阅读说明：本技术 一种低温水泥基材料强度诱导剂 (Low-temperature cement-based material strength inducer ) 是由 张剑峰 程铠 贾洋 曾明 周紫晨 于 2021-08-24 设计创作，主要内容包括：本发明公开了一种低温水泥基材料强度诱导剂,其组成按质量百分数计如下：强度快速发展组分60％-70％；流变组分7％-18％；微膨胀组分15％-25％；调凝组分0.5％-1％；防冻组分1％-10％。本发明的诱导剂可使水泥基材料的低温条件下缩短凝结时间,短时间内强度快速发展,早期强度高,可实现尽早脱模,缩短建设周期。导剂促进水泥基材料强度快速发展,能避免冻害现象的发生,同时能增强防水效果、防腐蚀效果。组成组分来源广泛,价格低廉,使用成本较低。在水泥基材料拌制时加入,搅拌均匀后即能发挥功效,使用方便。(The invention discloses a strength inducer of a low-temperature cement-based material, which comprises the following components in percentage by mass: 60% -70% of a component with rapid development strength; 7% -18% of rheological component; 15% -25% of a micro-expansion component; 0.5 to 1 percent of coagulation regulating component; 1 to 10 percent of antifreezing component. The inducer of the invention can shorten the setting time of cement-based materials under low temperature conditions, rapidly develop the strength in a short time, have high early strength, realize early demoulding and shorten the construction period. The conductive agent promotes the rapid development of the strength of the cement-based material, can avoid the occurrence of freezing injury, and can enhance the waterproof effect and the anticorrosion effect. The components have wide sources, low price and low use cost. The cement-based material is added when being stirred, and the efficacy can be exerted after even stirring, and the use is convenient.)

1. The strength inducer for the low-temperature cement-based material is characterized by comprising the following components in percentage by mass:

2. the strength inducer of claim 1, wherein the strength-promoting component is a mixture of nuclei of ground cement and aluminous cement or sulphoaluminate cement, or a mixture of nuclei of ground cement and aluminous cement and sulphoaluminate cement; the proportion of the fine cement crystal nuclei is 10-20 wt%.

3. The strength inducer of a low-temperature cement-based material according to claim 1, wherein said ground cement nuclei are produced by grinding a portion of the mortar after screening recycled concrete, and the screen residue of a 45 μm square-hole screen is not more than 25%.

4. The strength inducer for a low-temperature cement-based material according to claim 1, wherein the rheological component is any one or more of silica fume, fly ash and stone powder.

5. The strength inducer of a low-temperature cement-based material according to claim 1, wherein said micro-expansive component is any one or a mixture of gypsum, azo compounds, and light burned magnesium oxide.

6. The strength inducer of a low-temperature cement-based material as claimed in claim 1, wherein said set-regulating component is any one or more of tartaric acid, boric acid, and lithium carbonate.

7. The strength inducer of a low-temperature cement-based material according to claim 1, wherein said anti-freezing component is any one or more of sodium formate, sodium nitrate, calcium formate, and sodium sulfate.

8. A cement-based material, characterized in that the strength inducer of the low-temperature cement-based material of any one of claims 1 to 7 is added, and the dosage of the inducer is 20 to 35 wt% of the dosage of powder in the cement-based material.

Technical Field

The invention belongs to the technical field of cement additives, and particularly relates to a strength inducer for a low-temperature cement-based material.

Background

In recent years, the economy of China is continuously and rapidly developed, and the projects such as domestic and foreign railways, roads, house buildings and the like, which are acquired by each large engineering construction unit, are more and more, and the concrete construction situation under the low-temperature condition in winter is inevitably faced. In low-temperature weather, the strength of the constructed concrete, particularly the early strength, is unfavorable, and the concrete can be subjected to freeze-thaw damage, salt corrosion damage and external force damage under the low-temperature and negative-temperature condition, so that the concrete can finally bring great damage to the structure of the concrete and can even completely destroy the concrete structure seriously.

In order to ensure the quality of concrete engineering under low temperature, the common methods mainly comprise: the temperature of the concrete raw material is increased to improve the overall temperature of the concrete, the early strength admixture is doped to promote the hydration of the cement, the heat loss in the pouring process is reduced, and the heat preservation and maintenance are realized. The implementation of the measures needs a constructor to do detailed deployment and planning aiming at the whole process of concrete construction, and the constructor can have better effect by executing the measures only with delicateness, even if the measures are carried out, the project period is inevitably prolonged to a certain extent, and the management cost and the quality cost of the project are greatly increased.

CN201110049598.X discloses a low-temperature concrete early strength agent, although the strength of a cement block is 13.5MPa in 12 hours, 18.5MPa in 24 hours and 30MP in three days under the condition that the environmental temperature is approximately 4 ℃; but the use effect is uncertain under the condition of lower than 0 ℃, and the composition is complex and the production is inconvenient.

CN201180009505.9 discloses a cement accelerator which, although having optimum setting and strength development at low temperatures of 5 to 15 ℃ and at the same time still having a sufficiently long processing time at high temperatures of 20 to 30 ℃; but the use effect is uncertain below 5 ℃.

CN201810165759.3 discloses a low-temperature curing agent for a cement-based grouting material of a deep-water underwater concrete structure, which improves the groutability of the cement-based grouting material, although the strength of the cement-based grouting material in a low-temperature environment of 0-5 ℃ is not lower than that of the cement-based grouting material in the same mixing ratio under standard curing at 20 ℃; but the use effect is uncertain under the condition of lower than 0 ℃, the grouting material is only used in the grouting material, and the material price of the composition product is expensive.

Disclosure of Invention

The invention mainly aims to provide an inducer for inducing the strength of a cement-based material to rapidly develop at a low temperature of-10-5 ℃, so that the cement-based material can reach the design strength in a short time without special external heat preservation measures, thereby greatly shortening the construction period and saving the engineering cost; meanwhile, the comprehensive quality of the concrete can be improved, and the same effect of improving the durability of the structure is remarkable.

In order to achieve the purpose, the technical scheme is as follows:

the strength inducer of the low-temperature cement-based material comprises the following components in percentage by mass:

according to the scheme, the strength rapid development component is a mixture of a ground cement crystal nucleus and high-alumina cement or sulphoaluminate cement, or a mixture of the ground cement crystal nucleus, the high-alumina cement and the sulphoaluminate cement; the proportion of the fine cement crystal nuclei is 10-20 wt%.

In the scheme, the ground cement crystal nucleus is prepared by grinding the part of the mortar screened by the recycled concrete, and the screen residue of a 45-micron square-hole screen is not more than 25 percent.

According to the scheme, the rheological component is any one or mixture of more of silica fume, fly ash and stone powder.

According to the scheme, the micro-expansion component is one or a mixture of more of gypsum, azo compounds and light calcined magnesia.

According to the scheme, the coagulation regulating component is one or a mixture of tartaric acid, boric acid and lithium carbonate.

According to the scheme, the antifreezing component is any one or mixture of sodium formate, sodium nitrate, calcium formate and sodium sulfate.

The strength inducer for cement-based materials is added into the cement-based materials, and the dosage of the inducer is 20-35 wt% of the dosage of powder in the cement-based materials.

The strength rapid development inducer accelerates the hydration process of cement under low temperature conditions through the comprehensive action among the components, and under the extremely low temperature environment of-10-5 ℃, the inducer with the mass ratio of powder materials of 25-35% is doped into the material, so that the 1d strength and the 3d strength of the cement-based material are not lower than 70% and 80% of the strength of the cement-based material with the same mixing ratio under the standard curing conditions. The inducer can flexibly allocate the proportion of each component according to the actual situation and the engineering requirement, and simultaneously meets the requirements of construction time, setting time and strength in all aspects.

The cement and the common cement in the cement-based material form a composite cement system, wherein: the high-alumina cement is hydrated as a fast-setting and fast-hardening cementing material to generate CAH₁₀And C₂AH₈The two crystals are mutually staggered and overlapped to form a strong crystal synthetic body, so that high early strength can be obtained; the ettringite generated by the hydration of the sulphoaluminate cement forms a framework, and the generated aluminum glue and the C-S-H gel together enable the structure to be firmer and denser. The cement and the common cement have comprehensive effects, so that the early strength of the cement-based material under the low-temperature condition is greatly improved, and the later strength is not influenced. In addition, sodium formate, sodium nitrate, calcium formate, sodium sulfate and the like are added as antifreeze agents, and due to the interference effect of the antifreeze agents on hydrogen bonds among water molecules, the freezing point of the slurry can be lowered, new dynamic balance is achieved in a subzero low-temperature environment, ice and liquid coexistence is achieved, so that continuous hydration reaction of cement is guaranteed, and the influence of temperature on the hydration process is weakened. The micro-expansion effect of gypsum, azo compounds and magnesium oxide in the inducer can resist the volume shrinkage caused by the rapid hydration of cement, the rheological agent can improve the water retention and cohesiveness of the cement-based material, and the rheological agent is also important for ensuring the durability of the cement-based material

Compared with the prior art, the invention has the following beneficial effects:

according to the principle of rainwater formation, the finely ground cement crystal nucleus introduced into the inducer can stimulate the rapid reaction of the cementing material and can also become an agglomeration nucleus for reaction, thereby being beneficial to improving the hydration speed of the cement-based material and improving the homogeneity of the structure, and particularly improving various performances of a weak area.

Compared with the traditional expanding agent, the light-burned magnesium oxide provides expansion stress within the strength development range of 5-25MPa, and the compensation shrinkage effect is stable and effective for a long time.

The inducer of the invention can shorten the setting time of cement-based materials under low temperature conditions, rapidly develop the strength in a short time, have high early strength, realize early demoulding and shorten the construction period.

The inducer of the invention promotes the rapid development of the strength of the cement-based material, can avoid the occurrence of freezing injury, and can enhance the waterproof effect and the anticorrosion effect.

The inducer has the advantages of wide component sources, low price and low use cost.

The inducer is added when the cement-based material is stirred, and can play a role after being uniformly stirred, so that the use is convenient.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The strength inducer of the low-temperature cement-based material in the specific embodiment of the invention comprises the following components in percentage by mass:

60% -70% of a component with rapid development strength; 7% -18% of rheological component; 15% -25% of a micro-expansion component; 0.5 to 1 percent of coagulation regulating component; 1 to 10 percent of antifreezing component.

The strength-developing component used in the following examples is a mixture of nuclei of ground cement with aluminous cement or sulphoaluminate cement, or a mixture of nuclei of ground cement with aluminous cement and sulphoaluminate cement; the proportion of the fine cement crystal nuclei is 10-20 wt%. The ground cement crystal nucleus is prepared by grinding a mortar part screened by recycled concrete, and the screen residue of a 45-micron square-hole screen is not more than 25%.

The rheological component is any one or mixture of more of silica fume, fly ash and stone powder; the specific surface area of the silica fume is more than 18000m²/kg，SiO₂The content is more than 94%; the fly ash is grade II ash specified by a standard; the fineness of the stone powder is more than or equal to 800 meshes.

The micro-expansion component is one or a mixture of more of gypsum, azo compound and light calcined magnesia; CaO content in the gypsum exceeds 39 wt%, SO₃More than 57 wt%; the content of magnesium oxide in the light-burned magnesium oxide is more than or equal to 85 percent, the reaction time is less than or equal to 120s, and the 7d limited expansion rate in water at 20 ℃ is more than or equal to 0.03 percent.

The coagulation regulating component is one or more of tartaric acid, boric acid and lithium carbonate.

The antifreezing component is any one or mixture of sodium formate, sodium nitrate, calcium formate and sodium sulfate.

Weighing the strength rapid development component and the rheological component according to the weight percentage, and then putting the components into a mixer to be uniformly mixed for 10-15 min; and adding the rest other components for further mixing for 15-25min, wherein the uniformly mixed powder is the low-temperature cement-based material strength inducer.

Example 1

An inducer for rapid development of strength of cement-based materials comprises the following components in percentage by mass: 60% of a strength rapid development component, 8% of a rheological component, 23% of a micro-expansion component, 0.64% of a coagulation regulating component and 8.36% of an antifreezing component.

The high-alumina cement, the sulphoaluminate cement and the ground cement crystal nucleus in the components with the rapid strength development are mixed according to the ratio of 60:30: 10; the rheological component is silica fume; the micro-expansion component is gypsum; the coagulation regulating component is formed by mixing tartaric acid and lithium carbonate 6:4, and both the tartaric acid and the lithium carbonate are industrial-grade compounds; the antifreezing component is industrial grade sodium formate.

The mixing amount of the inducer in the embodiment is 20% of the powder material, when in use, an internal mixing method is adopted, the inducer, other powder, sand and stone are uniformly mixed, water and a water reducing agent are added to be mixed to prepare concrete, the concrete is cured with a mold immediately after being formed, and the concrete is respectively placed under standard curing conditions of-10 ℃, 5 ℃ and 0 ℃ to be cured to a set age and then taken out to test the compressive strength. In this example, the concrete mixing ratio and the strength results are shown in Table 1 and Table 2, respectively.

TABLE 1C 40 concrete mixing ratio (kg/m)³)

TABLE 2 concrete Strength under curing conditions at different temperatures

Example 2

An inducer for rapid development of strength of cement-based materials comprises the following components in percentage by mass: 65% of strength rapid development component, 15% of rheological component, 15% of micro-expansion component, 0.82% of coagulation regulating component and 4.18% of antifreezing component.

The high-alumina cement, the sulphoaluminate cement and the ground cement crystal nucleus in the rapid strength development component are mixed according to the ratio of 70:15: 15; the rheological component is formed by compounding silica fume and fly ash according to the ratio of 40: 60; the micro-expansion component is light-burned magnesium oxide; the coagulation regulating component is formed by mixing tartaric acid and lithium carbonate according to a ratio of 45:55, wherein the tartaric acid and the lithium carbonate are industrial-grade compounds; the antifreezing component is formed by compounding sodium formate, calcium formate and sodium sulfate according to the ratio of 45:45:10, and the three are all industrial-grade compounds.

The mixing amount of the inducer in the embodiment is 30% of that of the powder material, when the concrete is used, an internal mixing method is adopted, the inducer, other powder, sand and stone are uniformly mixed, water and a water reducing agent are added to be mixed to prepare concrete, the concrete is cured with a mold immediately after being formed, and the concrete is placed under standard curing conditions of-10 ℃, 5 ℃ and 0 ℃ respectively and is taken out to test the compressive strength after being cured to a set age. In this example, the concrete mixing ratio and the strength results are shown in Table 3 and Table 4, respectively.

TABLE 3C 40 concrete mixing ratio (kg/m)³)

TABLE 4 concrete Strength under curing conditions at different temperatures

Example 3

An inducer for rapid development of strength of cement-based materials comprises the following components in percentage by mass: 70% of strength rapid development component, 9% of rheological component, 19% of micro-expansion component, 0.72% of coagulation regulating component and 1.28% of antifreezing component.

The sulphoaluminate cement and the milled cement crystal nucleus in the rapid strength development component are mixed according to the ratio of 80: 20; the rheological component is formed by compounding silica fume and stone powder according to the ratio of 80: 20; the micro-expansion component is prepared by azo compound and gypsum according to the ratio of 2: 98; the coagulation regulating component is formed by mixing boric acid and lithium carbonate according to a ratio of 50:50, wherein the boric acid and the lithium carbonate are industrial compounds; the antifreezing component is sodium nitrate, which is an industrial grade compound.

The mixing amount of the inducer in the embodiment is 30% of that of the powder material, when the powder material is used, an internal mixing method is adopted, the inducer, other powder and sand are uniformly mixed in a dry mode, water and a water reducing agent are added for mixing and forming, mold curing is immediately carried out after forming, the mixture is respectively placed at-10 ℃, at-5 ℃ and at 0 ℃ under standard curing conditions to be cured to a set age, and then the mixture is taken out to test the compressive strength. In this example, the mixing ratio of the grouting material is shown in Table 5, and the strength results are shown in Table 6.

TABLE 5 Sleeve grouting ratio (kg/t)

Ordinary silica 42.5 cement	Water (W)	Quartz sand	Polycarboxylic acid water reducing agent powder	Induction agent
					350	117	500	1.25	150

TABLE 6 Sleeve grouting Strength under curing conditions at different temperatures

Example 4

An inducer for rapid development of strength of cement-based materials comprises the following components in percentage by mass: 66 percent of strength rapid development component, 12 percent of rheological component, 15 percent of micro-expansion component, 0.95 percent of coagulation regulating component and 6.05 percent of antifreezing component.

The high aluminum salt cement and the ground cement crystal nucleus in the rapid strength development component are mixed according to the ratio of 60: 40; the rheological components are silica fume and fly ash according to the weight ratio of 50:50 are compounded; the micro-expansion component is formed by compounding an azo compound and light-burned magnesium oxide 5: 95; the coagulation regulating component is formed by mixing boric acid and lithium carbonate according to a ratio of 40:60, wherein the boric acid and the lithium carbonate are industrial compounds; the antifreezing component is formed by compounding sodium nitrate and calcium formate at a ratio of 50:50, and both are industrial-grade compounds.

The mixing amount of the inducer in the embodiment is 34.5 percent of that of the powder material, when in use, an internal mixing method is adopted, the inducer, other powder, sand and stone are uniformly mixed, water and a water reducing agent are added for mixing and forming, the mixture is immediately cured with a mold after forming, and the mixture is respectively placed at-10 ℃, at-5 ℃ and at 0 ℃ and cured under standard curing conditions to a set age, and then taken out for testing the compressive strength. In this example, the mixing ratio of the grouting material is shown in Table 7, and the strength results are shown in Table 8.

TABLE 7 Sleeve grouting ratio (kg/t)

Ordinary silica 42.5 cement	Water (W)	Quartz sand	Polycarboxylic acid water reducing agent powder	Induction agent
					360	135	450	1.6	190

TABLE 8 Sleeve grouting Strength under curing conditions at different temperatures

The above-mentioned embodiments are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions, equivalents, etc. made within the scope of the principles of the present invention should be included in the scope of the present invention.