JP2011207625A - Method for preventing wash-out of cementitious composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for imparting anti-washout property to a cementitious composition for concrete, cement masonry or the like to be exposed to water.SOLUTION: At least one polycationic polymer selected from the group consisting of quaternary amine and tertiary amine of 0.01 to 1.00 wt.%, at least one organic viscosity-modifying agent of 0.0005 to 0.5 wt.% and an inorganic viscosity-modifying agent of 0 to 5.0 wt.% working so as to swell upon exposure to water are added to a hydratable cementitious binder.

Description

  The present invention relates to a method for providing washout prevention to cementitious compositions such as concrete and cement masonry exposed to water. In particular, the present invention relates to at least one polycationic polymer, at least one organic viscosity modifier, and optionally at least one inorganic viscosity to prevent washout in harsh situations such as underwater or underground facilities. It relates to the use of denaturing agents.

  The concept of “washout” is used herein to refer to the loss of hydrated cement or concrete when placed in an environment exposed to water, which is the mineral content from the cement. Chemical leaching as well as physical removal of particles from the mixture.

  Materials that can receive washout from new cement or concrete compositions are commonly used to supplement hydrated cementitious binder systems, ie Portland cement, fly ash, granular blast furnace slag, silica, or Portland cement. Any pozzolanic powder, such as other pozzolans. The materials to be washed out can also include fine aggregate materials (eg, sand) in the case of mortar and concrete exposed to water.

  Washout can occur, for example, when the cementitious composition is exposed to severe water streams in underwater or underground construction. Under such construction conditions, concrete is usually constructed by pumping a cementitious composition in the form of a slurry to the construction point. For harsh applications, viscosity modifiers such as cellulose ethers, natural gums or synthetic thickeners can be used. For less severe conditions, organic viscosity modifiers can be used to prevent washout. However, for severe construction such as underwater facilities, the viscosity-modifying polymer can be used to increase the viscosity of concrete to the point where it does not have the ability to pump easily or does not have any pumping capacity. The material cannot be used. Thus, there is a need for a new method for providing washout prevention of hydrated cementitious compositions.

  In overcoming the difficulties of the prior art, the inventors have found that the use of at least one polycationic polymer and at least one organic viscosity modifier such as a heteropolysaccharide gum does not cause pumping difficulties. It has been found that a hydrated cementitious composition provides excellent washout prevention. Such properties are desirable when applying cementitious compositions in environments where water exposure is severe. Otherwise, such harsh construction tends to wash out the cement / concrete component and cause the cement component and particulate fines to be washed away into the water.

  In a preferred embodiment of the present invention, an inorganic viscosity modifier such as bentonite clay can be used to further enhance the washout prevention properties of the above components.

An exemplary method of the present invention for providing washout prevention to a hydrated cementitious composition so that the material in the cementitious composition is not substantially lost upon exposure to water is A plurality of nitrogen-containing moieties selected from the group consisting of quaternary amines and tertiary amines present in an amount of 0.01 to 1.00 percent based on the dry weight of the cementitious binder; At least one polycationic polymer containing: (b) an amount of 0.05 to 0.5 percent based on the dry weight of the cementitious binder, (i) a polysaccharide (eg, cellulose ether, starch ether) ); (Ii) heteropolysaccharide gums (eg, diutane, welan); (iii) synthetic water soluble polymers (eg, polyacrylamide and derivatives thereof) At least one organic viscosity modifier selected from the group consisting of polyethylene oxide and copolymers thereof, water soluble polyurethanes, and hydrophobically modified associative thickeners; and (c) an amount of said cementitious binder It comprises an inorganic viscosity modifier that acts to swell upon exposure to water, from 0 to 5.0 percent by weight on a dry weight basis.

  In a further preferred embodiment, a “polycarboxylate” polymer, preferably a polymer having polyoxyalkylene side chains that serve to disperse cement particles, can further enhance the fluidity of cement or concrete.

  In the past, polyheterosaccharide gums have been used in concrete, but it has been found that these alone do not provide sufficient washout prevention in harsh applications (eg, in water). Alternatively, when the polyheterosaccharide gum is mixed with a polycarboxylate cement dispersant that can be used to reduce the amount of water required to mix the cement or concrete composition, the washout resistance is sufficient. Not enhanced.

  Surprisingly, however, the inventors have found that the addition of a polycationic polymer, a nitrogen-containing polycationic polymer, provides a significant improvement in washout prevention compared to a heteropolysaccharide gum used alone. I found out that it brings.

  Furthermore, the present inventors have found that addition of bentonite clay (inorganic viscosity modifier) further enhances washout prevention.

  The aforementioned components may be combined separately or together in the hydrated cementitious composition to be treated. Preferably, the heteropolysaccharide and bentonite clay can be added as dry powder additives; the polycationic polymer and the polycarboxylate polymer can be added in liquid form. If not separate, separate addition is preferred because the bentonite-type clay absorbs one or more of the liquid components (eg, polycarboxylate polymer).

  The present invention provides a cementitious structure formed using the method described above, wherein components (a) and (b), preferably component (c), are also combined with the hydrated cementitious composition. Preferably, the structure is formed in water, surrounded by water and cured without substantial loss of material due to chemical leaching or particle washout.

  The present invention provides: (a) a plurality of nitrogen-containing moieties selected from the group consisting of quaternary amines and tertiary amines present in an amount of 0.01 to 1.00 percent based on the dry weight of the cementitious binder. At least one polycationic polymer containing: (b) an amount of 0.005 to 0.5 percent based on the dry weight of the cementitious binder, (i) a polysaccharide (eg, cellulose ether, starch ether) ); (Ii) heteropolysaccharide gums (eg, diutane, welan); (iii) synthetic water-soluble polymers (eg, polyacrylamide and its derivatives, polyethylene oxide and its copolymers, water-soluble polyurethanes, and hydrophobically modified associations) At least one organic viscosity modifier selected from the group consisting of: And (c) a hydrated cementitious composition comprising an inorganic viscosity modifier that acts to swell upon exposure to water, the amount of which is 0 to 5.0% by weight based on the dry weight of the cementitious binder A novel blend for addition to is also provided.

  Further advantages and features of the present invention are described in further detail later in this specification.

  As used herein, the term “hydrated cementitious composition” refers to a composition that cures or cures upon addition of water. Such compositions include Portland cement and are supplemented with limestone, hydrated lime, fly ash, blast furnace slag, silica fume or other materials (some of which are commonly referred to as “Pozzolans”), and water To obtain (usually but not exclusively) a mixture of hydrated cementitious binders. Cement mortar is a paste that additionally contains fine aggregate (eg, sand); concrete is a mortar that additionally contains coarse aggregate (eg, crushed gravel, stone). Accordingly, the “cementaceous” composition of the present invention refers to and includes all of the foregoing. For example, the cementitious composition may optionally contain the required amount of the appropriate material, optionally, for example, hydrated cementitious binder (cement with or without pozzolans), water, and fines and / or coarse aggregate. It can be formed by mixing with fibers (eg steel, synthetic polymers or combinations of such fiber materials) that are sometimes used to prevent shrinkage cracking and / or to reinforce concrete.

  The present invention provides a hydrated cementitious material, particularly in harsh applications where cementitious binders, pozzolans, and fines are susceptible to washout and / or washout with water in the environment (eg, underwater, underground). Provides excellent washout prevention.

  As explained in the summary of the present invention, the present invention provides: (a) at least one polycationic polymer, preferably a nitrogen-containing polymer having multiple cationic functional groups; and (b) at least one organic viscosity modification. With the use of an agent, preferably a polysaccharide.

  The polycationic polymer of component (a) is selected from polyamines, more preferably polyquaternary amines or polytertiary amines having a high cation density. Advantageously, for this purpose, for example, a condensation polymer of epichlorohydrin and dimethylamine (EPI-DMA), polydiallyldimethylammonium chloride (DADMAC), guanidine, cyanoammonium chloride, formaldehyde condensation product (DICY) , And variants of the polymers described above can be used. A description of the type of cationic polymer is found in US patent application 2007/0287794. The chemical structure of a preferred polycationic polymer, EPI-DMA, is shown below.

The organic viscosity modifier of component (b) can be a natural or synthetic, high molecular weight or associative polymer. This can be selected from cellulose ether, polyacrylamide or modified polyacrylamide, HEUR thickener, polyvinyl alcohol, polyethylene glycol, polysaccharide gum, and any other organic polymer that increases the viscosity of water. Preferably, the organic viscosity modifier is selected from polysaccharide gums such as welan gum, diutan gum, guar gum, gum arabic, duran gum, diutan gum, lanthanum gum, and xanthan gum. These heteropolysaccharides are described in US Patent Application 2006/0166837. The structure of the heteropolysaccharide is shown below.

As a preferred example, the structure of diutan gum is also shown.

  In addition to the above (a) polycationic polymer and (b) organic viscosity modifier, further exemplary methods and compositions of the present invention may further comprise an inorganic viscosity modifier as component (c). Inclusion of this additional component is preferred because it can enhance washout prevention. Thus, exemplary inorganic viscosity modifiers (component (c)) of the present invention include any clay having the ability to swell upon exposure to water, along with components (a) and (b). Montmorillonite type clays such as bentonite can preferably be used as the additional component (c) in the present invention.

  A preferred bentonite clay contains sodium ions and calcium ions in the structure. Japanese Patent Application No. 6-183799 discloses such bentonite bentonite clay to reduce sludge from the manufacture of concrete products. The clay mineral described in JP-A-6-183799 is also applicable to the present invention for the purpose of enhancing the washout prevention disclosed in this specification.

In still further exemplary embodiments of the invention, polycarboxylate polymers that serve to disperse the cement can be used. The use of polycarboxylate polymers for cement dispersion is well known. Preferred polycarboxylate polymers have a comb structure with pendant polyoxyalkylene groups and an anionic skeleton. This anionic group is usually a carboxylic acid, but other ionic or latent acidic groups can also be found on the polymer backbone. The polyoxyalkylene pendant group is usually a polyethylene glycol with a molecular weight range of 400 to 5,000. Polypropylene glycol groups can also be used to some extent and the polycarboxylate polymer can have long or short chain pendant groups as desired. The chemical bond between the backbone and the pendant group is usually done using alkyl ether or ester bonds, although it is also known to use amide, imide, and / or other linking groups for this purpose.

In addition to polyoxyalkylene pendant groups such as short chain alkyls (ie, having less than 8 carbon-C ₈ ), in order to confer attributes such as adsorption capacity, surface activity, and hydrodynamic radius to the polymer, Alkanol and / or alkylaryl groups can optionally be incorporated into the polymer structure.

  The use of an optional polycarboxylate polymer for cement dispersion purposes can provide enhanced fluidity as well as enhanced washout resistance to the concrete.

  Preferred amounts of the washout-preventive admixture of the present invention are (a) 0.01-1% by weight for polycationic polymers; (b) 0.005-0.5 for organic viscosity modifiers. And (c) 0-5% by weight relative to the inorganic viscosity modifier. If an inorganic viscosity modifier is used, the minimum amount is 0.05-5% by weight based on the weight of the cementitious binder.

  To provide a single concrete blend, the above ingredients can be combined together or more preferably added separately to the cementitious composition to be treated. For example, a polycationic polymer and an optional (but preferred) polycarboxylate polymer (cement dispersant) can be added in liquid form, preferably together, and possibly combined with other known concrete admixture components. is there. Such admixture components may include accelerators, retarders, strength enhancers, air entrainers, air defoamers or air control agents, or combinations thereof; whereas organic viscosity modifiers and inorganic viscosity modifiers Can be added in combination in the form of dry powder additives along with other additives normally incorporated into dry form cement or concrete mixes such as silica fume, fly ash, limestone powder, fibers, etc.

  While this invention has been described in this specification using a limited number of embodiments, these specific embodiments limit the scope of this invention described and claimed in this specification. Is not intended to be. There are modifications and variations from the described embodiments. Specifically, the following examples are given as specific illustrations of aspects of the claimed invention. It should be understood that the invention is not limited to the specific details set forth in the examples. Parts and percentages in the examples and the rest of this specification are by weight unless otherwise stated.

  Further, any number range recited in this specification or in the claims, such as those representing a particular set of properties, units of measure, conditions, physical states or percentages, is any Any number that falls within such a range, including any subset of the numbers in the range, is intended to be explicitly incorporated herein by reference or otherwise. For example, whenever a numerical range with a lower limit RL and an upper limit RU is disclosed, any number R falling within this range is specifically disclosed. In particular, a number R in the range R = RL + k * (RU−RL) is specifically disclosed. Where k is a variable ranging from 1% to 100% in 1% increments, for example, k is 1%, 2%, 3%, 4%, 5%,... 50%, 51%, 52%, ... 95%, 96%, 97%, 98%, 99% or 100%. Furthermore, any numerical range represented by any two values of R calculated above is also specifically disclosed.

Example 1
A concrete mix was prepared by using a concrete mix design of a sample submerged in water according to the Japanese Society of Civil Engineers standard (JSCE-D104-2007) and a test procedure for preventing washout.

  As shown below, the admixture ingredients were added according to the weight percent (%) based on the weight of the cementitious binder. Measurements according to JSCE-D104-2007 were made for slump flow, air content, suspended solids, pH, setting time, and 24-hour compressive strength. Table 1 below shows the concrete mix design used.

Table 2 shows the blend composition used in the concrete examples.

Next, concrete samples containing this admixture were tested for washout prevention, and the results are shown in Table 3 below.

  As shown in Table 3, the test results obtained with the blends and methods of the present invention showed that a significant reduction in suspended solids in the cementitious composition was obtained. It is also noteworthy that the blends of the present invention lower the pH value of water. This indicates that the underwater concrete material releases only a small amount of material components into the water. This example also ensures that the present invention does not have any negative impact on concrete performance such as setting time, strength, and durability.

  The principles, preferred embodiments, and modes of operation of the present invention have been described in the foregoing specification. However, the invention, which is intended to be protected in this specification, should not be construed as limited to what has been disclosed, since the specific forms are to be regarded as illustrative rather than restrictive. Variations and modifications can be made by those skilled in the art without departing from the spirit of the invention.

Claims (7)

A hydrated cementitious binder;
(A) at least containing a plurality of nitrogen-containing moieties selected from the group consisting of quaternary amines and tertiary amines present in an amount of 0.01 to 1.00 percent based on the dry weight of the cementitious binder. One polycationic polymer;
(B) from the group consisting of (i) a polysaccharide; (ii) a heteropolysaccharide gum; (iii) a synthetic water-soluble polymer, wherein the amount is 0.005 to 0.5 percent based on the dry weight of the cementitious binder. At least one organic viscosity modifier selected; and (c) an inorganic viscosity modifier that acts to swell upon exposure to water, wherein the amount is from 0 to 5.0% based on the dry weight of the cementitious binder. A method for providing washout prevention in a hydrated cementitious composition comprising coalescing an agent so that the material in the cementitious composition is not substantially lost upon exposure to water.   The method of claim 1, wherein in the introducing step, the polycationic polymer is a polyquaternary ammonium polymer.   The method of claim 1, wherein, in the introducing step, the organic viscosity modifier is a heteropolysaccharide selected from the group consisting of welan gum, diutan gum, guar gum, gum arabic, dulan gum, lanthanum gum, and xanthan gum.   The method of claim 1, wherein, in the introducing step, the inorganic viscosity modifier is bentonite clay and the amount of bentonite is at least 0.05 to 5.0% based on the dry weight of the cementitious binder.   The method of claim 1, further comprising introducing a polycarboxylate polymer having polyoxyalkylene pendant groups that serve to disperse the cement particles into the hydrated cementitious binder. Method.   In the introduction step, the polycationic polymer of component (a) and the polycarboxylate polymer are introduced into the hydrated cement binder in liquid form; and at least one organic viscosity modification of component (b) 6. The method of claim 5, wherein the agent and the inorganic viscosity modifier of component (c) are introduced as a powder into the hydrated cement binder.   A cementitious structure obtained by the method according to claim 1.