JPH0323249A - Production of fiber-reinforced cement product - Google Patents

Abstract

PURPOSE:To improve strength by placing a fiber matte produced by allowing fibers to adhere to each other by means of a binder on a molding form and impregnating the above matte with cement mortar with a specific composition. CONSTITUTION:A fiber matte produced by allowing uniformly dispersed fibers, such as alkali glass fibers, to adhere to each other by means of 3-20wt.% binder and having >=5mm thickness and <=0.1g/cm<3> bulk density is placed on a molding form. Subsequently, cement mortar produced by blending 100 pts. (by weight, the same applies to the following) cement, 50-150 pts. silica sand in which average grain size is regulated to <=200mum and 20wt.% of the grains are passed through a 105mum sieve, 10-50 pts. water, and 0.8-3 pts. water reducing agent is placed on the fiber matte while applying vibrations and impregnated into the fiber matte, followed by hardening. By this method, fiber-reinforced cement products can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing fiber-reinforced cement products. [Prior Art and its Problems] Cement, along with iron, is a basic material for construction and civil engineering. can be,
Currently, approximately 70 million tons are used annually in Japan. The reason why cement has come to be used in such large quantities is because of its excellent properties such as high compressive strength, excellent weather resistance, and the ability to harden easily by simply mixing it with water. This is because it is cheap. However, even with such excellent properties, cement has the problem of low tensile strength, and various methods are being considered to solve this problem. One of these efforts is to try to reinforce cement with fibers such as glass fiber, carbon fiber, aramid fiber, vinylon, etc., and these efforts are now being put into practical use. Among them, glass fiber reinforced cement (hereinafter simply referred to as GRC) is the most commonly used cement, which is used as interior and exterior materials for buildings, pillar covers, beam covers, soundproof walls, cable troughs, sewage pipes, planters, handrails, unit toilets, etc. It is widely used in the fields of architecture and civil engineering. GRC's precept methods include the spray method, premix method, and mortar injection method, each of which is used depending on the purpose and application. The spray method is the most effective method, in which cement mortar pumped by a mortar pump and glass fibers cut by a roving cutter are discharged by air pressure from different outlets of a spray gun, reaching the formwork surface, and then compacted by a defoaming roller. Widely adopted. This method has high strength because a skilled worker operates a spray gun and laminates GRC in layers, so it is ideal for making products with high added value with thin walls and complex shapes. , when making thick-walled products or products with relatively simple shapes, such as plate-shaped products,
It takes too much time and costs too much. In the spray method, it is possible to reduce the cost of spraying by introducing robots for the spraying work. However, the biggest problem with the spray method is the entrainment of air bubbles caused by spraying fibers and mortar with air pressure, and it is no exaggeration to say that the quality of GRC depends on the degree of compaction by the defoaming roller. However,
It is impossible for robots to perform this compaction satisfactorily.

In recent years, automatic spraying methods have been put into practical use, in which a traversing spray gun is used to spray onto formwork on a continuously moving conveyor, but even with this method, defoaming either relies on manual labor or is insufficient. The reality is that it is hardened in this state. The premix method is a method in which mortar and short fibers are mixed in advance with a mixer and then poured into a designated mold, and vibration is generally applied after pouring. This method can save labor compared to the spray method, and the molding cost is accordingly low, but the reinforcing efficiency is low because the fibers are randomly oriented in three dimensions.
Furthermore, due to the damage to the fibers during kneading, the strength of the GRC obtained is approximately half that of the spray method. Therefore, it cannot be applied to parts such as exterior wall materials of buildings, especially curtain wall panels, which could lead to a major accident in the unlikely event of an accident. Another problem with the premix method is that premix mortar containing several percent fiber has extremely poor fluidity compared to plain mortar. This becomes a big problem when supplying premix mortar to the formwork and when distributing the premix mortar to every corner of the formwork. In order to solve this problem, the premix method has no choice but to increase the water/cement ratio, which further deteriorates the physical properties of GRC. The mortar injection method is a method in which a glass fiber continuous strand mat is attached to a formwork, the formwork is sealed, and mortar is press-fitted. This method uses not premixed mortar;
Since it is a brain mortar, it is easy to feed into the formwork, and impregnation with cement and mortar can be easily achieved by press-fitting, which solves the problems with the premix method mentioned above. However, in the mortar injection method, the proportion of formwork required for GRC products is high, and expensive closed formwork must be introduced.Even if the molding cost can be reduced through mechanization and labor saving, the total cost is still lower than that of the conventional method. The result is no different from the spray method or premix method. Furthermore, when closed formwork is used, it is not possible to observe or check the state of cement mortar placement and inclusion, so defects that could be prevented in advance with open formwork may occur when the formwork is removed. There are also cases where it appears later. Therefore, the present inventors proposed a new manufacturing method that eliminates the defects of the above-mentioned manufacturing methods for GRC products.
I proposed it as issue 05. The manufacturing method disclosed in this patent involves uniformly dispersing fibers and adhering them to each other with a binder, with a thickness of at least 51 mm and a bulk density of 0.5 mm. The method includes the steps of placing a fiber mat of Ig/cm or less on the formwork surface, placing cement mortar, impregnating the fiber mat with cement mortar by applying vibration, and hardening the cement mortar. This is a manufacturing method for fiber-reinforced cement products. According to the manufacturing method of the patent, the bulk density of the fiber mat is 0. I
g/cs or less, and by providing a certain amount of voids between the fibers, we aim to eliminate uneven distribution of cement mortar in the fiber mat. However, in a fiber mat with the above-mentioned bulk density, silica sand with a relatively small particle size easily passes between the fibers, but silica sand with a large particle size or silica sand with a small particle size but agglomerated can clog the fibers. It becomes difficult for cement mortar to permeate through the mat, and silica sand tends to accumulate on the upper layer of the fiber mat, and so-called cavities occur inside the mat, where the cement mortar is not impregnated. Therefore, even if we try to move the silica sand to the lower layer of the fiber mat by lengthening the vibration process or increasing the vibration width, the result is that the distribution of cement mortar will be uneven between the upper layer and the lower layer. However, there is a problem in that the strength of the upper and lower layers of the GRC product after curing differs, making it difficult to obtain a product as designed. In addition, if the vibration process is made longer or the vibration amplitude is increased in this way, when tiles are placed between the formwork surface and the fiber mat to produce tiled panels, the tiles may come into contact with each other and be damaged. arise. The particle size of the silica sand has a large effect on the impregnability of the cement mortar into the fiber mat, but good impregnation cannot be obtained simply by selecting and using silica sand with a small particle size. In other words, when using silica sand with a small particle size, the surface area of the entire silica sand becomes large, which impairs fluidity. In order to increase fluidity, it is possible to increase the amount of water in the cement mortar, but if the amount of water increases, the drying shrinkage of the GRC product will increase, making it easier to warp and making it impossible to obtain a high-strength product. ．． [Objective of the Invention 1] The present invention was made to solve the above-mentioned conventional problems, and impregnation of cement mortar into the fiber mat is carried out quickly, and when it is made into a GRC product, no warpage occurs. High strength GR. The purpose is to provide a manufacturing method for C￥A products. [Means for Solving the Problems] The method for manufacturing GRC products of the present invention attempts to achieve the above objectives by using silica sand with a small particle size, suppressing cement agglomeration, and using a large amount of water reducing agent. In other words, the process includes a step of installing a uniformly distributed mat on the mold surface, a step of impregnating the fiber mat with cement mortar by pouring cement mortar and applying vibration, and a step of hardening the cement mortar. The raw material composition for mortar is 5 parts of silica sand to 100 parts by weight of cement.
0 to 150 parts by weight, 3a to 50 parts by weight of water, water reducing agent 0.8
The silica sand is characterized by having an average particle size of 200 μm or less, and particles that pass through a 105 μm sieve account for 20% by weight or more of the total. [Function] Are the fibers in the fiber mat used in the present invention in the in-plane direction? It is made by dispersing them in one layer and adhering them to each other with a binder. The type of binder for adhering the fibers is not particularly limited, but includes powdered and liquid polyester resins, epoxy resins, vinyl acetate resins, acrylic resins, and ethylene i.
3: Acid vinyl resin, phenol resin, etc. can be used, and the optimum amount to be applied is 3 to 20% by weight based on the 5 fibers. Any type of fiber can be used, but alkali-resistant glass fiber containing crushed ZrO, which is inexpensive, easy to work with, and alkali-resistant, can be used to make cement mortar into a mat. Immediate impregnation becomes impossible. It is desirable that the thickness of the mat be 5 mm or more, and a thickness of 5 to 25 mm is optimal. However, the wall thickness of the mat is determined from the wall thickness required for a GRC product, and the reason for setting it above 5III1 here is that if it is less than 5m1, it will deflect more when bending stress is applied. This is because if cracks form in the material, it poses a problem as a building material. Next, we will explain the raw material composition of cement mortar and the reasons for limiting the silica sand particle size distribution. Note that parts by weight here refer to cement 1
The value is for 00 parts by weight. Silica sand is added as aggregate, and if it is less than 50 parts by weight, G
The amount of RC shrinkage is large, making it easy for products to warp and crack. If it exceeds 150 parts by weight, the reinforcing efficiency of the fibers will deteriorate, resulting in a decrease in the strength of the GRC. Furthermore, if the average particle size of the silica sand is larger than 200 μm and the number of particles passing through a 105 μm sieve is less than 20 parts by weight, the cement mortar will not be sufficiently impregnated into the fiber mat, and voids of unimpregnated portions will occur in the GRC. If the water content is 30 parts by weight or more, the cement mortar will not be impregnated into the fiber mat, and if the water content is 50 parts by weight or more, the amount of shrinkage of the GRC after curing will increase, causing warping and cracking, resulting in a weakened strength. A water reducing agent has the effect of suppressing cement agglomeration, and by mixing 0.8 parts by weight or more of this water reducing agent, even if silica sand with a small particle size is selected and used, it can be used without using a large amount of water. It is possible to improve the impregnation of cement mortar into fiber mats. However, if more than 3 parts by weight is used, component separation will occur in the cement mortar and it will be prone to breathing. As the vibration method in the present invention, all known vibration methods such as vibration from the top, vibration from the bottom, and lateral vibration are possible, but vertical vibration is preferably performed using a table vibrator. In addition, it is more preferable to use a table vibrator to apply vertical vibration having a horizontal direction, for example, a direction from the center of the table vibrator toward the outer end. The reason why vertical vibration with horizontal directionality is preferable is that when cement mortar is poured onto a fiber mat that has been placed on a formwork in advance and is formed by applying vibration, the cement that has entered the fiber mat once This is because mortar is difficult to spread laterally due to normal vibrations, and it is easier to move cement mortar laterally by adding horizontal directionality to the vertical vibrations of the table vibrator. In the present invention, cement refers to Boltland cement,
Includes known cements such as alumina cement, blast furnace cement, quick hardening cement, and low alkaline cement. Further, the process of curing cement mortar includes known curing methods such as indoor curing, underwater curing, and steam curing. [Examples] The present invention will be described below based on Examples, but the present invention is not limited thereto. The GRC board was prepared as follows. A steel formwork is placed on top of the MinwitJi table vibrator, and a length IOc is placed inside the formwork.
Made by adhering alkali-resistant glass fibers to each other with a polyester resin Table 1 and following Tables below Shiraki Mighty 150J (product name) manufactured by Kao Corporation Next, cement mortar shown in Table 2 using the silica sand shown in Table 1 above. A GRC board was prepared by adding cement mortar in an amount sufficient to fill the mat, and then applying vibration at 3600 rpm for 1 minute. The next day, the degree of impregnation of the demolded cement mortar was observed, and the bending strength of the GRC board after 28 days of age was measured. The results of those observations and measurements are shown in the lower column of Table 2. From the results shown in Table 2, Examples 1 to 5 of the present invention (, t [Effects of the Invention] According to the method for producing fiber reinforced cement of the present invention described above, the mortar cement is well incorporated into the fiber mat. , it is possible to produce high-strength GRC plates without warping.

Claims (1)

[Claims] (1) Made of uniformly dispersed fibers bonded together with a binder, with a thickness of at least 5 mm and a bulk density of 0.1 g.
/cm or less on the formwork surface, placing cement mortar and applying vibration to impregnate the fiber mat with cement mortar, and hardening the cement mortar. The raw material composition is 100 parts by weight of cement and 50 parts by weight of silica sand.
~150 parts by weight, 30-50 parts by weight of water, 0.8~ of water reducing agent
3 parts by weight, and the silica sand has an average particle size of 20
A method for producing a fiber-reinforced cement product, characterized in that particles having a size of 0 μm or less and passing through a 105 μm sieve account for 20% by weight or more of the total.