CN110041007A - A kind of impervious marble powder composite blend and its application - Google Patents

Abstract

The invention provides an impermeable marble powder composite admixture and application thereof. The impermeable marble powder composite admixture, in parts by weight, comprises the following components: modified marble powder: 75-90 parts, modified Metakaolin: 10-25 parts, rubber powder: 2-6 parts, basalt fiber: 0.5-1.5 parts. The impermeable marble powder composite admixture of the present invention is prepared by modifying marble powder and metakaolin, and then compounding with rubber powder and basalt fiber to prepare an admixture for concrete. The synergistic effect of the four greatly improves the impermeability type of the present invention. The reactivity of marble powder composite admixture with cement is used in the preparation of concrete, which can form overlapping organic-inorganic three-dimensional interpenetrating network structure inside the concrete, thereby greatly improving the distribution of the pore structure of the concrete and improving the concrete structure. The compactness of the concrete makes the concrete have higher mechanical properties and durability.

Description

An impermeable marble powder composite admixture and its application

technical field

The invention relates to the technical field of concrete, in particular to an impermeable marble powder composite admixture.

Background technique

In recent years, with the rapid advancement of infrastructure construction in my country, the demand for concrete has increased sharply, and the amount of concrete admixtures has also increased. However, due to insufficient resources of high-quality mineral admixtures and uneven regional distribution, commonly used admixtures (slag, fly ash, volcanic ash, etc.) are faced with the current situation of resource shortage and increased transportation costs, resulting in high concrete production costs. , poor economic efficiency, etc. In view of this situation, it is imperative to find a new concrete mineral admixture to alleviate the shortage of existing admixtures.

my country's marble resources are rich, widely used, and the output is huge. In 2015, the output of natural marble building panels in my country reached 335 million square meters. However, in the process of mining and processing, wastes that account for about 20% to 50% of the original stone are generated, which are ground into concrete. Mineral admixtures can solve the problems of resource waste and environmental pollution faced by the marble industry, and at the same time will promote the green and sustainable development of the concrete industry.

Scholars at home and abroad have carried out a lot of research on marble powder concrete. The results show that in terms of physical mechanics, marble powder with low content (generally below 10%) can improve the working performance of concrete, promote cement hydration, and improve concrete strength, especially early strength. However, with the continuous increase of the marble powder content, the concrete strength loss is relatively large. In terms of durability, impermeability is an important indicator to characterize the durability of concrete. Marble powder can improve the carbonization resistance of concrete. However, due to the increase of porosity and pore size in marble powder concrete, the impermeability of concrete decreases. , its electric flux increases with the increase of marble powder content, which will also lead to a decrease in its resistance to chloride ion penetration.

To sum up, the available amount of marble powder in concrete is small at present, which is not conducive to the impermeability of concrete, thus limiting the extensive use of marble powder. Therefore, it is necessary to propose a marble powder composite mineral admixture, which can improve the durability of concrete under the premise of ensuring good working and mechanical properties.

SUMMARY OF THE INVENTION

In view of this, the present invention aims to propose an impermeable marble powder composite admixture to solve the problems of low utilization rate of existing marble powder and poor application effect in concrete.

In order to achieve the above object, the technical scheme of the present invention is achieved in this way:

An impermeable marble powder composite admixture, by weight, comprises the following components:

Modified marble powder: 75-90 parts,

Modified metakaolin: 10-25 parts,

Rubber powder: 2 to 6 parts,

Basalt fiber: 0.5 to 1.5 parts.

Optionally, the modified marble powder is obtained by modifying marble powder with an activator.

Optionally, the modification method of the modified marble powder comprises the following steps:

Prepare 50% activator solution;

Using the fluidized bed-chemical vapor deposition method, the atomized activator solution is evenly wrapped on the surface of the marble powder, and then, after drying, crushing and sieving, the modified marble powder is obtained.

Optionally, the activator accounts for 1-3% of the total amount of the marble powder.

Optionally, the activating agent comprises Yuanming powder, soda ash, and triisopropanolamine; the mass ratio of the Yuanming powder, the soda ash, and the triisopropanolamine is (55-65):(35 ~40): (1~3).

Optionally, the modified metakaolin is prepared by modifying metakaolin with a silane coupling agent.

Optionally, the modification method of described modified metakaolin comprises the following steps:

The silane coupling agent is prepared into a diluent with a mass concentration of 1.5-3% with absolute ethanol;

The metakaolin is soaked in the diluent, stirred and heated in a constant temperature water bath, then filtered and air-dried to obtain the modified metakaolin.

Optionally, the rubber powder is redispersible vinyl acetate-ethylene copolymer rubber powder.

Another object of the present invention is to provide an application of the above impermeable marble powder composite admixture in concrete, in which the concrete includes cement; the impermeable marble powder composite admixture replaces 15 ~30% of the cement.

Compared with the prior art, the impermeable marble powder composite admixture of the present invention has the following advantages:

1. The impermeable marble powder composite admixture of the present invention is prepared by compounding the marble powder and metakaolin with the rubber powder and the basalt fiber to prepare the admixture for concrete, because the modified marble powder has a high performance. and the agglomeration effect of the modified metakaolin is effectively reduced. At the same time, the basalt fibers can form a three-dimensional random distribution network system inside the concrete, exerting the fiber bridging effect, and the rubber powder can form polymers with cement hydration Gel fills the voids of cement and stone, and the synergistic effect of the four greatly improves the reactivity of the impermeable marble powder composite admixture of the present invention and cement. When it is used for the preparation of concrete, it can form overlapping staggered structures inside the concrete. The organic-inorganic three-dimensional interpenetrating network structure can greatly improve the distribution of the pore structure of the concrete, improve the compactness of the concrete, and then make the prepared concrete have higher mechanical properties and durability.

2. The impermeable marble powder composite admixture of the present invention is prepared by compounding modified marble powder and modified metakaolin with rubber powder and basalt fiber, wherein the modified marble powder and modified metakaolin are It has good morphological effect and filling effect. It can be used in the preparation of concrete to optimize the gradation of cementitious materials in concrete, which is beneficial to further improve the pore structure of concrete, improve the compactness of concrete, and further improve the Mechanical properties and durability of concrete.

3. The impermeable marble powder composite admixture of the present invention uses modified marble powder as the main raw material, and the proportion of its content in the impermeable marble powder composite admixture of the present invention can reach more than 85%. The impermeable marble powder composite admixture invented by the invention is used in the preparation of concrete, and its replacement amount for cement can reach 30%, that is, the utilization rate of marble powder in concrete can reach more than 25%, which not only solves the problem of marble powder. The problem of high value-added utilization avoids its pollution to the environment, and is conducive to the shortage of resources in the concrete industry.

Detailed ways

Marble powder has good morphological effect and filling effect, which can significantly improve the working performance of concrete, but its low activity is not conducive to the development of concrete strength, which limits its application in concrete; metakaolin is a silica-alumina amorphous active material , which can react with cement hydration products to generate pozzolanic gel and improve the strength of concrete, but its surface energy is large, it is easy to agglomerate and requires a large amount of water, which is detrimental to the working performance of concrete; basalt fiber has natural compatibility with concrete, in the The dispersibility in concrete is good, and the uniformly dispersed basalt fibers form a three-dimensional random distribution network system in the concrete, exerting the fiber bridging effect, which can not only support the aggregate, but also penetrate the micro-cracks, effectively preventing the development of micro-cracks. Improve the impermeability and crack resistance of concrete; dispersible polymer powder dissolves in water to form polymer emulsion, with the progress of cement hydration, polymer gel gradually fills in the pores of cement stone and forms a polymer film, and polymerizes at the same time The active groups in the medium can react with the hydration products to form a three-dimensional network structure that is stacked and intertwined, which improves the adhesion between cement and aggregates and fibers, improves the interface bonding, effectively inhibits the development of micro-cracks, and improves the impermeability of concrete. performance. Based on this, the present invention, after the marble powder and metakaolin are modified, compound basalt fiber and redispersible latex powder to prepare an impermeable marble powder composite admixture, so as to improve the application effect of marble powder in concrete, and then improve its utilization in concrete.

Among them, in the present invention, in order to improve the activity of marble powder and metakaolin, the specific surface area of marble powder is preferably not less than 600 m ² /kg, D50 is preferably not more than 10 μm, and the mass of SiO ₂ and Al ₂ O ₃ in metakaolin is 100%. The fractional content is preferably not less than 95%, the surface area is preferably not less than 1350m ² /kg, and in order to make the basalt fiber have a good dispersion effect in the concrete, the single filament diameter of the basalt fiber is preferably 13-16 μm, and the aspect ratio is preferably More than 1000, the elastic modulus is preferably more than 95 GPa, and the elongation at break is preferably not less than 2%.

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

The present invention will be described in detail below with reference to the embodiments.

Example 1

An impermeable marble powder composite admixture (MI), by weight, comprising the following components:

Modified marble powder: 75 parts,

Modified metakaolin: 25 parts,

Rubber powder: 3 parts,

Basalt fiber: 1 serving.

Wherein, the rubber powder is redispersible vinyl acetate-ethylene copolymer rubber powder, and its solid content is greater than 98%; the monofilament diameter of the basalt fiber is preferably 15 μm, the length is preferably 18 mm, and the elastic modulus is preferably greater than 95 GPa, The elongation at break is preferably not less than 2%.

In the present embodiment, the modification method of modified marble powder comprises the following steps:

The activator solution with a concentration of 50% is prepared in the super disperser, wherein the activator for preparing the activator solution includes Yuanming powder, soda ash and triisopropanolamine; the mass of Yuanming powder, soda ash and triisopropanolamine The ratio is 60:38:2;

Using the fluidized bed to chemical vapor deposition method, the activator solution atomized by the atomizer is evenly wrapped on the surface of the marble powder in the fluidized bed, and then the powder is collected, and the collected powder is dried, The modified marble powder is obtained by crushing and sieving, wherein the activator accounts for 1% of the total amount of the marble powder, the specific surface area of the marble powder is preferably 667 m ² /kg, and the D50 is preferably 8.52 μm.

In this embodiment, the surface of the marble powder is modified by the fluidized bed-chemical vapor deposition method, and the activator is evenly coated on the surface of the marble powder to form a nano-modified layer, which can effectively improve the activity of the marble powder, thereby improving the cement slurry. The amount of Ca(OH) ₂ in the body that can react with active SiO ₂ and active Al ₂ O ₃ in metakaolin in the pozzolanic ash reaction is beneficial to increase the amount of gels such as CSH and CASH that can fill the concrete pores in the concrete. Improve the mechanical properties and durability of concrete, and at the same time, the activator of cyanobacterial powder and triisopropanolamine have a good early strength effect, which can promote the hydration of cement, and further increase the production of hydration products, thereby further improving the concrete. mechanical properties and durability.

Moreover, in the present embodiment, the modification method of modified metakaolin comprises the following steps:

The silane coupling agent is prepared into a diluent with a mass concentration of 3% with absolute ethanol;

Soak the metakaolin in the diluent, then place it in a constant temperature water tank at 40°C, stir at a medium speed for 45 minutes, filter, and air dry it naturally to obtain the modified metakaolin, wherein the specific surface area of the metakaolin is 1350 m ² / kg.

In this embodiment, the metakaolin is modified with a silane coupling agent, which can effectively reduce the agglomeration effect of metakaolin, improve the pozzolanic reaction efficiency with the hydration product Ca(OH) ₂ in the concrete, and further improve the mechanical properties of the concrete. performance and durability, and the improvement of the agglomeration effect of metakaolin can reduce its water demand, thereby improving the working performance of concrete. The efficiency of the pozzolanic reaction with cement, in addition, the silane coupling agent can enhance the bonding ability of hardened concrete particles, thereby improving the mechanical properties of concrete.

Example 2

The difference between this embodiment and the above-mentioned embodiment is that the impermeable marble powder composite admixture (MII) of this embodiment, in parts by weight, includes the following components:

Modified marble powder: 83 parts,

Modified metakaolin: 17 parts,

Rubber powder: 4 parts,

Basalt fiber: 0.5 parts.

In the modification process of marble powder, the activator accounts for 1.5% of the total amount of marble powder.

During the modification process of metakaolin, the silane coupling agent was prepared into a diluent with a mass concentration of 2% with absolute ethanol.

Example 3

The difference between this embodiment and the above-mentioned embodiment is that the impermeable marble powder composite admixture (MIII) of this embodiment, in parts by weight, includes the following components:

Modified marble powder: 90 parts,

Modified metakaolin: 10 parts,

Rubber powder: 6 parts,

Basalt fiber: 1.5 parts.

In the modification process of marble powder, the activator accounts for 3% of the total amount of marble powder.

During the modification process of metakaolin, the silane coupling agent was prepared into a diluent with a mass concentration of 1.5% with absolute ethanol.

The application effect of the impermeable marble powder composite admixture of Examples 1 to 3 was tested in concrete, and compared with the marble powder composite admixture of the comparative example, wherein the marble powder composite admixture of the comparative example was Marble powder and metakaolin in the material (DM) are all unmodified, and the ratio of each raw material is the same as in Example 1. Table 1 shows the mixing ratio of concrete prepared by using the impermeable marble powder composite admixtures of Examples 1 to 3 and the marble powder composite admixture in the comparative example. The cement in Table 1 is P O 42.5, the sand is medium sand in the II interval, its fineness modulus is 2.4, the crushed stone is 5-25mm continuous gradation, and the water reducing agent is polycarboxylate with a solid content of 20%. Water agent.

Table 1

According to GB/T 50080-2016 "Test Method for Performance of Concrete Mixtures" and GB/T 50081-2016 "Test Method for Mechanical Properties of Concrete", the mechanical properties and durability of concrete in Table 1 are tested, and the test results are shown in Table 2 .

Table 2

As can be seen from Table 2, compared with the single admixture of marble powder (Blank 2), the admixtures of Examples 1 to 3 are used to prepare concrete, and the slump of the concrete mixture is slightly reduced, but it is still much higher than that of the blank. The slump of the concrete mixture of 1 shows that the admixtures of Examples 1 to 3 can significantly improve the working performance of concrete. Compared with the admixtures of the comparative example, the admixtures of Examples 1 to 3 have higher activity, and the strength of the prepared concrete at each age develops better, even exceeding the strength of the blank group.

According to GBT50082-2009 "Test method for long-term performance and durability of ordinary concrete", the deformation performance (drying shrinkage) and impermeability of concrete in Table 1 were tested. The test results are shown in Table 3.

table 3

It can be seen from Table 3 that adding 15-30% of the admixtures of Examples 1 to 3 can reduce the drying shrinkage of concrete and improve the impermeability of concrete. Compared with the admixtures of the comparative example, the admixtures of Examples 1 to 3 significantly reduce the drying shrinkage of concrete and improve the impermeability of marble powder concrete under the premise of ensuring the working performance and mechanical properties of concrete. The concrete impermeability grades of Examples 1 to 3 all reach P10 or higher, which is 30-70% lower than the concrete impermeability coefficient of the blank group.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. within.

Claims (9)

1. a kind of impervious marble powder composite blend, which is characterized in that by weight, including following components:

Modified marble powder: 75~90 parts,

Modified metakaolin: 10~25 parts,

Rubber powder: 2~6 parts,

Basalt fibre: 0.5~1.5 part.

2. impervious marble powder composite blend according to claim 1, which is characterized in that the modified marble powder It is made for marble powder through exciting agent is modified.

3. impervious marble powder composite blend according to claim 2, which is characterized in that the modified marble powder Method of modifying, comprising the following steps:

The excitation agent solution that compound concentration is 50%；

Using fluidized bed-chemical vapour deposition technique, the excitation agent solution after atomization is uniformly wrapped in marble powder surface, Then, by drying, being crushed, be sieved to get modified marble powder.

4. impervious marble powder composite blend according to claim 2 or 3, which is characterized in that the exciting agent accounts for The 1~3% of the marble powder total amount.

5. impervious marble powder composite blend according to claim 4, which is characterized in that the exciting agent includes member Bright powder, soda ash, triisopropanolamine；The anhydrous sodium sulphate, the soda ash, the triisopropanolamine mass ratio be (55~65): (35 ~40): (1~3).

6. impervious marble powder composite blend according to claim 1, which is characterized in that the modified metakaolin It is made for metakaolin through silane coupler modified.

7. impervious marble powder composite blend according to claim 6, which is characterized in that the modified metakaolin Method of modifying the following steps are included:

Silane coupling agent is configured to the dilution that mass concentration is 1.5~3% with dehydrated alcohol；

Metakaolin is immersed in the dilution, is stirred and water bath with thermostatic control heating, then, filtering, natural air drying is to get changing Property metakaolin.

8. impervious marble powder composite blend according to claim 1, which is characterized in that the rubber powder is to divide again Dissipate vinyl acetate-ethylene copolymer rubber powder.

9. application of the impervious marble powder composite blend described in any item of the claim 1 to 8 in concrete, special Sign is that the concrete includes cement；The impervious marble powder composite blend equivalent replace 15~30% it is described Cement.