CN117285275A - Nano silicate gel and preparation method thereof - Google Patents

Abstract

The invention discloses a nano silicate gel and a preparation method thereof, wherein the nano silicate gel comprises the following components in parts by weight: nano silicon oxide, superfine grinding clinker, orthosilicic acid, deionized water, a dissolving-out agent, a silane coupling agent and nano cellulose; wherein, 15 to 23 parts of nano silicon oxide, 54 to 90 parts of superfine grinding clinker, 20 to 26 parts of orthosilicic acid, 1200 to 1800 parts of deionized water, 0.3 to 0.5 part of dissolution agent, 16 to 29 parts of silane coupling agent and 17 to 28 parts of nano cellulose. Wherein the eluting solvent comprises CuSO ₄ 、FeSO ₄ 、Na ₂ SO ₄ One or more of the following. Through the mode, the nano silicate gel prepared by the method can be externally doped into concrete to improve the workability and early strength of the concrete.

Description

Nano silicate gel and preparation method thereof

Technical Field

The invention relates to the technical field of silicate gel, in particular to nano silicate gel and a preparation method thereof.

Background

In the ready-mixed concrete industry, the shortage of the multiplexing type additive for improving the workability and early strength of concrete at the same time can only additionally introduce the organic additive such as an early strength agent and a viscosity modifier according to the requirements of the two, and the organic additive is often limited by raw materials when used for adjustment, and when the raw materials of the concrete are changed, the ratio of the organic additive to the original concrete can be inadapted. Therefore, it is required to design a product that effectively improves both early strength and workability of concrete.

Disclosure of Invention

The invention aims to solve the technical problems that: the invention provides a nano silicate gel and a preparation method thereof, which are used for solving the problems of concrete cohesiveness and difficult preparation of early strength and greatly reducing the possibility of concrete segregation.

The technical scheme of the invention is as follows: the nano silicate gel comprises, by weight, 15-23 parts of nano silicon oxide, 54-90 parts of superfine grinding clinker, 12-16 parts of orthosilicic acid, 1200-1800 parts of deionized water, 0.3-0.5 part of a stripping agent, 16-29 parts of a silane coupling agent and 17-28 parts of nano cellulose.

Preferably, the nano silicon oxide is prepared by a sol-gel method, the particle size is 20-60 nm, the purity is 99%, and the dosage is 17-21 parts.

Preferably, the superfine powder clinker comprises one or two of ground tricalcium silicate and ground dicalcium silicate, wherein the ground tricalcium silicate is obtained by grinding the tricalcium silicate by a high-fine powder grinding machine, the fineness is between 8 and 15 mu m, and the purity is 99%; the dicalcium silicate is obtained by grinding dicalcium silicate by a high-fine powder grinder, the fineness is between 8 and 15 mu m, the purity is 99%, and the dosage is 68 to 76 parts.

Preferably, the orthosilicic acid is colorless transparent colloid, and has a chemical formula of H ₄ SiO ₄ The density is 2.62-2.65 mg/m ³ The dosage is 13-15 parts.

The deionized water is pure water which does not contain ionic substances after being treated.

Preferably, the stripping agent is CuSO ₄ 、FeSO ₄ 、Na ₂ SO ₄ One or more of the following.

Preferably, the silane coupling agent is gamma-aminopropyl triethoxysilane, and the dosage is 19-26 parts.

Preferably, the width of the nanocellulose is 20-50 nm, the length is 0.8-2 um, the purity is 99%, and the dosage is 21-24 parts.

The preparation method of the nano silicate gel comprises the following steps:

step one: weighing the components according to the mass ratio, adding nano silicon oxide and superfine grinding clinker into a planetary mixer to stir for 15s, adding 20-25 parts of deionized water into the planetary mixer to stir for 150s to obtain gel component slurry, adding 575-780 parts of deionized water and orthosilicic acid while stirring the slurry after standing for 240s, stirring for more than 300s after finishing feeding to obtain initial silicate gel, and standing the initial silicate gel for 150min; in the process, the superfine grinding clinker is subjected to hydration reaction to generate calcium hydroxide and hydrated calcium silicate gel, nano silicon oxide and calcium hydroxide in the product of the nano silicon oxide can be subjected to secondary reaction to generate hydrated calcium silicate gel, so that the calcium silicate product is increased, part of calcium hydroxide can be consumed at the same time, and the concentration of the hydrated calcium silicate gel is increased; meanwhile, after the orthosilicic acid is added, residual calcium hydroxide can be consumed to form hydrated calcium silicate gel, and on the other hand, redundant orthosilicic acid is dissolved and then dispersed between clinker particles and hydrated calcium silicate products, and self-polycondensation reaction is carried out in deionized water medium to form the polycondensate silicic acid with a net-shaped structure, and the structure has stronger water retention performance, so that the surface tension of the hydrated calcium silicate gel suspension is improved, and a state with non-Newtonian fluid characteristics is formed. In order to prevent calcium silicate gel formed in the whole hydration reaction process from being overlapped with each other to form a continuous strength structural unit, more deionized water is added for continuous stirring to disperse the calcium silicate hydrate products, so that the single nano calcium silicate hydrate is formed. The condensed silicic acid in the suspension keeps the clinker which is not reacted and the hydrated calcium silicate in a dispersed state, so that the subsequent overlapping formation of a large particle structure of hydration reaction products is avoided.

Step two: stirring the initial silicate gel after standing at the speed of 300r/min, dropwise adding 0.3-0.5 part of a dissolving agent at a constant speed, controlling the dropwise adding time to be 30-35 min to obtain a dissolved silicate gel, and simultaneously adding the nanocellulose into 600-1000 parts of deionized water for stirring and dissolving to obtain a nanocellulose solution;

step three: adding the nano cellulose solution into the dissolved silicate gel, stirring at the speed of 500r/min for 60s, then adding the silane coupling agent into a stirrer, continuously stirring for 120s to obtain nano silicate gel suspension, standing the suspension for 24h, press-filtering by a press filter to remove excessive water, putting the press-filtered product into a baking oven, setting the temperature of the baking oven at 120-140 ℃, and baking for 24h to obtain nano silicate gel powder.

In the second and third steps, the free calcium in the suspension is absorbed by the dissolving agent, so that the purity of the reaction product is further improved. In an aqueous medium, ethoxysilane groups of the silane coupling agent are hydrolyzed to form silanol, the surface of the nano-cellulose contains a large number of hydroxyl groups, the silanol and the hydroxyl groups are subjected to condensation reaction to form stable covalent bonds, and unreacted hydroxyl groups on the surface of the nano-cellulose are adsorbed on the surface of hydrated calcium silicate gel, so that the nano-silicate gel capable of adjusting the cohesiveness and early strength of the concrete is obtained.

The application of nano silicate gel in concrete.

The beneficial effects of the invention are as follows:

1. the nano silicate gel powder prepared by the method is put into concrete, and after the nano hydrated calcium silicate gel particles are fully stirred, the nano hydrated calcium silicate gel particles are uniformly dispersed into the concrete slurry, the silanol end of a silane coupling agent and nano cellulose are adsorbed on the surface of the nano hydrated calcium silicate, and a large number of hydroxyl groups on the surface of the nano cellulose increase the hydrogen bonding acting force of water molecules, so that the concrete slurry becomes more viscous, and the network structure formed by the condensation polymerization silicic acid attached to the periphery reduces the flow among the water molecules, so that the cohesiveness of the whole fluid of the concrete is improved;

2. the nano calcium silicate gel particles uniformly dispersed in the concrete slurry can fully exert the 'induction molding' effect, the strength structure formed by hydration of the gel material slurry in the concrete can be rapidly molded on the nano calcium silicate gel particles and are mutually connected to form strength, meanwhile, the components of the nano calcium silicate gel particles are the same as the components of hydration products of the concrete gel material slurry, the nano calcium silicate gel can be well filled into gaps formed after the concrete is hardened, the generation of microcracks is reduced, and the possibility of cracking of the concrete is reduced while the early strength of the concrete is effectively improved;

3. along with the progress of slurry hydration reaction in the concrete, the alkalinity in the concrete is improved, nano cellulose is not adsorbed on the surface of nano silicate gel any more, the nano cellulose in the slurry is subjected to polycondensation reaction in an alkaline environment to form long-chain fiber macromolecules, and the fiber macromolecules are distributed in a strength structure of the hardened concrete, so that the toughness of the concrete can be effectively improved, and the fracture resistance of the concrete is improved.

Detailed Description

The technical solution of the present invention is further illustrated by the following detailed description, which is given by way of illustration and not limitation.

Example 1: the preparation of the nano silicate gel comprises the following steps:

(1) The weight portions are as follows: 15 parts of nano silicon oxide and 54 parts of superfine grinding clinker are put into a planetary mixer to be mixed for 15 seconds, 20 parts of deionized water is added into the planetary mixer to be mixed for 150 seconds, gel component slurry is obtained, after the slurry is kept stand for 240 seconds, 580 parts of deionized water and 12 parts of orthosilicic acid are added while mixing the slurry, after the material is fed, the mixture is mixed for more than 300 seconds, initial silicate gel is obtained, and the initial silicate gel is kept stand for 150 minutes.

(2) Stirring the initial silicate gel after standing in the step (1) at a speed of 300r/min, dropwise adding 0.4 part of dissolving agent at a constant speed, and controlling the dropwise adding time to be 30-35 min to obtain the dissolved silicate gel. Simultaneously, 17 parts of nanocellulose is put into 600 parts of deionized water to be stirred and dissolved, so that nanocellulose solution is obtained.

(3) Adding the nanocellulose solution in the step (2) into the dissolved silicate gel, stirring at the speed of 500r/min for 60s, then adding 16 parts of silane coupling agent into a stirrer, continuously stirring for 120s to obtain a nano silicate gel suspension, standing the suspension for 24h, then press-filtering excessive water by using a press filter, putting a press-filtered product into a baking oven, setting the temperature of the baking oven at 120 ℃, and baking for 24h to obtain the nano silicate gel powder.

Example 2: the preparation of the nano silicate gel comprises the following steps:

(1) The weight portions are as follows: adding 19 parts of nano silicon oxide and 72 parts of superfine grinding clinker into a planetary mixer to mix for 15s, adding 22 parts of deionized water into the planetary mixer to mix for 150s to obtain gel component slurry, adding 640 parts of deionized water and 14 parts of orthosilicic acid while mixing the slurry after the slurry is kept stand for 240s, mixing for more than 300s after the material is added to obtain initial silicate gel, and keeping the initial silicate gel stand for 150min.

(2) Stirring the initial silicate gel after standing in the step (1) at a speed of 300r/min, dropwise adding 0.4 part of dissolving agent at a constant speed, and controlling the dropwise adding time to be 30-35 min to obtain the dissolved silicate gel. And simultaneously, 22 parts of nanocellulose is added into 700 parts of deionized water to be stirred and dissolved, so as to obtain nanocellulose solution.

(3) Adding the nanocellulose solution in the step (2) into the dissolved silicate gel, stirring at the speed of 500r/min for 60s, then adding 23 parts of silane coupling agent into a stirrer, continuously stirring for 120s to obtain a nano silicate gel suspension, standing the suspension for 24h, press-filtering excessive water by using a press filter, putting the press-filtered product into a baking oven, setting the temperature of the baking oven at 130 ℃, and baking for 24h to obtain the nano silicate gel powder.

Example 3: the preparation of the nano silicate gel comprises the following steps:

(1) The weight portions are as follows: adding 23 parts of nano silicon oxide and 54-90 parts of superfine grinding clinker into a planetary mixer to stir for 15s, adding 25 parts of deionized water into the planetary mixer to stir for 150s to obtain gel component slurry, adding 720 parts of deionized water and 16 parts of orthosilicic acid while stirring the slurry after the slurry is kept stand for 240s, stirring for more than 300s after the material addition is finished to obtain initial silicate gel, and keeping the initial silicate gel stand for 150min.

(2) Stirring the initial silicate gel after standing in the step (1) at a speed of 300r/min, dropwise adding 0.4 part of dissolving agent at a constant speed, and controlling the dropwise adding time to be 30-35 min to obtain the dissolved silicate gel. Meanwhile, 28 parts of nano cellulose is put into 1000 parts of deionized water to be stirred and dissolved, so as to obtain a nano cellulose solution.

(3) Adding the nanocellulose solution in the step (2) into the dissolved silicate gel, stirring at the speed of 500r/min for 60s, then adding 29 parts of silane coupling agent into a stirrer, continuously stirring for 120s to obtain a nano silicate gel suspension, standing the suspension for 24h, press-filtering excessive water by using a press filter, putting the press-filtered product into a baking oven, setting the temperature of the baking oven at 140 ℃, and baking for 24h to obtain the nano silicate gel powder.

The nano silicate gel prepared in the examples 1 to 3 is respectively doped into concrete marked by C30 and C60 according to the proportion of 5% of cementing materials, and the proportion of the concrete is shown in the following table in parts by mass:

TABLE 1 concrete mix ratio

	Cement and its preparation method	Mineral powder	Fly ash	Broken stone	Machine-made sand	Water and its preparation method	Nano silicate gel
								C30	190	40	90	940	900	160	16
C60	280	60	80	1020	890	135	21

In addition, a control group was set, control group 1 was C30 concrete without nano silicate gel, and control group 2 was C60 concrete without nano silicate gel. The properties are shown in tables 2 and 3:

TABLE 2C30 concrete Performance index

Table 3C60 concrete Performance index

As can be seen from the results of tables 2 and 3, in both C30 and C60 grade concrete, the early strength (1 d and 7 d) of the concrete was greatly improved after the nano silicate gel was incorporated, and especially in example 2, the 1d compressive strength of the C30 and C60 concrete was increased by 190% and 158%, respectively, while the later strength was not lower than that of the control group under the condition that the early strength was greatly improved. And under the action of the nanocellulose, the flexural strength of the concrete is greatly improved.

After the nano silicate gel is doped, the cohesiveness and the water retention of the concrete are improved, so that the segregation resistance of the concrete is greatly improved, and in the embodiment 2 and the embodiment 3, the segregation resistance of the C30 and the C60 concrete is 99 percent.

Comprehensive comparison shows that when the formula value of the nano silicate gel is lower than the preferred range, the improvement effect and the workability on the early strength are not as good as those of the preferred range; above the preferred range, the strength of the concrete is not lower than the preferred range, but slump and expansion are rapidly decreased, and fluidity is far lower than the preferred range.

The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.

Claims (9)

1. The nano silicate gel is characterized by comprising, by weight, 15-23 parts of nano silicon oxide, 54-90 parts of superfine grinding clinker, 12-16 parts of orthosilicic acid, 1200-1800 parts of deionized water, 0.3-0.5 part of a dissolving agent, 16-29 parts of a silane coupling agent and 17-28 parts of nano cellulose.

2. The nano silicate gel according to claim 1, wherein: the nano silicon oxide is prepared by a sol-gel method, the particle size is 20-60 nm, the purity is 99%, and the dosage is 17-21 parts.

3. The nano silicate gel according to claim 1, wherein: the superfine powder clinker comprises one or two of ground tricalcium silicate and ground dicalcium silicate, wherein the ground tricalcium silicate is obtained by grinding the tricalcium silicate by a high-fine powder grinding machine, the fineness is between 8 and 15 mu m, and the purity is 99%; the dicalcium silicate is obtained by grinding dicalcium silicate by a high-fine powder grinder, the fineness is between 8 and 15 mu m, the purity is 99%, and the dosage is 68 to 76 parts.

4. The nano silicate gel according to claim 1, wherein: the orthosilicic acid is colorless transparent colloid, and has a chemical formula of H ₄ SiO ₄ The density is 2.62-2.65 mg/m ³ The dosage is 13-15 parts.

5. The nano silicate gel according to claim 1, wherein: the stripping agent is CuSO ₄ 、FeSO ₄ 、Na ₂ SO ₄ One or more of the following.

6. The nano silicate gel according to claim 1, wherein: the silane coupling agent is gamma-aminopropyl triethoxysilane, and the dosage is 19-26 parts.

7. The nano silicate gel according to claim 1, wherein: the width of the nano cellulose is 20-50 nm, the length is 0.8-2 um, the purity is 99%, and the dosage is 21-24 parts.

8. A process for the preparation of nano silicate gel according to claims 1-7, characterized in that: the method comprises the following steps:

step one: weighing the components according to the mass ratio, adding nano silicon oxide and superfine grinding clinker into a planetary mixer to stir for 15s, adding 20-25 parts of deionized water into the planetary mixer to stir for 150s to obtain gel component slurry, adding 575-780 parts of deionized water and orthosilicic acid while stirring the slurry after standing for 240s, stirring for more than 300s after finishing feeding to obtain initial silicate gel, and standing the initial silicate gel for 150min;

step two: stirring the initial silicate gel after standing at the speed of 300r/min, dripping a dissolving agent at a constant speed, controlling the dripping time to be 30-35 min to obtain a dissolved silicate gel, and simultaneously adding the nanocellulose into 600-1000 parts of deionized water to be stirred and dissolved to obtain a nanocellulose solution;

step three: adding the nano cellulose solution into the dissolved silicate gel, stirring at the speed of 500r/min for 60s, then adding the silane coupling agent into a stirrer, continuously stirring for 120s to obtain nano silicate gel suspension, standing the suspension for 24h, press-filtering by a press filter to remove excessive water, putting the press-filtered product into a baking oven, setting the temperature of the baking oven at 120-140 ℃, and baking for 24h to obtain nano silicate gel powder.

9. Use of the nano silicate gel according to claims 1-8 in concrete.