阅读说明：本技术 一种复合早强剂及其制备方法 (Composite early strength agent and preparation method thereof ) 是由 盛秀群 于 2019-11-18 设计创作，主要内容包括：本发明公开一种复合早强剂及其制备方法,属于建筑材料技术领域。本发明早强剂包括以下组分：硫酸钠3-5份、硫酸铁1-5份、甲酸钙5-10份、活性纳米二氧化硅5-10份、醇胺5-10份、异辛醇磷酸酯1-3份、减水剂1.5-2.5份。本发明配方科学,制备方法简单,可有效缩短水泥的水化凝结时间,提高抗压、抗折强度,具备很好的市场应用潜力。(The invention discloses a composite early strength agent and a preparation method thereof, belonging to the technical field of building materials. The early strength agent comprises the following components: 3-5 parts of sodium sulfate, 1-5 parts of ferric sulfate, 5-10 parts of calcium formate, 5-10 parts of active nano silicon dioxide, 5-10 parts of alcohol amine, 1-3 parts of isooctanol phosphate and 1.5-2.5 parts of a water reducing agent. The invention has scientific formula and simple preparation method, can effectively shorten the hydration and setting time of cement, improves the compressive strength and the flexural strength, and has good market application potential.)

1. The composite early strength agent is characterized by comprising the following components in parts by weight: 3-5 parts of sodium sulfate, 1-5 parts of ferric sulfate, 5-10 parts of calcium formate, 5-10 parts of active nano silicon dioxide, 5-10 parts of alcohol amine, 1-3 parts of isooctanol phosphate and 1.5-2.5 parts of a water reducing agent.

2. The composite early strength agent as claimed in claim 1, wherein the alcohol amine is diethanolamine or triisopropanolamine.

3. The composite early strength agent as claimed in claim 1, wherein the water reducing agent is a polycarboxylic acid water reducing agent.

4. The composite early strength agent as claimed in claim 1, wherein the active nano-silica is prepared by the following method:

(1) weighing 5g of nano SiO₂Adding 100mL of toluene into a 250mL three-neck flask, oscillating and dispersing for 5min under ultrasonic waves, then heating to 80 ℃, and magnetically stirring for 15min at constant temperature; adding 10mL of dodecyl trimethyl silane, and reacting at the constant temperature of 80 ℃ for 1 h;

(2) carrying out suction filtration on the mixture obtained in the step (1) by using a vacuum pump, and removing toluene to obtain a primary product; dispersing the silicon dioxide particles in 200mL of ethanol, and performing ultrasonic treatment for 60min to remove the dodecyl trimethyl silane physically adsorbed on the surfaces of the silicon dioxide particles; and performing suction filtration again to obtain a silicon dioxide filter cake, repeating the process for 5 times, drying at 50 ℃, and uniformly grinding by using a mortar to obtain solid powder, namely the active nano silicon dioxide.

5. A method for preparing the composite early strength agent as claimed in any one of claims 1 to 4, which comprises the following steps:

(1) preparing active nano silicon dioxide: weighing 5g of nano SiO₂Adding 100mL of toluene into a 250mL three-neck flask, oscillating and dispersing for 5min under ultrasonic wave, then heating to 80 ℃, and keeping constantStirring for 15min under warm magnetic force; adding 10mL of dodecyl trimethyl silane, and reacting at the constant temperature of 80 ℃ for 1 h;

(2) carrying out suction filtration on the mixture obtained in the step (1) by using a vacuum pump, and removing toluene to obtain a primary product; dispersing the silicon dioxide particles in 200mL of ethanol, and performing ultrasonic treatment for 60min to remove the dodecyl trimethyl silane physically adsorbed on the surfaces of the silicon dioxide particles; performing suction filtration again to obtain a silicon dioxide filter cake, repeating the process for 5 times, drying at 50 ℃, and uniformly grinding by using a mortar to obtain solid powder, namely the active nano silicon dioxide;

(3) weighing the following raw material components in proportion: 3-5 parts of sodium sulfate, 1-5 parts of lithium carbonate, 5-10 parts of calcium formate, 5-10 parts of active nano silicon dioxide, 5-10 parts of alcohol amine, 1-3 parts of isooctanol phosphate and 1.5-2.5 parts of a water reducing agent for later use;

(4) the sodium sulfate, the ferric sulfate, the calcium formate, the alcohol amine, the isooctyl alcohol phosphate and the water reducing agent are placed in a reaction kettle and stirred and mixed evenly, then the active nano-silica is added in three times and mixed evenly to obtain the composite early strength agent.

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to a composite early strength agent and a preparation method thereof.

Background

The concrete early strength agent is one of the main varieties of concrete admixtures. So far, early strength admixtures developed successively at home and abroad mainly comprise: inorganic salt early strength agents such as chloride, sulfate, nitrite and silicate; organic early strength agents such as triethanolamine, calcium formate and urea; various composite early-strength additives, such as an early-strength water reducing agent, an early-strength antifreezing agent, an early-strength pumping agent and the like.

In the construction process of the concrete, a long time is needed from setting and hardening caused by hydration to expected strength, and the early strength of the concrete can be obviously improved by adding the early strength agent, so that the curing time is shortened. The early strength agent is also called a strength promoter, and can adjust the setting and hardening speed of concrete. The early strength agent is generally required to be added during winter construction or in concrete engineering with early strength requirements, so that the demolding and curing time is shortened, the construction progress is accelerated, the construction quality is effectively improved, and the concrete construction cost is saved. The winter in northeast, northwest and northeast regions is longer, the temperature sometimes drops below 10 ℃ in concrete construction, and the freezing injury can be effectively avoided by adding the early strength agent or the early strength water reducing agent.

The following three types of early strength agents are commonly used: 1) chloride-based early strength agents, e.g. CaCl₂It has good effect, besides improving the early strength of concrete, it also has the effect of accelerating coagulation and preventing frostbite, and its cost is low, and its dosage is 1% -2%, and its defect is that it can make reinforcing bar be rusted. In steel bar concrete, CaCl₂The addition amount of the corrosion inhibitor is not more than 1 percent of the dosage of the cement, and the corrosion inhibitor is usually compounded with NaNO 2. 2) The early strength agent of sulfate series, such as sodium sulfate, also called anhydrous sodium sulphate, is white powder, the proper mixing amount is 0.5% -2%, most of the early strength agent is used in a compound way, such as NC, and the early strength agent is a compound early strength agent formed by mixing and grinding sodium sulfate, calcium saccharate and green sand. 3) Organic early strength agent the organic early strength agents mainly include triethanolamine, triisopropanolamine, methanol, ethanol, etc., and the most commonly used is triethanolamine. The triethanolamine is colorless or light yellow transparent oily liquid, is easy to dissolve in water, has the retarding function and is not only mixed but also mixed with other early strength agents.

The early strength agent matured in the market at present has single component and poor effect, and part of the early strength agent contains organic matters and is harmful to the environment and human bodies. Therefore, it is necessary to develop a safe, environment-friendly and efficient early strength agent to overcome the defects in the prior art.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a composite early strength agent and a preparation method thereof. The technical scheme adopted by the invention is as follows:

the composite early strength agent comprises the following components in parts by weight: 3-5 parts of sodium sulfate, 1-5 parts of ferric sulfate, 5-10 parts of calcium formate, 5-10 parts of active nano silicon dioxide, 5-10 parts of alcohol amine, 1-3 parts of isooctanol phosphate and 1.5-2.5 parts of a water reducing agent.

The alcohol amine is diethanolamine or triisopropanolamine.

The water reducing agent is a polycarboxylic acid water reducing agent.

The active nano silicon dioxide is prepared by the following method:

(1) weighing 5g of nano SiO2 in a 250mL three-neck flask, adding 100mL of toluene, oscillating and dispersing for 5min under ultrasonic waves, then heating to 80 ℃, and magnetically stirring for 15min at constant temperature; adding 10mL of dodecyl trimethyl silane, and reacting at the constant temperature of 80 ℃ for 1 h;

(2) carrying out suction filtration on the mixture obtained in the step (1) by using a vacuum pump, and removing toluene to obtain a primary product; dispersing the silicon dioxide particles in 200mL of ethanol, and performing ultrasonic treatment for 60min to remove the dodecyl trimethyl silane physically adsorbed on the surfaces of the silicon dioxide particles; and performing suction filtration again to obtain a silicon dioxide filter cake, repeating the process for 5 times, drying at 50 ℃, and uniformly grinding by using a mortar to obtain solid powder, namely the active nano silicon dioxide.

A preparation method of a composite early strength agent comprises the following steps:

(1) preparing active nano silicon dioxide: weighing 5g of nano SiO2 in a 250mL three-neck flask, adding 100mL of toluene, oscillating and dispersing for 5min under ultrasonic waves, then heating to 80 ℃, and magnetically stirring for 15min at constant temperature; adding 10mL of dodecyl trimethyl silane, and reacting at the constant temperature of 80 ℃ for 1 h;

(2) carrying out suction filtration on the mixture obtained in the step (1) by using a vacuum pump, and removing toluene to obtain a primary product; dispersing the silicon dioxide particles in 200mL of ethanol, and performing ultrasonic treatment for 60min to remove the dodecyl trimethyl silane physically adsorbed on the surfaces of the silicon dioxide particles; performing suction filtration again to obtain a silicon dioxide filter cake, repeating the process for 5 times, drying at 50 ℃, and uniformly grinding by using a mortar to obtain solid powder, namely the active nano silicon dioxide;

(3) weighing the following raw material components in proportion: 3-5 parts of sodium sulfate, 1-5 parts of lithium carbonate, 5-10 parts of calcium formate, 5-10 parts of active nano silicon dioxide, 5-10 parts of alcohol amine, 1-3 parts of isooctanol phosphate and 1.5-2.5 parts of a water reducing agent for later use;

(4) the sodium sulfate, the ferric sulfate, the calcium formate, the alcohol amine, the isooctyl alcohol phosphate and the water reducing agent are placed in a reaction kettle and stirred and mixed evenly, then the active nano-silica is added in three times and mixed evenly to obtain the composite early strength agent.

The using method comprises the following steps: adding the prepared early strength agent into ordinary portland cement, and uniformly mixing to prepare a cement sample, wherein the dosage of the raw materials is as follows by weight percent: 1% of early strength agent and 99% of 42.5 grade ordinary portland cement.

Has the advantages that: the nano silicon dioxide is widely used in the building industry as a reinforcing substance of a cement-based material, and can improve the mechanical property and the corrosion resistance of the cement-based material. Under the condition of normal temperature, the cement slurry doped with the nano silicon dioxide has the phenomena of shortened setting time and improved early strength. However, when the common nano silicon dioxide powder is added into the building material, the phenomena of powder agglomeration and the like can occur, so that the early strength effect is greatly weakened.

According to the invention, the modifier is used for modifying the nano silicon dioxide, so that the agglomeration effect of the nano silicon dioxide is greatly improved. Unsaturated bonds ≡ Si-O-and ≡ Si-with high reactivity exist on the surfaces of nano-silica particles, and in the initial stage of cement hydration, the unsaturated bonds ≡ Si-and-Si-react with calcium hydroxide generated by cement hydration to generate hydrated calcium silicate gel with small particle size on the surfaces of the nano-silica particles, the hydrated calcium silicate gel with small particle size has the effect of reducing nucleation potential barriers of crystals (calcium hydroxide, ettringite and the like) and can be used as nucleation activation points of hydration reaction, hydration products can directly and continuously grow on the surfaces of the nano-silica, and rapid hydration of the cement is promoted. And meanwhile, isooctanol phosphate is added, so that in practical application, isooctanol phosphate is easy to permeate into gaps among fine particles, the distribution of components such as a surfactant and the like on the surfaces of the nano particles is promoted, and the agglomeration effect is further reduced. Fe³⁺Is high valence cation, and can compress the double diffusion layers of C-S-H colloidal particles to accelerate the coagulation of C-S-H colloidal particles and reduce their concentration in liquid phase to accelerate C₃S and C₂S is hydrated to improve early strength. The calcium formate can reduce pH value of the system and accelerate C₃And the hydration of S improves the setting and hardening speed of the cement. The added polycarboxylic acid water reducing agent is matched with the modified nano silicon dioxide ions and the calcium formate, so that mutual aggregation and agglomeration among cement particles are avoided, the dispersity is increased, the dissolving speed of mineral components of cement clinker is increased, the initial reaction of cement is accelerated, and the formation of a crystallization product is accelerated.

The invention has scientific formula and simple preparation method, can effectively shorten the hydration and setting time of cement, improves the compressive strength and the flexural strength, and has good market application potential.

Detailed Description

The technical solution of the present invention is further described below with reference to specific embodiments, but is not limited thereto.