阅读说明：本技术 碱激发剂、碱激发凝胶材料、混凝土和混凝土的制备方法 (Alkali activator, alkali-activated gel material, concrete and preparation method of concrete ) 是由 李朗 唐振中 向青云 于 2020-12-03 设计创作，主要内容包括：本发明涉及一种碱激发剂、碱激发凝胶材料、混凝土和混凝土的制备方法。以重量份计,所述碱激发剂的制备原料包括：硫酸盐7-18份；磷酸盐3-14份；生石灰10-15份。采用廉价的生石灰、磷酸盐和硫酸盐作为三元体系碱激发剂,极大地降低了碱激发胶凝材料的成本,且施工性能好,制备的混凝土凝结时间可控,强度高,无开裂现象。(The invention relates to an alkali activator, an alkali-activated gel material, concrete and a preparation method of the concrete. The alkali activator comprises the following raw materials in parts by weight: 7-18 parts of sulfate; 3-14 parts of phosphate; 10-15 parts of quicklime. Cheap quicklime, phosphate and sulfate are used as the ternary system alkali activator, so that the cost of the alkali-activated cementing material is greatly reduced, the construction performance is good, the setting time of the prepared concrete is controllable, the strength is high, and the cracking phenomenon is avoided.)

1. The alkali activator is characterized by comprising the following raw materials in parts by weight:

7-18 parts of sulfate;

3-14 parts of phosphate;

10-15 parts of quicklime.

2. The alkali activator according to claim 1, characterized in that it is prepared from the following raw materials in parts by weight:

13-18 parts of sulfate;

9-14 parts of phosphate;

10-15 parts of quicklime.

3. Alkali-activator according to claim 2, characterized in that the sulphate is selected from sodium sulphate and/or potassium sulphate.

4. Alkali-activator according to claim 2, characterized in that said phosphate is selected from sodium and/or potassium phosphates.

5. An alkali-activated gel material, comprising an alkali activator and an activating material;

the alkali activator comprises the following raw materials in parts by weight:

7-18 parts of sulfate;

3-14 parts of phosphate;

10-15 parts of quicklime.

6. The alkali-activated gel material of claim 5, wherein the activating material is a reactive mineral.

7. The alkali-activated gel material of claim 6, wherein the activated mineral is selected from one or more of silica fume, metakaolin, mineral fines and fly ash.

8. The alkali-activated gel material of any one of claims 5-7, wherein the alkali-activated gel material is prepared from the following raw materials in parts by weight:

9. a concrete prepared from the alkali-activated gel material according to any one of claims 5 to 8, an aggregate, an admixture and water.

10. The concrete according to claim 9, wherein the raw materials for preparation comprise, in parts by weight:

11. the concrete according to claim 9 or 10, wherein the admixture is a water reducing agent.

12. Concrete according to claim 9 or 10, characterized in that the aggregate is sand.

13. The preparation method of the concrete is characterized by comprising the following steps:

mixing sulfate, phosphate, quicklime, an excitation material and aggregate to prepare powder;

mixing the additive and water to prepare a liquid material;

mixing the powder material and the liquid material;

the weight part of the sulfate is 7-18 parts; 3-14 parts of phosphate; the weight portion of the quicklime is 10-15.

Technical Field

The invention relates to the technical field of building materials, in particular to an alkali activator, an alkali-activated gel material, concrete and a preparation method of the concrete.

Background

Cement and concrete using cement as a cementing material play a significant role in the development process of the human economic society as products in the early twentieth century, and the performance of cement and concrete is gradually improved in the last hundred years. However, since the twenty-first century, with the development of human economic society and the increasing requirements for environmental protection, cement has not been able to meet the requirements of people for environmental protection. The production of cement (usually "two mills and one burning") consumes a lot of natural resources (such as limestone, clay, etc.) and energy, and discharges a lot of carbon dioxide, causing greenhouse effect, which causes irreversible damage to the environment. Finding a new type of low energy consumption, environmentally friendly cementitious material is therefore an important task for scientists in the relevant field since the twenty-first century.

The alkali-activated cementing material is a novel inorganic cementing material which takes alkali metal or alkaline-earth metal oxide as an activator and takes one or more minerals rich in aluminum, silicon and calcium as the activator, wherein the activator plays a catalytic role in the hydration of the activator. Compared with cement, the alkali-activated cementing material has lower carbon dioxide emission and lower energy consumption, and meanwhile, the alkali-activated cementing material has the characteristics of acid and chemical corrosion resistance, high-temperature resistance, fire resistance, low heat conductivity coefficient, low permeability, quick setting and early strength under specific conditions and the like. On one hand, the solid waste discharged by other industries can be effectively utilized, and on the other hand, the defects of the Portland cement in certain properties (such as high temperature resistance and sulfate corrosion resistance) can be made up so as to meet the requirements of certain engineering fields. The alkali-activated cementing material has the advantages of low carbon emission, reasonable utilization of industrial solid wastes and the like, and has become a focus of attention of researchers at present.

However, in the using process of the traditional alkali-activated cementing material, due to poor construction performance, the process control is unstable, and the popularization and application of the alkali-activated cementing material are seriously hindered. The reason is that the alkali-activator reacts with the exciting material to generate new substances, so that the activator is rapidly lost in a large quantity, active ions are greatly reduced, and in addition, the newly generated substances are likely to be attached to the surface to block the active ion reaction path, so that the hydration reaction rate of the alkali-activator catalyzed exciting material is high, the reaction is rapidly slowed down or basically terminated, generally speaking, the initial setting time of the traditional alkali-activated gel material is 10-30min, and the initial setting time of the gel material which does not meet the conventional requirement of the cement industry is greater than or equal to 45min, so that the large-scale engineering application of the gel material is hindered. In addition, the traditional alkali-activated gel material has the defects of easy cracking and the like, and is limited in engineering application. In addition, a part of alkali-activated cementing materials use water glass as an activator, which has poor workability, and compared with mature cement, the cost is not advantageous, which is one of the reasons why the popularization and application of alkali-activated cementing materials are hindered.

Disclosure of Invention

Based on this, the invention adopts cheap quicklime, phosphate and sulfate as the alkali activator of the ternary system, greatly reduces the cost of alkali-activated cementing material, and has good construction performance, controllable setting time of the prepared concrete, high strength and no cracking phenomenon.

The alkali activator comprises the following raw materials in parts by weight:

7-18 parts of sulfate;

3-14 parts of phosphate;

10-15 parts of quicklime.

In one embodiment, the alkali activator is prepared from the following raw materials in parts by weight:

13-18 parts of sulfate;

9-14 parts of phosphate;

10-15 parts of quicklime.

In one embodiment, the sulfate is selected from sodium sulfate and/or potassium sulfate. The sodium hydroxide and/or potassium hydroxide generated by the reaction of the sodium hydroxide and the calcium hydroxide can be used as active ions to catalyze and excite the material to carry out hydration reaction.

In one embodiment, the phosphate is selected from sodium phosphate and/or potassium phosphate. The sodium hydroxide and/or potassium hydroxide generated by the reaction of the sodium hydroxide and the calcium hydroxide can be used as active ions to catalyze and excite the material to carry out hydration reaction.

The invention also provides an alkali-activated gel material.

The alkali-activated gel material comprises an alkali activator and an activating material;

the alkali activator comprises the following raw materials in parts by weight:

7-18 parts of sulfate;

3-14 parts of phosphate;

10-15 parts of quicklime.

In one embodiment, the excitation material is a reactive mineral. In the alkali-activated system, active ions activate the active mineral substances, and the active mineral substances form a three-dimensional network structure microscopically through a depolymerization-repolymerization process, so that a gelled material with strength is formed.

In one embodiment, the active mineral is selected from one or more of silica fume, metakaolin, mineral powder and fly ash. The cost can be greatly saved, the industrial solid waste can be recycled, and higher economic and social benefits can be generated.

In one embodiment, the preparation raw materials of the alkali-activated gel material comprise, by weight:

if the amount of the active mineral is less than 21 parts, the microscopically formed three-dimensional network tends to be unstable, resulting in insufficient strength and poor durability.

In one embodiment, the sulfate is selected from sodium sulfate and/or potassium sulfate. The sodium hydroxide and/or potassium hydroxide generated by the reaction of the sodium hydroxide and the calcium hydroxide can be used as active ions to catalyze and excite the material to carry out hydration reaction.

In one embodiment, the phosphate is selected from sodium phosphate and/or potassium phosphate. The sodium hydroxide and/or potassium hydroxide generated by the reaction of the sodium hydroxide and the calcium hydroxide can be used as active ions to catalyze and excite the material to carry out hydration reaction.

The invention also provides concrete.

The preparation raw materials of the concrete comprise the alkali-activated gel material, aggregate, an additive and water.

In one embodiment, the preparation raw materials of the concrete comprise, by weight:

in one embodiment, the admixture is a water reducing agent. The water reducing agent can reduce the water consumption, improve the compressive strength of concrete and increase the fluidity and the working performance of the cementing material.

In one embodiment, the aggregate is sand.

The invention also provides a preparation method of the concrete.

The preparation method of the concrete comprises the following steps:

mixing sulfate, phosphate, quicklime, an excitation material and aggregate to prepare powder;

mixing the additive and water to prepare a liquid material;

mixing the powder material and the liquid material;

the weight part of the sulfate is 7-18 parts; 3-14 parts of phosphate; the weight portion of the quicklime is 10-15.

Liquid and liquid, powder and powder are easier to be mixed uniformly, the powder and liquid are easy to agglomerate, and the powder and liquid can be dispersed/stirred uniformly in a longer time; if the powder is added to the liquid in several portions, the stirring time is increased.

Compared with the prior art, the invention has the following beneficial effects:

the invention adopts cheap quicklime, phosphate and sulfate as the alkali activator of the ternary system, thus greatly reducing the cost of the alkali-activated cementing material, wherein the quicklime can generate calcium hydroxide after meeting water, the calcium hydroxide can react with the sulfate to generate calcium sulfate precipitate and active ions, and the calcium sulfate is slightly soluble in water, so on one hand, the invention can play a role in slowing down the reaction rate of the calcium hydroxide and the sulfate, and under the condition, the active ions are not easy to be rapidly reduced in a large quantity, thus being slowly released, prolonging the hydration reaction time of the activated material and prolonging the initial setting time. On the other hand, newly generated calcium sulfate is not easy to adhere to the surface of a reactant to block an active ion passage, so that the hydration reaction of the material is promoted by the catalysis of the active ions, the hydration reaction is ensured to be carried out smoothly on the basis of prolonging the initial setting time, and the strength of the concrete is improved. Meanwhile, phosphate is added, and calcium hydroxide can also react with the phosphate to generate calcium phosphate and active ions. On one hand, the addition of the phosphate can accelerate the reaction rate of calcium hydroxide and the phosphate to a certain extent, promote the release of active ions, and play a role in coordinating the excitation effect and coordinating the initial setting time. On the other hand, active ions are also generated due to the addition of phosphate, and due to the homoionic effect, the reactions of the active ions and the calcium hydroxide and the sulfate are mutually restricted, the reaction rates of the two reactions are coordinately controlled, and the phenomenon that the reaction rate of the calcium hydroxide and the sulfate is too slow or the reaction rate of the calcium hydroxide and the phosphate is too fast is avoided. The sulfate, the phosphate and the quicklime are all powder materials, have good construction performance and can be directly added with water for stirring; the coagulation time is controllable, the initial setting time is controllable within 45min-2h, and the final setting time is controllable within 1h-3 h; high strength, 28d compressive strength even up to more than 60MPa, and no cracking phenomenon.

Detailed Description

The present invention will be described in further detail with reference to specific examples. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

An alkali activator comprises the following raw materials in parts by weight:

7-18 parts of sulfate;

3-14 parts of phosphate;

10-15 parts of quicklime.

Wherein, calcium hydroxide can be generated after quicklime meets water, and the reaction equation is as follows:

CaO+H₂O＝Ca(OH)₂

the reaction equation of calcium hydroxide and sulfate is as follows:

Ca(OH)₂+SO₄ ^2-＝CaSO₄↓+2OH^-

the calcium hydroxide can react with the sulfate to generate calcium sulfate sediment and active ions, and the characteristic that the calcium sulfate is slightly soluble in water can play a role in slowing down the reaction rate of the calcium hydroxide and the sulfate on one hand. On the other hand, newly generated calcium sulfate is not easy to adhere to the surface of a reactant to block an active ion passage, so that the hydration reaction of the material is promoted by the catalysis of the active ions, the hydration reaction is ensured to be carried out smoothly on the basis of prolonging the initial setting time, and the strength of the concrete is improved.

Specifically, the mechanism by which calcium sulfate can act to slow the rate of reaction between calcium hydroxide and sulfate is as follows:

inorganic chemical reaction rate and solubility product constant K_spHas a large relation of solubility product constant K_spIs defined as: at a certain temperature, an equilibrium of precipitation dissolution and generation exists between the insoluble electrolyte crystal and ions dissolved in the solution, which is called a precipitation dissolution equilibrium, and an equilibrium constant thereof is called a solubility product constant (i.e. a precipitation equilibrium constant). The size of the solubility product reflects the solvency of the material. It changes due to changes in temperature and the dissolution of other electrolytes, and is therefore usually given as a single electrolyte measured at a particular temperature. The equilibrium constants of the reaction are expressed as follows:

A_nB_m(s)＝nA^m+(aq)+mB^n-(aq)，K_sp＝[A^m+]ⁿ·[B^n-]^m

solubility product rule:

q (product of ion concentration, expression and K described above)_spSame) of size K_spBy comparison, according to the chemical equilibrium shift principle, it can be known that:

when Q is>K_spWhen the solution is supersaturated, the solution moves leftwards in a balanced manner, and precipitates are separated out;

when Q is<K_spWhen the solution is unsaturated, if the precipitate still exists in the solution, the solution is balanced and moved to the right, and the precipitate is dissolved;

when Q is equal to K_spWhen the method is used, the solution is a saturated solution and is in a precipitation and dissolution equilibrium state, and no precipitate is generated and dissolved.

The above rule can be used to judge the occurrence of precipitation and dissolution, and is called a solubility product rule.

According to the solubility product rule and the equilibrium principle: solubility product constant K_spThe smaller the reaction proceeds to the right, the faster the precipitation proceeds, and conversely the solubility product constant K_spThe larger the reaction proceeds to the left, the faster the precipitation proceeds and the slower the precipitation.

After inspection, calcium sulfate CaSO₄·2H₂O solubility 0.255g, K_sp＝9.1×10^-6The solubility product constant is large, and the precipitation rate is slow, so that the generation of calcium sulfate can play a role in slowing down the reaction rate of calcium hydroxide and sulfate.

Preferably, the sulphate is selected from sodium sulphate and or potassium sulphate.

For example, sodium sulfate reacts with calcium hydroxide according to the following equation:

Ca(OH)₂+Na₂SO₄＝CaSO₄↓+2NaOH

the reaction is a reaction of weak base to generate strong base, the reaction is completed because calcium sulfate precipitation is generated and moves rightwards, and the generated sodium hydroxide is used as active ions and can catalyze and excite materials to carry out hydration reaction.

Meanwhile, phosphate is added into the alkali activator, and calcium hydroxide can also react with the phosphate to generate calcium phosphate and active ions. On one hand, the addition of the phosphate can accelerate the reaction rate of calcium hydroxide and the phosphate to a certain extent, promote the release of active ions, and play a role in coordinating the excitation effect and coordinating the initial setting time. On the other hand, active ions are also generated due to the addition of phosphate, and due to the homoionic effect, the reactions of the active ions and the calcium hydroxide and the sulfate are mutually restricted, the reaction rates of the two reactions are coordinately controlled, and the phenomenon that the reaction rate of the calcium hydroxide and the sulfate is too slow or the reaction rate of the calcium hydroxide and the phosphate is too fast is avoided.

Specifically, the mechanism by which calcium phosphate can act to accelerate the reaction rate of calcium hydroxide and phosphate is as follows:

by inspection, calcium phosphate Ca₃(PO₄)₂Solubility of 2X 10^-3g，K_sp＝2.0×10^-29The solubility product constant is small, the precipitation rate is high, and the calcium hydroxide and phosphate reaction rate can be accelerated.

Preferably, the phosphate is selected from sodium phosphate and/or potassium phosphate.

For example, sodium phosphate reacts with calcium hydroxide according to the following equation:

3Ca(OH)₂+2Na₃PO₄＝Ca₃(PO₄)₂↓+6NaOH

the reaction is also a reaction of weak base to generate strong base, the reaction is completed because calcium phosphate precipitation is generated and moves rightwards, and the generated sodium hydroxide is used as active ions and can catalyze and excite materials to carry out hydration reaction.

According to the invention, cheap quicklime, phosphate and sulfate are used as the ternary system alkali activator, so that the cost of the alkali-activated cementing material is greatly reduced, and the raw materials are all powder materials, have good construction performance and can be directly added with water and stirred for use; the coagulation time is controllable, the initial setting time is controllable within 45min-2h, and the final setting time is controllable within 1h-3 h; high strength, 28d compressive strength even up to more than 60MPa, and no cracking phenomenon.

An alkali-activated gel material comprising an alkali activator and an activator material;

the alkali activator comprises the following raw materials in parts by weight:

7-18 parts of sulfate;

3-14 parts of phosphate;

10-15 parts of quicklime.

Preferably, the excitation material is a reactive mineral. In the alkali-activated system, active ions activate the active mineral substances, and the active mineral substances form a three-dimensional network structure microscopically through a depolymerization-repolymerization process, so that a gelled material with strength is formed.

It can be understood that the active mineral substance can be industrial solid waste with pozzolanic activity, which can form a high-strength gelled material with an activator, can greatly save cost, can recycle the industrial solid waste, and can generate high economic benefit and social benefit.

Preferably, the active mineral is selected from one or more of silica fume, metakaolin, mineral powder and fly ash.

Preferably, the mineral powder is superfine mineral powder, the particle size is 10-15 mu m, and the specific surface area is 700m²/kg。

Preferably, the fly ash is a first grade fly ash.

In one embodiment, the preparation raw materials of the alkali-activated gel material comprise, by weight:

if the amount of the active mineral is less than 21 parts, the microscopically formed three-dimensional network tends to be unstable, resulting in insufficient strength and poor durability.

In one embodiment, the sulfate is selected from sodium sulfate and/or potassium sulfate. The sodium hydroxide and/or potassium hydroxide generated by the reaction of the sodium hydroxide and the calcium hydroxide can be used as active ions to catalyze and excite the material to carry out hydration reaction.

In one embodiment, the phosphate is selected from sodium phosphate and/or potassium phosphate. The sodium hydroxide and/or potassium hydroxide generated by the reaction of the sodium hydroxide and the calcium hydroxide can be used as active ions to catalyze and excite the material to carry out hydration reaction.

The concrete is prepared from the alkali-activated gel material, aggregate, an additive and water.

In a preferred embodiment, the preparation raw materials of the concrete comprise the following components in parts by weight:

in a more preferred embodiment, the concrete is prepared from the following raw materials in parts by weight:

preferably, the admixture is a water reducing agent. The water reducing agent can reduce the water consumption, improve the compressive strength of concrete and increase the fluidity and the working performance of the cementing material.

More preferably, the water reducing agent is a polycarboxylic acid water reducing agent.

Preferably, the aggregate is sand.

In one embodiment, the sand is fine sand having a fineness modulus of 2.1-2.5.

A preparation method of concrete comprises the following steps:

mixing sulfate, phosphate, quicklime, active mineral substances and aggregate to prepare powder;

mixing the additive and water to prepare a liquid material;

mixing the powder material and the liquid material;

the weight part of the sulfate is 7-15 parts; 3-14 parts of phosphate; 10-15 parts of quicklime; the weight portion of the active mineral substance is 21-40 portions.

Liquid and liquid, powder and powder are easier to be mixed uniformly, the powder and liquid are easy to agglomerate, and the powder and liquid can be dispersed/stirred uniformly in a longer time; if the powder is added to the liquid in several portions, the stirring time is increased.

The concrete of the invention can be suitable for places with higher automation degree, such as the production of prefabricated parts in a PC factory.

The following examples and comparative examples are further described below, and the starting materials used in the following examples can be commercially available, unless otherwise specified, and the equipment used therein can be commercially available, unless otherwise specified. The sodium sulfate, sodium phosphate and quicklime used in the following examples and comparative examples are all technical grade, and are finely ground white powders with a mesh number of more than 200; the additive is a polycarboxylic acid water reducing agent, and the manufacturer is Guangdong Ruian scientific and technical industry Co., Ltd; the fineness modulus of the fine sand is 2.1-2.5.

Example 1

The embodiment provides an alkali activator, an alkali-activated gel material, concrete and a preparation method of the concrete, wherein the preparation method of the concrete comprises the following steps:

weighing 13 parts of sodium sulfate, 14 parts of sodium phosphate, 14 parts of quicklime, 21 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Example 2

The embodiment provides an alkali activator, an alkali-activated gel material, concrete and a preparation method of the concrete, wherein the preparation method of the concrete comprises the following steps:

weighing 15 parts of sodium sulfate, 9 parts of sodium phosphate, 15 parts of quicklime, 30 parts of first-grade fly ash, 20 parts of fine sand, 10 parts of water and 1 part of polycarboxylic acid water reducing agent.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Example 3

The embodiment provides an alkali activator, an alkali-activated gel material, concrete and a preparation method of the concrete, wherein the preparation method of the concrete comprises the following steps:

weighing 13 parts of sodium sulfate, 3 parts of sodium phosphate, 10 parts of quicklime, 40 parts of first-grade fly ash, 20 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent in parts by weight.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Example 4

The embodiment provides an alkali activator, an alkali-activated gel material, concrete and a preparation method of the concrete, wherein the preparation method of the concrete comprises the following steps:

weighing 18 parts of sodium sulfate, 14 parts of sodium phosphate, 14 parts of quicklime, 21 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent in parts by weight.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Example 5

The embodiment provides an alkali activator, an alkali-activated gel material, concrete and a preparation method of the concrete, wherein the preparation method of the concrete comprises the following steps:

weighing 13 parts of sodium sulfate, 5 parts of sodium phosphate, 14 parts of quicklime, 21 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Comparative example 1

The present comparative example provides an alkali-activated agent, an alkali-activated gel material, concrete, and a method of preparing concrete, the method comprising the steps of:

weighing 5 parts of sodium sulfate, 14 parts of sodium phosphate, 14 parts of quicklime, 21 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Comparative example 2

The present comparative example provides an alkali-activated agent, an alkali-activated gel material, concrete, and a method of preparing concrete, the method comprising the steps of:

weighing 13 parts of sodium sulfate, 19 parts of sodium phosphate, 14 parts of quicklime, 21 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Comparative example 3

The present comparative example provides an alkali-activated agent, an alkali-activated gel material, concrete, and a method of preparing concrete, the method comprising the steps of:

weighing 13 parts of sodium sulfate, 14 parts of sodium phosphate, 9 parts of quicklime, 21 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Comparative example 4

The present comparative example provides an alkali-activated agent, an alkali-activated gel material, concrete, and a method of preparing concrete, the method comprising the steps of:

weighing 13 parts of sodium sulfate, 14 parts of sodium phosphate, 19 parts of quicklime, 21 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Comparative example 5

The present comparative example provides an alkali-activated agent, an alkali-activated gel material, concrete, and a method of preparing concrete, the method comprising the steps of:

weighing 13 parts of sodium sulfate, 14 parts of sodium phosphate, 14 parts of quicklime, 16 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent.

Premixing sodium sulfate, sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Comparative example 6

This comparative example provides an alkali-activated agent, an alkali-activated gel material, concrete, and a method of making concrete, which is substantially the same as example 1, with the main differences being: sodium sulfate was not added, and the procedure was as follows:

weighing 14 parts of sodium phosphate, 14 parts of quicklime, 21 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent in parts by weight.

Premixing sodium phosphate, quicklime, first-grade fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

Comparative example 7

The present comparative example provides an alkali-activated agent, an alkali-activated gel material, concrete, and a method of preparing concrete, the method of preparing concrete being substantially the same as in comparative example 1, with the main differences being: sodium phosphate is replaced by sodium carbonate, and the method comprises the following steps:

weighing 14 parts of sodium carbonate, 14 parts of quicklime, 21 parts of first-grade fly ash, 26 parts of fine sand, 10 parts of water and 2 parts of polycarboxylic acid water reducing agent in parts by weight.

Premixing sodium carbonate, quicklime, first-level fly ash and fine sand to prepare powder;

uniformly mixing a polycarboxylic acid water reducing agent and water to prepare a liquid material;

and mixing the powder and the liquid, uniformly stirring until slurry with better fluidity is formed, and injecting the slurry into a mould after testing the performance to prepare the concrete.

The formulations of examples 1 to 5 and comparative examples 1 to 7 are summarized in tables 1 and 2.

The concrete of examples 1 to 5 and comparative examples 1 to 7 were tested according to the following test methods: the test results of national standards GB/T50080-2016 standard for testing the performance of common concrete mixtures and GB/T50081-2019 standard for testing the physical and mechanical properties of concrete are shown in tables 1 and 2.

TABLE 1

TABLE 2

As can be seen from tables 1 and 2, the initial setting time of the concrete prepared from the alkali-activated gelling material of examples 1 to 5 is greater than 45min, and meets the initial setting time regulation of national Standard "general Portland Cement" GB175-2007 (the initial setting time of Portland cement is not earlier than 45min, the initial setting time of Portland cement, Portland slag cement, pozzolana Portland cement, fly ash Portland cement and composite Portland cement is not earlier than 45min, and the initial setting time regulation of ordinary concrete is not less than 45min), so that the concrete can be normally constructed, and the concrete strength is high. The concrete prepared in the examples 1, 2 and 4 has better comprehensive properties, and compared with the concrete prepared in the example 1, the concrete prepared in the example 4 has more sodium sulfate content and longer initial setting time, but calcium sulfate is attached to the surface of a reactant to influence the strength of the reactant. In examples 3 and 5, the relative addition amount of sodium phosphate was small, the initial setting time of concrete was long, and the construction time was wasted, and the strength was decreased due to insufficient alkalinity caused by a small amount of sodium hydroxide.

The sodium sulfate addition amount of comparative example 1 is less than 7 parts, the reaction rate of calcium hydroxide with sodium sulfate and sodium phosphate is integrally accelerated, the slow-release effect of sodium hydroxide is weakened, the initial setting time is shortened, construction is not facilitated, and the strength is reduced due to the fact that the generation amount of sodium hydroxide is reduced and the alkalinity is insufficient. The sodium phosphate of comparative example 2 is added in an amount of more than 14 parts, the reaction rate of calcium hydroxide with sodium sulfate and sodium phosphate is integrally accelerated, the slow-release effect of sodium hydroxide is weakened, the initial setting time is shortened, and the construction is not facilitated. The quicklime of comparative example 3 added in an amount of less than 10 parts, the quicklime of comparative example 4 added in an amount of more than 15 parts, the setting time is shortened and the strength is lowered, the strength lowering of comparative example 3 should be associated with the generation of less calcium hydroxide and further less sodium hydroxide, and the strength lowering of comparative example 4 should be associated with the inhibition of the growth of crystals such as siloxahedron and alxahedron by a large amount of calcium hydroxide in the alkali-excited system. The primary fly ash of comparative example 5 added in an amount of less than 21 parts tends to form a microscopically unstable three-dimensional network structure, resulting in insufficient strength, and at the same time, the hydration product is reduced, resulting in a reduction in gel time and poor durability.

Comparative example 6 is only added with sodium phosphate, and comparative example 7 is only added with sodium carbonate, so that the reaction rate of calcium hydroxide and sodium phosphate or sodium carbonate is faster, the initial setting time of concrete is shortened, and the workability is poor.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.