JP2014091651A - Cement mortal mixed with bamboo fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide cement mortal mixed with bamboo fiber, which has beautiful surface condition at a cured condition by effectively preventing crack caused by shrinkage during a curing reaction.SOLUTION: The cement mortal mixed with bamboo fiber is produced by mixing cement, sand and water, and further mixing 0.1 wt.% to 0.7 wt.% of bamboo fiber obtained by crushing bamboo to be fibrous having an average length of 1 cm or more based on the cement and the sand.

Description

  The present invention relates to a cement mortar formed by mixing bamboo fibers, and more particularly to a cement mortar that is applied to a hardened concrete surface or the like and mixed with bamboo fibers that are optimal for use in preventing cracks in a cured state.

  The increase in unmanaged desolated bamboo forests erodes adjacent forests and houses, or may cause dangers such as landslides, so effective use of bamboo forests is also required from the viewpoint of disaster prevention. In traditional Japanese houses, bamboo was laid on the grid grid inside the earth wall to reinforce the wall. However, in recent years, dirt walls are not used in buildings, and the amount of bamboo used is significantly reduced.

  By the way, in order to effectively use bamboo, a block in which bamboo chips are hardened with cement mortar has been developed. This block is used as a paving body or a block material that makes use of moderate water permeability and water retention, required strength, soft texture and the like.

JP 2009-67665 A

  The soil wall of a conventional Japanese house is reinforced with rod-shaped bamboo laid in a grid pattern that is embedded, but it takes a lot of work, and depending on this structure, the strength of the soil wall itself Can not be so strong. In addition, this clay wall cannot prevent cracks after drying due to the rod-shaped bamboo material to be embedded, and mixes straw etc. to prevent cracks, but even with straw, There are drawbacks that cannot be prevented.

  On the other hand, a block in which bamboo chips are cemented with cement mortar can achieve water permeability and water retention with bamboo chips, but cannot prevent cracking of cement mortar after hardening. Cement mortar realizes extremely high strength in a hardened state that cannot be compared with soil walls, and is therefore used for various applications that require strength. However, when cement and mortar undergo a curing reaction between water and cement, moisture is lost due to the reaction and shrinks. If the shrinkage is constrained at that time, a resisting tensile force is generated, and if the tensile force that the cement mortar in this state cannot withstand is exceeded, the surface of the mortar is cracked. Cracks not only detract from the aesthetics, but also may facilitate the penetration of rainwater, carbon dioxide, etc. from the cracks and promote the deterioration of cement mortar.

  The present invention has been developed for the purpose of solving the above drawbacks. An important object of the present invention is to provide a cement mortar in which bamboo fibers that effectively prevent cracking due to shrinkage in the curing reaction and become a clean surface state in a cured state are mixed.

Means for Solving the Problems and Effects of the Invention

  The cement mortar of the present invention is mixed with bamboo fiber in cement, sand and water. Bamboo fiber is obtained by crushing bamboo into a fiber having an average length of 1 cm or more. The mixing amount of bamboo fiber is 0.1% by weight or more and 0.7% by weight or less based on cement and sand.

  The above-mentioned cement mortar is characterized in that it can effectively prevent cracks due to shrinkage in the curing reaction and can provide a clean surface state in the cured state. This is because the above cement mortar mixes bamboo fibers having a length of 1 cm or more by crushing bamboo at a specific ratio. Bamboo fiber made by crushing bamboo mixed with cement mortar improves tensile strength and effectively prevents cracks generated by shrinkage due to the curing reaction of cement and water.

  In the cement mortar of the present invention, the mixing amount of bamboo fibers can be 0.6% by weight or less based on the total weight of cement and sand. Since this cement mortar adjusts the mixing amount of bamboo fiber to a more optimal value, it can further improve the tensile strength and prevent cracks more effectively.

  In the cement mortar of the present invention, the mixing amount of bamboo fibers can be 0.5% by weight or less based on the total weight of cement and sand. Since this cement mortar adjusts the mixing amount of bamboo fibers to an optimum value, it can further improve the tensile strength and prevent cracks very effectively.

  The cement mortar of the present invention can be applied to the surface of the casing with a predetermined thickness. This cement mortar has the characteristics that it can be adhered to the surface of the housing so as not to peel off by improving the adhesive strength to the surface of the housing. This is because the bamboo fibers exposed on the surface of the cement mortar are entangled and firmly bonded to the surface of the casing. Bamboo fibers obtained by crushing bamboo have numerous irregularities on the surface, and are therefore firmly bonded to the surface of the casing via a binder.

  The cement mortar of the present invention can be applied to the surface of a concrete body. This cement mortar can be firmly bonded to the concrete surface in a cured state so as not to peel off. This is because the bamboo fiber is crushed and the bamboo fibers with numerous irregularities on the surface are exposed on the surface, which is entangled and firmly bonded to the concrete surface.

  The cement mortar of the present invention can be applied to a grid lattice core of a wooden building. This cement mortar can be applied to a grid lattice core to effectively prevent surface cracks in the cured state. Therefore, this cement mortar can be used in place of the earth wall of a wooden building, and an extremely tough wall body that cannot be realized with a conventional earth wall can be constructed. Moreover, there is a feature that a tough wall can be constructed while preventing cracks on the surface.

  The cement mortar of the present invention can have an average thickness of bamboo fibers of 1 mm or more and 3 mm or less. Since this cement mortar also sets the thickness of the bamboo fiber to an optimum state, it achieves excellent tensile strength and bending strength while more reliably preventing cracking in the cured state of the cement mortar.

It is sectional drawing which shows the state which apply | coats the cement mortar concerning the Example of this invention to the concrete surface. It is sectional drawing which shows the state which uses the cement mortar concerning the Example of this invention for the wall of a wooden building. It is a front view which shows the state which measures the tensile strength of a test piece. It is a front view which shows the state which measures the bending strength of a test piece. It is a front view which shows the state which measures the shear strength of a test piece. It is a front view which shows the surface state in 7 days after the age of the cement mortar of Example 1 of this invention. It is a front view which shows the surface state after 28 days of age of the cement mortar of Example 1 of this invention. It is a front view which shows the surface state in 55 days after the age of the cement mortar of Example 1 of this invention. It is a front view which shows the surface state of the cement mortar of the comparative example 1 after the age of 7 days. It is a front view which shows the surface state of the cement mortar of the comparative example 1 after the age of 28 days. It is a front view which shows the surface state in 55 days after the age of the cement mortar of the comparative example 1.

  Embodiments of the present invention will be described below with reference to the drawings. However, the Example shown below illustrates the cement mortar for materializing the technical idea of this invention, Comprising: This invention does not specify a cement mortar for the following uses and use conditions.

  In the cross-sectional view of FIG. 1, a cement mortar is attached to a surface of a housing 1 that is a building or a civil engineering structure such as a concrete surface, and the mortar layer 2 is provided by curing the cement mortar. This cement mortar is applied to the surface of the casing to a predetermined thickness, for example, 10 mm to 50 mm. The cement mortar hardens and adheres to the housing surface. This cement mortar can prevent cracks in the hardened state and finish the surface of the casing cleanly.

  In the cross-sectional view of FIG. 2, cement mortar is applied to both surfaces of a core body 4 assembled in a grid pattern between pillars 3 and cured to form a mortar layer 2 as a wooden building wall. The wall body has a grid lattice core 4 embedded in a hardened cement mortar. This structure can realize a wooden construction of an earthquake-resistant structure as an extremely tough wall body by using a reinforcing bar for the core body 4 in a grid lattice shape. Also, since there is no cracking on the surface of the cured mortar layer, the cloth is adhered to the surface, or a decorative paint is applied, or a finishing wall is applied to a predetermined thickness with a trowel. Surface finish is possible.

  The cement mortar is a mixture of cement, sand and water, but the cement mortar of the present invention is further mixed with bamboo fibers. The cement mortar is mixed with 1.5 to 3.5 sand with respect to the cement 1 by weight.

  Bamboo fiber is obtained by crushing bamboo into fibers. This bamboo fiber is embedded in cement mortar and has an average length of 1 cm or more in order to effectively prevent cracks on the surface after the curing reaction. This bamboo fiber preferably has an average length of 1 cm to 8 cm, more preferably 1 cm to 5 cm. If the bamboo fiber is too short, it will be difficult to effectively prevent cracking after the curing reaction, and conversely, if the average length is increased, the short bamboo fiber will be separated, resulting in poor yield, and the bamboo fiber raw material. Cost increases. Therefore, considering the degree of cracking after the curing reaction and the raw material cost of the bamboo fiber, bamboo fiber having the optimum length for the application is used.

  When bamboo is crushed to produce bamboo fiber, scrap is produced along with bamboo fiber. Bamboo fiber is produced by removing the debris produced during crushing. The scrap is removed from the bamboo fiber by passing through countless slits having an interval of 1 mm to 3 mm, for example. By adjusting the gap between the slits, the size of the separated waste, in other words, the thickness of the selected bamboo fiber can be controlled. The amount of debris to be removed can be reduced by narrowing the interval between slits, and the amount of debris to be removed can be increased by increasing the interval between slits. Increasing the spacing between the slits and increasing the amount of debris removed from the bamboo fibers results in fewer bamboo fibers being selected and higher manufacturing costs. This is because the thin bamboo fibers are removed together with the waste. The interval between the slits is adjusted so that the average thickness of the bamboo fibers is 1 mm or more and 3 mm or less. For example, a bamboo fiber having a slit interval of 1.2 mm and an average thickness of 1 mm to 3 mm can be selected.

The cement mortar has an addition amount of bamboo fiber of 0.1% by weight or more and 0.7% by weight or less, preferably 0.2% by weight or more based on the weight of cement and sand, and 0.6% It is adjusted to not more than wt%, more preferably not more than 0.5 wt%, and most preferably about 0.35 wt%. This is because the cement mortar, if the bamboo fiber content is too small or too large, decreases the strength and cannot effectively prevent cracks. For example, a cement mortar in which the amount of bamboo fiber mixed is 0.35% by weight with respect to cement and sand is improved by 7% in tensile strength after 7 days of age, compared to a material not mixed with bamboo fiber. Bending strength is improved by 6% to 8%, shear strength is improved by about 10%, cracks are reduced to 1/4 or less, and compressive strength is extremely higher than 50 N / mm ² which is comparable to that without bamboo fiber mixing. Realize superior characteristics.

[Example 1]
In the weight ratio, sand twice as much as cement 1 is mixed, and further, 0.35% by weight bamboo fiber is mixed with the total weight of cement and sand. A bamboo fiber having an average length of about 3 cm and an average thickness of 1.5 mm is used. 0.5 liter of water is added to 1 kg of cement and kneaded to obtain cement mortar. The cement mortar is attached to a concrete surface on a square having a thickness of 15 mm and an outer shape of 30 cm × 30 cm, and the crack after the curing reaction is measured.

Furthermore, using the same cement mortar, when making a test piece and measuring the tensile strength, bending strength, and shear strength of the age of 7 days,
The tensile strength was 4.36 N / mm ² , which was improved by 107% and 7% compared to 4.07 N / mm ² of the tensile strength of the test piece of Comparative Example 1 in which no bamboo fiber was added.
The bending strength was 8.18 N / mm ² , which was improved by 106% and 6% with respect to the bending strength of 7.75 N / mm ² of the test piece of Comparative Example 1 to which no bamboo fiber was added.
The shear strength was 15.3 N / mm ² , which was improved by 112% and 12% with respect to the shear strength of 13.7 N / mm ² of the test piece of Comparative Example 1 to which no bamboo fiber was added.

However, as for the tensile strength, a test piece having a diameter of 50 mm and a length of 100 mm was measured in accordance with the split tensile strength test method of JISA1113 concrete at each age, and the average value of three pieces was obtained. FIG. 3 shows a state in which the tensile strength of the test piece is measured. As shown in this figure, the test piece is gradually and strongly pressed by the upper and lower pressure plates 5, the maximum load P (N) when the test piece is broken is measured, and the tensile strength f (N / mm ² ).

In this formula, d is the diameter of the test piece and is 50 mm.
l is the length of the test piece, 100mm

The bending strength was determined by averaging three rectangular parallelepiped test pieces each having a side of 40 mm × 40 mm × 160 mm in accordance with the physical test method of JIS R5201 cement at each age. FIG. 4 shows a state in which the bending strength of the test piece is measured. As shown in this figure, a test piece is placed on two rods 6 having a diameter of 10 mm and a center interval of 100 mm, and the pressure rod 7 having a diameter of 10 mm is gradually and strongly applied from the middle of the two rods 6. The maximum load F (N) when the test piece is broken is measured, and the bending strength R (N / mm ² ) is measured by the following formula.

However, in this formula, l is the distance between two rods of 100 mm
b is the dimension of one side of the rectangular parallelepiped, 40mm

The shear strength was determined by averaging three rectangular parallelepiped test pieces each having a side of 40 mm × 40 mm × 160 mm by the simple two-surface shear test method of a test apparatus at each age. FIG. 5 shows a state in which the shear strength of the test piece is measured. As shown in this figure, when a test piece is placed on the two bars 8 and is gradually strongly pressed with a pressure bar 9 having a width equal to the intermediate distance between the two bars 8, and the test piece is destroyed. The maximum load P (N) is measured, and the shear strength τ (N / mm ² ) is measured by the following equation.

However, in this formula, A is the cross-sectional area of the test piece and is 40 × 40 mm ² .

  Moreover, the crack after 7 days of age decreased remarkably to 1/4 or less with respect to the comparative example which does not mix bamboo fiber. Furthermore, after 7 days of age of the cement mortar of this example, after 28 days of age, cracks after 55 days of age are shown in FIG. 6 to FIG. 8, after 7 days of age of the cement mortar of the comparative example in which no bamboo fiber is added, The cracks after 28 days of age and 55 days of age are shown in FIGS.

  From these figures, it becomes clear that the cement mortar of the example can very effectively prevent cracking after the curing reaction. Since the cement mortar of the example prevents cracks after the curing reaction while effectively using bamboo material, it has a feature that can prevent cracks while reducing the raw material cost.

[Example 2]
The cement mortar was adjusted in the same manner as in Example, except that the amount of bamboo fiber mixed was 0.47% by weight with respect to the total weight of cement and sand, and adhered to the concrete surface with the same thickness and shape. Measure cracks. Moreover, when the same test piece as in the example was manufactured and the tensile strength, bending strength, and shear strength of the material 7 days were measured,
The tensile strength was 4.25 N / mm ² , an increase of 4% to 104% with respect to 4.07 N / mm ² of the tensile strength of the test piece of Comparative Example 1 to which no bamboo fiber was added.
The bending strength was 8.14 N / mm ² , which was improved by 105% and 5% with respect to the bending strength of 7.75 N / mm ² of the test piece of Comparative Example 1 to which no bamboo fiber was added.
Shear strength become 15.9N / mm ^2, was also improved 116% and 16% with respect to shear strength 13.7 N / mm ² of the test piece of Comparative Example 1 without the addition of bamboo fiber.

[Example 3]
The cement mortar was adjusted in the same manner as in Example, except that the amount of bamboo fiber mixed was 0.23% by weight based on the total weight of cement and sand, and adhered to the concrete surface with the same thickness and shape. Measure cracks. Moreover, when the same test piece as in the example was manufactured and the tensile strength, bending strength, and shear strength of the material 7 days were measured,
The tensile strength was 4.34 N / mm ² , which was improved by 107% and 7% compared to 4.07 N / mm ² of the tensile strength of the test piece of Comparative Example 1 to which no bamboo fiber was added.
The bending strength was 8.12 N / mm ² , which was improved by 105% and 5% with respect to the bending strength of 7.75 N / mm ² of the test piece of Comparative Example 1 to which no bamboo fiber was added.
The shear strength was 14.8 N / mm ² , which was an increase of 108% and 8% with respect to the shear strength of 13.7 N / mm ² of the test piece of Comparative Example 1 to which no bamboo fiber was added.

[Comparative Example 1]
A cement mortar is prepared in the same manner as in Example, except that bamboo fiber is not mixed, and the crack is measured by adhering to the concrete surface with the same thickness and shape. Moreover, when the same test piece as the Example was manufactured and the tensile strength, bending strength, and shear strength of the material 7 days were measured, the tensile strength was 4.07 N / mm ² , the bending strength was 7.75 N / mm ² , The shear strength was 13.7 N / mm ² .

[Comparative Example 2]
The cement mortar was adjusted in the same way as in Example, except that the amount of bamboo fiber was 1.1% by weight based on the total weight of cement and sand, and adhered to the concrete surface with the same thickness and shape. Measure cracks. In addition, when the same test piece as in the example was manufactured and the tensile strength, bending strength, and shear strength were measured,
Tensile strength becomes 3.76N / mm ^2, it was reduced 93% and 7% by 4.07N / mm ² tensile strength of the test piece of Comparative Example 1 without the addition of bamboo fiber.
The bending strength was 6.79 N / mm ² , which was 12% lower than the bending strength of 7.75 N / mm ² of the test piece of Comparative Example 1 to which no bamboo fiber was added.
The shear strength was 13.7 N / mm ² , which was equivalent to the shear strength of 13.7 N / mm ² of the test piece of Comparative Example 1 to which no bamboo fiber was added.

DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Mortar layer 3 ... Column 4 ... Core body 5 ... Pressure plate 6 ... Rod 7 ... Pressure rod 8 ... Bar 9 ... Pressure bar

Claims (7)

A cement mortar made by mixing cement, sand and water,
Bamboo fibers made by crushing bamboo into fibers with an average length of 1 cm or more mixed with bamboo fibers made by mixing 0.1 wt% and 0.7 wt% of cement and sand Cement mortar.   The cement mortar mixed with bamboo fibers according to claim 1, wherein the mixing amount of the bamboo fibers is 0.6% by weight or less based on cement and sand.   The cement mortar mixed with bamboo fibers according to claim 1, wherein the mixing amount of the bamboo fibers is 0.5% by weight or less based on cement and sand.   A cement mortar mixed with bamboo fibers according to any one of claims 1 to 3, which is applied to the surface of the casing in a predetermined thickness.   The cement mortar mixed with bamboo fibers according to claim 4, wherein the surface of the casing is a hardened concrete surface.   The cement mortar mixed with bamboo fibers according to any one of claims 1 to 3, wherein the cement mortar is a cement mortar applied to a grid lattice core of a wooden building.   The cement mortar mixed with bamboo fibers according to any one of claims 1 to 6, wherein the average thickness of the bamboo fibers is 1 mm or more and 3 mm or less.

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