JPS6363700B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for strengthening and repairing a slate roof whose physical properties have deteriorated over time. (Prior Art) Today, slate (6 to 12 mm thick), which is made of cement mixed with asbestos and other fibers, is widely used as a roofing material for factories, railway platforms, warehouses, etc. Generally, the lifespan of this type of slate is said to be 20 years, but in places with harsh climatic and atmospheric conditions, such as coasts and industrial areas, it is seen that its strength decreases markedly after more than 10 years. .
Particularly in recent years, the increase in the number of industrial furnaces that burn heavy oil and the number of automobiles that use gasoline as fuel has led to an increase in the generation of sulfur dioxide gas, and the cement content in the slate dissolves in the sulfur dioxide, causing the physical properties of the slate to deteriorate at an accelerated pace. It's progressing. Many asbestos powders are attached to the surface of deteriorated asbestos slate in an unstable state, and considering that asbestos is designated as a strong carcinogen, measures to prevent its dispersion should be implemented immediately. It must be. (Problem to be solved by the invention) One of the solutions is to replace the roof with new slate, but 1) Complete curing with sheets, etc. is required to prevent dirt inside the building and damage to machinery and equipment. It is. 2) Factories, etc. will have to close for several days for roof replacement work. 3) It is difficult to dispose of a huge amount of deteriorated slate waste. 4) Most asbestos is imported, and its price is high, which goes against the national policy of resource conservation. There are numerous problems. As a further step, several methods and materials for repairing and regenerating deteriorated slate are introduced. One of the methods that has been widely used recently is A) cationic SBR latex/cement mixing method. This method involves thoroughly washing the deteriorated slate roof with water, mixing a cationic styrene-butane diene rubber latex into a mixture of cement and silica sand, and using this to spray the slate onto the slate to increase its strength. , construction thickness is
It is about 0.5 to 0.2 mm [This is based on the "Manufacturing method of cationic synthetic rubber latex" by Japan Synthetic Rubber Co., Ltd.
A patent application was filed as JP 48-10615 and the patent application was published]. In addition, B) The deteriorated surface is washed with high-pressure water and the deteriorated slate is impregnated with a solution containing a sodium silicate-based aqueous solution, a lithium hydroxide aqueous solution, lithium silicate, and an alkali metal component, which is called the B) Refreet method. There is also a method to strengthen slate [this has been patented by Nissan Chemical Industries, Ltd. as a ``binder'', ``coating bonding method'', and ``method for preventing surface deterioration of inorganic materials'', and has been patented by the Japanese Patent Publication Show.
No. 50-30658, Special Publication No. 50-2162, Special Publication No. 53-
The patent application was published as No. 19609]. Furthermore,
Although there is a method of combining the above-mentioned cationic latex cement spraying with the refrigeration method, in any method of regenerating deteriorated slate, if the penetrating binder penetrates into the slate sufficiently, an increase in the strength of the slate can be expected. . However, as mentioned earlier, the cement content in the slate has been dissolved and flowed out by sulfurous acid, etc., and a layer of fine asbestos is stacked up in a network shape to a thickness of several mm, so the surface layer of the slate is mixed with synthetic resin. With the cement resin paste, only water is separated, making it difficult to adhere to the remaining slate base, and since the water is separated, the strength of the resin paste is insufficient. Also, although sodium silicate paste is a material that penetrates well into deteriorated slate, the strength of the paste is greatly influenced by the quality of washing with water. Therefore, a sufficient improvement in strength cannot be expected in slate used for factory roofs, which generate a large amount of dust. In order to completely implement these methods, it is essential to thoroughly clean the surface of the slate to be repaired using high-pressure water washing, but since slate is not a flat plate but has a corrugated shape, complete cleaning is not easy. It is extremely difficult to clean slate, especially on slates where dust has accumulated from bauxite smelting plants and steel mills. Also, high-pressure water washing can further damage deteriorated slate, making cleaning work dangerous. The present invention has been developed in view of the above, and is completely different from the conventional construction method described above, in which new slate is formed using cement mortar mixed with synthetic resin emulsion, and deteriorated slate is used as a formwork to completely clean the slate. The aim is to provide a new reinforcement repair method that can solve the difficulties of repair work in one fell swoop and can be easily and reliably constructed without stopping work at the factory. (Means for Explaining Problems) The structure of the present invention will be explained based on the attached embodiment drawings. Fig. 1 is a sectional view showing a slate laminated structure formed by a construction method as an embodiment of the present invention. FIG. 2 is a sectional view showing a slate laminated structure formed by a construction method as another example. That is, the method for strengthening and repairing slate roofs of the present invention uses slate whose physical properties have deteriorated over time as a formwork for base panels in slate roof structures, without essentially cleaning the upper surface of the slate. The gist of this method is to spray coat cement mortar mixed with synthetic resin emulsion and fibers to a thickness of 2 to 6 mm on this upper surface to form a new slate layer. More specifically, acrylic copolymer resin emulsion,
Synthetic resin emulsion such as vinyl acetate copolymer emulsion or synthetic rubber latex is mixed with cement, fibers, aggregate, etc. to make a reinforcing repair material for slate thin layer finish, and the deteriorated slate is used as formwork for base panels. The point is that it can be applied to the surface of the slate by spraying it to a thickness of 2 to 6 mm, and a new slate layer can be formed regardless of whether it is in close contact with the deteriorated slate. Regarding slate roof 1, Building Standards Act Enforcement Ordinance No.
25 on the steel frame 2 at the fixed load based on the 84-article structural calculation.
There is a regulation for the permissible load of Kg/ ^m2 , and the heaviest large wave asbestos slate board is 12.3Kg/ ^m2 , so slate reinforcement repair material of 12.7Kg/ ^m2 is installed between them. If there is room for the load to be used and the specific gravity of cement mortar mixed with synthetic resin is approximately 2.0, the maximum construction thickness will be approximately 6.3 mm. Furthermore, the weight of the deteriorated slate 10 is reduced by the amount lost, and the degree of safety increases accordingly. The cement used in the present invention is generally widely used such as Portland cement and white cement. Examples of acrylic copolymer resins include emulsion polymers of polymethyl methacrylate, polyalkyl methacrylate, polyethyl methacrylate, methyl methacrylate-styrene, and methyl methacrylate/alphamethylstyrene copolymers. In addition to acrylic copolymers, vinyl emulsions such as vinyl acetate, vinyl oxide, Beover, and ethylene-vinyl acetate copolymers, as well as synthetic rubber latexes such as styrene-butadiene, chloroprene, and NBR, have weather resistance. It is preferred because of its water resistance. Furthermore, the above-mentioned fibers include alkali-resistant ceramic/glass fibers with a length of 1 to 3 cm.
Thickness of 30 to 50 denier, nylon,
Fibers such as vinylon and polypropylene may also be used. Generally 0.3~ for ceramic/glass fiber
20-40 denier with a length of 0.6 cm is easy to use.
In addition to the above-mentioned synthetic resin emulsion and cement, there are aggregates and additives that can be mixed as a slate reinforcing and repairing material. As aggregates, silica sand of size 3 to 7, lightweight aggregates such as perlite and pumice, and fine aggregates such as river sand and crushed stone powder are used, but dry silica sand of size 4 to 6 is used. easy. Further, depending on the situation, water reducing agents, penetrants, stabilizers, thickeners, antifoaming agents, and the like may be used in combination as additives, but among these, water reducing agents are the most important. When spraying, it is preferable to use an appropriate amount of a water-reducing agent such as a lignin derivative or a water-soluble salt of a betaine or indazoline surfactant, since the smaller the water content, the smaller the shrinkage and the lower the incidence of cracks. This makes water 40~
It can be suppressed to 45% by weight. Care must be taken because if too large a quantity is mixed in, the stability of the synthetic resin emulsion will deteriorate. When transporting this slate reinforcement repair material to high places with a hose, poval, sodium alginate, Metrose, etc. are used as thickeners to prevent the mixture from separating. There is no need to add it if it is sent to a height that does not cause separation. The weight ratio of the cement, synthetic resin emulsion, aggregate, and fibers to be mixed is 5 parts as the resin solid component of the acrylate resin emulsion per 100 parts of cement.
~40 parts, aggregate in the range of 150-400 parts, and fibers in the range of 0.5 parts or less. If the resin solid content of the acrylate resin emulsion is less than 5 parts per 100 parts of cement, the moisture in the sprayed mortar will evaporate quickly and the strength will deteriorate, and if it exceeds 40 parts, it will be too soft and will be expensive. It becomes uneconomical. If the aggregate is less than 150 parts by weight of cement (to 100 parts of cement, the same shall apply hereinafter), there is too much cement and cracks are likely to occur after drying.
If it exceeds 400 parts, there will be many voids and drying will be too rapid, making it impossible to obtain sufficient resin mortar strength. The fibers used should be used in a weight ratio of less than 0.5 parts to cement; if this exceeds this, they will form lumps in the hose during spraying, making transportation difficult. The viscosity of mortar is moderate when the slump is less than 16 cm and up to 32 cm; if the slump exceeds 16 cm, the viscosity is too high and it becomes difficult to transport with a hose or spray. Furthermore, if the slump is less than 32 cm, the solid content such as aggregate and the liquid content such as synthetic resin emulsion tend to separate in the hose and become clogged in the hose, making construction impossible. The gist of the method for repairing a deteriorated slate roof 1 using a slate reinforcement repair material mixed with an appropriate component ratio and viscosity as described above is to repair the deteriorated surface layer 1.
1 is used as a base panel, and the above-mentioned reinforcing repair material is sprayed onto the upper surface thereof, and a new slate 20 made of the above-mentioned reinforcing repair material is formed by allowing the old slate to be separated from the old slate 10. . The specific steps are 1. Take safety measures such as setting up fishing nets and installing footboards in order to prevent repair workers from falling. 2 If the hole is a large hole (approximately 20 to 30 cm or more), cut a piece of slate of the same shape to a size larger than the hole and apply adhesive such as cement paste to the back side of the hole. Press it against it to close it. In the case of a small hole, cut cheesecloth, glass cloth, or punch carpent to an appropriate size, dip or coat it in the above-mentioned spray reinforcement repair material, and stick it to the hole. 3. Inspect the bolts 3 and nuts 4 that hold the old slate 10 in place, tighten any loose ones appropriately, and replace any that have fallen off with new bolts and nuts. 4 As shown in Fig. 1, a bell-shaped cap 5 with a hole for the bolt to pass through is filled with spray reinforcement repair material, and the bolts 3 and nuts 4 are coated and waterproofed from above. (This step may be carried out in the final step as shown in Figure 2.) 5. Use a pressure tank and compressor for general mortar spraying as a spraying machine, and use compressed air at the nozzle. Mix liquid reinforcement repair material and perform spraying construction. Pressure feeding can be done using a piston ring and a diaphragm pump, and the pressure is 50~
The pressure is 380Kg/cm ² , and the compressor is used at a pressure of 2 or more and about 4 to 7Kg/cm ² . Construction capacity is
0.3-1.0m ³ /Hr with average thickness of 5mm 60-200
m ² /Hr is the range that can be applied, and if the speed exceeds this speed, it is difficult to spray to a uniform thickness, and it is also dangerous when using scaffolding at high places. The spraying procedure is to perform reciprocating spraying at a 45° angle to the wave-shaped undulations of the slate.
Obtain the specified thickness within 6 mm. Construction thickness is 1-2mm
Care must be taken as the parts shown are not strong enough. (Function) In the reinforcement repair method described above, since the deteriorated slate 1 is used as a formwork for the base panel without being cleaned, the construction is simple and economical. Furthermore, since cement mortar mixed with synthetic resin emulsion and fibers is used as the reinforcing repair material, the newly formed slate layer 20 is
It maintains the image of slate and is said to be extremely strong. (Example) A reinforced repair material was prepared with the formulation shown in Table 1 below,
A mortar feeder and two compressors are used to apply a compressor to the top surface of the deteriorated slate roof at a rate of approximately 6 kg/ ^m2 .
It was sprayed at a speed of 150m ² /Hr.

[Table] After curing for 28 days, we randomly sampled 5 points from ^100m2 and inspected the thickness, and found that the thickness was 2.5mm.
They were 3.1mm, 3.2mm, 3.5mm, and 3.6mm. These tensile strengths were within 25 to 30 Kg/cm ² , which was more than twice as high as the tensile strength of new asbestos slate, which was 10 to 12 Kg/cm ² . By the way, the slate 10 used for repair is 18
It was used on the coast of Amagasaki City, Hyogo Prefecture for many years, and the tensile strength of this deteriorated slate is 0 to 2.
It had decreased to Kg/ ^cm2 . The tensile strength of this slate reinforced with cationic styrene-butadiene mortar cement is 8 to 10 Kg/cm ² .
The tensile strength of the material reinforced with a sodium silicate type agent was 6 to 8 kg/cm ² . (Effects of the Invention) As described above, according to the slate roof reinforcement repair method of the present invention, there is no need to remove deteriorated slates, and therefore there is no need to suspend work at the factory, making it simple and economical. It is possible to strengthen and repair slate roofs, and the resulting new slate layer is extremely strong, which has a significant effect on the industry.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a slate layered structure formed by a construction method as an embodiment of the present invention, and FIG. 2 is a slate layered structure formed by a construction method as another embodiment of the present invention. FIG. Explanation of symbols, 10... Deterioration slate, 11...
Deteriorated slate surface layer, 20... new slate.

Claims (1)

[Claims] 1 In slate roof structures, slate whose physical properties have deteriorated over time is used as formwork for base panels, and synthetic resin is applied to this top surface to a thickness of 2 to 6 mm without essentially cleaning the top surface. A method for strengthening and repairing slate roofs, which is characterized by spraying cement mortar mixed with emulsion and fibers to form a new slate layer.