An anti-compressive and anti-cracking mortar and its processing method

Abstract

The present invention provides a compression-resistant and crack-resistant mortar and its processing method. The compression-resistant and crack-resistant mortar is prepared from the following raw materials in parts by weight: 60-90 parts of cement, 100-200 parts of machine-made sand, 70-80 parts of fly ash, 20-50 parts of composite fiber, and 10-50 parts of water. The mortar prepared by the present invention has high compressive strength and good crack resistance; the incorporation of composite fiber into the mortar improves the adhesion of the mortar, enhances the compressive performance and strength, and at the same time can inhibit the shrinkage and cracking of the mortar, improving the crack resistance ability.

Description

Technical Field

[0001] The present invention relates to the field of mortar, and particularly to a compressive and crack-resistant mortar and its processing method. Background Art

[0002] Mortar is composed of cement, sand, and water, and is commonly used for surface enhancement protection of building surfaces and insulation systems. During the daily use of buildings, mortar is often exposed to sunlight, rain erosion, pressure impact, etc. Due to the brittle texture and low tensile strength of mortar, it is prone to cracking during use, resulting in reduced compressive performance, durability, and strength, affecting the durability, stability, and safety of buildings. Summary of the Invention

[0003] In view of this, the present invention provides a compressive and crack-resistant mortar and its processing method.

[0004] The technical solution of the present invention is realized as follows:

[0005] A compressive and crack-resistant mortar, comprising the following raw materials in parts by weight: 60 - 90 parts of cement, 100 - 200 parts of manufactured sand, 70 - 80 parts of fly ash, 20 - 50 parts of composite fiber, and 10 - 50 parts of water, wherein the composite fiber is composed of modified pineapple leaf fiber, chitosan fiber, and steel fiber.

[0006] Further, the compressive and crack-resistant mortar comprises the following raw materials in parts by weight: 80 parts of cement, 160 parts of manufactured sand, 75 parts of fly ash, 30 parts of composite fiber, and 20 parts of water.

[0007] Further, the composite fiber is composed of modified pineapple leaf fiber, chitosan fiber, and steel fiber in a mass ratio of 1.2 - 1.6:0.1 - 0.2:2 - 3.

[0008] Further, the preparation of the modified pineapple leaf fiber comprises the following steps:

[0009] (1) Treat pineapple leaves with alkali solution to obtain pineapple leaf fiber;

[0010] (2) Add a radical initiator and a vinyl monomer to the pineapple leaf fiber obtained in step (1) for grafting reaction to obtain grafted pineapple leaf fiber;

[0011] (3) Extract the grafted pineapple leaf fiber obtained in step (2) with an organic solvent to obtain modified pineapple leaf fiber.

[0012] Further, the mass ratio of the pineapple leaves, radical initiator, and vinyl monomer is: 0.5 - 3:0.01 - 0.05:1 - 5.

[0013] Further, in step (1), the lye is one of sodium hydroxide solution, calcium hydroxide solution, and potassium hydroxide solution; the mass concentration of the lye is 10% - 20%.

[0014] Further, in step (2), the radical initiator is at least one or more of azobisisobutyronitrile, azobisisoheptonitrile, and dimethyl azobisisobutyrate.

[0015] Further, in step (2), the vinyl monomer is at least one or more of acrylonitrile, acrylic acid, and methyl methacrylate.

[0016] Further, in step (3), the organic solvent is at least one of dichloromethane, acetone, and ether.

[0017] Further, the processing method of the compressive and crack-resistant mortar includes the following steps: mixing cement, fly ash, machine-made sand, and water to obtain a mixed material; adding composite fibers to the mixed material and stirring at a rate of 200 - 500 rpm for 30 - 40 min to prepare the compressive and crack-resistant mortar.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The mortar prepared according to the raw materials and ratios of the present invention has high compressive strength and good crack-resistant performance; adding composite fibers to the mortar improves the bondability of the mortar, enhances the compressive performance, increases the compressive strength, and at the same time can inhibit the shrinkage and cracking of the mortar and improve the crack-resistant ability. Among them, the modified pineapple leaf fibers are incorporated into the mortar, and the elongation at break is increased, which helps to reduce the cracks generated during the use of the mortar and improve the crack-resistant performance; the tensile strength of the modified pineapple leaf fibers is increased, and a stronger network structure is formed with chitosan fibers and steel fibers, effectively improving the compressive strength of the mortar. The capillary effect of chitosan fibers is significant, which is beneficial to the water retention of the mortar, replenishes water for the dry shrinkage deformation after long-term use of the mortar, reduces the cracking of the mortar, and improves the crack-resistant performance. Specific Embodiments

[0020] To better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0021] The experimental methods used in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0022] The reagents, etc. used in the embodiments of the present invention can be obtained from commercial channels unless otherwise specified.

[0023] Example 1 - A Compressive and Crack-Resistant Mortar

[0024] A. Soak pineapple leaves in a 15% sodium hydroxide solution by mass concentration for 2 h to obtain pineapple leaf fibers.

[0025] B. Add azobisisobutyronitrile and acrylonitrile to the pineapple leaf fiber obtained in step A, and carry out grafting reaction to obtain grafted pineapple leaf fiber; the mass ratio of pineapple leaf, azobisisobutyronitrile and acrylonitrile is: 1:0.01:1.5.

[0026] C. Use acetone to extract the grafted pineapple leaf fiber obtained in step C to obtain modified pineapple leaf fiber.

[0027] D. Take 60 parts of cement, 160 parts of manufactured sand, 80 parts of fly ash, and 30 parts of water by weight and mix them to obtain a mixed material; take 30 parts of a composite fiber composed of modified pineapple leaf fiber, chitosan fiber and steel fiber with a mass ratio of 1.2:0.1:2 by weight and add it to the mixed material, and stir at a rate of 200 rpm for 30 min to obtain compressive and crack-resistant mortar.

[0028] Example 2 - A compressive and crack-resistant mortar

[0029] A. Soak pineapple leaves in a 15% sodium hydroxide solution by mass concentration for 2 h to obtain pineapple leaf fiber.

[0030] B. Add azobisisobutyronitrile and acrylonitrile to the pineapple leaf fiber obtained in step A, and carry out grafting reaction to obtain grafted pineapple leaf fiber; the mass ratio of pineapple leaf, azobisisobutyronitrile and acrylonitrile is: 1.2:0.02:2.

[0031] C. Use acetone to extract the grafted pineapple leaf fiber obtained in step C to obtain modified pineapple leaf fiber.

[0032] D. Take 70 parts of cement, 160 parts of manufactured sand, 80 parts of fly ash, and 30 parts of water by weight and mix them to obtain a mixed material; take 30 parts of a composite fiber composed of modified pineapple leaf fiber, chitosan fiber and steel fiber with a mass ratio of 1.5:0.2:2 by weight and add it to the mixed material, and stir at a rate of 200 rpm for 30 min to obtain compressive and crack-resistant mortar.

[0033] Example 3 - A compressive and crack-resistant mortar

[0034] A. Soak pineapple leaves in a 15% sodium hydroxide solution by mass concentration for 2 h to obtain pineapple leaf fiber.

[0035] B. Add azobisisobutyronitrile and acrylonitrile to the pineapple leaf fiber obtained in step A, and carry out grafting reaction to obtain grafted pineapple leaf fiber; the mass ratio of pineapple leaf, azobisisobutyronitrile and acrylonitrile is: 2:0.03:4.

[0036] C. Use acetone to extract the grafted pineapple leaf fiber obtained in step C to obtain modified pineapple leaf fiber.

[0037] D. Take 80 parts by weight of cement, 200 parts of machine-made sand, 80 parts of fly ash, and 30 parts of water and mix them to obtain a mixed material; take 40 parts by weight of a composite fiber composed of modified pineapple leaf fiber, chitosan fiber, and steel fiber with a mass ratio of 1.6:0.2:3 and add it to the mixed material, and stir at a rate of 200 rpm for 30 min to prepare a compressive and crack-resistant mortar.

[0038] Comparative Example 1

[0039] The difference between this comparative example and Example 1 is that the modified pineapple leaf fiber is replaced with pineapple leaf fiber.

[0040] Take 60 parts by weight of cement, 160 parts of machine-made sand, 80 parts of fly ash, and 30 parts of water and mix them to obtain a mixed material; take 30 parts by weight of a composite fiber composed of pineapple leaf fiber, chitosan fiber, and steel fiber with a mass ratio of 2:1:1 and add it to the mixed material, and stir at a rate of 200 rpm for 30 min to prepare a compressive and crack-resistant mortar.

[0041] Comparative Example 2

[0042] The difference between this comparative example and Example 1 is that the composite fiber is replaced with steel fiber.

[0043] Take 60 parts by weight of cement, 160 parts of machine-made sand, 80 parts of fly ash, and 30 parts of water and mix them to obtain a mixed material, take 30 parts by weight of steel fiber and add it to the mixed material, and stir at a rate of 200 rpm for 30 min to prepare a compressive and crack-resistant mortar.

[0044] Comparative Example 3

[0045] The difference between this comparative example and Example 1 is that the proportions of modified pineapple leaf fiber, chitosan fiber, and steel fiber in the composite fiber are the same.

[0046] A. Soak pineapple leaves in a 15% sodium hydroxide solution with a mass concentration for 2 h to obtain pineapple leaf fiber.

[0047] B. Add azobisisobutyronitrile and acrylonitrile to the pineapple leaf fiber obtained in step A and carry out a grafting reaction to obtain grafted pineapple leaf fiber; the mass ratio of pineapple leaf, azobisisobutyronitrile, and acrylonitrile is: 1:0.01:1.5.

[0048] C. Use acetone to extract the grafted pineapple leaf fiber obtained in step C to obtain modified pineapple leaf fiber.

[0049] D. Take 60 parts by weight of cement, 160 parts of machine-made sand, 80 parts of fly ash, and 30 parts of water and mix them to obtain a mixed material; take 30 parts by weight of a composite fiber composed of modified pineapple leaf fiber, chitosan fiber, and steel fiber with a mass ratio of 1:1:1 and add it to the mixed material, and stir at a rate of 200 rpm for 30 minutes to prepare a compressive and crack-resistant mortar.

[0050] Take the samples of Examples 1 to 3 and Comparative Examples 1 to 3, and determine the compressive strength and crack width according to the standard test methods for the fracture aging and induced tensile stress characteristics of mortar and concrete under restricted shrinkage as specified in GB / T 17671-1999 Test Method for Strength of Cement Mortar (ISO Method) and ASTM C1581 / C1581M-2009a. The experimental results are shown in Table 1:

[0051] Table 1. Compressive Strength and Crack Width of Experimental Examples 1 to 3 and Comparative Examples 1 to 3

[0052] Test items Compressive strength (Mpa) Crack width (mm) Example 1 45.2 0.05 Example 2 45.8 0.03 Example 3 49.0 0.02 Comparative example 1 40.1 0.08 Comparative example 2 41.9 0.07 Comparative example 3 43.9 0.06

[0053] The compressive strengths of Examples 1 to 3 are all above 45 Mpa. As the addition of the composite fiber increases, the crack width decreases; compared with Comparative Example 1, the compressive strength of Example 1 is increased by 11%, and the crack width is reduced by 37%; compared with Comparative Example 2, the compressive strength of Experimental Example 1 is increased by 8%, and the crack width is reduced by 29%; compared with Comparative Example 2, the compressive strength of Experimental Example 1 is increased by 3%, and the crack width is reduced by 16%.

[0054] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A compressive and crack-resistant mortar, characterized in that, It comprises the following raw materials in parts by weight: 60 - 90 parts of cement, 100 - 200 parts of manufactured sand, 70 - 80 parts of fly ash, 20 - 50 parts of composite fiber, and 10 - 50 parts of water. The composite fiber is composed of modified pineapple leaf fiber, chitosan fiber, and steel fiber with a mass ratio of 1.2 - 1.6:0.1 - 0.2:2 - 3. The preparation of the modified pineapple leaf fiber comprises the following steps: (1) Treat the pineapple leaf with an alkali solution to obtain pineapple leaf fiber. The alkali solution is one of sodium hydroxide solution, calcium hydroxide solution, and potassium hydroxide solution; the mass concentration of the alkali solution is 10% - 20%. (2) Add a radical initiator and a vinyl monomer to the pineapple leaf fiber obtained in step (1). The mass ratio of the pineapple leaf, radical initiator, and vinyl monomer is: 0.5 - 3:0.01 - 0.05:1 - 5, and carry out a grafting reaction to obtain grafted pineapple leaf fiber. The radical initiator is at least one or more of azobisisobutyronitrile, azobisisoheptonitrile, and dimethyl azobisisobutyrate, and the vinyl monomer is at least one or more of acrylonitrile, acrylic acid, and methyl methacrylate. (3) Extract the grafted pineapple leaf fiber obtained in step (2) with an organic solvent to obtain modified pineapple leaf fiber. The organic solvent is at least one of dichloromethane, acetone, and ether.

2. The compressive and crack-resistant mortar according to claim 1, wherein It comprises the following raw materials in parts by weight: 80 parts of cement, 160 parts of manufactured sand, 75 parts of fly ash, 30 parts of composite fiber, and 20 parts of water.

3. The processing method of the compression-resistant and crack-resistant mortar according to claim 1, characterized in that: It comprises the following steps: Mix the cement, fly ash, manufactured sand, and water to obtain a mixed material; add the composite fiber to the mixed material and stir at a rate of 200 - 500 rpm for 30 - 40 min to obtain compressive and crack-resistant mortar.