Ready-mixed concrete using hydrolyzed polymaleic anhydride as main chelating agent and preparation method thereof

Abstract

The invention discloses a kind of ready-mixed concrete with hydrolyzed polymaleic anhydride as main chelating agent, according to weight percentage, including the following components: cement 14.9% 38.9%, admixture 0 21.9%, machine-made sand 32.1% 71.7%, coarse aggregate 0 45.7%, chelating agent 0.0073% 0.011%, water reducer 0.3% 0.53% and water;The proportion of the chelating agent is the weight percentage accounting for the sum of cement and admixture, and the chelating agent is hydrolyzed polymaleic anhydride, and sodium polyacrylate or aminotri(methylene phosphonic acid) are further added in the chelating agent. The present invention applies chelating agent to ready-mixed concrete, improves concrete working performance, can make the viscosity of concrete mixture reduce, rheology is enhanced, and coarse aggregate ratio is improved, has positive significance to the development of ready-mixed concrete.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to a ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent and a preparation method thereof. Background Art

[0002] Since the 21st century, the ready-mix concrete industry has experienced rapid growth, and improving the performance of ready-mix concrete has become increasingly important. During the production process, ready-mix concrete can suffer from problems such as poor fluidity, excessive viscosity, and segregation. Currently, these issues are addressed by adding common admixtures such as water reducers.

[0003] Hydrolyzed polymaleic anhydride, as a metal ion chelating agent, can chelate metal ions in sediment or mica to form loose microparticles in water. This provides excellent dispersion, preventing them from agglomerating into large particles. It acts as a lubricating particle in the concrete mix, facilitating smooth movement between components. It can also be combined with other chelating agents to enhance the effect. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art.

[0005] In order to achieve the above invention purpose, the technical solution provided by the present invention is as follows:

[0006] A ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent comprises the following components, expressed in percentage by weight: 14.9%-38.9% cement, 0-21.9% admixture, 32.1%-71.7% machine-made sand, 0-45.7% coarse aggregate, 0.0073%-0.011% chelating agent, 0.3%-0.53% water reducer, and water; the chelating agent is hydrolyzed polymaleic anhydride and the additive is sodium polyacrylate or aminotrimethylphosphonic acid; the cement and admixture are mixed to form a cementitious material;

[0007] When the additive is sodium polyacrylate, and the mass ratio of sodium polyacrylate to hydrolyzed polymaleic anhydride is 1:3, the weight percentage of the chelating agent in the gelling material is 0.011%; when the mass ratio of sodium polyacrylate to hydrolyzed polymaleic anhydride is 1:1, the weight percentage of the chelating agent in the gelling material is 0.0073%;

[0008] When the additive is aminotrimethylenephosphonic acid, when the mass ratio of aminotrimethylenephosphonic acid to hydrolyzed polymaleic anhydride is 1:3, the weight percentage of the chelating agent in the ready-mixed concrete is 0.011%; when the mass ratio of aminotrimethylenephosphonic acid to hydrolyzed polymaleic anhydride is 1:1, the weight percentage of the chelating agent in the cementitious material is 0.0073%.

[0009] Furthermore, the cement in the machine-made sand is silicate cement or ordinary silicate cement.

[0010] Furthermore, the admixture of the machine-made sand is at least one of fly ash and slag powder.

[0011] Furthermore, the machine-made sand is a machine-made sand with a high stone powder content.

[0012] Furthermore, the water reducing agent for machine-made sand is a polycarboxylic acid-based water reducing agent with a water reduction rate of 30-40%.

[0013] A method for preparing ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent, the method specifically comprising the following steps:

[0014] S1, adding cement and admixture into the mixer and pre-mixing into mixture A;

[0015] S2, mixing the chelating agent and the water reducing agent with water in proportion and stirring evenly to form additive B;

[0016] S3, mixing the mixture A and the additive B and stirring them uniformly to form a mixture C; the hydrolyzed polymaleic anhydride in the chelating agent chelates the calcium and magnesium metal ions in the cement, forming a solubility limit effect, thereby improving the fluidity of the concrete;

[0017] S4, add coarse aggregate and machine-made sand into mixture C in proportion, and continue to stir evenly to form ready-mixed concrete.

[0018] Furthermore, the fluidity of the ready-mixed concrete made of machine-made sand is ≥180 mm.

[0019] Furthermore, when the chelating agent is hydrolyzed polymaleic anhydride and sodium polyacrylate, the sodium polyacrylate and the hydrolyzed polymaleic anhydride chelate calcium and magnesium metal ions in cement, coarse aggregate and machine-made sand, thereby reducing the adsorption and consumption of the water reducer by the calcium and magnesium ions. At the same time, the sodium polyacrylate ionizes in water to produce choline acid anions, which attract the positive charges on the surface of the stone powder in the machine-made sand and are adsorbed on the surface of the stone powder. The chain links in the adsorbed molecules are fixed on the surface of the stone powder, and the chain links also extend into the adsorption layer formed by the solution in the form of chain links or chain tails. Due to the steric hindrance effect and the principle of like charges repelling each other, the stone powder is dispersed in the solution, thereby reducing the viscosity of the concrete.

[0020] Furthermore, when the chelating agent is hydrolyzed polymaleic anhydride and aminotri(methylenephosphonic acid), aminotri(methylenephosphonic acid) and hydrolyzed polymaleic anhydride chelate calcium and magnesium metal ions in cement, coarse aggregate and machine-made sand. At the same time, the complex of aminotri(methylenephosphonic acid) forms a stable solvated water film on the cement surface, slowing down the cement hydration process and delaying the reduction of the fluidity of ready-mixed concrete.

[0021] Based on the above technical solution, the present invention has achieved the following technical effects through practical application of a ready-mixed concrete and preparation method using hydrolyzed polymaleic anhydride as the main chelating agent:

[0022] 1. The present invention discloses a ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent and a preparation method thereof. The chelating agent is applied to ready-mixed concrete to improve the working performance of the concrete, thereby reducing the viscosity of the concrete mixture, enhancing the rheological properties, and increasing the proportion of coarse aggregate, which has positive significance for the development of ready-mixed concrete.

[0023] 2 The chelating agent used in the ready-mixed concrete with hydrolyzed polymaleic anhydride as the main chelating agent of the present invention is widely used, non-toxic and harmless, can be degraded by microorganisms, is a recognized green and environmentally friendly chemical, and is of great significance to environmental protection.

[0024] 3. The chelating agent used in the ready-mixed concrete with hydrolyzed polymaleic anhydride as the main chelating agent of the present invention can reduce the adsorption of the stone powder in the machine-made sand to the water reducer through adsorption competition, thereby improving the use effect of the water reducer and having positive significance for the application of machine-made sand.

[0025] 4. The present invention provides a method for preparing ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent. The method has a simple preparation process, easy access to raw materials, high economic benefits, and reduced production costs. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and effects of the present invention more clearly understood, the present invention is described below using specific examples. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0027] In an embodiment of the present invention:

[0028] The test method for the fluidity of the concrete is carried out in accordance with JGJ / T70-2009;

[0029] The test method for the compressive strength of the concrete is carried out in accordance with GB / T 50107-2010;

[0030] The cement is Portland cement with a strength grade of 52.5;

[0031] The stone powder content of the machine-made sand is 5%;

[0032] The water reducer is a polycarboxylic acid liquid water reducer.

[0033] Example 1

[0034] A ready-mixed concrete with hydrolyzed polymaleic anhydride as a main chelating agent includes the following components, recorded in percentage by weight: 14.91% cement, 11.29% admixture, 63.48% machine-made sand, 0.0073% hydrolyzed polymaleic anhydride, 0.35% water reducer and 9.71% water; the proportion of hydrolyzed polymaleic anhydride is the weight percentage of the total weight of cement and admixture.

[0035] A method for preparing ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent, the method specifically comprising the following steps:

[0036] S1, adding cement and admixture into the mixer and pre-mixing into mixture A;

[0037] S2, mixing the hydrolyzed polymaleic anhydride and the water reducer with water in proportion and stirring evenly to form additive B;

[0038] S3, mixing the mixture A and the additive B and stirring them uniformly to form a mixture C; hydrolyzing the calcium and magnesium metal ions in the polymaleic anhydride chelate cement to form a solubility limit effect and improve the fluidity of the concrete;

[0039] S4, adding machine-made sand and coarse aggregate into mixture C in proportion, and continuing to stir evenly to form ready-mixed concrete.

[0040] When no chelating agent is added, the fluidity of the concrete is 158 mm after 1 hour, and the consistency loss is 45.8% after 1 hour. When the chelating agent is added, the fluidity of the ready-mixed concrete is 230 mm after 1 hour, and the consistency loss is 29.8% after 1 hour. By comparison, the fluidity of the concrete with the chelating agent is greater than that of the concrete without the chelating agent.

[0041] The test showed that the 7-day compressive strength of the ready-mixed concrete increased by 36.8%, and the 28-day compressive strength increased by 26%.

[0042] Example 2

[0043] A ready-mixed concrete with hydrolyzed polymaleic anhydride as a main chelating agent comprises the following components, expressed in percentage by weight: 14.91% cement, 11.29% admixture, 63.48% machine-made sand, 0.0073% hydrolyzed polymaleic anhydride, 0.0018% sodium polyacrylate, 0.35% water reducer and 9.71% water; the proportions of hydrolyzed polymaleic anhydride and sodium polyacrylate are the weight percentages of the total weight of cement and admixture.

[0044] A method for preparing ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent, the method specifically comprising the following steps:

[0045] S1, put cement and admixture into a mixer, weigh sodium polyacrylate in proportion and add it into the mixer, and pre-mix to form mixture A;

[0046] S2, mixing the hydrolyzed polymaleic anhydride and the water reducer with water in proportion and stirring evenly to form additive B;

[0047] S3, mixing the mixture A and the additive B and stirring them uniformly to form a mixture C; hydrolyzing the calcium and magnesium metal ions in the polymaleic anhydride chelate cement to form a solubility limit effect and improve the fluidity of the concrete; sodium polyacrylate and the hydrolyzed calcium and magnesium metal ions in the polymaleic anhydride chelate cement, coarse aggregate and machine-made sand, while the sodium polyacrylate adjusts the viscosity of the concrete;

[0048] S4, adding machine-made sand and coarse aggregate into mixture C in proportion, and continuing to stir evenly to form ready-mixed concrete.

[0049] When no chelating agent was added, the concrete had a fluidity of 158 mm after one hour, and a 1-hour consistency loss of 45.8%. When a chelating agent was added, the ready-mixed concrete had a fluidity of 240 mm after one hour, and a 1-hour consistency loss of 35.6%. By comparison, the concrete with the chelating agent had a greater fluidity after one hour than the concrete without the chelating agent.

[0050] The test showed that the 7-day compressive strength of the ready-mixed concrete increased by 39.5%, and the 28-day compressive strength increased by 6.8%.

[0051] Example 3

[0052] A ready-mixed concrete with hydrolyzed polymaleic anhydride as a main chelating agent comprises the following components, expressed in percentage by weight: 14.91% cement, 11.29% admixture, 63.48% machine-made sand, 0.0037% hydrolyzed polymaleic anhydride, 0.0037% aminotri(methylenephosphonic acid), 0.35% water reducer and 9.71% water; the proportions of hydrolyzed polymaleic anhydride and aminotri(methylenephosphonic acid) are percentages by weight of the total weight of cement and admixture.

[0053] A method for preparing ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent, the method specifically comprising the following steps:

[0054] S1, adding cement and admixtures into a mixer, weighing amino tris(methylene phosphonic acid) in proportion and adding it into the mixer, and pre-mixing to form a mixture A;

[0055] S2, mixing the hydrolyzed polymaleic anhydride and the water reducer with water in proportion and stirring evenly to form additive B;

[0056] S3, mixing the mixture A and the additive B and stirring them uniformly to form a mixture C; hydrolyzing the calcium and magnesium metal ions in the polymaleic anhydride chelate cement to form a solubility limit effect and improve the fluidity of the concrete; amino tris (methylene phosphonic acid) and the calcium and magnesium metal ions in the hydrolyzed polymaleic anhydride chelate cement, coarse aggregate and machine-made sand, while the amino tris (methylene phosphonic acid) has a coagulation and rust-inhibiting effect on the ready-mixed concrete;

[0057] S4, adding machine-made sand and coarse aggregate into mixture C in proportion, and continuing to stir evenly to form ready-mixed concrete.

[0058] When no chelating agent was added, the concrete had a fluidity of 158 mm after 1 hour, and a 1-hour consistency loss of 45.8%. When a chelating agent was added, the ready-mixed concrete had a fluidity of 220 mm after 1 hour, and a 1-hour consistency loss of 18.7%. By comparison, the fluidity of the concrete with the chelating agent after 1 hour was greater than that of the concrete without the chelating agent.

[0059] The test showed that the 7-day compressive strength of the ready-mixed concrete increased by 26.98%, and the 28-day compressive strength increased by 2.5%.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention, which should all be included in the scope of the technical solutions for which protection is requested by the present invention.

Claims

1. A ready-mixed concrete with hydrolyzed polymaleic anhydride as the main chelating agent, characterized in that: The composition comprises the following components in percentage by weight: 14.9%-38.9% cement, 0-21.9% admixture, 32.1%-71.7% machine-made sand, 0-45.7% coarse aggregate, 0.0073%-0.011% chelating agent, 0.3%-0.53% water reducer and water; the chelating agent is hydrolyzed polymaleic anhydride and the additive is sodium polyacrylate or aminotrimethylphosphonic acid; the cement and admixture are mixed to form a cementitious material; When the additive is sodium polyacrylate and the mass ratio of sodium polyacrylate to hydrolyzed polymaleic anhydride is 1:3, the weight percentage of the chelating agent in the gelling material is 0.011%; when the mass ratio of sodium polyacrylate to hydrolyzed polymaleic anhydride is 1:1, the weight percentage of the chelating agent in the gelling material is 0.0073%; When the additive is aminotrimethylenephosphonic acid and the mass ratio of aminotrimethylenephosphonic acid to hydrolyzed polymaleic anhydride is 1:3, the weight percentage of the chelating agent in the ready-mixed concrete is 0.011%; when the mass ratio of aminotrimethylenephosphonic acid to hydrolyzed polymaleic anhydride is 1:1, the weight percentage of the chelating agent in the cementitious material is 0.0073%.

2. The ready-mixed concrete with hydrolyzed polymaleic anhydride as the main chelating agent according to claim 1, characterized in that: The cement is silicate cement or ordinary silicate cement.

3. The ready-mixed concrete with hydrolyzed polymaleic anhydride as the main chelating agent according to claim 1, characterized in that: The admixture is at least one of fly ash and slag powder.

4. The ready-mixed concrete with hydrolyzed polymaleic anhydride as a main chelating agent according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid water reducing agent with a water reduction rate of 30-40%.

5. The ready-mixed concrete with hydrolyzed polymaleic anhydride as a main chelating agent according to claim 1, characterized in that: The machine-made sand includes stone powder.

6. A method for preparing ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent, using the ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent according to any one of claims 1 to 5, characterized in that: The method specifically comprises the following steps: S1, adding cement and admixture into the mixer and pre-mixing into mixture A; S2, mixing the chelating agent and the water reducing agent with water in proportion and stirring evenly to form additive B; S3, mixing the mixture A and the additive B and stirring them uniformly to form a mixture C; the hydrolyzed polymaleic anhydride in the chelating agent chelates the calcium and magnesium metal ions in the cement, forming a solubility limit effect, thereby improving the fluidity of the concrete; When the chelating agent is hydrolyzed polymaleic anhydride and sodium polyacrylate, the sodium polyacrylate and the hydrolyzed polymaleic anhydride chelate calcium and magnesium metal ions in cement, coarse aggregate and machine-made sand, reducing the adsorption and consumption of the water reducer by the calcium and magnesium ions. At the same time, the sodium polyacrylate ionizes in water to produce carboxylate negative ions, which attract the positive charges on the surface of the stone powder in the machine-made sand and are adsorbed on the surface of the stone powder. The chain links in the adsorbed molecules are fixed on the surface of the stone powder and extend into the adsorption layer formed by the solution in the form of chain links or chain tails. Due to the steric hindrance effect and the principle of like charges repelling each other, the stone powder is dispersed in the solution, thereby reducing the viscosity of the concrete. When the chelating agent is hydrolyzed polymaleic anhydride and aminotrimethylenephosphonic acid, the aminotrimethylenephosphonic acid and the hydrolyzed polymaleic anhydride chelate calcium and magnesium metal ions in cement, coarse aggregate and machine-made sand, and the aminotrimethylenephosphonic acid complex forms a stable solvated water film on the cement surface, slowing down the cement hydration process and delaying the reduction of the fluidity of the ready-mixed concrete; S4, add coarse aggregate and machine-made sand into mixture C in proportion, and continue to stir evenly to form ready-mixed concrete.

7. The method for preparing ready-mixed concrete using hydrolyzed polymaleic anhydride as a main chelating agent according to claim 6, characterized in that: The fluidity of the ready-mixed concrete is ≥180 mm.