A slow-heat-heat-storage-heat-conduction synergistic temperature control anti-cracking cement-based material and a preparation method thereof

Abstract

The application provides a slow heat-storage-heat conduction synergic temperature control anti-cracking cement-based material and a preparation method thereof, and relates to the technical field of cement-based building materials. The material constructs a slow heat-storage-heat conduction synergic temperature control system by introducing a slow heat polymer, phase change capsules with different phase change temperature thresholds and liquid alloy heat conduction materials into a cement base. The slow heat polymer is used for delaying the early hydration reaction of cement and reducing the initial heat release rate. The phase change capsules with different phase change temperature thresholds absorb hydration heat in stages during the hydration process, realizing the step-by-step regulation of hydration temperature rise. The liquid alloy heat conduction material has the characteristics of phase change heat storage and high heat conduction, and can form an efficient heat transfer channel in the cement base, promote the uniform diffusion of heat and reduce the local temperature gradient. The synergistic effect of the three makes the hydration heat release peak present a hump distribution, effectively inhibits the temperature rise peak and temperature stress in the hydration process of cement, and significantly improves the anti-cracking performance of the cement-based material.

Description

Technical Field

[0001] This invention relates to the field of cement-based building materials technology, and in particular to a slow-heating-heat storage-heat conduction synergistic temperature control and crack-resistant cement-based material and its preparation method, which is especially suitable for large-volume concrete projects with concentrated hydration heat release and significant temperature gradient. Background Technology

[0002] In modern infrastructure construction, large-volume concrete is widely used in hydraulic structures, transportation infrastructure, underground structures, and energy engineering. Due to the large size of the components and limited heat dissipation, the large amount of heat released during cement hydration tends to accumulate internally, causing the internal temperature of the concrete to rise rapidly, while the surface cools faster due to external environmental influences, thus creating a significant internal and external temperature difference and temperature gradient. This temperature difference induces significant thermal stress within the material. When the thermal stress exceeds the early tensile strength of the concrete, thermal cracks are easily generated, thereby weakening the overall integrity and durability of the structure.

[0003] Existing engineering practices typically employ low-heat cement, external cooling, and layered / segmented pouring to control temperature cracks. However, these methods suffer from drawbacks such as complex construction, high costs, or limited control effectiveness, making it difficult to achieve continuous and effective temperature regulation at the material level. Therefore, developing novel cement-based materials with endogenous temperature control capabilities has become an important direction for mitigating temperature cracking in large-volume concrete.

[0004] Phase change temperature control materials are considered an effective way to regulate the internal temperature of concrete because they can absorb or release a large amount of latent heat during phase change. However, existing phase change cement-based materials mostly rely on phase change components in a single phase change temperature range, and their regulatory effect is often concentrated within a limited temperature range, making it difficult to match the continuously changing exothermic characteristics during cement hydration. At the same time, common organic phase change materials have low thermal conductivity and limited interfacial bonding with the cement matrix, which can easily lead to heat retention in local areas, thus exacerbating the temperature gradient. In addition, relying solely on phase change heat absorption is insufficient to effectively regulate the heat release rate in the early stages of hydration, and the peak temperature rise remains too high.

[0005] Furthermore, existing temperature-controlled cement-based materials often suffer from deterioration in mechanical properties while improving the temperature field. On the one hand, some organic phase change materials have low bulk strength, easily forming weak mechanical zones after being incorporated into cement-based systems. On the other hand, insufficient interfacial bonding between phase change components and the cement matrix leads to a loose structure in the interfacial transition zone, which is detrimental to strength development. Retarding or heat-retarding admixtures, while delaying hydration reactions, may also weaken early strength formation, further limiting the application of temperature-controlled materials in load-bearing or high-safety-level engineering projects. Therefore, how to maintain or improve the mechanical properties of cement-based materials while achieving effective temperature control remains a pressing technological challenge.

[0006] On the other hand, while some retarding or heat-retarding additives can slow down the hydration reaction, their control over the heat of hydration is mainly reflected on a time scale, lacking the ability to regulate the spatial distribution of heat. Meanwhile, while high thermal conductivity fillers can improve heat transfer conditions, they may accelerate early heat release, leading to a further increase in the peak temperature. Therefore, a single temperature control method is insufficient to comprehensively address the needs for controlling the hydration heat release rate, peak temperature, and temperature gradient.

[0007] Based on the above problems, there is an urgent need to propose a cement-based material system that can synergistically regulate the heat release rate, store and redistribute heat, and improve the thermal conductivity of the material throughout the hydration process, thereby achieving effective reduction of temperature stress and systematic reduction of crack risk. Summary of the Invention

[0008] This invention provides a temperature-controlled and crack-resistant cement-based material with synergistic effects of slow heating, heat storage, and heat conduction, and its preparation method. By introducing slow heating polymers, phase change capsules with different phase change temperature thresholds, and liquid alloy thermally conductive materials into the cement matrix, a multi-mechanism coupled temperature control system is constructed. While effectively reducing the peak value of hydration exothermic heat and temperature gradient, the good mechanical properties and structural stability of the cement-based material are maintained, thereby achieving a synergistic improvement in temperature control, crack resistance, and mechanical properties.

[0009] This invention provides a heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material, comprising, by weight: Cement matrix: composed of 85-100 parts cement and 35-50 parts water; Retarded polymer: The dosage is 0.1–0.6% or 0.1–0.6 parts of the cement content; Phase change capsules with different phase change temperature thresholds: the dosage is 2.5–15% or 2.5–15 parts of cement content; Liquid alloy thermal conductive material: the dosage is 1–9% or 1–9 parts of the cement content; The heat-retarding polymer is a modified sugar polymer with a multi-hydroxyl and multi-carboxyl structure; the phase change capsule is a silica-coated nano- and micro-phase change capsule with a phase change temperature range of 30–60°C; and the liquid alloy thermal conductive material is a liquid metal or alloy coated with a polymer film with a melting point of 60–80°C.

[0010] In one possible design, the heat-retarding polymer is one of chitosan, sodium alginate, chitin, or starch, obtained through acylation modification.

[0011] In one possible design, the core material of the phase change capsule is one or a combination of fatty acids, paraffin, n-octadecane, or polyethylene glycol.

[0012] In one possible design, the nanophase change capsules have a particle size of 300–600 nm, the microphase change capsules have a particle size of 20–80 μm, and the phase change enthalpy is 180–200 J / g.

[0013] In one possible design, the coating polymer of the liquid alloy thermal conductive material is one of polyvinyl alcohol, ethylene-vinyl acetate copolymer, hydroxypropyl methylcellulose, or ethyl cellulose.

[0014] In one possible design, the particle size of the liquid alloy thermally conductive material is 30–70 μm, and the thermal conductivity is 70–85 W / (m·K).

[0015] In one possible design, the heat-retarding polymer, phase change capsule, and liquid alloy thermally conductive material work synergistically to give the cement hydration heat release curve a camel-hump distribution, thereby achieving stepwise regulation of the hydration temperature rise and suppression of temperature stress.

[0016] In another parallel technical solution, the synergistic temperature control and crack resistance cement-based material for slowing down heat, storing heat, and conducting heat includes a cement matrix, a slowing polymer, phase change capsules with different phase change temperature thresholds, and a liquid alloy thermal conductive material; wherein, cement accounts for 87.5–100 parts, water accounts for 40–50 parts; the slowing polymer content is 0.2–0.4 wt.% or 0.2–0.4 parts of cement mass; nano and micro phase change capsules with different phase change temperature thresholds replace 5–10 wt.% or 5–10 parts of cement; and the liquid alloy thermal conductive material content is 2–8 wt.% or 2–8 parts of cement mass.

[0017] The thermally slowing, thermal storage, and thermally conductive synergistic temperature-controlled and crack-resistant cementitious material of this invention achieves systematic regulation of the temperature evolution throughout the entire cement hydration process through the coupling effect of three mechanisms: thermal slowing regulation, phase change thermal storage, and efficient thermal conductivity. The thermally slowing polymer, through its polyhydroxy and polycarboxyl group structure, interacts with the cement hydration system, slowing down the hydration reaction rate, dispersing the early heat release process, effectively weakening the initial heat release intensity, and creating favorable conditions for subsequent thermal storage and thermal conductivity regulation. Silica-coated nano- and micron-sized phase change capsules with different phase change temperature thresholds undergo phase changes in different temperature ranges during hydration. By absorbing and releasing latent heat, they continuously regulate the hydration heat release, preventing a concentrated release of heat in a short period, thereby reducing the peak hydration temperature rise and smoothing the temperature change process. The liquid alloy thermally conductive material possesses both high thermal conductivity and phase change thermal storage characteristics. Its polymer coating structure facilitates the formation of a stable interface with the cement matrix, absorbing some heat while promoting rapid heat transfer and uniform diffusion within the matrix, reducing local heat accumulation and temperature gradients. The aforementioned slowing, heat storage, and heat conduction effects work together to maintain a relatively smooth temperature evolution characteristic of cement-based materials during both the hydration heating and cooling stages. This achieves effective temperature control and crack resistance without compromising the continuous structure and mechanical stability of the material, thus balancing temperature control performance and load-bearing capacity.

[0018] Secondly, a method for preparing a temperature-controlled and crack-resistant cementitious material with a synergistic effect of slowing down heat, storing heat, and conducting heat, as described in the first aspect or its various possible designs, includes the following steps: (1) Take 1 / 2 of the total mixing water and premix it with phase change capsules with different phase change temperature thresholds, and then treat it with ultrasound to obtain a uniformly dispersed A phase slurry; (2) Mix cement, slow-heating polymer and polymer-coated liquid alloy heat-conducting material in a dry state and stir at low speed until uniform; (3) Add the remaining 1 / 2 of the mixing water to the mixture in step (2), and obtain a uniform cement paste after low-speed and high-speed mixing; (4) Add the A phase slurry from step (1) to the cement slurry from step (3), continue stirring, and then discharge the material; (5) After the slurry is discharged, it is shaped, vibrated and cured according to standard to obtain the slow-heating-heat storage-heat conduction synergistic temperature control and crack-resistant cement-based material.

[0019] In one possible design, the ultrasonic treatment time in step (1) is 3-8 min; the low-speed stirring time in step (2) is 0.5-2 min; the low-speed stirring time in step (3) is 1-2 min, and the high-speed stirring time is 20-50 s; the stirring time in step (4) is 20-50 s.

[0020] Thirdly, the present invention provides an application of a heat-slowing, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material as described in the first aspect or its various possible designs in large-volume concrete engineering projects. The large-volume concrete temperature-controlled and crack-resistant engineering projects include concrete projects in hydraulic dams, bridge foundations, underground structures, nuclear power plant foundations, and large industrial foundations where temperature cracks are easily generated due to the accumulation of hydration heat.

[0021] This invention provides a heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled crack-resistant cement-based material and its preparation method, which has at least the following beneficial effects: This invention provides a synergistic temperature-controlled and crack-resistant cementitious material and its preparation method that utilizes a slow-heating, heat-storage, and heat-conducting process. By synergistically introducing a slow-heating polymer, phase change capsules with different phase change temperature thresholds, and a liquid alloy thermally conductive material into the cementitious system, it achieves systematic regulation of heat generation, accumulation, and transfer during the hydration reaction, resulting in a more uniform and controllable internal temperature evolution of the concrete. The slow-heating polymer smooths the hydration heat release process, while the phase change capsules with different phase change temperature thresholds continuously absorb and release heat during hydration, effectively reducing the peak hydration temperature rise and lowering the rate of temperature change. The liquid alloy thermally conductive material promotes uniform heat diffusion within the material, reducing localized heat accumulation and temperature gradients, thereby significantly reducing the risk of temperature stress concentration and temperature crack formation during hydration. This synergistic regulation effectively slows down the rate of temperature rise within the cementitious material, lowers the maximum temperature level, and weakens the thermal stress concentration caused by temperature gradients. At the same time, the interfaces between each functional component and the cement matrix are stable, the internal structure of the material is continuous and complete, and no obvious weak mechanical areas are formed due to the introduction of temperature-controlling components. This allows the resulting cement-based material to maintain good overall stability and load-bearing capacity while achieving temperature-controlled crack resistance. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0023] Figure 1 This is a schematic diagram comparing the hydration exothermic curve of cement prepared by the method of the present invention with the hydration exothermic curve obtained by the comparative example.

[0024] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0025] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0026] In the technical solution of this invention, the collection, storage, use, processing, transmission, provision and disclosure of relevant data and information comply with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0027] The technical solution of the present invention and how the technical solution of the present invention solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0028] Example 1 This invention provides a heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material, mainly composed of the following components: 95 parts cement, 47.5 parts water; Heat-retarding polymer: 0.2 parts of modified starch with a polyhydroxy and polycarboxylic acid structure; Phase change capsules with different phase change temperature thresholds: 5 parts of silica-coated n-octadecane nano-phase change capsules; Liquid alloy thermal conductive material: Bi-In-Sn liquid alloy coated with polyvinyl alcohol, 3 parts.

[0029] The above materials are prepared according to the following steps (1)–(5).

[0030] (1) Mix half of the total water with silica-coated nano and micro phase change capsules, and sonicate for 5 min to form a uniformly dispersed A-phase slurry; (2) Mix cement, slow-heating polymer and liquid alloy thermal conductive material in a dry state and stir at low speed for 1 min; (3) Add the remaining half of the mixing water, stir at low speed for 1.5 min, and stir at high speed for 30 s to form a uniform slurry; (4) Add the A-phase slurry obtained in step (1), continue stirring for 30 seconds, and then discharge the material; (5) The target material is obtained by molding, compacting and curing according to standard conditions.

[0031] Example 2 This invention provides a heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material, mainly composed of the following components: 95 parts cement, 47.5 parts water; Heat-retarding polymer: 0.2 parts of modified chitosan with a multi-hydroxyl and multi-carboxyl structure; Phase change capsules with different phase change temperature thresholds: 5 parts of silica-coated paraffin nano-phase change capsules; Liquid alloy thermal conductive material: 6 parts of polyvinyl alcohol-coated Bi-In-Sn liquid alloy.

[0032] The above materials were prepared according to steps (1)–(5) as described in Example 1.

[0033] Example 3 This invention provides a heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material, mainly composed of the following components: 95 parts cement, 47.5 parts water; Heat-retarding polymer: 0.2 parts of modified sodium alginate with a polyhydroxy and polycarboxylic acid structure; Phase change capsules with different phase change temperature thresholds: 5 parts of silica-coated paraffin nano-phase change capsules; Liquid alloy thermal conductive material: 6 parts of polyvinyl alcohol-coated Bi-In-Sn liquid alloy.

[0034] The above materials were prepared according to steps (1)–(5) as described in Example 1.

[0035] Example 4 This invention provides a heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material, mainly composed of the following components: 95 parts cement, 47.5 parts water; Heat-retarding polymer: 0.2 parts of modified chitosan with a multi-hydroxyl and multi-carboxyl structure; Phase change capsules with different phase change temperature thresholds: Micron-sized phase change capsules of silica-coated paraffin, 5 parts; Liquid alloy thermal conductive material: 8 parts of polyvinyl alcohol-coated Bi-In-Sn liquid alloy.

[0036] The above materials were prepared according to steps (1)–(5) as described in Example 1.

[0037] Example 5 This invention provides a heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material, mainly composed of the following components: 90 parts cement, 45 parts water; Heat-retarding polymer: 0.4 parts of modified chitosan with a multi-hydroxyl and multi-carboxyl structure; Phase change capsules with different phase change temperature thresholds: 5 parts of nano-phase change capsules with silica-coated n-octadecane and 5 parts of micron-sized phase change capsules with silica-coated paraffin. Liquid alloy thermal conductive material: 8 parts of polyvinyl alcohol-coated Bi-In-Sn liquid alloy.

[0038] The above materials were prepared according to steps (1)–(5) as described in Example 1.

[0039] Comparative Example 1 Comparative Example 1 is a plain cement paste without any modified materials, consisting of 100 parts cement and 50 parts water, prepared according to the following steps: (1) Mix cement and mixing water at low speed for 1.5 min and at high speed for 30 s to form a uniform slurry; (2) The target material is obtained by molding, compacting and curing according to standard conditions.

[0040] It should be noted that the parts in the above embodiments and comparative examples are all by weight.

[0041] Performance testing: Experiments were conducted on Examples 1-5 and the comparative examples above, mainly measuring the 72-hour hydration exothermic curve, 3-day and 28-day compressive strength, and thermal conductivity. Table 1 below lists the test results of Examples 1-5 and the comparative examples above.

[0042] Table 1 Performance Test Results

[0043] As shown in Table 1, the experimental results indicate that, compared with the comparative examples, the cement-based materials described in Examples 1–5 all exhibited varying degrees of reduction in the peak hydration heat release rate during the early stages of hydration. This demonstrates that the introduced synergistic system of slowing heat release, heat storage, and heat conduction can effectively regulate the cement hydration heat release process. With the increasing synergistic effect of the functional components, the decrease in the peak hydration heat release rate gradually increases, and the hydration heat release process shifts from a single concentrated peak to a dispersed, multi-stage characteristic. In particular, the hydration heat release curve of Example 5 exhibits a distinct "hump" distribution, with the hydration heat release peak effectively lengthened and dispersed. This helps reduce the concentrated release of heat in a short period, thereby slowing down the internal temperature rise rate of the cement-based material and mitigating the risk of temperature gradient and thermal stress concentration.

[0044] Regarding mechanical and thermal properties, Examples 1–5 significantly reduced the peak hydration heat release rate while maintaining relatively stable compressive strength and thermal conductivity. Compared to the comparative examples, the 3-day and 28-day compressive strengths of each example did not show significant deterioration, indicating that the introduction of the temperature-controlling component did not damage the load-bearing structure of the cement-based material. Simultaneously, the thermal conductivity remained within a similar range, indicating that the internal heat transfer capacity of the material was not adversely affected. In particular, Example 5 achieved the maximum reduction in the peak hydration heat release rate while maintaining reasonable 28-day compressive strength and thermal conductivity, demonstrating a good synergistic relationship between heat retarding, heat storage, and thermal conductivity regulation. These results indicate that the cement-based material of this invention can effectively control temperature while maintaining both mechanical and thermal conductivity properties, making it suitable for engineering applications sensitive to temperature cracking and requiring structural stability.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A type of cement-based material with synergistic temperature control and crack resistance through heat slowing, heat storage, and heat conduction, characterized in that: By weight, it includes: Cement matrix: composed of 85-100 parts cement and 35-50 parts water; Retarded polymer: The dosage is 0.1–0.6% or 0.1–0.6 parts of the cement content; Phase change capsules with different phase change temperature thresholds: the dosage is 2.5–15% or 2.5–15 parts of cement content; Liquid alloy thermal conductive material: the dosage is 1–9% or 1–9 parts of the cement content; The heat-retarding polymer is a modified sugar polymer with a multi-hydroxyl and multi-carboxyl structure; the phase change capsule is a silica-coated nano- and micro-phase change capsule with a phase change temperature range of 30–60°C; and the liquid alloy thermal conductive material is a liquid metal or alloy coated with a polymer film with a melting point of 60–80°C.

2. The heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cementitious material according to claim 1, characterized in that, The heat-retarding polymer is one of chitosan, sodium alginate, chitin, or starch, obtained through acylation modification.

3. The heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cementitious material according to claim 1, characterized in that, The core material of the phase change capsule is one or a combination of fatty acids, paraffin, n-octadecane, or polyethylene glycol.

4. The heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material according to claim 1 or 3, characterized in that, The nano-phase change capsules have a particle size of 300–600 nm, the micro-phase change capsules have a particle size of 20–80 μm, and the phase change enthalpy is 180–200 J / g.

5. The heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material according to claim 1, characterized in that, The coating polymer of the liquid alloy thermal conductive material is one of polyvinyl alcohol, ethylene-vinyl acetate copolymer, hydroxypropyl methylcellulose, or ethyl cellulose.

6. The heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cement-based material according to claim 1 or 5, characterized in that, The liquid alloy thermally conductive material has a particle size of 30–70 μm and a thermal conductivity of 70–85 W / (m·K).

7. The heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cementitious material according to claim 1, characterized in that, The synergistic effect of the slow-heating polymer, phase change capsule, and liquid alloy thermally conductive material results in a camel-hump distribution in the cement hydration heat release curve, achieving stepwise regulation of hydration temperature rise and suppression of temperature stress.

8. A method for preparing a heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cementitious material as described in any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Take 1 / 2 of the total mixing water and premix it with phase change capsules with different phase change temperature thresholds, and then treat it with ultrasound to obtain a uniformly dispersed A phase slurry; (2) Mix cement, slow-heating polymer and polymer-coated liquid alloy heat-conducting material in a dry state and stir at low speed until uniform; (3) Add the remaining 1 / 2 of the mixing water to the mixture in step (2), and obtain a uniform cement paste after low-speed and high-speed mixing; (4) Add the A phase slurry from step (1) to the cement slurry from step (3), continue stirring, and then discharge the material; (5) After the slurry is discharged, it is shaped, vibrated and cured according to standard to obtain the slow-heating-heat storage-heat conduction synergistic temperature control and crack-resistant cement-based material.

9. The preparation method according to claim 8, characterized in that, The ultrasonic treatment time in step (1) is 3-8 min; the low-speed stirring time in step (2) is 0.5-2 min; the low-speed stirring time in step (3) is 1-2 min, and the high-speed stirring time is 20-50 s; the stirring time in step (4) is 20-50 s.

10. The application of a heat-retarding, heat-storing, and heat-conducting synergistic temperature-controlled and crack-resistant cementitious material as described in any one of claims 1 to 7 in large-volume concrete engineering, characterized in that, The large-volume concrete temperature control and crack resistance project includes concrete projects in hydraulic dams, bridge foundations, underground structures, nuclear power plant foundations, and large industrial foundations that are prone to temperature cracks due to the accumulation of hydration heat.

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