Phosphorylated polycondensate as high efficiency water reducing agent and preparation method thereof

Abstract

The present invention discloses a phosphorylated polycondensate high-performance water-reducing agent with a phosphorylated melamine derivative, instead of a conventional carboxyl group or sulfonic group, as a main adsorption group. The use of aryl alkoxypolyether as a side chain of the polymer provides a strong steric effect to improve the dispersibility and dispersion-retaining properties of the polymer. A polycondensate high-performance water-reducing agent and a method for preparing the same provided by the present invention have excellent overall performance, high adaptability for current low-grade raw materials of concrete, strong market demands, and vast application prospects. Additionally, the polycondensate has an advanced preparation process provided with the characteristics of industrially scalable production, which offers the prospect of a core technology in the field of water-reducing agent of concrete so as to promote development of the industry.

Claims

1. A phosphorylated polycondensate high-performance water-reducing agent, having a molecular structure represented by the following formula I: ##STR00022## wherein the molecular structure of the polymer comprises three building blocks A, B, and C, formed by condensation of the corresponding monomers phosphorylated melamine A, an aldehyde B and an aryl alkoxy compound C, and the molecular structure is a comb-like structure; the three monomers has a mole ratio of m:n:p=1.5 to 4.5:1.8 to 3.2:1; the monomer A is phosphorylated melamine having a structure selected from the following monodentate structure II and bidentate structure III; ##STR00023## the monomer B is one of formaldehyde, acetaldehyde and benzaldehyde compounds, or a mixture thereof in any ratio; the monomer C is either a phenoxypolyoxyalkylene ether ora phenylaminopolyoxyalkylene ether, and monomer C has a molecular weight (Mw) of 1000 to 6000, wherein R.sup.4 and R.sup.5 are H, OH, NH.sub.2 or polyether side chain moieties of the phenoxypolyoxyalkylene ether or phenylaminopolyoxyalkylene ether, provided that R.sup.4 and R.sup.5 cannot both be H, OH or NH.sub.2; and the phosphorylated polycondensate high-performance water-reducing agent has a weight average molecular weight of 10000 to 50000.

2. The phosphorylated polycondensate high-performance water-reducing agent of claim 1, wherein the monomer A is prepared by the Mannich reaction of melamine, phosphorous acid, and formaldehyde, in the presence of an acid catalyst; wherein a molar ratio of the materials is melamine:phosphorous acid:formaldehyde:acid (H.sup.+)=1:1.0 to 1.2:1.1 to 1.5:0.2 to 1.2.

3. The phosphorylated polycondensate high-performance water-reducing agent of claim 1, wherein the monomer B is formaldehyde.

4. A method for preparing the phosphorylated polycondensate high-performance water-reducing agent of claim 1, comprising subjecting the three monomers to polycondensation in a presence of an acid catalyst at a pH of 1 to 3 to obtain the phosphorylated polycondensate high-performance water-reducing agent; wherein the reaction temperature is 100 to 150 C., the reaction time is 1 to 10 h, and the reaction system uses water as solvent; the apparatus is equipped with a condenser (tube) for reflux so as to prevent dissipation of water or the aldehyde in the system to affect the reaction conditions; and the acid catalyst is selected from sulfonic acid, sulfuric acid, trifluoroacetic acid (TFAA), 4-toluene sulfonic acid (pTSA), monochloroethanoic acid (MCAA), glacial acetic acid, hydrochloric acid, and formic acid, or a mixture thereof in any ratio.

5. The method of claim 4, wherein the preparation specifically comprises three steps: preparation of the monomer A, the polycondensation and neutralization, wherein the neutralization uses a pH adjusting agent selected from sodium hydroxide and potassium hydroxide.

6. The phosphorylated polycondensate high-performance water-reducing agent of claim 1, wherein the three monomers has a mole ratio of m:n:p=2.0 to 3.0:2.4 to 2.8:1.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The following examples are provided to describe in greater detail the molecular structure and preparation process of a polycondensate high-performance water-reducing agent of the present invention, and these examples are given for illustrative purpose to enable those skilled in the art to understand and implement the content of the present invention, and are not intended to limit the scope of the present invention. Any equivalent change or modification made according to the spirit and essence of the present invention shall fall within the protection scope of the present invention.

(2) Test conditions of molecular weight: the molecular weight of the polycondensates in all the examples of the present invention was determined using aqueous gel-permeation chromatography (GPC) under the following experimental conditions: gel column: Shodex SB806+803 columns in series; mobile phase: 0.1M NaNO.sub.3 aqueous solution; mobile phase velocity: 1.01 ml/min; injection: 20 l 0.5% aqueous solution; detector: Shodex RI-71 differential refractive index detector; standard: PEG GPC calibration standards (Sigma-Aldrich, molecular weight 1010000, 478000, 263000, 118000, 44700, 18600, 6690, 1960, 628, 232).

(3) Synthesis parameters of the monomer A in each example are shown in Table 1.

(4) TABLE-US-00001 TABLE 1 Synthesis parameters of monomer A Molar ratio of materials Monomer A melamine:phosphorous acid:aldehyde:H.sup.+ Sample 1 1:1.05:1.2:0.8 Sample 2 1:1.1:1.05:1.0 Sample 3 1:1.0:1.5:0.2 Sample 4 1:1.2:1.0:1.2 Sample 5 0 1:1.1:1.3:1.0 Sample 6 1:1.0:1.1:1.2 Comparative sample1 1:0.6:0.8:0.1 Comparative sample2 1:1.5:1.8:1.6

(5) Synthesis parameters of a sample of the water-reducing agent in each example are shown in Table 2.

(6) TABLE-US-00002 TABLE 2 Synthesis parameters of modified water-reducing agents Molecular Monomer weight of molar polymer Monomer A Monomer B Monomer C ratio (10.sup.4) Sample 1 Formaldehyde Phenoxypolyoxyalkylene ether Mw = 2500 m:n:p = 2.4:2.6:1 25000 Sample 2 Formaldehyde Phenoxypolyoxyalkylene ether Mw = 4500 m:n:p = 3.0:2.8:1 24000 Sample 3 Formaldehyde p- hydroxylphenoxypolyoxyalkylene ether Mw = 3500 m:n:p = 1.5:1.8:1 12000 Sample 4 Formaldehyde p- aminophenoxypolyoxyalkylene ether Mw = 4000 m:n:p = 4.5:3.2:1 46000 Sample 5 Acetaldehyde p- hydroxylphenylainopolyoxyalkylene ether Mw = 6000 m:n:p = 2.0:2.5:1 32000 Sample 6 Benzaldehyde Phenylaminopolyoxyalkylene ether Mw = 1000 m:n:p = 2.4:2.8:1 38000 Com- parative sample 1 0 Formaldehyde Phenoxypolyoxyalkylene ether Mw = 750 m:n:p: = 0.8:1.2:1 7500 Com- parative sample 2 Formaldehyde Phenoxypolyoxyalkylene ether Mw = 7000 m:n:p = 5.0:3.8:1 64500 Note: the dosing ratios in these steps all refer to a molar ratio of monomer A, monomer B and monomer C.

Synthesis Example 1

(7) (1) Preparation of Monomer A

(8) 126.02 g (1.0 mol) melamine, 86.10 g (1.05 mol) phosphorous acid and 100 ml water were placed into a 1000 ml reaction flask, 78.4 g (0.8 mol) sulfuric acid was added, the temperature was raised to 100 C. for 10 min, 97.30 g (1.2 mol) of a 37% aqueous formaldehyde solution was dropwise added, a condenser tube was installed, and the reaction was heated to reflux for 3 h and cooled for later use.

(9) (2) Condensation

(10) 250 g (0.1 mol) of a monomer C (phenoxypolyoxyalkylene ether) and 52.8 g (0.24 mol) of the monomer A (monosubstituted phosphorylated melamine) were sequentially added in a 1000 ml round-bottomed flask, the temperature was raised to 80 C., 21.08 g (0.26 mol) of a 37% aqueous formaldehyde solution was dropwise added, and the reaction was maintained at 120 C. for 6 h.

(11) (3) Neutralization

(12) 34.67 g (0.26 mol) of a 30% sodium hydroxide solution was added and 480 g water was added to adjust the system to a pH=8 to 9, to prepare a high-performance polycondensate water-reducing agent at a weight concentration of about 40%, as a clear light brown viscous liquid. The polycondensate was determined by aqueous gel-permeation chromatography to have a weight average molecular weight of 25000.

Synthesis Example 2

(13) (1) Preparation of Monomer A

(14) 126.05 g (1.0 mol) melamine, 90.20 g (1.1 mol) phosphorous acid and 100 ml water were placed into a 1000 ml reaction flask, 98.0 g (1.0 mol) sulfuric acid was added, the temperature was raised to 100 C. for 10 min, 85.14 g (1.05 mol) of a 37% aqueous formaldehyde solution was dropwise added, a condenser tube was installed, and the reaction was heated to reflux for 3 h and cooled for later use.

(15) (2) Condensation

(16) 450 g (0.1 mol) of a monomer C (phenoxypolyoxyalkylene ether) and 66.0 g (0.3 mol) of the monomer A (monosubstituted phosphorylated melamine) were sequentially added in a 2000 ml round-bottomed flask, the temperature was raised to 80 C., 22.70 g (0.28 mol) of a 37% aqueous formaldehyde solution was dropwise added, and the reaction was maintained at 110 C. for 5 h.

(17) (3) Neutralization

(18) 41.3 g (0.31 mol) of a 30% sodium hydroxide solution was added and 800 g water was added to adjust the system to a pH=8 to 9, to prepare a high-performance polycondensate water-reducing agent at a weight concentration of about 40%, as a clear light brown viscous liquid. The polycondensate was determined by aqueous gel-permeation chromatography to have a weight average molecular weight of 24000.

Synthesis Example 3

(19) (1) Preparation of Monomer A

(20) 126.0 g (1.0 mol) melamine, 82.06 g (1.0 mol) phosphorous acid and 100 ml water were placed into a 1000 ml reaction flask, 19.6 g (0.2 mol) sulfuric acid was added, the temperature was raised to 100 C. for 10 min, 121.62 g (1.5 mol) of a 37% aqueous formaldehyde solution was dropwise added, a condenser tube was installed, and the reaction was heated to reflux for 3.5 h and cooled for later use.

(21) (2) Condensation

(22) 350 g (0.1 mol) of a monomer C (p-hydroxylphenoxypolyoxyalkylene ether) and 33.0 g (0.15 mol) of the monomer A (monosubstituted phosphorylated melamine) were sequentially added in a 2000 ml round-bottomed flask, the temperature was raised to 80 C., 14.60 g (0.18 mol) of a 37% aqueous formaldehyde solution was dropwise added, and the reaction was maintained at 130 C. for 7 h.

(23) (3) Neutralization

(24) 25.33 g (0.15 mol) of a 30% sodium hydroxide solution was added and 600 g water was added to adjust the system to a pH=8 to 9, to prepare a high-performance polycondensate water-reducing agent at a weight concentration of about 40%, as a clear light brown viscous liquid. The polycondensate was determined by aqueous gel-permeation chromatography to have a weight average molecular weight of 12000.

Synthesis Example 4

(25) (1) Preparation of Monomer A

(26) 126.04 g (1.0 mol) melamine, 98.4 g (1.2 mol) phosphorous acid and 100 ml water were placed into a 1000 ml reaction flask, 117.6 g (1.2 mol) sulfuric acid was added, the temperature was raised to 100 C. for 10 min, 81.08 g (1.0 mol) of a 37% aqueous formaldehyde solution was dropwise added, a condenser tube was installed, and the reaction was heated to reflux for 3 h and cooled for later use.

(27) (2) Condensation

(28) 400 g (0.1 mol) of a monomer C (p-aminophenoxypolyoxyalkylene ether) and 99.0 g (0.45 mol) of the monomer A (monosubstituted phosphorylated melamine) were sequentially added in a 2000 ml round-bottomed flask, the temperature was raised to 80 C., 14.60 g (0.18 mol) of a 37% aqueous formaldehyde solution was dropwise added, and the reaction was maintained at 110 C. for 6 h.

(29) (3) Neutralization

(30) 38.67 g (0.29 mol) of a 30% sodium hydroxide solution was added and 775 g water was added to adjust the system to a pH=8 to 9, to prepare a high-performance polycondensate water-reducing agent at a weight concentration of about 40%, as a clear light brown viscous liquid. The polycondensate was determined by aqueous gel-permeation chromatography to have a weight average molecular weight of 46000.

Synthesis Example 5

(31) (1) Preparation of Monomer A

(32) 126.03 g (1.0 mol) melamine, 180.4 g (2.2 mol) phosphorous acid and 150 ml water were placed into a 1000 ml reaction flask, 196 g (2.0 mol) sulfuric acid was added, the temperature was raised to 100 C. for 10 min, 210.81 g (2.6 mol) of a 37% aqueous formaldehyde solution was dropwise added, a condenser tube was installed, and the reaction was heated to reflux for 4 h and cooled for later use.

(33) (2) Condensation

(34) 600 g (0.1 mol) of a monomer C (p-hydroxylphenylaminopolyoxyalkylene ether) and 62.8 g (0.2 mol) of the monomer A (disubstituted phosphorylated melamine) were sequentially added in a 2000 ml round-bottomed flask, the temperature was raised to 80 C., 27.5 g (0.25 mol) of a 40% aqueous acetaldehyde solution was dropwise added, and the reaction was maintained at 120 C. for 6 h.

(35) (3) Neutralization

(36) 82.67 g (0.62 mol) of a 30% sodium hydroxide solution was added and 1010 g water was added to adjust the system to a pH=8 to 9, to prepare a high-performance polycondensate water-reducing agent at a weight concentration of about 40%, as a clear light brown viscous liquid. The polycondensate was determined by aqueous gel-permeation chromatography to have a weight average molecular weight of 32000.

Synthesis Example 6

(37) (1) Preparation of Monomer A

(38) 126.06 g (1.0 mol) melamine, 164.0 g (2.0 mol) phosphorous acid and 150 ml water were placed into a 1000 ml reaction flask, 215.6 g (2.2 mol) sulfuric acid was added, the temperature was raised to 100 C. for 10 min, 194.59 g (2.4 mol) of a 37% aqueous formaldehyde solution was dropwise added, a condenser tube was installed, and the reaction was heated to reflux for 4 h and cooled for later use.

(39) (2) Condensation

(40) 100 g (0.1 mol) of a monomer C (phenylaminopolyoxyalkylene ether) and 75.36 g (0.24 mol) of the monomer A (disubstituted phosphorylated melamine) were sequentially added in a 1000 ml round-bottomed flask, the temperature was raised to 80 C., 29.68 g (0.28 mol) of a benzaldehyde solution was dropwise added, and the reaction was maintained at 120 C. for 8 h.

(41) (3) Neutralization

(42) 85.33 g (0.64 mol) of a 30% sodium hydroxide solution was added and 350 g water was added to adjust the system to a pH=8 to 9, to prepare a high-performance polycondensate water-reducing agent at a weight concentration of about 40%, as a clear light brown viscous liquid. The polycondensate was determined by aqueous gel-permeation chromatography to have a weight average molecular weight of 38000.

Comparative Example 1

(43) (1) Preparation of Monomer A

(44) 126.00 g (1.0 mol) melamine, 49.2 g (0.6 mol) phosphorous acid and 100 ml water were placed into a 1000 ml reaction flask, 9.8 g (0.1 mol) sulfuric acid was added, the temperature was raised to 100 C. for 10 min, 64.86 g (0.8 mol) of a 37% aqueous formaldehyde solution was dropwise added, a condenser tube was installed, and the reaction was heated to reflux for 3 h and cooled for later use.

(45) (2) Condensation

(46) 75 g (0.1 mol) of a monomer C (phenoxypolyoxyalkylene ether) and 17.6 g (0.08 mol) of the monomer A (monosubstituted phosphorylated melamine) were sequentially added in a 500 ml round-bottomed flask, the temperature was raised to 80 C., 9.73 g (0.12 mol) of a 37% aqueous formaldehyde solution was dropwise added, and the reaction was maintained at 160 C. for 10 h.

(47) (3) Neutralization

(48) 10.67 g (0.08 mol) of a 30% sodium hydroxide solution was added and 150 g water was added to adjust the system to a pH=8 to 9, to prepare a high-performance polycondensate water-reducing agent at a weight concentration of about 40%, as a clear light brown viscous liquid. The polycondensate was determined by aqueous gel-permeation chromatography to have a weight average molecular weight of 7500.

Comparative Example 2

(49) (1) Preparation of Monomer A

(50) 126.01 g (1.0 mol) melamine, 123 g (1.5 mol) phosphorous acid and 100 ml water were placed into a 1000 ml reaction flask, 156.8 g (1.6 mol) sulfuric acid was added, the temperature was raised to 100 C. for 10 min, 145.95 g (1.8 mol) of a 37% aqueous formaldehyde solution was dropwise added, a condenser tube was installed, and the reaction was heated to reflux for 3 h and cooled for later use.

(51) (2) Condensation

(52) 700 g (0.1 mol) of a monomer C (phenoxypolyoxyalkylene ether) and 110 g (0.5 mol) of the monomer A (monosubstituted phosphorylated melamine) were sequentially added in a 2000 ml round-bottomed flask, the temperature was raised to 80 C., 30.81 g (0.38 mol) of a 37% aqueous formaldehyde solution was dropwise added, and the reaction was maintained at 120 C. for 8 h.

(53) (3) Neutralization

(54) 49.33 g (0.47 mol) of a 30% sodium hydroxide solution was added and 1250 g water was added to adjust the system to a pH=8 to 9, to prepare a high-performance polycondensate water-reducing agent at a weight concentration of about 40%, as a clear light brown viscous liquid. The polycondensate was determined by aqueous gel-permeation chromatography to have a weight average molecular weight of 64500.

Application Example 1

(55) To evaluate dispersibility of the high-performance polycondensate water-reducing agent prepared in the present invention for cement paste, testing of fluidity of cement paste was performed according to the GB/T8077-2000 standard. The experimental results are shown in Table 3.

(56) In all the application examples of the present invention, unless otherwise stated, the cement used was Onoda 52.5R.P.II cement, the sand was medium sand having a fineness modulus Mx=2.6, and the stone was continuously graded broken stone having a particle size of 5 to 20 mm. Testing of fluidity of cement paste was preformed with reference to the GB/T8077-2000 standard, where 87 g of the water addition was used and the fluidity of cement paste was determined on a flat glass after stirring for 3 min. Determination of slump and slump loss was performed with reference to related provisions in JC473-2001 Pumping Aid for Concrete.

(57) TABLE-US-00003 TABLE 3 Fluidity of cement pastes of samples Solid content/ Fluidity of paste/mm Sample No. wt % 0 min 60 min Sample 1 0.12 250 255 Sample 2 0.12 262 257 Sample 3 0.12 246 248 Sample 4 0.12 252 256 Sample 5 0.12 237 230 Sample 6 0.12 247 240 Comparative sample1 0.12 202 158 Comparative sample2 0.12 185 178 Commercial PCA1 0.12 248 225 Commercial PCA2 0.12 252 218

(58) The data in Table 3 shows that the polycondensate water-reducing agents synthesized according to the preparation method of the present invention have excellent water-reducing and slump-retaining properties, and at a same dosage of 0.12%, compared to the commercial high-performance polycarboxylic acid water-reducing agents (PCA1 and PCA2), have an equivalent initial fluidity of cement paste, but have significantly better 60-minute slump retention, indicating that the polycondensate has excellent dispersion properties and dispersion-retaining properties of cement paste.

(59) The results from the control samples show that when the ratio of the materials diverges too much from the suggested range, the molecular weight of the polymer is too large or too small, so that the initial fluidity of cement paste of the samples is smaller and the loss increases. Therefore, the new polycondensate water-reducing agent provided by the present invention has excellent dispersion properties and dispersion-retaining properties of cement paste that are initially equivalent to those of the polycarboxylic acid water-reducing agent, and significantly better slump retention that is far superior to that of conventional naphthalene-based, amino, aliphatic, and melamine-based water-reducing agents.

Application Example 2

(60) To evaluate adaptability of the polycondensate water-reducing agent of the present invention for cement, initial fluidity of cement paste is tested according to the method of determining fluidity of cement paste in GB/T8077-2000 Methods for testing uniformity of concrete admixture, using 300 g of cement, 87 g of water addition, and self-provided and commercial polycarboxylic acid (PCA) water reducing agents as control samples, and using a paste mixer. The test results are shown in Table 4.

(61) TABLE-US-00004 TABLE 4 Adaptability of samples for various cements Solid Fluidity of cement paste/mm content/ Onoda Helin Conch Jidong Qilianshan wt % cement cement cement Cement Cement Sample 1 0.12 246 252 240 239 233 Sample 2 0.12 251 248 242 246 231 Sample 3 0.12 238 241 236 233 227 Sample 4 0.12 240 245 241 236 230 Sample 5 0.12 236 242 232 230 228 Sample 6 0.12 234 240 231 232 227 Comparative 0.12 190 196 181 173 156 sample1 Comparative 0.12 167 185 176 168 152 sample2 Commercial 0.12 232 245 210 162 113 PCA1 Commercial 0.12 218 235 176 169 121 PCA2

(62) The data in Table 4 shows that the polycondensate water-reducing agents provided by the present invention have good adaptability for cement, and exhibit stable fluidity of cement paste among cements produced in different regions.

(63) In contrast, the initial fluidity of cement paste of the control samples is low, but relatively instable among different cements. In addition, the commercial polycarboxylic acid water-reducing agents (PCA) exhibit large fluctuation among different cements and have poor adaptability for cement.

Application Example 3

(64) To evaluate adaptability of the polycondensate of the present invention for clay, initial fluidity of paste is tested according to a method of determining fluidity of cement paste in GB/T8077-2000 Methods for testing uniformity of concrete admixture, using 300 g of cement (Helin cement), 87 g of water addition, respectively 0.5% and 1% of montmorillonite based on the binder, and self-provided polycondensate water-reducing agent and polycarboxylic acid (PCA) water reducing agent as control samples, and using a paste mixer. The test results are shown in Table 5.

(65) TABLE-US-00005 TABLE 5 Clay resistance test of samples Solid Fluidity of cement paste/mm content/ Mixed with 0.5% Mixed with 1.0% wt % Initial montmorillonite montmorillonite Sample 1 0.12 248 240 233 Sample 2 0.12 240 236 232 Sample 3 0.12 235 240 241 Sample 4 0.12 248 245 246 Sample 5 0.12 236 246 242 Sample 6 0.12 228 220 232 Comparative 0.12 203 195 186 sample1 Comparative 0.12 210 203 201 sample2 Commercial 0.12 226 196 102 PCA1 Commercial 0.12 235 203 110 PCA2

(66) The data in Table 5 shows that the polycondensate water-reducing agents provided by the present invention have resistance to montmorillonite, and when mixed with montmorillonite at 0.5% and 1.0% of the amount of the adhesive cement respectively, have an equivalent slump flow without significant decrease in terms of fluidity of paste compared to that without montmorillonite; the control samples all exhibit low initial fluidity due to differences from the samples in segment structure and molecular weight, and when mixed with respective contents of montmorillonite, exhibit decreased slump flow values to a different extent; and the commercial polycarboxylic acid water-reducing agent (PCA) exhibits fluidity of paste that is rapidly decreased with increase in dosage of montmorillonite by even above 50%. In the market environment in which the quality of concrete aggregates and admixtures gradually becomes poor, the polycondensate water-reducing agent has vast engineering application prospects and the clay resistance thereof will be gradually recognized by the market.

Application Example 4

(67) To evaluate adaptability of the polycondensate of the present invention for sulfate, initial fluidity of paste is tested according to a method of determining fluidity of cement paste in GB/T8077-2000 Methods for testing uniformity of concrete admixture, using 300 g of cement (Helin cement), 87 g of water addition, respectively 0.5% and 1% of sodium sulfate based on the binder, and self-provided and commercial melamine (SM)-based water reducing agents as control samples, and using a paste mixer. The test results are shown in Table 6.

(68) TABLE-US-00006 TABLE 6 Sulfate resistance test of samples Solid Fluidity of cement paste/mm content/ Mixed with 0.5% Mixed with 1.0% wt % Initial sodium sulfate sodium sulfate Sample 1 0.12 248 245 243 Sample 2 0.12 258 253 249 Sample 3 0.12 234 236 232 Sample 4 0.12 246 243 236 Sample 5 0.12 238 231 226 Sample 6 0.12 236 242 235 Comparative 0.12 215 211 198 sample1 Comparative 0.12 204 206 200 sample2 Commercial 0.12 229 178 130 PCA1 Commercial 0.12 235 186 115 PCA2

(69) The data in Table 6 shows that the polycondensate water-reducing agents provided by the present invention have resistance to interference from sulfate ions, and since the adsorption ability of phosphate ions is larger than that of sulfonate ions, in the cement paste system, when mixed with sodium sulfate at 0.5% and 1% of the amount of the adhesive cement respectively, there is no significant decrease in slump flow in terms of fluidity of paste compared to that without the sulfate salt; and the commercial polycarboxylic acid water-reducing agent (PCA) exhibits decreased fluidity of paste to a certain degree with increase in dosage of the sulfate salt, which indicates that competitive adsorption of sulfate ions with respect to the polycarboxylic acid water-reducing agent occurs on the surface of cement particles. In a high-sulfate cement system in which the quality of concrete admixtures is poor, the polycondensate water-reducing agent has potential and vast application prospects because of resistance to sulfates.

Application Example 5

(70) The indexes such as water-reducing rate, air content and slump-retaining ability of the polycondensate water-reducing agent were measured, according to the test requirements of high-performance water-reducing agent in the GB8076-2008 standardConcrete Admixtures, using Helin cement, machine-made sand having a mud content of 1.8% and a fineness modulus of 3.3, and continuously graded broken stone having a mud content of 0.6% and nominal particle sizes of 5-10 mm and 10-20 mm, in the mixing ratio specified in Table 7. The results are shown in Table 8.

(71) TABLE-US-00007 TABLE 7 Mixing ratio of concrete for testing Machine- 5-10 10-20 Raw Fly Slag made mm mm materials Cement ash powder sand stone stone Water Mixing ratio, 240 85 75 886 380 570 174 Kg/m.sup.3

(72) TABLE-US-00008 TABLE 8 Results of performance testing of polycondensate water-reducing agent Water- Slump flow Solid reduc- Air Slump (mm) (mm) Sample content ing rate content After After name (%) (%) (%) Initial 1 h Initial 1 h Sample 1 0.12 29.2 3.8 215 193 468 432 Sample 2 0.12 28.6 3.6 220 189 472 441 Sample 3 0.12 27.2 3.5 213 178 465 431 Sample 4 0.12 28.3 3.7 206 192 457 429 Sample 5 0.12 27.9 4.1 214 196 469 438 Sample 6 0.12 28.4 3.9 221 186 476 445 Comparative 0.12 20.3 2.3 175 152 410 / sample1 Comparative 0.12 19.6 2.1 163 146 403 / sample2 Commercial 0.12 27.9 3.6 182 / 412 / PCA1 Commercial 0.12 28.5 3.8 193 / 423 / PCA2 Note: / indicates that concrete has no slump and slump flow values

(73) The data of flowability of concrete in Table 8 show that under the conditions of machine-made sand having a mud content of 1.8% and stone having a mud content of 0.6% as aggregates, the newly synthesized polycondensate water-reducing agents exhibit better slump values and slump-retaining ability than that of the commercial polycarboxylic acid (PCA) water reducing agents, which indicates that the polycondensate water-reducing agent has good adaptability for machine-made sand and stone having a high mud content and has obvious anti-mud effect.

(74) The polycondensate water-reducing agent provided by the present invention has a novel structure, simple preparation process and low material costs, and uses the incorporated phosphate group, in place of conventional carboxyl group and sulfonic group, as a main adsorption group, such that the overall performance of the conventional water-reducing agent is improved. The polycondensate water-reducing agent exhibits good adaptability for cement, resistance to clays and resistance to competitive adsorption of sulfate ions, and has strong advantages and vast market prospects in the current market environment in which the quality of concrete admixtures and aggregates is poor.