Ultralow-heat-release cement as well as preparation method and application thereof
By combining cement with dicalcium silicate-tetracalcium ferroaluminate cement clinker in a large volume concrete structure and adding chelating agent, the temperature rise and crack problems caused by the hydration heat of traditional cement are solved, and ultra-low heat exothermic and early strength are improved.
Patent Information
- Application Number
- CN202510317183.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-07-01
AI Technical Summary
In large-volume concrete structures, the heat released during traditional cement hydration is difficult to dissipate quickly, resulting in a sharp rise in the internal temperature of the concrete, which may trigger cracks and affect the integrity and durability of the structure.
By combining different varieties of cement with dicalcium silicate-tetracalcium ferroalaluminate cement clinker, the synergistic coupling between cement hydration products is used to improve early strength, and by adding chelating agents such as ammonia triacetic acid, hydration of tetracalcium ferroalaluminate is promoted and hydration and exothermic.
The goal of ultra-low heat release was achieved, with hydration heat release reduced by 3 to 13%, and the early strength increased by 10 to 30%. At the same time, the overall performance of concrete was improved, and the internal temperature rise and crack formation caused by cement heat release was prevented.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of building materials, and particularly to an ultra-low heat-releasing cement, its preparation method and application. Background Art
[0002] In the construction process of large-volume concrete structures, such as key infrastructures like dams and nuclear power plants, the application of low-heat cement is particularly crucial. Due to their huge size and continuity, these structures have extremely high requirements for the thermal and mechanical properties of materials. Traditional cement releases a large amount of heat during the hydration and hardening process, which becomes a significant problem in large-volume concrete because the heat generated inside is difficult to quickly dissipate to the environment, resulting in a sharp rise in the internal temperature of the concrete. This temperature rise may not only cause temperature difference stresses between the inside and outside of the concrete, but also lead to the formation of harmful cracks, affecting the integrity and durability of the structure. Therefore, preventing the internal temperature rise caused by the hydration heat of cement and the subsequent cracking problem has become a core challenge in design and construction.
[0003] To address this challenge, low-heat cement came into being. It achieves a more ideal balance of thermal and mechanical properties by optimizing the mineral composition and using admixtures in combination. Specifically, low-heat cement usually contains a relatively high content of dicalcium silicate (C2S), and the proportions of tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF) are relatively low. In addition, active admixtures such as fly ash and slag may be added. These admixtures can not only reduce the hydration heat, but also improve the late strength and other properties of the concrete. However, due to the increase in the content of dicalcium silicate, the early strength development of low-heat cement is relatively slow, which means its early bearing capacity may be inferior to that of ordinary cement, posing a challenge to the project progress that needs to bear the load as soon as possible or reach a specific strength.
[0004] Therefore, there is an urgent need to develop a new cement and its preparation method to improve the above problems. Summary of the Invention
[0005] In view of this, the present invention provides an ultra-low heat-releasing cement, its preparation method and application. By compounding different types of cement with dicalcium silicate-tetracalcium aluminoferrite cement clinker and using the synergistic coupling effect between the hydration products of the cement, the early strength is improved and the goal of ultra-low heat release is achieved.
[0006] In a first aspect, the present invention provides an ultra-low heat-releasing cement, which comprises the following components by mass parts: 30 - 90 parts of cement, 10 - 70 parts of dicalcium silicate-tetracalcium aluminoferrite clinker, and 0.01 - 0.05 parts of chelating agent.
[0007] Based on the above technical solutions, preferably, the cement is selected from one of low-heat cement P·LH32.5, medium-heat cement P·MH42.5, or ordinary Portland cement P·Ⅰ52.5.
[0008] Based on the above technical solutions, preferably, the dicalcium silicate-tetracalcium ferroaluminate clinker, by mass percentage, includes: C2S 59-80%, C4AF 20-40%, and impurity phase 1-5%. Among them, the impurity phase mainly includes calcium silicates (such as C3S, CS, etc.), calcium aluminates (such as C 12 A7, CA, etc.), and iron-containing minerals (such as CF, etc.) other than dicalcium silicate and iron phase / tetracalcium ferroaluminate.
[0009] Based on the above technical solutions, preferably, the chelating agent is selected from one of triethanolamine, ethylenediaminetetraacetic acid, hydroxyethyldiaminetriacetic acid, and nitrilotriacetic acid.
[0010] Based on the above technical solutions, preferably, the ultra-low heat-releasing cement, by mass parts, includes the following components: 30-90 parts of cement, 10-70 parts of dicalcium silicate-tetracalcium ferroaluminate clinker, and 0.01-0.05 parts of nitrilotriacetic acid.
[0011] In the second aspect, the present invention provides a method for preparing the above ultra-low heat-releasing cement, and the method includes: weighing the corresponding mass parts of cement, dicalcium silicate-tetracalcium ferroaluminate clinker, and chelating agent, and mixing them to obtain the ultra-low heat-releasing cement.
[0012] Based on the above technical solutions, the preparation method of the dicalcium silicate-tetracalcium ferroaluminate clinker includes:
[0013] Using steel slag and / or carbonized steel slag, calcium-containing raw material, silicon-containing raw material, and aluminum-containing raw material as initial raw materials, mixing, calcining, and cooling to obtain the dicalcium silicate-tetracalcium ferroaluminate clinker;
[0014] Among them, the carbonized steel slag is prepared by carbonizing CO2 into water in which steel slag is dispersed; the calcium-containing raw material is selected from one or more of limestone, red mud, or steel slag; the silicon-containing raw material is selected from one or more of high-silica sandstone, low-silica sandstone, or silica fume; the aluminum-containing raw material is selected from one or more of fly ash, low-silica sandstone, or bauxite.
[0015] Based on the above technical solutions, preferably, using carbonized steel slag, calcium-containing raw material, silicon-containing raw material, and aluminum-containing raw material as initial raw materials to provide the corresponding mass parts of oxides, including: CaO, SiO2, Al2O3, Fe2O3; mixing, calcining, and cooling to obtain the dicalcium silicate-tetracalcium ferroaluminate clinker;
[0016] By adopting the above technical solution, using carbonized steel slag as raw material, compared with CaCO3 in limestone, the size of the carbonized calcium carbonate is smaller, and Ca 2+ is more likely to migrate, promoting the formation of silicate cement clinker minerals, reducing the calcination temperature, increasing the hydration activity of the clinker, and improving the clinker strength. Using carbonized steel slag to prepare dicalcium silicate-tetracalcium ferroaluminate cement clinker can effectively activate these two minerals, so that when compounded with cement, it can produce better synergistic effects with other minerals. Moreover, after the steel slag is carbonized, compared with the untreated one, the impurity ions in its RO phase are more likely to break away from the chemical binding state and transform into the free state. When using carbonized steel slag to prepare dicalcium silicate-tetracalcium ferroaluminate cement clinker, it is easy to enter the mineral crystal structure, increasing the mineral activity.
[0017] Specifically, the preparation of the dicalcium silicate-tetracalcium ferroaluminate clinker includes the following steps:
[0018] Step 1: Under stirring conditions, mix the steel slag and water at a volume ratio of 1:20, continuously introduce CO2 gas into the mixture at a flow rate of 0.3 - 0.6 ml / min until the pH value of the mixed solution reaches 7, then stop. This completes the carbonization of the steel slag. Filter and dry the solid filter residue to obtain carbonized steel slag;
[0019] Step 2: According to the chemical composition and ratio of the dicalcium silicate-tetracalcium ferroaluminate cement clinker, prepare the corresponding raw materials according to the corresponding mass fractions of oxides respectively. The source of Fe2O3 is provided by the carbonized steel slag;
[0020] Step 3: Grind the raw materials corresponding to Step 2 until the particle size does not exceed 75 μm, and mix for 6 - 8 h to obtain the raw meal of dicalcium silicate-tetracalcium ferroaluminate cement;
[0021] Step 4: Prepare the raw meal cake of the dicalcium silicate-tetracalcium ferroaluminate cement in Step 3, calcine it, and cool it to obtain the dicalcium silicate-tetracalcium ferroaluminate cement clinker. On the basis of the above technical solution, preferably, in Step 3, the calcination process is: heat up to 1250 °C - 1350 °C within 125 min - 270 min, and keep it warm for 30 min - 40 min; the heating rate is 5 - 10 °C / min.
[0022]
[0023] By adopting the above technical solution, the mineral activity can be maximally activated, the reaction process can be promoted, and thus the early and late strengths of the cement are improved, meeting the requirements of high-performance concrete and other applications. And a moderate heating rate helps to uniformly heat the materials, enabling each chemical component to fully react and avoiding internal stress concentration or local overheating caused by too fast heating. This method promotes the effective formation of dicalcium silicate and tetracalcium aluminoferrite minerals, ensuring the integrity and stability of the mineral structure.
[0024] Based on the above technical solution, preferably, it further includes: Step Five: Grinding the dicalcium silicate-tetracalcium aluminoferrite cement clinker obtained in Step Four to a particle size not exceeding 75 μm.
[0025] Based on the above technical solution, preferably, the mixing time is 6 - 8 h.
[0026] In the third aspect, the present invention relates to the application of the above ultra-low heat-releasing cement in building dams and nuclear power plants.
[0027] The ultra-low heat-releasing cement, its preparation method and application provided by the present invention have the following beneficial effects compared with the prior art:
[0028] (1) The present invention provides an ultra-low heat-releasing cement. By compounding and using the cement with dicalcium silicate-tetracalcium aluminoferrite cement clinker, the synergistic coupling effect between the hydration products of the two cements can improve the early strength. Compared with commercially available low-heat cement, the ultra-low heat-releasing cement provided by the present invention has the characteristics of low hydration heat release and high early strength. Specifically, the hydration heat release can be reduced by 3 - 13%, and the early strength can increase by 10 - 30%.
[0029] (2) The ultra-low heat-releasing cement of the present invention is doped with a chelating agent, which can promote the hydration of tetracalcium aluminoferrite. Nitrilotriacetic acid (NTA) is used as a metal complexing agent for Fe ions. The complexing effect between NTA and Fe ions may increase the adsorption amount on the surface of cement particles, contribute to the formation of a large number of hydration products with a low Al / Fe ratio, increase the stability of the hydration products, reduce the transformation from AFt to AFm, and improve the performance of the ultra-low heat cement. Specific Embodiments
[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.
[0031] Example 1
[0032] First step, this embodiment provides a dicalcium silicate - tetracalcium aluminoferrite cement clinker, including 63% C2S, 32% C4AF and 5% impurity phase; the preparation of this cement clinker includes the following steps:
[0033] Step 1: Under stirring conditions, mix the steel slag in Step 1 with water at a mass (g) - volume (ml) ratio of 1:20, introduce CO2 at a rate of 0.3 ml / min, stop carbonization when the pH reaches 7, filter, take the solid filtrate and dry it at 40 °C to obtain carbonized steel slag;
[0034] Step 2: According to the chemical composition and ratio of the components of the dicalcium silicate - tetracalcium aluminoferrite cement clinker, prepare the corresponding mass fractions of oxides respectively, including: 58 parts of CaO, 23 parts of SiO2, 7 parts of Al2O3, and 12 parts of Fe2O3; among them, CaO is provided by limestone, SiO2 is provided by high - silica sandstone, Al2O3 is provided by low - silica sandstone, and Fe2O3 is provided by carbonized steel slag;
[0035] Step 3: Grind the corresponding amounts of raw materials required in Step 2 to below 75 μm, and fully mix the ground materials for 6 h to obtain the raw meal of dicalcium silicate - tetracalcium aluminoferrite cement, where, in C4AF, the atomic ratio of Al to Fe is 1:1;
[0036] Step 4: Prepare the raw meal cake of the dicalcium silicate - tetracalcium aluminoferrite cement raw meal in Step 3 and carry out calcination. The calcination process is: heat up to 1250 °C at a heating rate of 10 °C / min within 125 min, and then keep it at this temperature for 40 min. After calcination, cool it below 100 °C within 5 min to obtain the dicalcium silicate - tetracalcium aluminoferrite cement clinker;
[0037] Step 5: Grind the dicalcium silicate - tetracalcium aluminoferrite cement clinker obtained in Step 4 to a particle size not exceeding 75 μm.
[0038] Second step, this embodiment provides a preparation method of an ultra - low heat - releasing cement, including: weighing 80 parts of low - heat cement, 20 parts of dicalcium silicate - tetracalcium aluminoferrite clinker and 0.05 part of NTA, putting them into a mixing tank and fully mixing for 6 h to obtain the ultra - low heat - releasing cement.
[0039] Measure the 28 - day strength and 3 - day and 28 - day hydration heat release values of the ultra - low heat cement in this embodiment according to GB / T 17671 and GB / T 12959. The test results are as follows: the 28 - day strength of the ultra - low heat cement in this embodiment is 43.1 MPa, the 3 - day hydration heat release value is 170 kJ / kg, and the 28 - day hydration heat release value is 253 kJ / kg.
[0040] Example 2
[0041] The difference from Example 1 is as follows: Weigh 50 parts of medium heat cement (P·MH42.5), 50 parts of dicalcium silicate-tetracalcium ferroaluminate clinker and 0.05 part of NTA, and put them into a mixing tank to mix thoroughly for 6 h to obtain ultra-low heat release cement.
[0042] Measure the 28-day strength and 3-day and 28-day hydration heat release values of the ultra-low heat cement of this example according to GB / T 17671 and GB / T 12959. The test results are as follows: The 28-day strength of the ultra-low heat cement of this example is 34.2 MPa, the 3-day hydration heat release value is 151 kJ / kg, and the 28-day hydration heat release value is 230 kJ / kg.
[0043] Example 3
[0044] The difference from Example 1 is as follows: Weigh 20 parts of ordinary Portland cement (P·Ⅰ52.5), 80 parts of dicalcium silicate-tetracalcium ferroaluminate clinker and 0.05 part of NTA, and put them into a mixing tank to mix thoroughly for 6 h to obtain ultra-low heat release cement.
[0045] Measure the 28-day strength and 3-day and 28-day hydration heat release values of the ultra-low heat cement of this example according to GB / T 17671 and GB / T 12959. The test results are as follows: The 28-day strength of the ultra-low heat cement of this example is 37.9 MPa, the 3-day hydration heat release value is 166 kJ / kg, and the 28-day hydration heat release value is 248 kJ / kg.
[0046] Comparative Example 1
[0047] The difference from Example 1 is as follows: Directly use low heat cement (P·LH32.5).
[0048] Measure the 28-day strength and 3-day and 28-day hydration heat release values of the low heat cement of this comparative example. The test results are as follows: The 28-day strength of the low heat cement of this comparative example is 33.1 MPa, the 3-day hydration heat release value is 195 kJ / kg, and the 28-day hydration heat release value is 288 kJ / kg.
[0049] Comparative Example 2
[0050] The difference from Example 1 is as follows: Directly use medium heat cement (P·LH42.5).
[0051] Measure the 28-day strength and 3-day and 28-day hydration heat release values of the low heat cement of this comparative example. The test results are as follows: The 28-day strength of the low heat cement of this comparative example is 43.1 MPa, the 3-day hydration heat release value is 236 kJ / kg, and the 28-day hydration heat release value is 290 kJ / kg.
[0052] Comparative Example 3
[0053] The difference from Example 1 is that ordinary Portland cement (P·Ⅰ52.5) is directly used.
[0054] The 28-day strength and the heat release values at 3 days and 28 days of the low-heat cement of this comparative example were measured, and the test results are as follows: The 28-day strength of the low-heat cement of this comparative example is 52.7 MPa, the heat release value at 3 days is 280 kJ / kg, and the heat release value at 28 days is 352 kJ / kg.
[0055] Comparative Example 4
[0056] The difference from Example 1 is that high belite low-heat samples are directly prepared using pure reagents according to the corresponding mineral chemical composition. The mineral composition of the high belite low-heat cement clinker is C3S 10%, C2S 60%, C3A 5%, and C4AF 25%. The calcination process is as follows: The temperature is raised to 1400 °C within 140 min at a heating rate of 10 °C / min, and then held at this temperature for 30 min. After calcination, the temperature is lowered to below 100 °C within 5 min. Then it is ground to a particle size not exceeding 75 μm.
[0057] According to GB / T 17671 and GB / T 12959, the 28-day strength and the heat release values at 3 days and 28 days of the low-heat cement of this comparative example were measured, and the test results are as follows: The 28-day strength of the low-heat cement of this comparative example is 28.5 MPa, the heat release value at 3 days is 175 kJ / kg, and the heat release value at 28 days is 250 kJ / kg.
[0058] By comparing Examples 1 to 3 and Comparative Examples 1 to 4, it can be seen that the low-heat release cement has better performance while having lower heat release during hydration. This is mainly attributed to the impurity ions of carbonized steel slag entering the dicalcium silicate-tetracalcium ferroaluminate clinker, improving the activity of the minerals; in addition, the dicalcium silicate-tetracalcium ferroaluminate clinker makes up for the blank in the early performance development of the low-heat cement, and has a synergistic strengthening effect with the low-heat cement, forming a dense and stable microstructure at 28 days, effectively improving the strength. At the same time, the compounding of the dicalcium silicate-tetracalcium ferroaluminate clinker will not overly reduce the strength performance of other types of cement, ensuring good performance while having low heat release during hydration. While the existing technology mainly uses highly active mineral admixtures to enhance strength, and additional hydration products are formed through the reaction of the cement hydration products with the active components in the mineral admixtures to increase strength.
[0059] Example 4
[0060] First step, this example provides a dicalcium silicate-tetracalcium ferroaluminate cement clinker, including C2S 79%, C4AF 18% and an impurity phase 3%; the preparation of this cement clinker includes the following steps:
[0061] Step 1: Under stirring conditions, the steel slag in step 1 is mixed with water at a mass (g)-volume (ml) ratio of 1:20, CO2 is introduced at a rate of 0.6 ml / min, and carbonization is stopped when the pH reaches 7, and the solid filtrate is taken and dried at 100° C. to obtain carbonized steel slag;
[0062] Step 2: According to the chemical composition and proportion of the components of the dicalcium silicate-iron phase cement clinker, prepare the corresponding mass fractions of oxides, including: 61 parts of CaO, 28 parts of SiO2, 4 parts of Al2O3, and 7 parts of Fe2O3; wherein CaO is provided by limestone, SiO2 is provided by silica fume, Al2O3 is provided by fly ash, and Fe2O3 is provided by carbonized steel slag;
[0063] Step 3: Grind the corresponding amount of raw materials required in step 2 to less than 75 μm, and fully mix the ground materials for 7 hours to obtain dicalcium silicate-tetracalcium aluminoferrate cement raw material, wherein the atomic ratio of Al to Fe in C4AF is 1:1;
[0064] Step 4: Prepare the dicalcium silicate-tetracalcium aluminoferrate cement raw material from step 3 into The raw cake is calcined, and the calcination process is: heating to 1350℃ within 270min at a heating rate of 5℃ / min, and then keeping at this temperature for 30min. After calcination, the temperature is reduced to below 100℃ within 5min to obtain dicalcium silicate-tetracalcium aluminoferrate cement clinker;
[0065] Step 5: Grind the dicalcium silicate-tetracalcium aluminoferrate cement clinker obtained in step 4 to a particle size not exceeding 75 μm.
[0066] In the second step, this embodiment provides a method for preparing ultra-low exothermic cement, comprising: weighing 90 parts of low-heat cement, 10 parts of dicalcium silicate-tetracalcium aluminoferrate clinker and 0.01 parts of NTA, putting them into a mixing tank and mixing them thoroughly for 8 hours to obtain ultra-low exothermic cement.
[0067] The 28d strength and 3d and 28d hydration heat release values of the ultra-low heat cement of this embodiment were measured according to GB / T 17671 and GB / T 12959, and the test results were as follows: the 28d strength of the ultra-low heat cement of this embodiment was 38.2 MPa, the 3d hydration heat release value was 189 kJ / kg, and the 28d hydration heat release value was 278 kJ / kg.
[0068] Comparative Example 5
[0069] The difference from Example 4 is that NTA is not used when preparing the ultra-low exothermic cement.
[0070] The 28d strength and 3d and 28d hydration heat release values of the ultra-low heat cement of this comparative example were measured according to GB / T 17671 and GB / T 12959, and the test results were as follows: the 28d strength of the ultra-low heat cement of this example was 30.8 MPa, the 3d hydration heat release value was 179 kJ / kg, and the 28d hydration heat release value was 263 kJ / kg.
[0071] By comparing Example 4 and Comparative Example 5, it can be seen that the use of NTA can significantly promote the performance of ultra-low heat cement, but will slightly increase the hydration heat. This is because NTA promotes the hydration process of C4AF and forms hydration products such as AFt. At the same time, these hydration products are also one of the sources of cement strength. Therefore, ultra-low heat cement using NTA has better strength performance.
[0072] Example 5
[0073] In the first step, this embodiment provides a dicalcium silicate-tetracalcium aluminoferrate cement clinker, comprising 70% C2S, 29% C4AF and 1% impurity phase; the preparation of the cement clinker comprises the following steps:
[0074] Step 1: Under stirring, the steel slag of step 1 is mixed with water at a mass (g)-volume (ml) ratio of 1:10, CO2 is introduced at a rate of 0.6 ml / min, and carbonization is stopped when the pH reaches 7, and the solid filtrate is taken and dried at 200° C. to obtain carbonized steel slag;
[0075] Step 2: According to the chemical composition and proportion of the components of the dicalcium silicate-iron phase cement clinker, prepare the corresponding mass fractions of oxides, including: 59 parts of CaO, 24 parts of SiO2, 4 parts of Al2O3, and 12 parts of Fe2O3; wherein CaO is provided by limestone, SiO2 is provided by silica fume, Al2O3 is provided by bauxite, and Fe2O3 is provided by carbonized steel slag;
[0076] Step 3: Grind the limestone, silica fume, bauxite and the carbonized steel slag dried in step 1 to less than 75 μm, and fully mix the ground materials for 7 hours to obtain dicalcium silicate-tetracalcium aluminoferrate cement raw material, wherein the atomic ratio of Al to Fe in C4AF is 1:1;
[0077] Step 4: Prepare the dicalcium silicate-tetracalcium aluminoferrate cement raw material from step 3 into The raw cake is calcined, and the calcination process is: heating to 1350℃ within 270min at a heating rate of 5℃ / min, and then keeping at this temperature for 30min. After calcination, the temperature is reduced to below 100℃ within 5min to obtain dicalcium silicate-tetracalcium aluminoferrate cement clinker;
[0078] Step 5: Grind the dicalcium silicate-tetracalcium aluminoferrite cement clinker obtained in Step 4 to a particle size not exceeding 75 μm.
[0079] Second, this embodiment provides a method for preparing an ultra-low heat release cement, including: weighing 90 parts of low heat cement, 10 parts of dicalcium silicate-tetracalcium aluminoferrite clinker, and 0.01 part of triethanolamine, putting them into a mixing tank and mixing thoroughly for 8 h to obtain the ultra-low heat release cement.
[0080] Measure the 28-day strength and 3-day and 28-day hydration heat release values of the ultra-low heat cement in this embodiment according to GB / T 17671 and GB / T 12959. The test results are as follows: The 28-day strength of the ultra-low heat cement in this embodiment is 37.5 MPa, the 3-day hydration heat release value is 179 kJ / kg, and the 28-day hydration heat release value is 263 kJ / kg.
[0081] Example 6
[0082] The difference from Example 5 is that this embodiment provides a method for preparing an ultra-low heat release cement, including: weighing 90 parts of low heat cement, 10 parts of dicalcium silicate-tetracalcium aluminoferrite clinker, and 0.01 part of ethylenediaminetetraacetic acid, putting them into a mixing tank and mixing thoroughly for 8 h to obtain the ultra-low heat release cement.
[0083] Measure the 28-day strength and 3-day and 28-day hydration heat release values of the low heat cement in this comparative example according to GB / T 17671 and GB / T 12959. The test results are as follows: The 28-day strength of the low heat cement in this comparative example is 37.2 MPa, the 3-day hydration heat release value is 176 kJ / kg, and the 28-day hydration heat release value is 260 kJ / kg.
[0084] Example 7
[0085] The difference from Example 5 is that this embodiment provides a method for preparing an ultra-low heat release cement, including: weighing 90 parts of low heat cement, 10 parts of dicalcium silicate-tetracalcium aluminoferrite clinker, and 0.01 part of hydroxyethyl ethylenediamine triacetic acid, putting them into a mixing tank and mixing thoroughly for 8 h to obtain the ultra-low heat release cement.
[0086] Measure the 28-day strength and 3-day and 28-day hydration heat release values of the low heat cement in this comparative example according to GB / T 17671 and GB / T 12959. The test results are as follows: The 28-day strength of the low heat cement in this comparative example is 36.6 MPa, the 3-day hydration heat release value is 184 kJ / kg, and the 28-day hydration heat release value is 266 kJ / kg.
[0087] In summary, when the ultra-low heat release cement of the present invention is applied in practice, it can reduce the sharp rise in internal temperature caused by the heat release of the cement, effectively prevent the formation of harmful cracks, and ensure the integrity and durability of the structure; at the same time, the good mechanical properties can ensure the rapid and efficient progress of construction, which helps to ensure the smooth progress of the project.
[0088] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.
Claims
1. An ultra-low exothermic cement, characterized in that: The invention comprises the following components by weight: 30 to 90 parts of cement, 10 to 70 parts of dicalcium silicate-tetracalcium aluminoferrate clinker and 0.01 to 0.05 parts of chelating agent.
2. The ultra-low exothermic cement according to claim 1, characterized in that: The cement is selected from one of low heat cement P·LH32.5, medium heat cement P·MH42.5 or ordinary silica cement P·I52.
5.
3. The ultra-low exothermic cement according to claim 1, characterized in that: The dicalcium silicate-tetracalcium aluminoferrate clinker comprises, by mass percentage, 59-80% C2S, 20-40% C4AF, and 1-5% impurity phase.
4. The ultra-low exothermic cement according to claim 1, characterized in that: The chelating agent is selected from one of triethanolamine, ethylenediaminetetraacetic acid, hydroxyethyldiaminetriacetic acid and nitrilotriacetic acid.
5. The ultra-low exothermic cement according to claim 4, characterized in that: The invention comprises the following components by weight: 30 to 90 parts of cement, 10 to 70 parts of dicalcium silicate-tetracalcium aluminoferrate clinker, and 0.01 to 0.05 parts of nitrilotriacetic acid.
6. A method for preparing the ultra-low exothermic cement according to any one of claims 1 to 5, characterized in that: The method comprises: weighing corresponding mass fractions of cement, dicalcium silicate-tetracalcium aluminoferrate clinker and a chelating agent, mixing them, and obtaining ultra-low exothermic cement.
7. The method for preparing ultra-low exothermic cement according to claim 6, characterized in that: The preparation method of the dicalcium silicate-tetracalcium aluminoferrate clinker comprises: Using steel slag and / or carbonized steel slag, calcium-containing raw materials, silicon-containing raw materials and aluminum-containing raw materials as initial raw materials, mixing, calcining and cooling to obtain dicalcium silicate-tetracalcium aluminoferrate clinker; Among them, the carbonized steel slag is obtained by carbonizing CO2 into water dispersed with steel slag, which is used to provide calcium and iron elements; the calcium-containing raw material is selected from one or more of limestone, red mud or steel slag, the silicon-containing raw material is selected from one or more of high-silicon sandstone, low-silicon sandstone or silica ash; the aluminum-containing raw material is selected from one or more of fly ash, low-silicon sandstone or bauxite.
8. The method for preparing ultra-low exothermic cement according to claim 7, characterized in that: The initial raw materials include carbonized steel slag, calcium-containing raw materials, silicon-containing raw materials and aluminum-containing raw materials.
9. The method for preparing ultra-low exothermic cement according to claim 6, characterized in that: The mixing time is 6 to 8 hours.
10. An application of the ultra-low exothermic cement according to any one of claims 1 to 5, characterized in that: The ultra-low heat release cement is used in the construction of dams and nuclear power plants.