A cementitious material with improved toughness

Abstract

The application discloses a kind of toughening cementitious materials, including 9.2~16.2wt% high-activity auxiliary cementitious material A, 49.4~53.5wt% high-performance cementitious material B and 30.3~41.4wt% high-toughness auxiliary cementitious material C in mass percentage, the high-activity auxiliary cementitious material A is one or more of silica fume, slag or high-calcium fly ash, the high-performance cementitious material B is high-iron phase high belite cement clinker, and the high-toughness auxiliary cementitious material C is modified rubber powder.The application starts from the angle of cement clinker, and high-performance cementitious material with high strength and large flexural-compressive ratio is prepared by adjusting cement clinker mineral composition, optimizing cement particle size distribution, adding high-toughness auxiliary cementitious material and other ways, which fundamentally alleviates the problem of large brittleness of cement-based materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cementitious materials, and particularly relates to a cementitious material with improved toughness. BACKGROUND

[0002] Cement-based materials have become the most widely used building material in the world due to their high compressive strength, good durability and low price. However, with the development of engineering construction, especially with the continuous development of high-strength concrete, the brittleness of concrete has become a more and more prominent problem. The root cause is that the low tensile strength of cement-based materials leads to the brittleness of concrete.

[0003] The tensile strength of cement-based materials is only 1 / 10 of the compressive strength, and the ultimate tensile elongation is only 1.0x10 -4 MPa. These shortcomings of cement-based materials cannot be eliminated by self-improvement, and the use of "complex" provides an effective solution to these problems. For example, adding high molecular polymer fibers to cement-based materials can significantly improve the early crack resistance of cement concrete, and adding steel fibers to cement-based materials can improve the compressive strength and tensile strength of cement concrete.

[0004] The Chinese patent with the publication number CN118271033A "Preparation method of super high performance fiber toughened cement-based composite material" uses the method of modifying aggregate and fiber to prepare a super high performance fiber toughened cement-based composite material, which improves the toughness and durability of concrete. In addition, polymer emulsion modified concrete provides an effective way to improve the toughness of concrete from the perspective of improving the performance of cementitious materials in concrete. High molecular polymers can form special bridge bonds due to the coordination effect between special functional groups and cement hydration products or metal ions, further enhancing the bonding force between materials and improving the toughness of cement-based materials. The Chinese patent with the publication number CN105819735A "Polymer in-situ toughened cement-based material and preparation method thereof" uses the method of combining polyvinyl alcohol and latex powder to prepare a cement-based material with good flowability, good workability, fast strength development and high flexural strength.

[0005] The above toughening methods have some limitations. Traditional fiber toughening can improve the crack resistance of cement-based materials, but it cannot inhibit the development of cracks at the micro level, and the toughening effect is limited. Polymer toughening has good effect and is currently the main method of cement-based toughening, but polymer toughening cement-based materials also has problems such as uneven distribution of polymers, poor compatibility and combination, which affect its application in actual engineering. SUMMARY

[0006] The present application aims at providing a cementitious material with improved toughness, which is prepared by adjusting the mineral composition of cement clinker, optimizing the particle size distribution of cement, and adding high-toughness auxiliary cementitious material, etc., from the perspective of cement clinker, so as to fundamentally relieve the problem of high brittleness of cement-based materials.

[0007] To achieve the above-mentioned object, the technical scheme adopted by the present application is as follows:

[0008] The cementitious material with improved toughness comprises the following components in percentage by mass: 9.2-16.2wt% high-activity auxiliary cementitious material A, 49.4-53.5wt% high-performance cementitious material B, and 30.3-41.4wt% high-toughness auxiliary cementitious material C, wherein the high-activity auxiliary cementitious material A is one or more of silica fume, slag, or high-calcium fly ash, the high-performance cementitious material B is high-iron-phase high belite cement clinker, and the high-toughness auxiliary cementitious material C is modified rubber powder.

[0009] Further, the mineral composition of the high-iron-phase high belite cement clinker is 32.07wt% C3S, 49.61wt% C2S, 1.96wt% C3A, and 16.36wt% C4AF.

[0010] The preparation method of the modified rubber powder is as follows:

[0011] S1, adding quicklime into water to obtain saturated lime water;

[0012] S2, after washing the surface impurities of rubber powder, putting the rubber powder into the saturated lime water, taking out the rubber powder after soaking for 20-24h;

[0013] S3, adding MgCl2·6H2O into the saturated lime water to obtain a mixed slurry, and the concentration ratio of Ca2+ and Mg2+ in the mixed slurry is 1:1; 2+ and Mg 2+ ;

[0014] S4, heating the mixed slurry to 80℃ and keeping the temperature for 1-1.5h, and continuously stirring during the heating and keeping process;

[0015] S5, re-adding the soaked rubber powder into the mixed slurry and continuously stirring, and the volume ratio of the rubber powder and the mixed slurry is 1:10, then introducing CO2 gas, and stopping the aeration and stirring when the pH value of the mixed slurry decreases to 7;

[0016] S6, taking out the rubber powder and washing it with anhydrous ethanol for multiple times, and then drying to obtain the modified rubber powder.

[0017] The rubber powder in S2 has no limitation in the amount of mixing, as long as it is completely immersed in saturated lime water; the CO2 gas in S5 is introduced at a speed of 65 L / (h·kg Ca(OH)2).

[0018] Further, the soaking time in S2 is 24 h, and the holding time in S3 is 1 h; the drying in S6 is placed in a 60℃ oven for drying for 5-6 h.

[0019] Further, the particle size range of the high-activity auxiliary cementitious material A is 0.15-3 μm, and the median diameter D 50 is 1.36 μm.

[0020] Further, the particle size range of the high-performance cementitious material B is 3-32 μm, and the median diameter D 50 is 16.78 μm.

[0021] Further, the particle size range of the high-toughness auxiliary cementitious material C is 32-80 μm, and the median diameter D 50 is 48.21 μm.

[0022] Further, the specific surface area of the high-toughness cementitious material is 360-380 m 2 / kg, and the 80 μm square hole screen residue is not more than 5%; the initial setting time is not earlier than 15 min, the final setting time is not later than 45 min; the water requirement is ≤30%, the 28d flexural strength is greater than 9.5 MPa, the 28d compressive strength is greater than 45 MPa, the 90d flexural strength is greater than 15 MPa, the 90d compressive strength is greater than 70 MPa, and the standard mortar flexural-pressure ratio is not less than 0.20.

[0023] Further, the mass percentage of the high-activity auxiliary cementitious material A, the high-performance cementitious material B, and the high-toughness auxiliary cementitious material C is calculated based on the packing model of the Dinge-Funk continuous particle size distribution.

[0024] Further, the calculation formula of the packing model is as follows:

[0025]

[0026] In the formula, U(D P ) is the mass percentage of the particle size D P ; D P is the particle size of the high-activity auxiliary cementitious material A / high-performance cementitious material B / high-toughness auxiliary cementitious material C; D max is the particle size of the largest particle in the system, and the D max value is 80 μm; D min is the particle size of the smallest particle in the system, and the D min0.15 μm; n is a distribution index, and n is 0.24-0.5.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] (1) The present application optimizes the particle size distribution of cement clinker by adding two kinds of auxiliary cementitious materials. As the high-activity auxiliary cementitious material A of finer cement particles (<3 μm), it avoids the problem that the early strength development is too fast to cause the later strength to be reversed, and optimizes the low hydration degree. As the high-toughness auxiliary cementitious material C of coarse cement particles (32-80 μm) which only plays a filling role, it avoids the waste of cement clinker, further reduces the amount of clinker, and saves the cost.

[0029] (2) The present application respectively incorporates two kinds of auxiliary cementitious materials with different particle sizes, i.e. the high-activity auxiliary cementitious material A with superfine particles and the high-toughness auxiliary cementitious material C with large particles. The two materials are synergistic with each other, and realize the synergistic enhancement of strength and toughness from the material itself. This toughening method is different from fiber toughening and polymer toughening.

[0030] (3) The present application divides the cementitious materials into three particle size intervals, and uses the Dinge-Funk continuous particle size distribution packing model to optimize the particle size ratio, so that the cementitious materials reach the closest packing, which not only ensures the compactness of the cement stone structure, but also reduces the water demand of the cementitious materials.

[0031] (4) The present application uses saturated lime water to modify the rubber powder. The calcium hydroxide and hydroxyl ion in the saturated lime water eliminate the zinc stearate on the surface of the rubber, increase the surface roughness of the rubber, and improve the hydrophilicity of the rubber powder. In addition, the Ca(OH)2-CO2 gas-liquid reaction method is used to generate calcium carbonate whiskers on the surface of the rubber powder. Both the rubber powder and the calcium carbonate whiskers can improve the splitting tensile strength of the cement-based material. At the same time, with the increase of the age, the calcium carbonate whiskers will chemically react with the aluminum in the cement to generate calcium aluminate, which can improve the interface performance between the rubber powder and the cement stone, and make the connection between them more compact. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0033] In the embodiment of the present application, the high-activity auxiliary cementitious material A is one or more of silica fume, slag or high-calcium fly ash, the high-performance cementitious material B is high-iron-phase high belite cement clinker, and the high-toughness auxiliary cementitious material C is modified rubber powder.

[0034] In the embodiment of the present application, the mineral composition of the high-iron-phase high belite cement clinker is 32.07wt% C3S, 49.61wt% C2S, 1.96wt% C3A and 16.36wt% C4AF.

[0035] In the embodiment of the present application, the preparation method of the modified rubber powder is as follows:

[0036] S1, adding quicklime into water to obtain saturated lime water;

[0037] S2, after cleaning the surface impurities of the rubber powder, putting the rubber powder into the saturated lime water, taking out the rubber powder after soaking for 24 hours;

[0038] S3, adding MgCl2·6H2O into the saturated lime water to obtain a mixed slurry, the concentration ratio of Ca2+ and Mg2+ in the mixed slurry is 1:1; 2+ and Mg 2+

[0039] S4, heating the mixed slurry to 80℃ and keeping the temperature for 1.5 hours, continuously stirring during the heating and keeping process;

[0040] S5, re-adding the soaked rubber powder into the mixed slurry and continuously stirring, then introducing CO2 gas, and stopping the aeration and stirring when the pH value of the mixed slurry decreases to 7;

[0041] S6, taking out the rubber powder, washing the rubber powder with anhydrous ethanol for multiple times, and then placing the rubber powder in a 60℃ oven for drying for 5-6 hours to obtain the modified rubber powder.

[0042] In the embodiment of the present application, the particle size range of the high-activity auxiliary cementitious material A is 0.15-3μm, and the median diameter D50 is 1.36μm.

[0043] In the embodiment of the present application, the particle size range of the high-performance cementitious material B is 3-32μm, and the median diameter D50 is 16.78μm.

[0044] In the embodiment of the present application, the particle size range of the high-toughness auxiliary cementitious material C is 32-80μm, and the median diameter D50 is 48.21μm.

[0045] Example 1

[0046] As a preferred embodiment of the present application, the disclosed cementitious material for improving toughness has the components shown in Table 1.

[0047] Table 1​

[0048] Component Mass % by weight Highly active supplementary cementitious material A 9.2 High performance cementitious material B 49.4 Highly ductile supplementary cementitious material C 41.4

[0049] Example 2

[0050] As a preferred embodiment of the present application, the present embodiment discloses a high toughness cementitious material, the components of which are shown in Table 2.

[0051] Table 2

[0052] Component Mass % by weight Highly active supplementary cementitious material A 10.6 High performance cementitious material B 50.6 Highly ductile supplementary cementitious material C 38.8

[0053] Example 3

[0054] As a preferred embodiment of the present application, the present embodiment discloses a high toughness cementitious material, the components of which are shown in Table 3.

[0055] Table 3

[0056] Component Mass % by weight Highly active supplementary cementitious material A 12.9 High performance cementitious material B 52.1 Highly ductile supplementary cementitious material C 35.0

[0057] Example 4

[0058] As a preferred embodiment of the present application, the present embodiment discloses a high toughness cementitious material, the components of which are shown in Table 4.

[0059] Table 4

[0060] Component Mass % by weight Highly active supplementary cementitious material A 16.2 High performance cementitious material B 53.5 Highly ductile supplementary cementitious material C Component Mass % by weight Highly active supplementary cementitious material A High performance cementitious material B Highly ductile supplementary cementitious material C 30.3

[0061] Comparative Example

[0062] The present comparative example is a 42.5 ordinary portland cement.

[0063] Standard mortar experiments were carried out on the high toughness cementitious materials of Examples 1-5 and the comparative example, and the specimen forming, curing, and strength testing methods were in accordance with the national standard "Cement Mortar Strength Testing Method (ISO Method)" GB / T 17671. After 28d and 90d of standard curing of the mortar specimens, compressive and flexural strength tests were carried out, and the test results are shown in Table 5 below.

[0064] Table 5

[0065]

[0066] As shown in Table 5, the compressive and flexural strength of the example 28d and 90d are both better than that of the ordinary 42.5 Portland cement, and the longer the age, the better the compressive and flexural strength of the example compared with the ordinary Portland cement, the growth rate of the compressive and flexural strength of the example is higher than that of the ordinary Portland cement, and the flexural compressive ratio of the example is also increased with the increase of the age, while the flexural compressive ratio of the ordinary Portland cement is decreased, which shows that the synergistic effect of the high belite cement clinker and the calcium carbonate whisker on the surface of the modified rubber powder not only ensures the long-term strength of the high toughness cementitious material, but also improves the toughness of the cementitious material.

[0067] Finally, it should be pointed out that: the above examples are only the preferred embodiments of the present application for illustrating the technical solutions of the present application, but not limiting them, and of course, they are not limiting the patent scope of the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application; that is to say, any modification or polishing without substantial significance in the main design idea and spirit of the present application, and the technical problems solved by the present application are still consistent with the present application, and they should be included in the protection scope of the present application; in addition, the technical solutions of the present application are directly or indirectly applied to other related technical fields, which are also included in the patent protection scope of the present application.

Claims

1. A cementitious material with improved toughness, characterized in that: The invention comprises the following components in mass percentage: 9.2-16.2 wt% of a high-activity auxiliary cementitious material A, 49.4-53.5 wt% of a high-performance cementitious material B, and 30.3-41.4 wt% of a high-toughness auxiliary cementitious material C, wherein the high-activity auxiliary cementitious material A is one or more of silica fume, slag, or high-calcium fly ash, the high-performance cementitious material B is a high-iron phase high-belite cement clinker, and the high-toughness auxiliary cementitious material C is a modified rubber powder; The preparation method of the modified rubber powder is: S1, adding quicklime to water to obtain saturated lime water; S2. After cleaning the surface impurities of the rubber powder, put it into saturated lime water and soak it for 20 to 24 hours before taking it out; S3, add MgCl2•6H2O to saturated lime water to obtain mixed slurry. 2+ and Mg 2+ The concentration ratio is 1:1; S4. Heat the mixed slurry to 80°C and keep it warm for 1-1.5 hours, stirring continuously during the heating and keeping warm process; S5. Add the soaked rubber powder back into the mixed slurry and continue stirring. The volume ratio of rubber powder to mixed slurry is 1:

10. Then, introduce CO2 gas. When the pH value of the mixed slurry drops to 7, stop aeration and stirring. S6. Take out the rubber powder, wash it with anhydrous ethanol several times, and then dry it to obtain modified rubber powder.

2. The toughness-enhancing gelling material according to claim 1, wherein: The mineral composition of the high-iron phase high-belite cement clinker is 32.07 wt% C3S, 49.61 wt% C2S, 1.96 wt% C3A, and 16.36 wt% C4AF.

3. A cementitious material with improved toughness according to claim 1, characterized in that: The soaking time in S2 is 24 hours, the heat preservation time in S4 is 1 hour, and the drying in S6 is drying in a 60° C. oven for 5 to 6 hours.

4. A cementitious material with improved toughness according to claim 1, characterized in that: The particle size of the highly active auxiliary gelling material A is in the range of 0.15 to 3 μm, and the median diameter D 50 1.36µm.

5. The toughness-enhancing gelling material according to claim 1, characterized in that: The particle size of the high performance gelling material B is in the range of 3 to 32 μm, and the median diameter D 50 It is 16.78µm.

6. A cementitious material with improved toughness according to claim 1, characterized in that: The particle size of the high-toughness auxiliary cementitious material C is in the range of 32 to 80 μm, and the median diameter D 50 It is 48.21µm.

7. The toughness-enhancing gelling material according to claim 1, characterized in that: The specific surface area of ​​the toughness-enhancing gelling material is 360-380 m 2 / kg, the residue on the 80µm square hole sieve does not exceed 5%; the initial setting time is not earlier than 15min, and the final setting time is not later than 45min; the water requirement is ≤30%, the 28d flexural strength is greater than 9.5MPa, the 28d compressive strength is greater than 45MPa, the 90d flexural strength is greater than 15MPa, the 90d compressive strength is greater than 70MPa, and the standard mortar flexural-compression ratio is not less than 0.

20.

8. The toughness-enhancing gelling material according to claim 1, characterized in that: The mass percentages of the high-activity auxiliary gelling material A, the high-performance gelling material B and the high-toughness auxiliary gelling material C are calculated based on the Dinge-Funk continuous particle size distribution stacking model.

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