significant reduction in water content of normal consistency cement paste is not achieved.

EXAMPLE 6

The solid polydispersed organic-mineral composition was used as in Example 4; the modifier's organic water reducing component was synthesized by means of the aldolic condensation and formaldehyde oxidation in thermodynamic stable conditions (as in Example 5) in the presence of a starting system that had hydroxyl and nitrate ions concurrently. The presence of nitrate ions in the starting system enables, through the utilization of its acidifying potential, the acceleration of the homopolymer synthesis with the required structure and the realization of the aldolic condensation process at a reactive mass temperature not higher than 70° C for 20 to 40 minutes. The use of the homopolymer, obtained under the conditions described in the solid polydispersed organic-mineral modifier, makes possible a modified cement with identical characteristics to that shown in Table 4, Line 3. EXAMPLE 7

The solid polydispersed organic-mineral composition was used as in Example 4; the modifier's organic water reducing component was synthesized by means of a formaldehyde homopolymerization in kinetically balanced conditions, which was achieved due to the formalin additions in the starting system. The polymer synthesis under these conditions results in an organic-mineral composition which, used to obtain a modified cement, assures results that are identical to those shown in Table 4, Line 3. Similar conditions for the homopolymer synthesis are particular useful for industrial production, since there is a considerable reduction in equipment and control of the technical process is simplified.

EXAMPLE 8

The solid polydispersed organic-mineral composition was used as in Example 4; the modifier's organic water reducing component was synthesized by means of a formaldehyde homopolymerization in kinetic (or thermodynamic) conditions in the presence of a starting system that consisted of several alkaline-earthy oxides and nitrates of metals with one or two valences, the components' mass relation being 1:3 - 1:5. In an another synthesis variance, a mixture of earth-alkaline hydroxides and the above-mentioned nitrates were used as the starting system, the components' mass proportions being 1:2.5 - 1:4. The starting systems' compositions used for the synthesis of the modifier's water reducing component and the characteristics of the modified cement systems, prepared as in Example 4, are shown in Table 6. From an analysis of the results, it can be seen that with all the proportions of the components indicated for the starting system, some similar characteristics are obtained for modified cement systems with the polydispersed solid organic-mineral compound.

If the component proportions for the starting system are outside the indicated limits, the characteristics of the modified cement systems will differ slightly from those of the control cement systems.

TABLE 6

Example 9

The solid polydispersed organic-mineral modifier was used as in Example 4; the organic water reducing component of the modifier was synthesized by means of the homopolymerization of formaldehyde in the presence of the starting system, which consisted of the mixture of one or various earth-alkaline metals with lithium, sodium, or potassium alkali in a proportion of 1 : 0.4 to 1 : 1. The presence of the homopolymer (obtained by means of the starting system of the aforementioned composition) in the solid polydispersed organic- mineral complex allows us to obtain a modified cement with some characteristics similar to the results shown in Table 6.

If the proportions in the starting system are found to be outside the indicated limits, the properties of the modified cement systems slightly suφass the characteristics of the control cement systems. Example 10

The solid polydispersed organic-mineral complex was used as in Example 4; the organic water reducing compound of the modifier was synthesized by the homopolymerization of formaldehyde in the presence of the starting system which consisted of a calcium hydroxide suspension, obtained by mixing quicklime or hydrated lime with water. The characteristics of the concrete, prepared with the modified cement which was obtained according to Example 1 are shown in Table 7.

TABLE 7

* Concrete without modifier

** Concrete with the control modifier

*** Concrete with the new proposed modifier

In order to complete the comparative studies, the composition of the concrete mixture had the following proportions of dry ingredients: cement: 1.0 sand: 2.7 coarse aggregates: 3.5

The analysis of the results which were obtained, clearly demonstrate that the application of the solid polydispersed organic-mineral complex reduces the volume of air In the concrete mixture 1.9 to 2.5 times in comparison with unmodified concrete, and 3.6 to 3.8 times when compared with concrete containing the control modifier. As a result, due to the increase in density in the composition of the modified cements by virtue of the proposed modifier. In all cases a significant increase in strength is obtained during the hardening process of the concretes.

Example 11

The solid polydispersed mineral-organic complex is used as in Example 4; the organic water reducing component of the modifier is synthesized by means of the homopolymerization of formaldehyde in the presence of the starting system; industrial nitrates were used as a component of this system. The results obtained were identical to the results in Table 6. The use of industrial nitrates in the composition of the starting system may be useful in cases of the application of modified cement for concrete work at low ambient temperatures, but higher than zero degrees centigrade.

Example 12

The solid polydispersed organic-mineral complex was used as in Example 4; for the synthesis process of the organic water reducing component, acid minerals were used as regulators of the degree of polymerization, which form water reducing salts with one ion of calcium. The application of the of the regulator of the degree of polymerization mentioned above allows us to obtain a homopolymer with adsorbent properties, similar to the example in Table 2, Line 2. The data on setting times for the cement mixture paste prepared with modified cement approximate the data in Table 2, Line 2; the concretes manufactured with this cement require a low water volume and have high strength at all test ages required by codes. The controls used in the tests are shown in Table 8. TABLE 8

The composition of the concrete mixture is equal to that in Example 10. " Concrete without modifier.

Example 13

The solid polydispersed organic-mineral complex was used as in Example 4; in the synthesis process of the organic water reducing component, individual carboxylic acids were used as regulators for the degree of polymerization, their derivations oxl-, haluros-, gen- or amino with an lonization constant of K larger than 10¹², or the mixture of two or more of the above-mentioned acids. The basic characteristics of the regulator for the degree of polymerization, the reactive mass, and the synthesized polymer, as well as some characteristics of the cement paste obtained from the modified cement with the solid polydispersed organic-mineral are shown in Table 9.

TABLE 9

From the data shown in Table 9 , it can be seen that the use of organic acids with constants of high ionization makes it possible to obtain homopolymers with the required adsorbent activity values; and the cement pastes prepared with modified cements, obtained by means of grinding portland clinker, calcium sulfate and the solid polydispersed organic-mineral, have setting times within code standards (Table 9, Lines 1 and 2). In using acids with an ionization constant of approximately 10^"12, a deterioration of the controllable characteristics of the polymer and of the paste prepared with modified cement can be observed; nevertheless, they are within code standards. A successive decrease in the value of the ionization constant gives unsatisfactory results (Table 9, Line 4).

Example 14

The solid, polydispersed organic-mineral complex Is utilized as in Example 4; compounds which form part of the starting system and the products of their chemical interaction are used as soluble salts in the water of the organic-mineral modifier. The authors' experiments demonstrate that the utilization of salts soluble in the water of the indicated composition results in modified cements whose basic characteristics are similar to the data shown in Table 4.

Example 15

The solid, polydispersed organic-mineral complex is utilized as in Example 4; setting accelerators and retardants for the cement systems were used as soluble salts in the water of the organic-mineral modifier. The results of the tests are shown in Table 10. TABLE 10

* Sodium gluconate was used as a hardening retarder. Other known retarders such as lignosulphates and nitrotrimetilenphosphonic acids behave in a similar manner.

** Calcium formiate was used as a hardening accelerator. Other known accelerators behave in a similar manner.

The utilization of hardening accelerators in the composition of the solid polydispersed organic-mineral complex can be useful when using modified cements with a high content of belite and when concrete work Is done at low temperatures above 0°C.

The utilization of hardening retarders are useful In hot, dry weather.

Example 16

The solid polydispersed organic-mineral composition was used as in Example 4. A mixture of calcium hydroxide with different mineral additives containing active components related to clinker minerals was used as the mineral base of the organic-mineral modifier. The composition of the modifier's mineral base and the results of tests obtained with modified cement are shown in Table 11. From Table 11 it can be seen that the solid polydispersed organic-mineral composition in all the proportions shown here can guarantee a reduction in water in normal consistency pastes of 31 to 36% and an increase in mechanical strength of 64 to 72% and 53 to 64% at the corresponding ages compared with the control mortar mixture (without modifier).

In addition to the mineral base components mentioned in Table 11 , it is convenient to use fly ash, calcined clay, tripoli, trass, calcined dolomite and others. Results obtained in tests using each of these mineral substances in the composition of the modifier are similar to those seen in Table 11.

Example 17

The solid polydispersed organic-mineral composition was used as in Example 16; mixtures of the active minerals mentioned above, with different specific surfaces, have been used as mineral base for the modifier. The specific surface of the components of the modifier's mineral base was from 1.500 to 25.000 cm²/gr and it was determined that with a specific surface of between 4.500 and 15.000 cm²/gr, results similar to those of Table 11 are obtained. With a lower specific surface of the modifier's mineral base mixture, the maximum content of water accepted by the modifier cannot be guaranteed, leading to worse conditions in the intergrinding of all components of modified cements. With a higher specific surface of the mineral base (more than 15.000 cm²/gr), the water content for paste of normal consistency is considerably increased.

Example 18

The solid polydispersed organic-mineral composition was used as in Example 16. To prepare the modified cement, white clinker of following mineralogical composition was used:

C3S = 71 % C2S = 15 % C3A = 8 % C4AF = 0.87 % other impurities

For the organic part of modifier, the colorless leucoform of the formaldehyde homopolymer was used, synthesized according to Example 6 to a temperature not higher than 70" C. Used as components of the mineral base of the modifier were:

- Calcium hydroxide with 98.7 % of Ca(OH)₂

- White limestone with a content of:

CaO 55.4% MgO 0.4 S 0.01

Si0₂ 0.8

AlzO_j 0.35

Fe₂0₃ 0.06

Ignition loss .42.96

Total = 100.00%

CaC0₃ content 98.30% other impurities

- Granulated blast furnace slag with the following composition:

Si0₂ 34.8%

Al₂0₃ 13.0

Fe₂0₃ 0.28

CaO 46.25

MgO 6.P

Total = 100.00%

- Calcined white metakaolin with the following composition:

Si0₂ 56.4%

Al₂0₃ 41.0

Fe₂0₃ 1.2

MgO 1.3 so₃ 0,1

Calcined white clay with the following composition: sιo₂ 75.1%

Al₂0₃ 15.0

MgO 3.6

SO, 0.1

From the results in Table 12 it can be seen that using the colorless leucoform of the formaldehyde homopolymer together with all components of the mineral base of the solid organic-mineral modifier (Table 12, Lines 1 to 4), a white modified cement is obtained without losing whiteness. If the control is used as an organic part of the modifier (the product of the co-polymerization of naphtalene sulphonate with formaldehyde) the coefficient of whiteness of white portland cement falls drastically (Table 12, Line 6).

Example 19

The solid polydispersed organic-mineral composition was used as in Example 4 with the puφose of improving the process of grinding clinker, increasing the specific surface area of portland cement and improving its granulometric composition . At a constant rate of mill production, the intergrinding of portland clinker, calcium sulphate and the solid polydispersed organic-mineral composition results in an increase in the specific surface area of cement from 4,400 to 5,600 cm²/g; at the same time the average diameter of particles was reduced from 51.1 to 2.4 microns, fluidity in the pneumatic transport system was Increased and degradation was reduced after prolonged storage.

Example 20

To improve the characteristics of the cementitious systems, the water soluble part of the modifier was used, which is a mixture of formaldehyde homopolymer with mineral and organic water soluble salts. Such a mixture is formed after adding the regulator for the degree of polymerization to the reactive mass. As an example we can see results of the use of the modifier in concrete, Table 13. The solid components of the concrete are the same as in Example 10. TABLE 11

TABLE 12

White cement samples without modifier were used . The prototype was used as the water reducing component of the solid organic-mineral modifier (Table 1 , Lines 5 and 6)

TABLE 13

From the data it can be seen that if the water soluble portion present in the proposed organic-mineral modifier is equal to the water cement ratio (W/C) value, the workability of the concrete mixture is significantly Improved or the water necessary to obtain the same slump is reduced more than 20 %. In all cases the strength of the concrete is improved at all ages (Table 13, Lines 2 - 3) when compared with concrete without modifier (Table 13, Line 1).

Data shown in Table 13 also indicate the advantages of the proposed modifier compared with the control (Table 13, Lines 4 - 5).

All the exposed examples confirm the improved characteristics of the solid polydispersed organic-mineral composition when compared with known modifiers for cementitious systems.

BIBLIOGRAPHY

1. Patent of USSR No. 3641053/29-33. Method of Plasticizer Preparation for Concrete Mixture, 1983.

2. Patent of CHSSR N222881. Method of Obtaining of Plasticizer oz. "razzhizhitel" for Inorganic Materials, 1981.

3. Patent of Japan N 11737. Obtaining of Dispercizer for Cement, 1963.

4. Babaev Sh. T., Bashlykov N.F., Serdyuk V.N. The Main Principals of Obtaining of High- Efficiency Cements with Low Water Demand. Moscow, Stroyizdat, 1991 , p. 76.

5. Babaev Sh. T. , Bashlykov N.F., Sorokin Y.V. Peculiarities of Technology and Properties of Concretes based on Cements with Low Water Demand. Moscow, Stroyizdat, 1992, p. 107.

Claims

WE CLAIM

1. A modifier of cementitious systems, comprising a solid polydispersed organic-mineral composition consisting essentially of a water reducing component, a mixture of water soluble organic and inorganic salts, and a mineral base, in which the modifier comprises an organic polymer with low adsorbent activity constituting the water reducing component; and a mixture of two or more active mineral substances with specific surfaces of no less than 1,500 cm²/gr. and a high adsorbent capacity with respect to water constituting the mineral base.

2. The modifier according to Claim 1, in which the water reducing component comprises a homopolymer of an organic polymer type, and obtained by a polymerization regulated by formaldehyde mixed with formalin with a mineral starting system, followed by adding a regulator for the degree of polymerization.

3. The modifier according to Claim 1 in which the solid polydispersed organic-mineral composition is obtained without using external heating sources.

4. The modifier according to Claim 1, in which the proportions of the ingredients are established as follows in mass %:

Formaldehyde homopolymer 10 - 16% Water soluble salts 22 - 33%

Mineral base 40 - 66%

Water 2 - 7%

5. The modifier according to Claim 2, in which the homopolymer is a product obtained from an aldolic condensation of a formaldehyde monomer in the presence of a starting system which maintains the pH of the constituents at no lower than 11.5 at a temperature of 42 to 85°C in conditions of a thermodynamic equilibrium which is obtained by adding the starting system to the monomer.

6. The modifier according to Claim 2, in which the homopolymer is a product obtained by an aldolic condensation and formaldehyde oxidation in conditions of thermodynamic equilibrium in the presence of a starting system containing concurrently hydroxyl and nitrate ions.

7. The modifier according to Claim 6, in which the polymer comprises products obtained by a homopolymerization of formaldehyde in a condition of kinetic equilibrium obtained by adding formalin to the starting system.

8. The modifier according to Claim 7, in which the starting system comprises a mixture of one or more metal earth- alkaline oxides (MeO) with nitrates (M(N0³)x, where x = 1 - 2] with a mass proportion of the components of MeO : M(N0³)x = 1:3 - 1:5, or a mixture of corresponding hydroxides with said nitrates in the proportion Me (OH). : M(N0_)x = 1:2.5 - 1:4.0.

9. The modifier according to Claim 7, in which the starting system comprises a mixture of one or more nitrates of earth-alkaline metals with alkali MOH (M = Li+, Na+ or K+) in a proportion of 1:0.4 - 1:1.

10. The modifier according to Claim 8, in which the starting system comprises calcium hydroxide constituting the reaction product obtained from a mixture of water with quicklime or hydrated lime.

11. The modifier according to Claim 8, in which an industrial nitrate constitutes the nitrate component for the starting system.

12. The modifier according to Claim 8 comprising a regulator for the degree of polymerization, the regulator comprising mineral acids forming water soluble salts with the earth-alkaline ion.

13. The modifier according to Claim 12, in which the regulator for the degree of polymerization comprises individual carboxylic acids, its derivates oxi, halures or amines with an ionization constant of K, >10 ^"12, or the mixture of two or more of the above-mentioned acids.

14. The modifier according to Claim 1, in which the water soluble salts include compounds forming part of the starting system and the products of its chemical interaction.

15. The modifier according to Claim 1, in which the water soluble salts include known hardening accelerators and retarders.

16. The modifier according to Claim 1, in which the mineral base of the solid polydispersed organic-mineral composition is a mixture of calcium hydroxide with one or more anhydrous minerals containing active mineral components with respect to Portland cement clinker minerals, with high adsorbent capacity with respect to water-compatible fly ash, calcium carbonate, micro silica, slag, volcanic ash, kaolin or clay.

17. The modifier according to Claim 16, in which mixtures of mineral components mentioned therein have a specific surface of more than 4,500 cm²/gr. to serve advantageously as the mineral base of the solid polydispersed organic-mineral composition.

18. The modifier according to Claim 1, for the purpose of modifying materials based on white cement, comprising the leucoform of the homopolymer formed at a temperature of no more than 70°C constituting the organic part of the solid polydispersed organic-mineral composition.

19. The modifier according to Claim 1, comprising an intermediate product consisting essentially of an aqueous solution of the solid polydispersed organic-mineral compound which is formed after adding a regulator for the degree of polymerization .