A ductile cement paste and a method for preparing the same

Abstract

The application discloses a kind of resilient cement paste and its preparation method, wherein cement paste includes G-grade cement 1000 parts;Silica flour 40 parts~50 parts;Quartz sand 150 parts~200 parts;Fluid loss additive 25 parts~30 parts;Ultrafine material 40 parts~50 parts;Expanding agent 25 parts~35 parts;Resistance reducing agent 8 parts~12 parts;Retarder 2 parts~3 parts;Early strength agent 15 parts~20 parts;Elastic agent 40 parts~45 parts;Toughening agent 20 parts~25 parts.The cement paste system of the application has good stress-strain resistance, lower Young's modulus and higher impact toughness, and when applied to cementing cement sheath, it can produce corresponding deformation capacity, reduce the occurrence of annular micro-gap;The load transfer coefficient of the Young's modulus of the cement paste system is reduced, which can optimize the stress environment of the casing;It can reduce or prevent the damage of cement sheath caused by shock, fracturing acidification, fluid density change in wellbore, etc. during drilling, and reduce air channeling caused by cement sheath rupture.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building construction materials, in particular to a tough and flexible cement paste and a preparation method thereof. BACKGROUND

[0002] For example, in the process of oilfield exploitation, due to the effect of the perforating polyenergy jet on the cement sheath, local rupture phenomenon occurs, which causes the interlayer channeling of oil, water and gas layers, and seriously affects the quality. Therefore, how to improve the cementing quality has become one of the important issues of oil well exploitation. Cementing operation is one of the most important links in oil and gas well drilling engineering, and its main purpose is to seal the oil, gas and water layers in the wellbore, protect the oil and gas well casing, increase the service life of the oil and gas well and improve the oil and gas production. The purpose of cementing is to obtain reliable annular cement stone and maintain the long-term integrity of the cement sheath to prolong the service life of the oil and gas well.

[0003] Cement stone is the main material for forming the cement sheath, which is a kind of concrete formed by mixing oil well cement with water, and then undergoing a series of chemical and physical changes due to hydration. Cement stone is a kind of anisotropic material, which often includes some un-hydrated cement particles, pores and micro-cracks formed during pouring, etc. Under normal circumstances, cement stone is a brittle material with congenital micro-defects, which has inherent defects such as low tensile strength, tensile strength far lower than compressive strength, poor anti-cracking performance and low impact toughness. Therefore, it is necessary to modify and optimize the existing cement stone, and to improve the toughness and other mechanical properties of the cement stone as much as possible.

[0004] According to the principle of composite materials, adding other fillers to the cement stone can change the dynamic mechanical properties of the cement stone. For example, the prior art has disclosed that adding other materials to the cement paste system can have a toughening effect. After adding fibers, not only the bending and shear strength of the cement stone can be increased, but also the elastic toughness of the cement stone can be increased, which has a toughening and crack stopping effect.

[0005] Document 1: "Experimental Study on Preparation of Ultra-high Ductility Cement-based Composite Material by Polyethylene Fiber" discloses that:

[0006] To further improve the tensile capacity of high performance cementitious composites, a kind of ultra-high ductility cementitious composites (UHDCC) was developed by using short-cut ultra-high molecular weight polyethylene (UHMWPE) fiber as reinforcement and cement mortar as matrix. The basic mechanical properties of UHDCC were investigated by direct tensile, uniaxial compression and three-point bending beam tests. The direct tensile test shows that UHDCC has excellent strain hardening and multiple cracking performance. At the ultimate state, the crack spacing of UHDCC is less than 2 mm, the maximum average crack width is less than 200 μm, the average tensile strength is 7.28 MPa, the average tensile strain at the peak strength reaches 12%, and the maximum tensile strain is more than 13%. The uniaxial compression test shows that the strains of UHDCC at 80% and 60% of the peak compressive strength are about 2.8% and 7.0% respectively, which indicates that UHDCC has strong compression deformation capacity. The bending toughness indices I10, I30, I50 and I60 of UHDCC are 10.1, 33.1, 54.4 and 65.6 respectively, which indicates that UHDCC has excellent bending deformation capacity. In addition, the results of three-point bending notched beam and single crack tests show that the ultra-high ductility of UHDCC is attributed to the excellent crack bridging capacity of polyethylene fiber.

[0007] Document 2: "Experimental Study on Mechanical Properties of Polyvinyl Alcohol Fiber Reinforced Cementitious Composites" discloses that:

[0008] The prism specimens of polyvinyl alcohol fiber reinforced cementitious composites were subjected to flexural test, and half of the specimens after flexural test were subjected to compressive test. The test results show that with the increase of PVA fiber content, the flexural strength of the specimens is greatly improved, the compressive strength is slightly improved first and then decreased, and the fiber plays a good toughening effect in the cement matrix.

[0009] Document 3: "Study on Bending Performance of Hybrid Fiber Reinforced Strain Hardening Cementitious Composites" discloses that:

[0010] The cement matrix material has a water-binder ratio of 0.25, the polyvinyl alcohol fiber in the hybrid system has a volume content of 1.5% and 1.7% respectively, and a certain volume content of basalt fiber is mixed to prepare polyvinyl alcohol-basalt fiber hybrid strain hardening cementitious composites. After 28 days of standard curing, the three-point bending test is performed on the composites. The results show that the PB-SHCC has the characteristics of bending strain hardening, the bending deflection is slightly weakened compared with the single-doped system, but the degree of weakening is not large, and it still has high ductility; when the content of basalt fiber is 0.1% to 0.3% and 0.8% to 1.0%, it is beneficial to the improvement of the initial cracking strength and bending strength of the composite material. In addition, based on ASTM C1018 and JSCE-SF4 standards, the bending toughness index and bending toughness factor are improved and defined, which can effectively evaluate the bending toughness of SHCC material, and the two types of indexes have good consistency.

[0011] From the literature 1 to the literature 3, it can be seen that adding various fibers in the cement matrix can significantly improve the part of the mechanical strength of the cement stone or concrete on the original basis, so that the endurance of the cement stone or concrete is enhanced. However, the fiber includes plant fiber, metal fiber and chemical fiber, and the fiber needs to be considered when adding the fiber material and size.

[0012] Document 4: Influence of Fiber Length on Strength and Toughness of Polyvinyl Alcohol Fiber Reinforced Cementitious Composites discloses that:

[0013] The results show that the fiber length has less effect on the compressive strength, and has greater effect on the flexural strength and toughness; with the increase of the fiber length, the fiber bridging effect energy increases, the composite material is more likely to have multiple crack phenomenon, so as to increase the deformation capacity and toughness. However, due to the influence of the fiber dispersion performance, when the fiber length increases to 18mm, the fiber bridging effect cannot be effectively played, and the flexural strength and toughness are reduced.

[0014] Micro-mechanical analysis results show that the greater the fiber length, the greater the ultimate tensile strength of the fiber reinforced cementitious composite material, and it is more likely to achieve multiple crack phenomenon, thereby improving the deformation capacity. In the stirring process of P-18 mixture, the fiber agglomeration phenomenon occurs obviously, so the flexural strength and deformation capacity of P-18 are both decreased compared with P-12. In order to ensure the full play of the fiber reinforcement and toughening effect, the dispersion of the fiber must be improved.

[0015] Document 5: Influence of PVA Fiber Length on Mechanical Properties of Ultra High Toughness Cementitious Composites discloses that:

[0016] Ultra high toughness cementitious composites (UHTCC) were prepared by using polyvinyl alcohol (PVA) fibers with length of 6mm, 8mm and 12mm, and the influence of different length fibers on the mechanical properties of the material was studied. The results show that: the increase of the fiber length will reduce the dispersion amount of the fiber in the dispersion medium, and will obviously inhibit the fluidity of the mixed slurry; the improvement of the fiber on the mechanical properties of the cement matrix mainly occurs in the early stage, under the same dosage, increasing the fiber length can make the sample obtain higher mechanical properties, but the increase of the fiber length reduces the enhancement effect on the mechanical properties at 28d, and the 28d flexural strength of the sample with 12mm fiber appears to be reversed. The 12mm fiber significantly improves the toughness and ductility of the sample at 3d age, but the improvement effect on the toughness and ductility of the sample at 7d and 28d is equivalent to that of the 6mm and 8mm fibers. Microscopic analysis shows that the fiber makes the microstructure of the hardened cement slurry more dense, the 12mm fiber is more seriously abraded than the 6mm and 8mm fibers in the process of resisting damage, and there is a fiber degradation phenomenon in the sample.

[0017] As can be seen from the literatures 4 and 5, the increase of the length of PVA fiber can enhance the partial mechanical properties of the early concrete, and the increase of the compressive strength is small, and the increase of the flexural strength and toughness is large. The length of PVA fiber will affect the dispersibility, and the longer the length is, the worse the dispersibility is. When the length of the fiber is increased to 18 mm, the long fiber cannot play the effect due to the influence of the dispersibility of the fiber, and the strength and toughness are reduced. The PVA fiber has certain hydrophilicity, and is easy to be intertwined into a ball in the mechanical stirring process, and thus the dispersibility in the concrete is poor.

[0018] Therefore, in order to obtain good strength of the cement stone, after the long PVA fiber is added, the problem of poor dispersibility should be solved, and the dispersibility of the PVA fiber in the concrete is improved as much as possible. SUMMARY

[0019] The purpose of the present application is to provide a tough and flexible cement paste, and the modified PVA fiber is used as a toughening agent. The toughening agent can still have good dispersibility in the case of long size of more than 10 mm, and the flexural capacity and toughness of the cement stone can be greatly improved.

[0020] In order to achieve the above purpose, one embodiment of the present application provides a tough and flexible cement paste, which comprises the following components:

[0021] 1000 parts of G-grade cement, 40-50 parts of silica powder, and 150-200 parts of quartz sand;

[0022] 25-30 parts of a fluid loss reducer, 40-50 parts of a superfine material, and 25-35 parts of an expansive agent;

[0023] 8-12 parts of a resistance reducing agent, 2-3 parts of a retarder, and 15-20 parts of an early strength agent;

[0024] 40-45 parts of an elastic agent, and 20-25 parts of a toughening agent.

[0025] Preferably, the tough and flexible cement paste comprises the following components:

[0026] 1000 parts of G-grade cement, 40 parts of silica powder, and 200 parts of quartz sand;

[0027] 28 parts of a fluid loss reducer, 45 parts of a superfine material, and 20 parts of an expansive agent;

[0028] 10 parts of a resistance reducing agent, 2 parts of a retarder, and 16 parts of an early strength agent;

[0029] 42 parts of an elastic agent, and 20 parts of a toughening agent.

[0030] Preferably, the superfine material is one or more of superfine calcium carbonate, superfine calcium oxide, and superfine aluminum oxide; and the particle size of the superfine material is 5-10 μm.

[0031] Preferably, the expansion agent is one of calcium sulphoaluminate expansion agent, calcium oxide expansion agent, and metal expansion agent; and the friction reducer is one of cationic friction reducer, anionic friction reducer, and non-ionic friction reducer.

[0032] Preferably, the retarder is one of low molecular weight cellulose and its derivatives, hydroxyl carboxylic acid, organic phosphonic acid, boric acid, complex, and lignosulfonate and its derivatives.

[0033] Preferably, the early strength agent is one of triethanolamine, calcium formate, and urea; and the elastic agent is rubber powder.

[0034] Preferably, the toughening agent is modified PVA fiber, the length of the modified PVA fiber is 10-13 mm, and the preparation method of the modified PVA fiber is as follows:

[0035] The PVA fiber is cut into 10-13 mm fiber yarns, added into an acetic acid solution, treated under the action of ultrasonic waves for 10-20 min, stirred in a 3%-5% w / v polystyrene sulfonic acid sodium solution at 50-60 ℃ for 10-20 min, added into vinyl trimethoxysilane for 15-20 min, finally added into an ethyl methyl sulfide acetate ethanol solution for 20-30 min at room temperature, and the PVA fiber is taken out after treatment.

[0036] Another object of the present application is to provide a method for preparing the elastic and tough cement paste, which comprises the following steps:

[0037] (1) uniformly mixing the formula amount of silica powder, quartz sand, superfine material, elastic agent, and toughening agent with 50% of the formula amount of G-grade cement to obtain dry mixture;

[0038] (2) uniformly mixing the formula amount of fluid loss agent, expansion agent, friction reducer, retarder, and early strength agent with the remaining 50% of the formula amount of G-grade cement, and then adding water to obtain wet mixture;

[0039] (3) under the condition of stirring, gradually adding the dry mixture into the wet mixture to obtain the elastic and tough cement paste, and the specific gravity of the elastic and tough cement paste is 1.85 g / cm 3 -2.25 g / cm 3 .

[0040] In summary, the present application has the following advantages:

[0041] The PVA fiber is added in the cement paste system, the long PVA fiber is used as a toughening agent, the flexural strength and toughness of the cement stone can be greatly improved, meanwhile, the PVA material is modified, the dispersion of the modified PVA material in the cement stone is better, the PVA fiber can be more uniformly dispersed in the cement paste system, and the age period of maintaining effective compressive strength and toughness is well increased. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The stress-strain curve of the embodiment 1 of the present application;

[0043] Figure 2 The stress-strain curve of the comparative example 1 of the present application;

[0044] Figure 3 The stress-strain curve of the embodiment 2 of the present application;

[0045] Figure 4 The stress-strain curve of the comparative example 2 of the present application;

[0046] Figure 5 The scanning diagram of the dispersion degree of the cement stone of the experimental group 1 of the present application;

[0047] Figure 6 The scanning diagram of the dispersion degree of the cement stone of the experimental group 2 of the present application. DETAILED DESCRIPTION

[0048] The present application discloses a kind of elastic toughness cement paste, including the following components:

[0049] G cement 1000 parts;Silica powder 40 parts-50 parts;Quartz sand 150 parts-200 parts;

[0050] Water loss reducing agent (Y201) 25 parts-30 parts;Ultrafine material 40 parts-50 parts;Expanding agent (Y506) 25 parts-35 parts;

[0051] Resistance reducing agent 8 (Y301) parts-12 parts;Retarder (Y103) 2 parts-3 parts;Early strength agent (Y401) 15 parts-20 parts;

[0052] Elastic agent (Y502) 40 parts-45 parts;Toughening agent (Y507) 20 parts-25 parts.

[0053] The preparation method of the cement paste of the present application includes the following steps:

[0054] (1) the formula amount of silica powder, quartz sand, ultrafine material, elastic agent and toughening agent are mixed with formula amount 50% G cement uniformly, and dry mixture is obtained;

[0055] (2) the formula amount of the fluid loss agent, the expansion agent, the drag reducer, the retarder, the early strength agent is mixed with the remaining 50% cement of G grade evenly, then water is added and stirred to obtain wet mixture;

[0056] (3) the dry mixture is gradually added into the wet mixture under stirring to obtain the elastic cement slurry, and the specific gravity of the elastic cement slurry is 1.85g / cm 3 ~2.25g / cm 3 .

[0057] The superfine material of the present application is one or more of superfine calcium carbonate, superfine calcium oxide and superfine aluminum oxide; the particle size of the superfine material is 5-10um. The superfine material has a good surface area ratio and is more easily introduced into the pores of the cement slurry system, thereby improving the packing rate of the cement slurry system. Under the condition of ensuring the rheological property of the cement slurry, the superfine material can increase the packing rate PVF of the cement slurry per unit volume, the greater the PVF, the higher the degree of close packing, the smaller the porosity and permeability of the cement stone, and the better the performance.

[0058] The expansion agent of the present application is one of calcium sulphoaluminate expansion agent, calcium oxide expansion agent or metal expansion agent.

[0059] The drag reducer of the present application is one of cationic drag reducer, anionic drag reducer and non-ionic drag reducer. The cationic drag reducer can be octadecyl trimethyl ammonium chloride, C12-14 alkyl dimethyl benzyl ammonium chloride, dioctadecyl dimethyl sodium chloride, hexadecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium chloride and sodium dodecyl benzene sulfonate; the non-ionic drag reducer can be polyethylene glycol octyl phenyl ether, nonyl phenol polyoxyethylene ether emulsifier, gum arabic, sorbitan monolaurate (Span-20, Span-40, Span-60 and Span-80), ethylene oxide adduct (Tween-20, Tween-40, Tween-60 and Tween-80), lauryl alcohol polyoxyethylene ether, coconut acid diethanolamide, oleic acid monoglyceride, polyoxyethylene castor oil and polyoxyethylene lanolin; the anionic drag reducer can be polypropionic acid, poly(amino) (meth) acrylic acid, poly(sodium) (meth) acrylic acid, fatty acid soap, sodium dodecyl sulfate, sodium lauryl alcohol polyoxyethylene ether sulfate, sodium cetyl polyoxyethylene ether phosphate.

[0060] The retarder of the present application has a retarding effect and can be one of low molecular weight cellulose and its derivatives, hydroxyl carboxylic acid, organic phosphonic acid, boric acid, complex and lignin sulfonate and its derivatives.

[0061] The early strength agent of the present application can be one of triethanolamine, calcium formate and urea.

[0062] The elastic agent of the present application can be rubber powder or other types of elastic agent, such as modified rubber, etc.

[0063] The toughening agent of the present application is an improved material, the toughening agent is modified PVA fiber, the use length of the modified PVA fiber is 10mm-13mm; the preparation method of the modified PVA fiber is:

[0064] The PVA fiber is cut into 10mm-13mm fiber yarn and added into acetic acid solution, treated under the action of ultrasonic wave for 10min-20min; after the treatment, stirred in 3%w / v-5%w / v polystyrene sulfonic acid sodium solution at 50℃-60℃ for 10min-20min; then added into vinyl trimethoxysilane and treated for 15min-20min, finally added into ethyl thioacetate ethanol solution and treated at room temperature for 20min-30min, after the treatment, the PVA fiber is taken out and used.

[0065] The modified PVA fiber of the present application has a reduced surface potential and a raised potential barrier between solid particles after the treatment, thereby forming a fiber which is easy to disperse and stable.

[0066] Example 1

[0067] A toughened cement slurry, comprising the following components:

[0068] G-grade cement 1000 parts; silicon powder 40 parts; quartz sand 200 parts;

[0069] Fluid loss reducer 28 parts; superfine material 45 parts; expanding agent 20 parts;

[0070] Drag reduction agent 10 parts; retarder 2 parts; early strength agent 16 parts;

[0071] Elastic agent 42 parts; toughening agent 20 parts.

[0072] Comparative Example 1: without adding toughening agent

[0073] A toughened cement slurry, comprising the following components:

[0074] G-grade cement 1000 parts; silicon powder 40 parts; quartz sand 200 parts;

[0075] Fluid loss reducer 28 parts; superfine material 45 parts; expanding agent 20 parts;

[0076] Drag reduction agent 10 parts; retarder 2 parts; early strength agent 16 parts;

[0077] Elastic agent 42 parts.

[0078] The cement slurry of Example 1 and Comparative Example 1 is prepared into cement stone according to the method of the present application or the prior art method, the density of the cement stone is 2.2g / cm 3 , and then detected by using the prior detection method, and the detection results are as follows.

[0079]

[0080] From Figure 1 and Figure 2 It can be seen that the strain value of the cement stone with the added toughening agent in the embodiment of the present application is 4-5 times larger than that of the cement stone without the added toughening material, the stress value is increased by 17.4 MPa, and the Young's modulus is reduced by 50%. The toughened cement has plastic deformation, and the bearing value is more than 20 MPa higher than that of the ordinary cement; it is indicated that the toughness of the cement stone is increased after the addition of the toughening agent.

[0081] Experimental Example 2:

[0082] G-grade cement 1000 parts; silicon powder 43 parts; quartz sand 180 parts;

[0083] fluid loss additive 26 parts; ultra-fine material 42 parts; expansion agent 28 parts;

[0084] drag reduction agent 11 parts; retarder 2 parts; early strength agent 16 parts;

[0085] elastic agent 42 parts; toughening agent 22 parts.

[0086] Comparative Example 2:

[0087] G-grade cement 1000 parts; silicon powder 43 parts; quartz sand 180 parts;

[0088] fluid loss additive 26 parts; ultra-fine material 42 parts; expansion agent 28 parts;

[0089] drag reduction agent 11 parts; retarder 2 parts; early strength agent 16 parts;

[0090] elastic agent 42 parts.

[0091] The cement paste of Example 2 and Comparative Example 2 is prepared into cement stone according to the method of the present application or the existing method, and the density of the cement stone is 1.90 g / cm 3 , and then the existing detection method is used for detection, and the detection results are as follows.

[0092]

[0093] From Figure 3 and Figure 4 It can be seen from the comparison of the triaxial stress of the toughened cement stone of the present application and the pure cement stone that the toughened cement stone of Example 2 of the present application shows obvious toughness characteristics, the Young's modulus is reduced by nearly one time, but the compressive strength of the cement stone does not decrease obviously, and the cement stone does not break within the measurable range of the instrument.

[0094] The cement slurry system of the present application is detected by field construction, and the two-stage one-stage cementing slurry both uses the tough cement slurry system of the embodiment 1 of the present application. The cementing construction is normal, and the sound amplitude value of the one-stage well section is measured after waiting for condensation. Through the statistics of the one-stage cementing sound amplitude value, it is found that the qualified rate of the one-stage cementing section is 100%, and the excellent rate reaches 92.8%; the specific detection parameters are as follows.

[0095]

[0096] Experimental example one: influence of different PVA fibers on dispersity

[0097] The toughening agent of the present application is modified PVA fiber, and the modified PVA fiber of the present application has a reduced surface potential and a raised potential barrier between solid particles after treatment, thereby forming a fiber that is easy to disperse and stable; and further, it is easier to disperse in the cement slurry system in the mixing process. In experimental example one of the present application, the dispersity of different PVA fibers is compared. The ingredients used in each group in experimental example one are as follows:

[0098] Experimental group 1:

[0099] A tough cement slurry, comprising the following components:

[0100] 1000 parts of G-grade cement, 40 parts of silica powder and 200 parts of quartz sand;

[0101] 28 parts of a fluid loss reducer, 45 parts of an ultra-fine material and 20 parts of an expansive agent;

[0102] 10 parts of a resistance reducing agent, 2 parts of a retarder and 16 parts of an early strength agent;

[0103] 42 parts of an elastic agent and 20 parts of a toughening agent.

[0104] The toughening agent is the modified PVA fiber of the present application.

[0105] Experimental group 2:

[0106] A tough cement slurry, comprising the following components:

[0107] 1000 parts of G-grade cement, 40 parts of silica powder and 200 parts of quartz sand;

[0108] 28 parts of a fluid loss reducer, 45 parts of an ultra-fine material and 20 parts of an expansive agent;

[0109] 10 parts of a resistance reducing agent, 2 parts of a retarder and 16 parts of an early strength agent;

[0110] 42 parts of an elastic agent and 20 parts of a toughening agent.

[0111] The toughening agent is a conventional unmodified PVA fiber.

[0112] The cement paste of the experimental group 1 and the experimental group 2 is prepared into cement stone according to the method of the present application combined with the prior art, and the dispersion degree of the fiber in the cement stone is detected by scanning method after waiting for 28 days. There are various detection calculation methods for the dispersion degree of the fiber in the cement stone, and the following detection method is adopted in the present application.

[0113] The detection method for the dispersion degree of the fiber in the cement stone of the present application is as follows:

[0114] (1) CT machine is used to scan the section of the cement stone, and CT images of each section are collected,

[0115] (2) the CT images are preprocessed by greying;

[0116] (3) the characteristic regions of the CT images are defined, and the characteristic regions include carbon fiber bundle region, fiber uniformly dispersed region and fiber-free region;

[0117] The region with a gray value of 0-63 is the carbon fiber bundle region;

[0118] The region with a gray value of 63-147 is the fiber uniformly dispersed region;

[0119] The region with a gray value of 147-205 is the fiber-free region;

[0120] (4) the pixel area of each characteristic region is calculated;

[0121] (5) the effective dispersion coefficient D of the chopped carbon fiber is calculated:

[0122]

[0123] Wherein, n = 1, 2, 3, …, N; A t,n = A e,n + A b,n + A c,n ;

[0124] A e,n is the pixel area of the carbon fiber uniformly dispersed region in the CT image of the nth layer;

[0125] A b,n is the pixel area of the fiber-free region in the CT image of the nth layer;

[0126] A c,n is the pixel area of the carbon fiber bundle region in the CT image of the nth layer.

[0127] The dispersion detection results of the experimental group 1 of the present application are as follows:

[0128]

[0129] The dispersion detection result of the experimental group 2 of the application is as follows:

[0130]

[0131] From the dispersion detection result of the application, it can be seen that after the PVA fiber is modified, the dispersion of the fiber in the cement stone formed by the prepared cement slurry is better, which is more conducive to maintaining the mechanical properties of long age.

Claims

1. A resilient cement paste, characterized in that, Includes the following components: 1000 parts of Grade G cement; 40-50 parts of silica fume; 150-200 parts of quartz sand; 25-30 parts of water loss reducing agent; 40-50 parts of ultrafine material; 25-35 parts of expansion agent; 8 to 12 parts drag-reducing agent; 2-3 parts retarder; 15-20 parts early-strength agent; 40 to 45 parts of elastic agent; Toughening agent 20-25 parts; The ultrafine material is one or more of ultrafine calcium carbonate, ultrafine calcium oxide, and ultrafine aluminum oxide; The toughening agent is modified PVA fiber, and the length of the modified PVA fiber used is 10mm~13mm; the preparation method of the modified PVA fiber is as follows: PVA fibers are chopped into 10mm-13mm filaments and added to an acetic acid solution. The solution is then treated with ultrasound for 10-20 minutes. After treatment, the fibers are stirred in a 3% w / v-5% w / v sodium polystyrene sulfonate solution at 50℃-60℃ for 10-20 minutes. Next, the fibers are added to vinyltrimethoxysilane and treated for 15-20 minutes. Finally, the fibers are added to an ethanol solution of ethyl methylthioester and treated at room temperature for 20-30 minutes. After treatment, the PVA fibers are removed and ready for use.

2. The elastic-tough cement paste as described in claim 1, characterized in that: Includes the following components: 1000 parts of Grade G cement; 40 parts of silica fume; 200 parts of quartz sand; 28 parts of dehydration reducer; 45 parts ultrafine material; 20 parts expanding agent; 10 parts drag-reducing agent; 2 parts retarder; 16 parts early-strength agent; 42 parts elastic agent; 20 parts toughening agent.

3. The elastic-tough cement paste as described in claim 1, characterized in that: The expanding agent is one of calcium sulfoaluminate expanding agent, calcium oxide expanding agent, or metal expanding agent; the drag reducing agent is one of cationic drag reducing agent, anionic drag reducing agent, or nonionic drag reducing agent.

4. The elastic-tough cement paste as described in claim 1, characterized in that: The retarder is one of low molecular weight cellulose and its derivatives, hydroxycarboxylic acid, organophosphonic acid, boric acid, and lignosulfonate and its derivatives.

5. The elastic-tough cement paste as described in claim 1, characterized in that: The early strength agent is one of triethanolamine, calcium formate, and urea; the elastic agent is rubber powder.

6. A method for preparing the elastic-tough cement paste according to any one of claims 1-5, comprising the following steps: (1) Mix the silica powder, quartz sand, ultrafine materials, elastic agent and toughening agent in the formula amount with 50% of the formula amount of grade G cement evenly to obtain dry mix; (2) Mix the water loss reducer, expansion agent, drag reducer, retarder, and early strength agent in the formula with the remaining 50% of grade G cement evenly, and then add water and stir evenly to obtain wet mixture; (3) Under stirring conditions, the dry mixture is gradually added to the wet mixture to obtain an elastic-tough cement paste with a specific gravity of 1.85 g / cm³. 3 ~2.25g / cm 3 .

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