Composite desert sand environment-friendly green concrete composite admixture and preparation method thereof

Abstract

The invention belongs to the technical field of concrete admixtures, and particularly relates to an environment-friendly concrete composite admixture compounded with desert sand and a preparation method of the environment-friendly concrete composite admixture. The desert sand water reducing agent is prepared from the following raw materials in parts by weight: 30 to 60 parts of desert sand, 20 to 30 parts of a modified high-performance water reducing agent, 10 to 12 parts of a pumping agent, 2 to 5 parts of sodium sulfate, 1 to 2 parts of polyaluminum chloride and 1 to 2 parts of sodium benzoate, comprising the following steps: S1, preparing a high-performance water reducing agent; and S2, preparing the modified high-performance water reducing agent. According to the composite desert sand environment-friendly green concrete composite admixture with the monoglyceride loaded nano silicon dioxide modified high-performance water reducing agent and the desert sand as main materials, under the condition that the doping amount is low, the water reducing rate is increased, the water reducing effect is enhanced, the plasticity retaining property is improved, and the size is relatively stable.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete admixtures, and specifically relates to a composite desert sand environmentally friendly green concrete composite admixture and a preparation method thereof. Background Art

[0002] Concrete admixtures refer to chemical substances added in addition to cementitious materials, aggregates, water and fiber components during the preparation of concrete, with the purpose of improving the performance of fresh concrete and (or) hardened concrete, while not causing harmful effects on the human body, organisms and the environment. Water reducers are a type of concrete admixture, including ordinary water reducers, high-efficiency water reducers and high-performance water reducers. From the perspective of water reducer production, low-concentration naphthalene-based water reducers still dominate the market. Naphthalene-based water reducers contain more sodium sulfate, which will lead to poor compatibility and reduced durability between water reducers and cement and other admixtures, and their environmental performance does not meet the standards. High-efficiency water reducers such as melamine high-efficiency water reducers and aminobenzenesulfonate high-efficiency water reducers, among which melamine has a relatively high cost, and the added concentration will be reduced accordingly, and the utilization rate in actual production is low. As the main component of aminobenzenesulfonate high-efficiency water reducer, aminobenzenesulfonate phenol formaldehyde condensate has a good water-reducing effect, but it is very easy to cause serious water seepage.

[0003] In the prior art, after searching, the invention patent with Chinese patent number CN114105517A discloses a polycarboxylic acid high-performance water-reducing agent, which includes the following components in mass percentage: polycarboxylic acid water-reducing agent 8%-15%, retarder 0.5%-3%, thixotropic agent 0.01%-0.1%, foam stabilizer 0.01%-0.05% and air entraining agent 0.01%-0.05%. However, in practical application, the above invention patent is highly sensitive to the mud content of aggregates, especially when the mud content of aggregates is high, it will affect the strength and durability of concrete, and has poor integration into machine-made sand and poor adaptability to admixtures such as desert sand. Summary of the invention

[0004] The purpose of the present invention is to provide a composite desert sand environmentally friendly green concrete composite admixture and a preparation method thereof, wherein monoglyceride-loaded nano-silicon dioxide-modified high-performance water-reducing agent is used as the main modified high-performance water-reducing agent, and desert sand and other raw materials are compounded by weight to obtain a concrete composite admixture.

[0005] The technical problem to be solved by the present invention is that after adding concrete admixtures, the strength and durability of concrete are low, and the integration and adaptability are poor.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A composite desert sand environmentally friendly green concrete composite admixture comprises the following raw materials by weight: 30-60 parts of desert sand, 20-30 parts of modified high-performance water reducing agent, 10-12 parts of pumping agent, 2-5 parts of sodium sulfate, 1-2 parts of polyaluminium chloride and 1-2 parts of sodium benzoate, wherein the modified high-performance water reducing agent refers to monoglyceride-loaded nano-silica modified high-performance water reducing agent.

[0008] The pumping agent includes one or more of calcium lignin sulfonate, sodium lignin sulfonate and magnesium lignin sulfonate.

[0009] Further, the modified high performance water reducing agent is prepared by the following steps:

[0010] S1. Ultrasonic dispersion of methacrylic acid in distilled water, dropwise addition of triethanolamine, placing in a stainless steel polytetrafluoroethylene lined reactor, introducing nitrogen at 50°C-60°C, stirring for 30min-40min, adding maleic anhydride, heating to 80°C-90°C, reacting for 3h-4h, vacuum distillation, purification, cooling to room temperature, adding toluene diisocyanate, stirring for 20min-30min, and obtaining a high performance water reducing agent;

[0011] S2. Ultrasonic dispersion of monoglyceride in high-performance water reducing agent, dropwise addition of nano-silicon dioxide suspension, addition of catalyst and initiator in a reaction kettle, control of temperature reaction, and post-treatment to obtain a modified high-performance water reducing agent.

[0012] In step S1, the mass ratio of methacrylic acid, maleic anhydride and toluene diisocyanate is (20-30): (10-12): (3-5), and the volume ratio of distilled water and triethanolamine is (50-60): (6-8), wherein toluene diisocyanate refers to a mixture of toluene-2,4-diisocyanate and toluene-2,6-diisocyanate.

[0013] Furthermore, step S2 is specifically as follows:

[0014] The monoglyceride is ultrasonically dispersed in the high-performance water reducing agent, and the nano-silica suspension is added dropwise. The mixture is heated to 40°C-50°C in a water bath, stirred for 15min-30min, and transferred to a stainless steel polytetrafluoroethylene lined reactor. Under the protection of nitrogen, N-ethylethylenediamine is added dropwise, dibenzoyl peroxide and zinc octanoate are added, the temperature is controlled at 90°C-100°C, the reaction is carried out for 2h-3h, and the mixture is fractionated by a rotary distiller. The mixture is cooled to room temperature, allowed to stand for 30min-40min, filtered, the filtrate is discarded, washed and dried, and the monoglyceride-loaded nano-silica modified high-performance water reducing agent, i.e., the modified high-performance water reducing agent, is obtained.

[0015] The solid content of the nano-silicon dioxide suspension in step S2 is ≤70wt%, and the composition of the silicon dioxide suspension includes: silicon dioxide powder, polyvinyl alcohol and ethanol, and the particle size of the silicon dioxide powder is 1nm-100nm.

[0016] The mass ratio of monoglyceride, dibenzoyl peroxide and zinc octanoate is (20-25): (1-3): (0.5-0.7), and the volume ratio of high-performance water reducer, nano silicon dioxide suspension and N-ethylethylenediamine is (25-30): (10-15): (2-4).

[0017] A method for preparing a composite desert sand environmentally friendly green concrete composite admixture comprises the following steps:

[0018] Desert sand, pumping agent, sodium sulfate, polyaluminium chloride and sodium benzoate are weighed by weight and put into a mixer, and a modified high-performance water reducer is added, mixed evenly, molded and granulated to obtain a composite desert sand environmentally friendly green concrete composite admixture.

[0019] Beneficial effects of the present invention:

[0020] 1. In this technical solution, the high-performance water-reducing agent modified by nano-silica loaded with monoglyceride has excellent water-reducing effect. The modified high-performance water-reducing agent has a comb-shaped molecular structure, and there are multiple active groups such as hydroxyl, carboxyl, carbonyl and sulfonic acid groups on the main chain, which have strong polarity; the active groups of the side chains such as carboxyl, hydroxyl, amino and ester groups have strong hydrophilicity. Monoglyceride and high-performance water-reducing agent form a good dispersed structure through the copolymerization reaction of unsaturated monomers under the combined action of steric hindrance and strong electrostatic repulsion, and nano-silica is attached to the pores of the structure through strong interaction forces, playing a synergistic role. Therefore, the high-performance water-reducing agent modified by nano-silica loaded with monoglyceride can improve the water reduction rate, enhance the water reduction effect, improve the plasticity, and has a relatively stable volume when the dosage is low.

[0021] 2. In this technical solution, the production cost of hydraulic concrete can be reduced by adding desert sand. Desert sand is a natural resource with a wide source and low cost, which can reduce the addition of sand and gravel resources, and the modified high-performance water reducer is also a green and environmentally friendly building material. It conforms to the concept of green environmental protection. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] The modified high performance water reducing agent is prepared by the following steps:

[0025] S1. Ultrasonic dispersion of 20 g methacrylic acid in 50 mL distilled water, dropwise addition of 6 mL triethanolamine, placed in a stainless steel polytetrafluoroethylene lined reactor, introduced nitrogen at 55 ° C, stirred for 35 min, added 10 g maleic anhydride, heated to 85 ° C, reacted for 3.5 h, vacuum distilled, purified, cooled to room temperature, added 3 g toluene diisocyanate, stirred for 25 min, and obtained a high performance water reducer;

[0026] S2. Ultrasonic disperse 20g monoglyceride in 25mL high-performance water reducer, add 10mL nano-silica suspension, heat to 45°C in a water bath, stir for 20min, transfer to a stainless steel polytetrafluoroethylene lined reactor, add 2mL N-ethylethylenediamine under the protection of nitrogen, add 1g dibenzoyl peroxide and 0.5g zinc octanoate, control the temperature at 95°C, react for 2.5h, distill with a rotary distiller, cool to room temperature, stand for 35min, filter, discard the filtrate, wash and dry to obtain monoglyceride-loaded nano-silica modified high-performance water reducer, i.e., modified high-performance water reducer.

[0027] Example 2

[0028] The modified high performance water reducing agent is prepared by the following steps:

[0029] S1. Ultrasonic dispersion of 25 g methacrylic acid in 55 mL distilled water, dropwise addition of 7 mL triethanolamine, placed in a stainless steel polytetrafluoroethylene lined reactor, introduced nitrogen at 55 ° C, stirred for 35 min, added 11 g maleic anhydride, heated to 85 ° C, reacted for 3.5 h, vacuum distilled, purified, cooled to room temperature, added 4 g toluene diisocyanate, stirred for 25 min, and obtained a high performance water reducer;

[0030] S2. Ultrasonic disperse 22.5 g monoglyceride in 27.5 mL high-performance water reducer, add 12.5 mL nano-silica suspension, heat to 45 ° C in a water bath, stir for 20 min, transfer to a stainless steel polytetrafluoroethylene lined reactor, and under the protection of nitrogen, add 3 mL N-ethylethylenediamine, add 2 g dibenzoyl peroxide and 0.6 g zinc octanoate, control the temperature at 95 ° C, react for 2.5 h, distill with a rotary distiller, cool to room temperature, stand for 35 min, filter, discard the filtrate, wash and dry to obtain monoglyceride-loaded nano-silica modified high-performance water reducer, i.e., modified high-performance water reducer.

[0031] Example 3

[0032] The modified high performance water reducing agent is prepared by the following steps:

[0033] S1. Ultrasonic dispersion of 30 g methacrylic acid in 60 mL distilled water, dropwise addition of 8 mL triethanolamine, placed in a stainless steel polytetrafluoroethylene lined reactor, introduced nitrogen at 55 ° C, stirred for 35 min, added 12 g maleic anhydride, heated to 85 ° C, reacted for 3.5 h, vacuum distilled, purified, cooled to room temperature, added 5 g toluene diisocyanate, stirred for 25 min, and obtained a high performance water reducer;

[0034] S2. Ultrasonic disperse 25g monoglyceride in 30mL high-performance water reducer, add 15mL nano-silica suspension, heat to 45°C in a water bath, stir for 20min, transfer to a stainless steel polytetrafluoroethylene lined reactor, add 4mL N-ethylethylenediamine under the protection of nitrogen, add 3g dibenzoyl peroxide and 0.7g zinc octanoate, control the temperature at 95°C, react for 2.5h, distill with a rotary distiller, cool to room temperature, stand for 35min, filter, discard the filtrate, wash and dry to obtain monoglyceride loaded nano-silica modified high-performance water reducer, i.e. modified high-performance water reducer.

[0035] Example 4

[0036] A method for preparing a composite desert sand environmentally friendly green concrete composite admixture comprises the following steps:

[0037] 30 parts of desert sand, 10 parts of pumping agent, 2 parts of sodium sulfate, 1 part of polyaluminium chloride and 1 part of sodium benzoate were weighed by weight and put into a mixer, 20 parts of the modified high-performance water reducing agent prepared in Example 1 were added, mixed evenly, molded and granulated to obtain a composite desert sand environmentally friendly green concrete composite admixture.

[0038] Example 5

[0039] A method for preparing a composite desert sand environmentally friendly green concrete composite admixture comprises the following steps:

[0040] 45 parts of desert sand, 11 parts of pumping agent, 3.5 parts of sodium sulfate, 1.5 parts of polyaluminium chloride and 1.5 parts of sodium benzoate were weighed by weight and put into a mixer, and 25 parts of the modified high-performance water reducing agent prepared in Example 2 were added, mixed evenly, molded and granulated to obtain a composite desert sand environmentally friendly green concrete composite admixture.

[0041] Example 6

[0042] A method for preparing a composite desert sand environmentally friendly green concrete composite admixture comprises the following steps:

[0043] 60 parts of desert sand, 12 parts of pumping agent, 5 parts of sodium sulfate, 2 parts of polyaluminium chloride and 2 parts of sodium benzoate were weighed by weight and put into a mixer, 30 parts of the modified high-performance water reducing agent prepared in Example 3 were added, mixed evenly, molded and granulated to obtain a composite desert sand environmentally friendly green concrete composite admixture.

[0044] Comparative Example 1

[0045] 20 g of methacrylic acid was ultrasonically dispersed in 50 mL of distilled water, 6 mL of triethanolamine was added dropwise, and the mixture was placed in a stainless steel polytetrafluoroethylene-lined reactor. Nitrogen was introduced at 55 ° C, stirred for 35 min, 10 g of maleic anhydride was added, the temperature was raised to 85 ° C, the reaction was performed for 3.5 h, and the mixture was distilled under reduced pressure, purified, cooled to room temperature, 3 g of toluene diisocyanate was added, and stirred for 25 min to obtain a high-performance water reducer.

[0046] Comparative Example 2

[0047] 30 parts of desert sand, 10 parts of pumping agent, 2 parts of sodium sulfate, 1 part of polyaluminium chloride and 1 part of sodium benzoate were weighed by weight and put into a mixer, and 20 parts of the high-performance water reducing agent prepared in Comparative Example 1 were added, mixed evenly, pressed into a mould and granulated.

[0048] Comparative Example 3

[0049] Weigh 30 parts of desert sand, 10 parts of pumping agent, 2 parts of sodium sulfate, 1 part of polyaluminium chloride and 1 part of sodium benzoate by weight and put them into a mixer without adding a water reducing agent. Mix well, press into a mould and make granules.

[0050] Examples 4-6 and Comparative Examples 2-3 were tested with reference to the test raw materials and mix ratios, concrete mixing, specimen preparation and admixture methods in DL / T 5100-2014 "Technical Specifications for Hydraulic Concrete Admixtures", and some indicators were measured according to GB8076-2008 "Concrete Admixtures". The results are shown in Table 1:

[0051] Table 1. Some performance indicators of the tested concrete of Examples 4-6 and Comparative Examples 2-3

[0052]

[0053]

[0054] As can be seen from Table 1, the performance indicators of Examples 4-6 meet the requirements for high-performance water-reducing agents in GB 8076-2008 "Concrete Admixtures", and the overall performance is better than that of Comparative Examples 2-3, indicating that by using monoglyceride-loaded nano-silica-modified high-performance water-reducing agent as the main modified high-performance water-reducing agent and compounding desert sand and other raw materials by weight, a concrete composite admixture is obtained, which has good water-reducing effect and green environmental protection performance.

[0055] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0056] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A composite desert sand environmentally friendly green concrete composite admixture, characterized in that: The following raw materials are included by weight: 30-60 parts of desert sand, 20-30 parts of modified high-performance water-reducing agent, 10-12 parts of pumping agent, 2-5 parts of sodium sulfate, 1-2 parts of polyaluminium chloride and 1-2 parts of sodium benzoate, wherein the modified high-performance water-reducing agent refers to a high-performance water-reducing agent modified with monoglyceride-loaded nano-silica.

2. The composite desert sand environmentally friendly green concrete composite admixture according to claim 1, characterized in that: The pumping agent includes one or more of calcium lignin sulfonate, sodium lignin sulfonate, and magnesium lignin sulfonate.

3. The composite desert sand environmentally friendly green concrete composite admixture according to claim 1, characterized in that: The modified high performance water reducing agent is prepared by the following steps: S1. Ultrasonic dispersion of methacrylic acid in distilled water, dropwise addition of triethanolamine, placing in a stainless steel polytetrafluoroethylene lined reactor, introducing nitrogen at 50°C-60°C, stirring for 30min-40min, adding maleic anhydride, heating to 80°C-90°C, reacting for 3h-4h, vacuum distillation, purification, cooling to room temperature, adding toluene diisocyanate, stirring for 20min-30min, and obtaining a high performance water reducing agent; S2. Ultrasonic dispersion of monoglyceride in high-performance water reducing agent, dropwise addition of nano-silicon dioxide suspension, addition of catalyst and initiator in a reaction kettle, control of temperature reaction, and post-treatment to obtain a modified high-performance water reducing agent.

4. The composite desert sand environmentally friendly green concrete composite admixture according to claim 3, characterized in that: In step S1, the mass ratio of methacrylic acid, maleic anhydride and toluene diisocyanate is (20-30):(10-12):(3-5), and the volume ratio of distilled water and triethanolamine is (50-60):(6-8), wherein toluene diisocyanate refers to a mixture of toluene-2,4-diisocyanate and toluene-2,6-diisocyanate.

5. The composite desert sand environmentally friendly green concrete composite admixture according to claim 3, characterized in that: Step S2 is specifically as follows: The monoglyceride is ultrasonically dispersed in the high-performance water reducing agent, and the nano-silica suspension is added dropwise. The mixture is heated to 40°C-50°C in a water bath, stirred for 15min-30min, and transferred to a stainless steel polytetrafluoroethylene lined reactor. Under the protection of nitrogen, N-ethylethylenediamine is added dropwise, dibenzoyl peroxide and zinc octanoate are added, the temperature is controlled at 90°C-100°C, the reaction is carried out for 2h-3h, and the mixture is fractionated by a rotary distiller. The mixture is cooled to room temperature, allowed to stand for 30min-40min, filtered, the filtrate is discarded, washed and dried, and the monoglyceride-loaded nano-silica modified high-performance water reducing agent, i.e., the modified high-performance water reducing agent, is obtained.

6. The composite desert sand environmentally friendly green concrete composite admixture according to claim 3, characterized in that: The solid content of the nano-silicon dioxide suspension in step S2 is ≤70wt%, and the composition of the silicon dioxide suspension includes: silicon dioxide powder, polyvinyl alcohol and ethanol, and the particle size of the silicon dioxide powder is 1nm-100nm.

7. The composite desert sand environmentally friendly green concrete composite admixture according to claim 5, characterized in that: The mass ratio of monoglyceride, dibenzoyl peroxide and zinc octanoate is (20-25): (1-3): (0.5-0.7), and the volume ratio of high-performance water reducer, nano-silicon dioxide suspension and N-ethylethylenediamine is (25-30): (10-15): (2-4).

8. A method for preparing the composite desert sand environmentally friendly green concrete composite admixture according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: Desert sand, pumping agent, sodium sulfate, polyaluminium chloride and sodium benzoate are weighed by weight and put into a mixer, and a modified high-performance water reducer is added, mixed evenly, molded and granulated to obtain a composite desert sand environmentally friendly green concrete composite admixture.

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