Nano-seed crystal activated natural pozzolanic material as well as preparation method and application of nano-seed crystal activated natural pozzolanic material
By incorporating quicklime, triethanolamine, and nanocrystal seeds through a graded grinding process, natural volcanic ash material activated by nanocrystal seeds was prepared, solving the problem of fly ash resource scarcity in Tibet and achieving efficient activation and improved concrete performance to meet the needs of hydropower projects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGJIANG RIVER SCI RES INST CHANGJIANG WATER RESOURCES COMMISSION
- Filing Date
- 2026-02-06
- Publication Date
- 2026-05-01
AI Technical Summary
The Tibetan Plateau region suffers from a scarcity of fly ash resources, and the activation technology for natural volcanic ash materials is energy-intensive and lacks sufficient activity, making it difficult to apply on a large scale in hydropower projects.
A natural pozzolanic material activated by nanocrystal seeds was prepared by incorporating quicklime, triethanolamine, and nanocrystal seeds through a graded grinding method. This improved the material's activity and formed a ternary composite cementitious system consisting of 50% medium-heat cement/low-heat cement, 20%~30% activated natural pozzolanic material, and 20%~30% fly ash.
It significantly improves the 28-day activity index of natural volcanic ash materials, reduces production energy consumption, meets the concrete performance requirements of hydropower projects in plateau areas, and has economic and environmental benefits.
Smart Images
Figure CN121948852A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of auxiliary cementitious materials, and more particularly to a natural volcanic ash material activated by nanocrystal seeds, its preparation method, and its application. Background Technology
[0002] The Tibetan Plateau region faces a shortage of fly ash resources. The fly ash needed for construction projects must be transported over long distances (over 1500 kilometers) via the Qinghai-Tibet Railway from Ningxia and Qinghai, incurring high costs and being significantly affected by fluctuations in transport capacity. Although natural volcanic ash materials (such as tuff powder) are widely distributed in the region, their 28-day strength activity index is low (less than 60%), making it difficult to directly replace high-quality fly ash in large-scale concrete applications such as hydropower projects.
[0003] SCMs, including fly ash, metallurgical slag, natural volcanic ash, biomass ash, post-consumer glass, and limestone, can improve concrete performance by partially replacing Portland cement. These improvements include increased paste density and durability, reduced heat of hydration and chloride ion permeability, improved volume stability, and enhanced resistance to chemical attack, while also offering cost and environmental benefits. However, existing activation technologies for natural volcanic ash materials suffer from the following fundamental drawbacks.
[0004] Calcination and grinding activation: This process is extremely energy-intensive. Due to the hardness of volcanic glass, the grinding process is difficult, and conventional equipment such as vertical roller mills and horizontal roller presses cannot handle it stably, making continuous production impossible.
[0005] Inter-grinding process activation: When natural volcanic ash and Portland cement clinker are co-graded and ground to prepare blended cement, the reactivity is significantly insufficient. To achieve the basic reactivity requirements, the mixture must be graded and ground to a fineness far exceeding that of ordinary Portland cement (OPC), leading to a sharp increase in energy consumption. More importantly, even with this energy-intensive inter-grinding method, the performance of the resulting product is still significantly inferior to that of a non-inter-grinding product where each component is processed separately and then blended.
[0006] In summary, current technologies still lack a method for activating natural volcanic ash materials that is both energy-efficient and low-cost, and suitable for large-scale application. This significantly restricts the effective utilization of local resources in remote areas such as Tibet. Therefore, developing innovative activation technologies has become crucial to solving this long-standing technical challenge. By activating natural volcanic ash materials to prepare cementitious materials, fly ash can be partially replaced, constructing a ternary composite cementitious system of cement, fly ash, and activated volcanic ash materials. This system possesses excellent mechanical and durability properties, which can not only alleviate the shortage of high-quality fly ash resources in western regions but also ensure the performance of engineering concrete and construction progress, thereby promoting the continuous advancement of hydraulic concrete materials and technologies. Summary of the Invention
[0007] To address the problems existing in the prior art, this invention provides a natural volcanic ash material activated by nanocrystal seeds, its preparation method, and its application. First, the natural volcanic ash material is graded and ground using a graded grinding method. Then, slaked lime, triethanolamine, and nanocrystal seeds are incorporated to obtain an activated natural volcanic ash material, significantly improving its activity. The activated natural volcanic ash material can be mixed with cement and fly ash as a cementitious material, improving the mechanical properties of the cementitious material.
[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a natural volcanic ash material activated by nanocrystal seeds, comprising the following components: natural volcanic ash material and auxiliary materials; the auxiliary materials include, by weight of natural volcanic ash material, 3.0%~5.0% quicklime, 0.04%~0.09% triethanolamine and 0.4%~0.6% nanocrystal seeds.
[0009] Furthermore, the nanocrystal seed is nano-silica or nano-calcium carbonate.
[0010] Furthermore, the natural volcanic ash material activated by the nanocrystal seeds comprises the following components: natural volcanic ash material and, by weight of the natural volcanic ash material, 4.0% quicklime, 0.06% triethanolamine and 0.5% nanocrystal seeds.
[0011] The present invention also provides a method for preparing natural volcanic ash material activated by nanocrystal seeds, comprising the following steps: using a graded grinding process, firstly, the natural volcanic ash material is mixed with triethanolamine grinding aid and subjected to primary graded grinding until its fineness is 25.0%~30.0% (45μm square hole sieve residue), then quicklime and triethanolamine are added and subjected to secondary graded grinding to obtain an intermediate product (fineness of 15.0%~20.0% 45μm square hole sieve residue), and finally, the remaining triethanolamine and nanocrystal seeds are added and mixed evenly with the intermediate product to obtain activated natural volcanic ash material.
[0012] Furthermore, the fineness of the pozzolanic material obtained by the graded grinding is 15.0%~20.0% (45μm square hole sieve residue).
[0013] Furthermore, the fineness of the quicklime and nanocrystal seeds is 5.0%~10.0% (residue on a 45μm square-hole sieve).
[0014] Furthermore, the amount of triethanolamine grinding aid added is 0.02% to 0.05% of the mass of the natural volcanic ash material, and the amount of the remaining triethanolamine added is 0.02% to 0.04% of the mass of the natural volcanic ash material. The triethanolamine is industrial grade with an effective content >98%.
[0015] The present invention also provides an application of the natural volcanic ash material activated by the aforementioned nanocrystal seeds in the preparation of cementitious materials.
[0016] Furthermore, the application method is a blending method.
[0017] Furthermore, the cementitious material comprises, by mass percentage: 50% medium-heat cement / low-heat cement, 20%~30% activated natural pozzolanic material and 20%~30% fly ash.
[0018] Compared with the prior art, the present invention has at least the following advantages and technical effects: This invention uses 50% medium-heat cement / low-heat cement as the basic cementitious component, and incorporates 20%~30% activated natural pozzolanic material and 20%~30% fly ash to construct a ternary system. The introduction of nanocrystals provides abundant nucleation sites for the pozzolanic reaction, effectively stimulating the potential activity of tuff powder. This system fully leverages the respective advantages of fly ash and tuff admixtures, forming a spatiotemporal complementary effect, increasing the 28-day activity index of natural pozzolanic material from the traditional less than 60% to a higher level, breaking through the technical bottleneck of its large-scale application in hydropower projects in the western plateau region.
[0019] Through the activation effect of nanocrystals on pozzolanic materials, the hydration reaction process among the components in the ternary composite system is optimized and coordinated, resulting in balanced strength development in both early and later stages. The "ball-bearing effect" of fly ash and the micro-aggregate filling effect of tuff powder in natural pozzolanic materials form a functional synergy in the ternary system, significantly improving the density of the paste. This makes the compressive and flexural strength of the composite cementitious material superior to that of a single admixture system. The ternary system can effectively leverage the spatiotemporal complementarity and functional synergy of cement and admixtures, meeting the stringent requirements for concrete mechanical properties in hydropower projects in high-altitude and cold regions.
[0020] This invention effectively solves the problems of scarce fly ash resources and high transportation costs in Tibet and other regions, realizing the high-value utilization of local natural volcanic ash materials (tuff powder). Through nano-crystal seed activation and co-doping technology, the traditional high-energy-consuming calcination / grinding activation method is avoided, significantly reducing production energy consumption and carbon emissions, achieving both economic and environmental benefits, and providing a sustainable technical path for the development of green building materials in plateau regions. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 Preparation process of natural volcanic ash materials activated by nanocrystal seeds; Figure 2 XRD patterns of natural volcanic ash materials with different fineness; Figure 3 SEM image of natural volcanic ash material with a fineness of 29.8%; Figure 4 SEM image of natural volcanic ash material with a fineness of 17.6%; Figure 5 The results of laser particle size analysis of natural volcanic ash materials after graded grinding at different finenesses. Detailed Implementation
[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0026] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0027] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0028] This invention provides a natural volcanic ash material activated by nanocrystal seeds, comprising the following components: natural volcanic ash material and, by mass percentage of natural volcanic ash material, 3%~5% quicklime, 0.04%~0.09% triethanolamine and 0.4%~0.6% nanocrystal seeds.
[0029] In some embodiments of the present invention, the nanocrystal seed is nano-silica or nano-calcium carbonate.
[0030] In some embodiments of the present invention, the natural volcanic ash material activated by the nanocrystal seeds comprises the following components: natural volcanic ash material and auxiliary materials, wherein the auxiliary materials comprise: 4% quicklime, 0.06% triethanolamine, 0.5% nanocrystal seeds and 95.44% natural volcanic ash material by mass percentage of the natural volcanic ash material.
[0031] The role of quicklime is to activate the volcanic activity of natural volcanic ash, promote the formation of ettringite (AFt) and CSH gel, and refine the crystal size.
[0032] The role of triethanolamine is to react with Al in cement. 3+ Fe 3+ It forms a water-soluble complex, which destroys the impermeable membrane on the surface of cement clinker, thereby accelerating the hydration of C3A in cement and generating a large amount of hydrated calcium aluminate. The hydration product AFt crystallizes well and is dense.
[0033] The role of seed crystals is twofold. On the one hand, they promote the volcanic ash reaction. Nano-seed crystals (such as nano-SiO2 and nano-CaCO3) have extremely high surface energy and can act as "seeds," preferentially adsorbing and rapidly reacting with calcium hydroxide to generate hydrated calcium silicate (CSH) gel, thus stimulating and accelerating the entire reaction process. On the other hand, specific nano-seed crystals (such as some nano-minerals) may act as "templates," inducing the active components in volcanic ash to grow according to specific crystal orientations, forming a more stable and stronger hydration product network structure.
[0034] This invention also provides a method for preparing natural volcanic ash material activated by nanocrystal seeds, comprising the following steps: using a graded grinding process, firstly, the natural volcanic ash material is mixed with triethanolamine grinding aid and subjected to primary graded grinding until its fineness is 25.0%~30.0% (45μm square hole sieve residue), then quicklime is added and subjected to secondary graded grinding to obtain an intermediate product (fineness of 15.0%~20.0% 45μm square hole sieve residue), and finally, nanocrystal seeds and the remaining triethanolamine are added and mixed evenly with the intermediate product to obtain activated natural volcanic ash material.
[0035] In some embodiments of the present invention, the fineness of the quicklime and nanocrystal seeds is 5%~10% (45μm square hole sieve residue), and the triethanolamine is industrial grade with an effective content >98%.
[0036] In some embodiments of the present invention, the amount of the triethanolamine grinding aid added is 0.02% to 0.05%, and the amount of the remaining triethanolamine added is 0.02% to 0.04%.
[0037] This invention also provides an application of the aforementioned nano-seed-activated natural volcanic ash material in the preparation of cementitious materials.
[0038] In some embodiments of the present invention, the application method is a blending method.
[0039] In some embodiments of the present invention, the cementitious material is composed of, by mass percentage, 50% medium-heat cement / low-heat cement, 20%~30% activated natural pozzolanic material and 20%~30% fly ash.
[0040] The chemical composition analysis results of the natural volcanic ash material used in the embodiments of the present invention are shown in Table 1.
[0041] Table 1. Main Chemical Composition (mass percentage) of Natural Volcanic Ash Material (Tuff) R₂O = Na₂O + 0.658K₂O Figure 1 The XRD patterns of natural volcanic ash materials with different fineness show that the diffraction peak intensities of each mineral phase gradually decrease as the fineness of the natural volcanic ash material decreases. This indicates that the degree of lattice distortion in the material is continuously increasing, the surface energy is continuously increasing, and some minerals begin to transform from crystalline to amorphous states, resulting in a gradual increase in their activity.
[0042] Figures 2-3 The images show SEM images of natural volcanic ash materials at different magnifications. As can be seen from the images, natural volcanic ash contains a large number of glassy fragments (glass chips) of varying sizes. Typical characteristics include curved, angular surfaces, flake-like or needle-like morphologies, and the formation of micron-scale pits or honeycomb structures on the surface. Furthermore, as the fineness of the natural volcanic ash material decreases, the mineral particles also show a gradual decreasing trend at the microscale.
[0043] Natural volcanic ash materials were graded and milled to obtain volcanic ash materials of different fineness. The strength and activity indices of the natural volcanic ash materials of different fineness after grading and milling are shown in Table 2. Table 2 Strength Activity Index of Natural Volcanic Ash (Tuff) (After Primary Grinding Only) Note: Fineness in Table 2 refers to the percentage of the mass remaining on a sieve with a mesh size of 45μm after grading and grinding.
[0044] As can be seen from Table 2, the strength activity index of the volcanic ash material increases with the increase of grinding time. Figure 4 The laser particle size distribution of natural volcanic ash material after graded grinding at different finenesses shows that the median particle size of natural volcanic ash material gradually decreases as the fineness decreases.
[0045] In the following examples, a natural volcanic ash material with a fineness of 17.6% was selected as an example for subsequent experiments.
[0046] Example 1 A natural volcanic ash material activated by nanocrystal seeds comprises the following raw material components: natural volcanic ash material and, by weight of natural volcanic ash material, 4% quicklime, 0.06% triethanolamine, and 0.4% nano-silica, wherein 0.03% of the triethanolamine is used as a grinding aid and 0.03% is used as a reinforcing agent incorporated after the natural volcanic ash material is graded and ground.
[0047] The preparation method employs a graded grinding process: First, natural volcanic ash material is mixed with triethanolamine grinding aid and subjected to primary grinding to achieve a fineness of 27.5% (45μm square-hole sieve residue); then, quicklime is added for secondary graded grinding to obtain an intermediate product; finally, nanocrystalline seeds and the remaining triethanolamine are added and mixed evenly with the intermediate product to obtain activated natural volcanic ash material with a fineness of 17.6% (45μm square-hole sieve residue).
[0048] Example 2 A natural volcanic ash material activated by nanocrystal seeds differs from Example 1 only in that the percentage of nano-silica is 0.5%. The preparation method is the same as in Example 1.
[0049] Example 3 A natural volcanic ash material activated by nanocrystal seeds differs from Example 2 only in that the percentage of nano-silica is 0.6%. The preparation method is the same as in Example 1.
[0050] Example 4 A natural volcanic ash material activated by nanocrystal seeds differs from Example 1 only in that nano-silica is replaced by nano-calcium carbonate. The preparation method is the same as in Example 1.
[0051] Example 5 A natural volcanic ash material activated by nanocrystal seeds differs from Example 2 only in that nano-silica is replaced by nano-calcium carbonate. The preparation method is the same as in Example 1.
[0052] Example 6 A natural volcanic ash material activated by nanocrystal seeds differs from Example 3 only in that nano-silica is replaced by nano-calcium carbonate. The preparation method is the same as in Example 1.
[0053] The strength activity index of the natural volcanic ash materials activated by nanocrystal seeds prepared in Examples 1-6 is shown in Table 3: Table 3 Strength Activity Index of Activated Natural Volcanic Ash Materials (Tuff) As shown in Table 3, the strength activity index of pozzolanic materials is significantly improved by adding quicklime, triethanolamine, and nanocrystals. The optimal addition is achieved with 0.6% nano-silica seeds.
[0054] Comparative Example 1 The only difference from Example 1 is that it does not contain triethanolamine and nanocrystal seeds, but only 3% quicklime is added.
[0055] Comparative Example 2 The only difference from Example 1 is that it does not contain triethanolamine and nanocrystal seeds, but only 4% quicklime is added.
[0056] Comparative Example 3 The only difference from Example 1 is that it does not contain triethanolamine and nanocrystal seeds, but only 5% quicklime.
[0057] The strength activity indices of the activated natural volcanic ash materials prepared in Comparative Examples 1-3 are shown in Table 4: Table 4 Strength Activity Index of Activated Natural Volcanic Ash Materials (Tuff) Compared with Table 2, Table 4 shows that the strength activity index of activated pozzolanic with only hydrated lime added is higher than that of only graded grinding, and it increases with the increase of hydrated lime content, but the degree of increase is not significant.
[0058] Comparative Example 4 The only difference from Example 1 is that no nano-seeds are added, the amount of quicklime is 4%, and the amount of triethanolamine is 0.02%.
[0059] Comparative Example 5 The only difference from Example 1 is that no nano-seeds are added, the amount of quicklime is 4%, and the amount of triethanolamine is 0.03%.
[0060] Comparative Example 6 The only difference from Example 1 is that no nano-seeds are added, the amount of quicklime is 4%, and the amount of triethanolamine is 0.04%.
[0061] The strength activity indices of the activated natural volcanic ash materials prepared in Comparative Examples 4-6 are shown in Table 5: Table 5 Strength Activity Index of Activated Natural Volcanic Ash Materials (Tuff) As shown in Tables 4 and 5, the addition of triethanolamine further improved the volcanic ash strength activity index, and the index increased with the increase of triethanolamine content.
[0062] Application examples The pozzolanic material activated by nanocrystal seeds prepared in Example 2 was used to prepare concrete, and the preparation ratios are shown in Table 6: Table 6 Mix Proportions for Roller-Compacted Concrete The compressive strength of the prepared concrete was tested, and the test results are shown in Table 7. Table 7 Mechanical and Durability Properties of Concrete with Combined Cement, Pozzolanic (Tuff), and Fly Ash As shown in Table 7, the combination of fly ash and activated natural pozzolanic material can leverage the respective effects of both fly ash and pozzolanic material, achieving a complementary effect in time and space and functional synergy. The mechanical properties of the system combining activated natural pozzolanic material and fly ash fall between those of single-admixture fly ash and single-admixture activated natural pozzolanic material. Specifically, the 180-day compressive strength of the combined system reaches 77.0% of that of single-admixture fly ash. Furthermore, this combined system meets the corresponding design requirements in terms of concrete mechanical properties, frost resistance, and impermeability. Therefore, the method of this invention for activating natural pozzolanic material can partially replace fly ash in concrete preparation, thus enabling the effective utilization of local resources in remote areas such as Tibet.
[0063] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A natural volcanic ash material activated by nanocrystal seeds, characterized in that, It includes the following raw material components: natural volcanic ash material and auxiliary materials; the auxiliary materials include 3.0%~5.0% quicklime, 0.04%~0.09% triethanolamine and 0.4%~0.6% nanocrystals, based on the mass percentage of natural volcanic ash material.
2. The natural volcanic ash material activated by nanocrystal seeds according to claim 1, characterized in that, The nanocrystal seed is nano-silica or nano-calcium carbonate.
3. The natural volcanic ash material activated by nanocrystal seeds according to claim 1, characterized in that, The auxiliary materials, by mass percentage of natural volcanic ash, include 4.0% quicklime, 0.06% triethanolamine, and 0.5% nanocrystals.
4. A method for preparing a natural volcanic ash material activated by nanocrystal seeds according to any one of claims 1 to 3, characterized in that, Includes the following steps: Grinding aids are added to natural volcanic ash material, and primary grinding is carried out. During the grinding process, quicklime and triethanolamine of appropriate mass fractions are added, and secondary grinding is continued to obtain intermediate product. The intermediate product, the remaining triethanolamine, and nanocrystal seeds are mixed evenly to obtain activated natural volcanic ash material.
5. The method for preparing natural volcanic ash material activated by nanocrystal seeds according to claim 4, characterized in that, The fineness of the natural volcanic ash material after primary grinding is 25.0%~30.0% residue on a 45μm square hole sieve, and the fineness of the natural volcanic ash material after secondary grinding is 15.0%~20.0% residue on a 45μm square hole sieve.
6. The method for preparing natural volcanic ash material activated by nanocrystal seeds according to claim 4, characterized in that, The fineness of the quicklime and nanocrystal seeds is 5.0%~10.0% residue on a 45μm square hole sieve, and the triethanolamine is industrial grade with an effective content >98%.
7. The method for preparing natural volcanic ash material activated by nanocrystal seeds according to claim 4, characterized in that, The grinding aid is a portion of triethanolamine, with an addition amount of 0.02% to 0.05% of the mass of the natural volcanic ash material, and the remaining triethanolamine is added at a rate of 0.02% to 0.04% of the mass of the natural volcanic ash material.
8. The application of the natural volcanic ash material activated by nanocrystal seeds as described in claim 1 in the preparation of cementitious materials.
9. The application in the preparation of cementitious materials according to claim 8, characterized in that, The application method is a blending method.
10. The application in the preparation of cementitious materials according to claim 8, characterized in that, The cementitious material comprises, by mass percentage: 50% medium-heat cement / low-heat cement, 20%~30% activated natural pozzolanic material, and 20%~30% fly ash.