Concrete containing titanium dioxide modified reef limestone whiskers and preparation method thereof

Abstract

The invention provides concrete containing titanium dioxide modified reef limestone whiskers and a preparation method of the concrete. The concrete is prepared from the following components in parts by weight: coral coarse aggregate, coral sand fine aggregate, cement, slag powder, fly ash, titanium dioxide modified reef limestone whisker, a water reducing agent and seawater. The preparation method comprises the following steps: weighing materials; uniformly mixing the coral coarse aggregate and the coral sand fine aggregate, and adding part of seawater to obtain a first premix; uniformly mixing cement, slag powder, fly ash and titanium dioxide modified reef limestone whiskers to obtain a second premix; and uniformly mixing the first premix and the second premix, adding the water reducing agent and the rest seawater, and uniformly mixing to obtain the concrete. The advantages of the marine environment are fully utilized, the coral aggregate and the coral sand are adopted as the concrete aggregate, and the titanium dioxide modified reef limestone whisker is added into the concrete, so that the strength is ensured, the cement consumption is effectively reduced, the carbon emission is reduced, and the green and sustainable development of the building industry is promoted.

Description

Technical Field

[0001] The invention relates to the field of building materials, in particular to concrete containing titanium dioxide modified reef limestone whiskers and a preparation method thereof. Background Art

[0002] The production of traditional concrete relies on a large amount of cement and natural aggregates (sand and gravel), which consumes a large amount of natural resources. The excessive exploitation caused by the huge demand for river sand and gravel has seriously damaged the natural environment. The carbon dioxide emitted during the cement production process has become one of the main sources of carbon dioxide emissions, further exacerbating the deterioration of the ecological environment.

[0003] In coastal areas, since most of the raw materials needed need to be transported from land, the economic burden of construction projects is increased. This leads to high transportation costs, which increases the economic burden of construction projects. How to adapt to local conditions, effectively utilize coastal resources, and reduce the use of cement has become an urgent problem to be solved. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a concrete containing titanium dioxide modified reef limestone whiskers and a preparation method thereof, which fully utilizes the advantages of the marine environment, adopts coral aggregate and coral sand as concrete aggregate, and adds titanium dioxide modified reef limestone whiskers to the concrete, while ensuring the strength, effectively reducing the amount of cement, reducing carbon emissions, and promoting the green and sustainable development of the construction industry.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a concrete containing titanium dioxide modified reef limestone whiskers, which comprises, by weight: 360-550 parts of coral coarse aggregate, 820-1200 parts of coral sand fine aggregate, 320-600 parts of cement, 115-185 parts of slag powder, 55-95 parts of fly ash, 45-70 parts of titanium dioxide modified reef limestone whiskers, 12-18 parts of water reducing agent, and 180-220 parts of seawater.

[0006] Furthermore, the diameter of the titanium dioxide modified reef limestone whiskers is 1-3 μm and the length is 20-200 μm.

[0007] Furthermore, the titanium dioxide modified reef limestone whiskers are obtained by modifying reef limestone whiskers with TiO2.

[0008] Furthermore, the titanium dioxide modified reef limestone whiskers are prepared according to the following method:

[0009] A1. Weigh 30-45 parts of reef limestone whiskers, 15-25 parts of tetrabutyl titanate, and 150-300 parts of deionized water by weight;

[0010] A2. Dissolve tetrabutyl titanate in deionized water and adjust the pH value to 4-7;

[0011] A3, adding the reef limestone whiskers to the solution of step A2, reacting for 1-2 hours under stirring, filtering the reaction product, washing and drying the filtered solid phase, and obtaining titanium dioxide modified reef limestone whiskers.

[0012] Furthermore, the reef limestone whiskers are prepared according to the following steps:

[0013] B1. Grind the reef limestone into fine powder and crush it to a particle size not greater than 100 μm;

[0014] B2, adding dilute hydrochloric acid to the reef limestone powder in step B1, reacting under stirring until no bubbles are generated, filtering, and washing the filtered solid; wherein the mass ratio of hydrochloric acid to reef limestone powder is 1:(8-12);

[0015] B3, calcining the washed solid obtained in step B2 at 850-950° C. for 2-4 hours, and then cooling naturally to obtain a solid powder;

[0016] B4, mixing the solid powder obtained in step B3 with deionized water to form a suspension, adjusting the pH value to 9-10, and growing whiskers at 60-80° C. for 24-48 hours; then, separating the whiskers and removing water to obtain reef limestone whiskers.

[0017] Furthermore, the coral coarse aggregate is a continuously graded aggregate with a particle size of 5-20 mm; the particle size of the coral sand fine aggregate is 0.1-2 mm, and the fineness modulus is 2.1-2.2.

[0018] Furthermore, the particle size of the fly ash is 5-20 μm.

[0019] Furthermore, the water reducer is a polycarboxylic acid high-efficiency water reducer, and its solid content is 38-40%.

[0020] A method for preparing concrete containing titanium dioxide modified reef limestone whiskers is specifically carried out according to the following steps:

[0021] S1. Weigh 360-550 parts of coral coarse aggregate, 820-1200 parts of coral sand fine aggregate, 320-600 parts of cement, 115-185 parts of slag powder, 55-95 parts of fly ash, 45-70 parts of titanium dioxide modified reef limestone whiskers, 12-18 parts of water reducing agent, and 180-220 parts of seawater by weight;

[0022] S2, the coral coarse aggregate and the coral sand fine aggregate are mixed evenly, and then 60-75 parts of seawater are added, and the mixing is continued evenly, and then allowed to stand to obtain a first premix; cement, slag powder, fly ash, and titanium dioxide modified reef limestone whiskers are mixed evenly to obtain a second premix;

[0023] S3, the first premix and the second premix are mixed evenly to obtain a mixed material, and then a water reducing agent and the remaining seawater are added to the mixed material, and mixed evenly to obtain a finished concrete.

[0024] Furthermore, step S2 is replaced by: mixing coral coarse aggregate and coral sand fine aggregate evenly, adding titanium dioxide modified reef limestone whiskers thereto and mixing evenly, then adding 60-75 parts of seawater thereto, continuing to mix evenly, and then standing to obtain a first premix; mixing cement, slag powder, and fly ash evenly to obtain a second premix.

[0025] Advantages of the present invention: The titanium dioxide modified reef limestone whisker concrete and the preparation method thereof of the present invention fully utilize the advantages of the marine environment, use coral aggregate and coral sand as concrete aggregate, and add titanium dioxide modified reef limestone whiskers into the concrete, while ensuring the strength, effectively reducing the amount of cement, reducing carbon emissions, and promoting the green and sustainable development of the construction industry. DETAILED DESCRIPTION

[0026] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments. The embodiments are only used to explain the present invention and do not limit the protection scope of the present invention.

[0027] Embodiment 1

[0028] The present embodiment provides a concrete containing titanium dioxide modified reef limestone whiskers, which includes, by weight: 550 parts of coral coarse aggregate, 1183 parts of coral sand fine aggregate, 340 parts of cement, 119 parts of slag powder, 59 parts of fly ash, 46 parts of titanium dioxide modified reef limestone whiskers, 12 parts of water reducing agent, and 180 parts of seawater.

[0029] In this embodiment, the coral coarse aggregate is a continuous graded material with a particle size of 5-20 mm and a bulk density of 910 kg / m 3 , apparent density 2220kg / m 3 .

[0030] In this embodiment, the particle size of the coral sand fine aggregate is 0.1-2 mm, the fineness modulus is 2.14, and the bulk density is 1460 kg / m 3 , apparent density 2610kg / m 3 .

[0031] In this embodiment, the cement used is P·II 52.5 type silicate cement with a fineness of 8.7 and a loss on ignition of 2.80%.

[0032] In this embodiment, the slag powder is S95 slag, with a specific surface area of ​​432 and a loss on ignition of 0.86%.

[0033] In this embodiment, the particle size of the fly ash is 5-20 μm, and the loss on ignition is 2.02%.

[0034] In this embodiment, the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, the solid content of which is 38-40%, and the water reducing rate is 40-45%.

[0035] In this embodiment, the seawater is taken from the South China Sea and filtered to obtain a seawater density of 1035 kg / m 3 .

[0036] In this embodiment, the titanium dioxide modified reef limestone whiskers have a whisker diameter of 1-3 μm and a length of 20-200 μm, which are obtained by modifying reef limestone whiskers with titanium dioxide, and the specific method is as follows:

[0037] A1. Weigh 30-45 parts of reef limestone whiskers, 15-25 parts of tetrabutyl titanate, and 150-300 parts of deionized water by weight;

[0038] A2. Dissolve tetrabutyl titanate in deionized water and stir at 50-80°C for 3-4 hours using a stirrer to ensure that the tetrabutyl titanate is completely dissolved; then, adjust the pH value of the solution to between 4 and 7 using dilute hydrochloric acid or sodium hydroxide;

[0039] A3. Add the reef limestone whiskers to the solution of step A2, stir and react for 1-2 hours, filter the reaction product, and wash the filtered solid with deionized water for multiple times to remove unreacted tetrabutyl titanate and other impurities until the pH value of the washing solution is close to neutral; then, dry at 60° C. to remove moisture to obtain dry titanium dioxide modified reef limestone whiskers.

[0040] Among them, the reef limestone whiskers are prepared according to the following method:

[0041] B1. Grind the reef limestone into fine powder and crush it to a particle size not greater than 100 μm;

[0042] B2. Put the reef limestone powder in step B1 into an acid container, add dilute hydrochloric acid (2-3wt%), and the acid: solid ratio is 1:10; stir gently, and the reaction time is generally 1-2 hours, until no bubbles are generated; filter, and wash the filtered solid with deionized water for multiple times until the pH value of the washing liquid is close to neutral;

[0043] B3, placing the washed solid obtained in step B2 in a high temperature furnace, setting the temperature to 900°C, calcining for 2-4 hours, and cooling naturally after calcination;

[0044] B4, mixing the solid powder obtained in step B3 with deionized water to form a suspension, adjusting the pH value to 9-10 with sodium hydroxide solution, heating to 60-80° C., and maintaining the temperature for 24-48 hours to promote the growth of whiskers; then, separating the precipitated whiskers by filtering or centrifuging, and then drying at low temperature to remove moisture to obtain dry reef limestone whiskers.

[0045] This embodiment also provides a method for preparing concrete containing titanium dioxide modified reef limestone whiskers, which is specifically carried out in the following steps:

[0046] S1. Weigh coral coarse aggregate, coral sand fine aggregate, cement, slag powder, fly ash, titanium dioxide modified reef limestone whiskers, water reducer, and seawater according to the above proportions;

[0047] S2, the coral coarse aggregate and the coral sand fine aggregate are stirred in a mixer at a speed of 40-60r / min for 1min to mix evenly; then add seawater of about one-third of the total amount of seawater thereto, continue mixing and stirring for 1min, and then stand for 3min to fill the pores of the coral coarse aggregate and the coral sand fine aggregate with water to obtain the first premix; cement, slag powder, fly ash, and titanium dioxide modified reef limestone whiskers are mixed evenly to obtain the second premix;

[0048] S3, adding the second premix to the first premix, mixing evenly with a mixer at a speed of 20-40 r / min to obtain a mixed material, then adding a water reducer and the remaining seawater to the mixed material, mixing evenly with a mixer at a speed of 20-40 r / min to obtain a finished concrete.

[0049] In this embodiment, step S2 can also be replaced by: stirring the measured coral coarse aggregate and coral sand fine aggregate in a mixer at a speed of 40-60r / min for 1 minute, adding titanium dioxide modified reef limestone whiskers, continuing to stir for 1 minute to mix evenly, and then adding about one third of the total amount of seawater to it, continuing to mix and stir for 1 minute, and then standing for 3 minutes to allow the water to fill the pores of the coral sand and coral aggregate to obtain a first premix; cement, slag powder, and fly ash are mixed evenly to obtain a second premix.

[0050] Embodiment 2

[0051] The difference between this embodiment and the first embodiment is that: a concrete containing titanium dioxide modified reef limestone whiskers comprises, by weight: 425 parts of coral coarse aggregate, 928 parts of coral sand fine aggregate, 481 parts of cement, 138 parts of slag powder, 69 parts of fly ash, 49 parts of titanium dioxide modified reef limestone whiskers, 14 parts of water reducer, and 220 parts of seawater.

[0052] Embodiment 3

[0053] The difference between this embodiment and the first embodiment is that: a concrete containing titanium dioxide modified reef limestone whiskers comprises, by weight: 412 parts of coral coarse aggregate, 901 parts of coral sand fine aggregate, 513 parts of cement, 147 parts of slag powder, 73 parts of fly ash, 52 parts of titanium dioxide modified reef limestone whiskers, 15 parts of water reducer, and 220 parts of seawater.

[0054] Embodiment 4

[0055] The difference between this embodiment and the first embodiment is that: a concrete containing titanium dioxide modified reef limestone whiskers comprises, by weight: 398 parts of coral coarse aggregate, 870 parts of coral sand fine aggregate, 550 parts of cement, 157 parts of slag powder, 79 parts of fly ash, 57 parts of titanium dioxide modified reef limestone whiskers, 16 parts of water reducer, and 220 parts of seawater.

[0056] Embodiment 5

[0057] The difference between this embodiment and the first embodiment is that: a concrete containing titanium dioxide modified reef limestone whiskers comprises, by weight: 382 parts of coral coarse aggregate, 834 parts of coral sand fine aggregate, 592 parts of cement, 169 parts of slag powder, 85 parts of fly ash, 63 parts of titanium dioxide modified reef limestone whiskers, 17 parts of water reducer, and 220 parts of seawater.

[0058] Embodiment 6

[0059] The difference between this embodiment and the first embodiment is that a concrete containing titanium dioxide modified reef limestone whiskers comprises, by weight: 410 parts of coral coarse aggregate, 879 parts of coral sand fine aggregate, 583 parts of cement, 183 parts of slag powder, 90 parts of fly ash, 65 parts of titanium dioxide modified reef limestone whiskers, 18 parts of water reducer, and 200 parts of seawater.

[0060] The concrete obtained in Examples 1 to 6 was cast and vibrated into concrete test blocks of 100 mm×100 mm×100 mm, and then the test blocks were placed in an indoor environment at a temperature of 20±3° C. for curing; then, the tensile strength and compressive strength of the concrete were tested respectively.

[0061] The following table shows the average strength data of concrete test blocks made from the concrete of Examples 1 to 6 after curing for 7 days and 28 days.

[0062]

[0063] In order to facilitate an intuitive comparison of the material compositions of the concretes of Examples 1 to 6, the following table is used to show the corresponding material compositions:

[0064]

[0065] The cement dosage ratio and cementitious material ratio of the concrete in Examples 1 to 6 are shown in the following table:

[0066]

[0067] Under the same strength, the comparison of the cement ratio of the existing concrete and the cement ratio of the concrete of Examples 1 to 6 is shown in the following table:

[0068] Example Concrete strength grade Example Cement ratio (%) Existing research cement ratio (%) Phase difference (%) Embodiment 1 C40 13.67 18.7 5.03 Embodiment 2 C50 20.70 24.00 3.30 Embodiment 3 C55 22.00 29.67 7.67 Embodiment 4 C60 23.43 33.91 10.48 Embodiment 5 C65 25.06 34.57 9.51 Embodiment 6 C70 24.03 34.36 10.32

[0069] Under the same strength, the comparison of the cementitious material ratio of the existing concrete and the cementitious material ratio of the concrete of Examples 1 to 6 is shown in the following table:

[0070]

[0071] It can be seen that in Examples 1 to 6, the proportion of cement in the concrete with the minimum strength is about 13.67%, and the proportion of cement in the concrete with the maximum strength is about 24.03%; in producing concrete of the same volume and strength, the present invention can reduce the amount of cement material used by 3.30%-10.48%, which can effectively reduce carbon emissions generated during construction projects.

[0072] In Examples 1 to 6, the cementitious material accounts for about 22.67% of the concrete with the minimum strength, and the cementitious material accounts for about 37.95% of the concrete with the maximum strength. In producing concrete of the same volume and strength, the present invention can reduce the amount of cementitious material used by 3.58%-10.43%, can reduce the amount of inland material transportation, reduce transportation costs, and achieve the effect of energy conservation and emission reduction.

[0073] The concrete containing titanium dioxide modified reef limestone whiskers of the present invention is a high-strength, low-carbon, environmentally friendly concrete with photocatalytic function. The abundant coral resources and reef limestone resources in coastal areas can be used, and renewable coral aggregates and coral sands can be selected as concrete aggregates, thereby reducing the dependence on inland natural resources, reducing transportation costs, and promoting the sustainable use of marine resources. The reef limestone whiskers are modified by titanium dioxide, thereby enhancing the thermal stability of the reef limestone whiskers, improving the basic bonding force between the reef limestone whiskers and cement, and giving the concrete the performance of absorbing carbon dioxide in the air and removing pollutants through photocatalytic reaction. Adding titanium dioxide modified reef limestone whiskers to concrete can reduce the amount of cement used, reduce the porosity, reduce the floating of coral aggregates, and improve the strength grade and durability of concrete using coral aggregates and coral sands as aggregates.

[0074] The above embodiments should not limit the present invention in any way, and any technical solutions obtained by equivalent replacement or equivalent conversion shall fall within the protection scope of the present invention.

Claims

1. A concrete containing titanium dioxide modified reef limestone whiskers, characterized in that: The concrete includes, by weight: 360-550 parts of coral coarse aggregate, 820-1200 parts of coral sand fine aggregate, 320-600 parts of cement, 115-185 parts of slag powder, 55-95 parts of fly ash, 45-70 parts of titanium dioxide modified reef limestone whiskers, 12-18 parts of water reducing agent, and 180-220 parts of sea water.

2. The concrete containing titanium dioxide modified reef limestone whiskers according to claim 1, characterized in that: The titanium dioxide modified reef limestone whisker has a diameter of 1-3 μm and a length of 20-200 μm.

3. The concrete containing titanium dioxide modified reef limestone whiskers according to claim 1, characterized in that: The titanium dioxide modified reef limestone whisker is obtained by modifying the reef limestone whisker with TiO2.

4. The concrete containing titanium dioxide modified reef limestone whiskers according to claim 3, characterized in that: The titanium dioxide modified reef limestone whiskers are prepared according to the following method: A1. Weigh 30-45 parts of reef limestone whiskers, 15-25 parts of tetrabutyl titanate, and 150-300 parts of deionized water by weight; A2. Dissolve tetrabutyl titanate in deionized water and adjust the pH value to 4-7; A3, adding the reef limestone whiskers to the solution of step A2, reacting for 1-2 hours under stirring, filtering the reaction product, washing and drying the filtered solid phase, and obtaining titanium dioxide modified reef limestone whiskers.

5. The concrete containing titanium dioxide modified reef limestone whiskers according to claim 3 or 4, characterized in that: The reef limestone whisker is prepared according to the following steps: B1. Grind the reef limestone into fine powder and crush it to a particle size not greater than 100 μm; B2, adding dilute hydrochloric acid to the reef limestone powder in step B1, reacting under stirring until no bubbles are generated, filtering, and washing the filtered solid; wherein the mass ratio of hydrochloric acid to reef limestone powder is 1:(8-12); B3, calcining the washed solid obtained in step B2 at 850-950° C. for 2-4 hours, and then cooling naturally to obtain a solid powder; B4, mixing the solid powder obtained in step B3 with deionized water to form a suspension, adjusting the pH value to 9-10, and growing whiskers at 60-80° C. for 24-48 hours; then, separating the whiskers and removing water to obtain reef limestone whiskers.

6. The concrete containing titanium dioxide modified reef limestone whiskers according to claim 1, characterized in that: The coral coarse aggregate is a continuously graded aggregate with a particle size of 5-20 mm; the coral sand fine aggregate has a particle size of 0.1-2 mm and a fineness modulus of 2.1-2.

2.

7. The concrete containing titanium dioxide modified reef limestone whiskers according to claim 1, characterized in that: The particle size of the fly ash is 5-20 μm.

8. The concrete containing titanium dioxide modified reef limestone whiskers according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, and its solid content is 38-40%.

9. A method for preparing a concrete containing titanium dioxide modified reef limestone whiskers as claimed in any one of claims 1 to 8, characterized in that: Follow these steps: S1. Weigh 360-550 parts of coral coarse aggregate, 820-1200 parts of coral sand fine aggregate, 320-600 parts of cement, 115-185 parts of slag powder, 55-95 parts of fly ash, 45-70 parts of titanium dioxide modified reef limestone whiskers, 12-18 parts of water reducing agent, and 180-220 parts of seawater by weight; S2, the coral coarse aggregate and the coral sand fine aggregate are mixed evenly, and then 60-75 parts of seawater are added, and the mixing is continued evenly, and then allowed to stand to obtain a first premix; cement, slag powder, fly ash, and titanium dioxide modified reef limestone whiskers are mixed evenly to obtain a second premix; S3, the first premix and the second premix are mixed evenly to obtain a mixed material, and then a water reducing agent and the remaining seawater are added to the mixed material, and mixed evenly to obtain a finished concrete.

10. The method for preparing concrete containing titanium dioxide modified reef limestone whiskers according to claim 9, characterized in that: The step S2 is replaced by: mixing the coral coarse aggregate and the coral sand fine aggregate evenly, adding the titanium dioxide modified reef limestone whisker thereto and mixing evenly, then adding 60-75 parts of seawater thereto, continuing to mix evenly, and then standing to obtain a first premix; and mixing cement, slag powder and fly ash evenly to obtain a second premix.

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