SU833757A1 - Method of making asbestos-cement articles - Google Patents

Description

The invention relates to construction materials, in particular, to the production of sheet-metal asbestos-cement products. A known method of forming asbestos cement sheet products, including the preparation and filtering of asbestos cement slurry, compacting the asbestos cement layer, layer-by-layer shaping of the sheet blank on a format drum, removal and moistening of the surface of the blank, at the rate of increasing: not the total moisture content of the blank by 1-5% solution of the additive before processing, nescrimer before profiling l. However, in the known method, additional moistening of the preform is accompanied by slight swelling, which increases the air porosity of the product, reduces the effectiveness of the use of a surfactant additive and the quality of the products after heat and moisture treatment. There is also known a method of manufacturing sheet asbestos-cement products, including preparing an asbestos-cement suspension, filtering it and compacting the asbestos-cement layer, layer-by-layer shaping the sheet blank on a format drum and moistening the second layer of the blank with an additive in strips connected by lines at future wave crests, and then processing it This method does not allow to reduce the air porosity of products and to improve their quality after heat and humidity treatment. This is due to the fact that the additional moistening of the workpiece on the format drum leads to an increase in the amount of air trapped in it, as well as to destructive phenomena associated with squeezing out additional moisture in the press section of the machine. The closest to the proposed method is the manufacture of asbestos products by molding the curing product by steaming and storing it in air-moisture conditions, followed by impregnation of aluminum sulphate for 50-60 I in an 18-20Z solution. The disadvantage of this method is also the increased porosity of the products leading to a decrease in their quality. The goal of the acquisition is to bend strength. This goal is achieved by the fact that in the method of manufacturing asbestos-cement products, which includes the molding of the workpiece, the impregnation with the additive solution and the hardening, the impregnation with the additive solution is carried out before hardening and after it is pressed under a pressure of 0.1-1.0 MPa on a substrate moistened with the same solution. Example 1. Dp sample preparation by the proposed method are mixed the following components, wt. asbestos of the Dzhetygara deposit P-5-50-15, cement of the Voskresensk cement plant — 85. A suspension with a concentration of 10 wt.% is prepared from this mixture. The suspension is moved for 30 minutes at. Samples were molded using the vacuum-suction method. Decorated samples with dimensions of 30x130 mm are immersed in a 40% calcium chloride solution (hardening accelerator) heated to 40 ° C, and they are held there until the release of air from them stops. After that, the samples are pressed to their previous thickness in a transparent, single-length-molded mold at a pressure of 0.1 MPa, each sample being separated from the bottom of the press mold and punch with cloths moistened in calcium chloride solution. Some of the samples prepared in this way are tested, and the remaining samples are steamed for 3 hours at. After the steaming, a part of the samples are tested, and the remaining samples are solid under air-humid conditions and tested at the age of 7 days. PRI mme r.2. Dp of obtaining samples for the proposed method mix the following components, aeq.%: Asbestos of Dzhetygara deposit P-5-50-10, cement of Voskresensky cement plant - 90. Prepare samples as in example 1. Molded samples are immersed in a solution of surfactant, sulfite alcohol stillage (sowing) with a concentration of 30%, heated before and kept there until the air is released from them. Samples were pressed at a pressure of 0.5 MPa. The conditions of hardening and testing of samples are similar to those given in Example 1. EXAMPLE 3. To prepare samples using the proposed method, the following components are mixed, wt.%: Asbestos from the Dzhetygarinsky Field P-5-50 - 15, cement from the Voskresensky Cement Plant - 85 Samples are prepared as in example I. Molded samples are immersed in a solution heated to 90 ° C and containing a hardening accelerator, calcium chloride (4 p% solution), and a surfactant sulfite-modified meta-cresol. melamine formaldehyde resin (MKMFS). and keep them there until the termination of air from them. The pressing of the samples was carried out at a pressure of I MPa. The curing and testing conditions of the samples are similar to those shown in Example 1-. EXAMPLE 4: Dp of obtaining samples according to the proposed 1. The method is used to mix the following components, wt.%: Asbestos from the Dzhetygara deposit P-5-50 - 15, cement from the Voskresensky cement plant - 85. Prepare samples similar to example 1. Molded samples immersed in a 20% solution of aluminum sulphate heated to, and held therein until the release of air from them is stopped. Pressing is carried out at a pressure of 0.5 MPa under conditions similar to example 1. The conditions of hardening and testing of samples are also similar to those shown in example 1. Example 5. DP sample preparation by the proposed method is mixed with the following components, wt.%: Asbestos of Dzhetygara deposit P-5-50 - 15, cement of Voskresensky cement plant - 85. Forms the samples as in example 2. Molded samples are immersed in 40% solution calcium flap, heated to 60 ° C, and kept there until the cessation of air from them. The pressing of the samples was carried out at a pressure of 1.2 MPa under conditions similar to example 1. The conditions of hardening and testing of the samples are also similar to those shown in example 1. EXAMPLE 6 To prepare the samples using the proposed method, the following components are displaced, wt% : Asbestos of the Dzhetygariysky field P-5-50 - 15, cement of the Voskresensky cement plant - 85, Forms samples similar to the example. The formed specimens are immersed in a 40% solution of calcium chloride heated to, and held in it until the release of air from them is stopped. Compression of samples to the previous thickness is carried out at a pressure of 0 MPa, but without a drip-liquid substrate (the gasket from a technical solution is not moistened with calcium chloride solution). The setting conditions and the test conditions of the samples are similar to those given in Example I.

The test results for all six examples are given in the table.

Chloride

Calcium 0.1 40 0.16 0.036 3.6

0.5 60 0.19 0.048 2.80

PRS

0.23 0.060 1.81

0.18 0.044 2.94

0.19 0.062 1.70

0.16 0.034 4.9 From the table it can be seen that the proposed method for the manufacture of asbestos cement products reduces the air porosity of freshly formed asbestos cement by 4.4-8v, 3 times. The strength of the bending of steamed asbestos cement increases and the bulk density decreases. The use of aluminum sulfate reduces air porosity and slightly improves the quality of asbestos cement .1.5134,22,201.78

1,5537,42,281,83

1.6241.52,341.90

156036,22,20180

168043,02,35193

149033.2. 2,11175 products, however, its effectiveness is lower than, for example, calcium chloride. This is due to the fact that aluminum sulphate forms in the body of asbestos cement an increased amount of stringite, which during steaming goes into monosulfoaluminate. This transition is carried out with a loss of strength of the material. An increase in the CBbmie pressing pressure of 1.0 MPa leads, as is desired from Example 5 and Example 3, to a sharp drop in the plasticity coefficient of the asbestos-cement billet, despite the fact that in this case other physical and mechanical indicators of asbestos-cement occur. A decrease in plasticity ratio means that the wolfing of such blanks will be accompanied by (Forming an increased number of cracks on the crests of the waves. This will inevitably lead to a decrease in the quality of the products, although this is not observed on the volleyable samples.

With a pressing pressure of less than 0 MPa, it is not possible to bring the samples to the same thickness (the thickness of the samples obtained is always greater than the outcome of the mix). As a result, a bonded asbestos cement sheet will contain a large number of cracks along the ridges and waves springs (since tensile stresses arising in bending asbestos cement increase rapidly with its thickness)

Pressing an asbestos-cement sample on an unmoistened gasket from a technical one (Example 6) results in an increase in the air porosity of the sample (Example 1). This is due to the fact that when the pressure is removed, some expansion of the sample occurs due to

its elastic deformations, and inside the asbestos cement pressure drops below atmospheric. As a result, an additional amount of moisture is absorbed from the moistened drop-liquid substrate into the sample, and its air porosity does not change. When the substrate is not moistened, an additional amount of air gets into the sample, and its air porosity grows.

Claims (3)

1. USSR author's certificate No. 310881, cl. From 04 To 15/16, 1969. 2. USSR author's certificate number 539852, cl. From 04/15/16, 1975. 3. USSR author's certificate number 601251, cl. From 04 to 15 / 16i 1975.