Accelerating agent, spraying material and spraying method employing it

Abstract: An accelerating agent which comprises calcium aluminate glass or calcium aluminosilicate glass, aluminum sulfate and pozzolanic material as effective components.

Description: The present invention relates to an accelerating agent, a spraying material and a spraying method employing it. Particularly, it relates to an accelerating agent which improves the quick setting property and adhesion of concrete sprayed to a ceiling or wall of a tunnel or pit, a spraying material comprising such an accelerating agent, and a spraying method employing such a spraying material. For the purpose of the present invention, a spraying concrete is a general term which covers a cement paste, mortar and concrete for spraying. Heretofore, it has been common that during excavation of a tunnel, a spraying concrete is sprayed on the excavated surface for lining to prevent falling of the excavated surface or collapse due to spring water. In tunneling work, it has been common that primary spraying is carried out to apply a spraying concrete to an excavated surface, and then secondary lining is carried out to form a concrete wall on the applied surface. However, there is a recent trend to widely employ a single shell system whereby the work is completed by the primary spraying only. Spraying methods for a spraying concrete are generally classified into two types of dry system and wet system. The dry system spraying method is a method wherein a dry mixed mixture of cement, aggregate and an accelerating agent is transported by compressed air and immediately prior to spraying, water is added and mixed, followed by spraying from a nozzle to the surface to be treated. The wet system spraying method is a method in which concrete kneaded with water is transported, and during the transportation, an accelerating agent is added and mixed, followed by spraying from a nozzle to the surface to be treated. As the accelerating agent to be used for the spraying, a composition comprising calcium aluminate and an alkali metal carbonate or aluminate, a composition comprising calcined alunite, lime or an alkali metal carbonate, or a composition comprising an alkali metal carbonate, hydroxide, silicate and aluminate, has been proposed (e.g. JP-B-56-27457 or JP-A-60-260452). These accelerating agents usually contain an alkali metal component which shows a strong alkaline nature, such as sodium or potassium in the form of a hydroxide, a carbonate, a silicate or an aluminate, in order to attain quick setting. Such an alkali metal component is strongly alkaline, and when incorporated in the spraying concrete, it may cause an alkali-aggregate reaction depending upon the type of aggregate used. Thus, it had a problem that it was likely to adversely affect a concrete structure. Further, such a strongly alkaline substance is soluble in water, and if it directly contacts the skin of a worker, it causes a serious damage to the skin, whereby the working environment at the excavation site will be substantially deteriorated. Further, there has been a problem that it is likely to dissolve in soil water, thus leading to environmental pollution of the surrounding area. To solve such a problem, a setting accelerator comprising calcium aluminate, calcium sulfoaluminate and a basic aluminum salt, was proposed as an accelerator for spraying which contains substantially no or little alkali metal component (JP-A-8-48553). However, such an accelerating agent had problems such that the quick setting property was inadequate, and rebound of the sprayed concrete was substantial, the loss of material was accordingly substantial, and dust was likely to be formed. The present inventors have conducted an extensive study to solve such problems and as a result, have found that by using a certain specific accelerating agent, it is possible to obtain a spraying concrete which provides excellent quick setting property without deteriorating the working environment or the surrounding environment. The present invention has been accomplished on the basis of this discovery. That is, the present invention provides an accelerating agent which comprises calcium aluminate glass or calcium aluminosilicate glass, aluminum sulfate and pozzolanic material as effective components as defined by claim 1 and claim 2, respectively, such an accelerating agent wherein the pozzolanic material is at least one member selected from the group consisting of silica fume, meta-kaolin, blast furnace slag and fly ash, a spraying material which comprises cement and such an accelerating agent as effective components, a spraying concrete which contains such a spraying material as an effective component, and a spraying method which sprays such a spraying concrete. Now, the present invention will be described in detail with reference to the preferred embodiments. The accelerating agent of the present invention comprises calcium aluminate glass or calcium aluminosilicate glass, aluminum sulfate and pozzolanic material as effective components. The calcium aluminate glass (hereinafter referred to as CA glass) to be used in the present invention, is necessary to impart a quick setting property and is usually prepared by mixing CaO material and Al 2 O 3 material, heating the mixture at a high temperature of e.g. from 1,200 to 1,700°C by e.g. an electric furnace to form a melt of calcium aluminate mineral represented, for example, by 3CaO·Al 2 O 3 , 12CaO·7Al 2 O 3 or CaO·Al 2 O 3 , and quenching the melt for vitrification. The calcium aluminosilicate glass (hereinafter referred to as CAS glass) to be used in the present invention is usually the one prepared by mixing CaO material, Al 2 O 3 material and SiO 2 material likewise to form a melt of calcium aluminosilicate mineral and quenching the melt for vitrification. It is preferred to use CAS glass rather than CA glass, since CAS glass is excellent in the quick setting property. As a method for quenching the melt of calcium aluminate or calcium aluminosilicate mineral, a high pressure air method may, for example, be mentioned wherein the melt is blown by high pressure air for cooling. The CaO material may, for example, be quick lime, slaked lime, limestone or calcium carbonate. The Al 2 O 3 material may, for example, be aluminum oxide, bauxite, diaspore, feldspar or clay. The SiO 2 material may, for example, be silica sand, clay, diatomaceous earth or silicon oxide. It is preferred to use calcium carbonate, aluminum oxide or silicon oxide, which does not substantially contain an alkali metal component. The CaO content in CA glass is preferably from 35 to 55 wt%. If the content of CaO is outside this range, no adequate quick setting property may sometimes be obtained. The composition of CAS glass preferably comprises from 40 to 50 wt% of CaO, from 40 to 50 wt% of Al 2 O 3 and from 10 to 20 wt% of SiO 2 . If CaO or Al 2 O 3 is outside such a range, no adequate quick setting property may sometimes be obtained. If SiO 2 is less than 10 wt%, high strength may not last for a long period of time, and if it exceeds 20 wt%, the initial strength may sometimes be low. For the purpose of the present invention, glass is meant for "one having a glass transition point" as commonly used in the field of glass. CA glass or CAS glass may not necessarily be entirely glass and may be one having a vitrification ratio of at least 60%. If the vitrification ratio is less than 60%, no adequate setting property may sometimes be obtained. The vitrification ratio may be determined by heating a sample at 1,000°C for 2 hours and then gradually cooling it at a cooling rate of 5°C/min, whereby area S 0 of the main peak of crystal mineral is obtained by a powder X-ray diffraction method, and the vitrification ratio is obtained from this S 0 and the main peak area S of the crystal in the sample by using the formula of glass vitrification ratio = (1-S/S 0 )×100. The particle size of CA glass or CAS glass of the present invention is not particularly limited, but it is at a level with a Blaine value of from 3,000 to 9,000 cm 2 /g. If the Blaine value is less than 3,000 cm 2 /g, no adequate accelerating property may sometimes be obtained, and even if it exceeds 9,000 cm 2 /g, no further effects may be expected. The aluminum sulfate to be used in the present invention, is necessary to improve the quick setting property, and commercially available aluminum sulfate may be used for this purpose without being influenced by impurities which are usually contained. The aluminum sulfate is available in the form of an anhydrous salt or the one containing water of crystallization, and either type may be used as it is. It is not restricted by the degree of water of crystallization. The particle size of aluminum sulfate is not particularly limited, but it is preferably at a level with a Blaine value of from 3,000 to 9,000 cm 2 /g. If the Blaine value is less than 3,000 cm 2 /g, no adequate quick setting property may sometimes be obtained, and even if it exceeds 9,000 cm 2 /g, no further effects may be expected. The amount of aluminum sulfate is preferably from 20 to 50 parts by weight, more preferably from 30 to 40 parts by weight, per 100 parts by weight of CA glass. If the amount is outside this range, no adequate quick setting property may sometimes be obtained. The pozzolanic material to be used in the present invention is a material containing reactive silicic acid, which cures upon reaction with calcium hydroxide. For example, it may be an artificial material such as silica fume, meta-kaolin, blast furnace slag or fly ash, or a natural material such as diatomaceous earth or volcanic ash. In the present invention, it is preferred to use one or more pozzolanic materials selected from the group consisting of silica fume, meta-kaolin, blast furnace slag and fly ash with a view to improving the quick setting property and reducing rebound of the spraying concrete. The silica fume to be used in the present invention is so-called silica flower, silica dust or microsilica, which is an industrial by-product formed during preparation of metal silicon useful as a starting material for various materials, or a ferro alloy such as a ferro silicon to be used for adding an alloy element to steel, or to be used as an acid removing agent or a desulfurization agent for the preparation of steel. The ferrosilicon or metal silicon is produced by using silica or high purity quartz, scrap iron and a reducing agent such as carbon or coal, as starting materials, and heating such materials to a high temperature close to 2,000°C by an electric furnace. During the production, silicon oxide formed as an intermediate product is glassified, and a part thereof scatters in air and is oxidized in an exhaust duct and recovered in a dust collector in the form of SiO 2 . Such SiO 2 is silica fume which is spherical ultrafine particles. The chemical composition of silica fume varies depending upon the materials used, the method for the production or the type of the main products. However, the main component is amorphous SiO 2 , and the SiO 2 content is preferably at least 80 wt%. The specific gravity is usually from 2.1 to 2.2, the bulk density is from 250 to 300 kg/m 3 , and the powder degree is at a level of a BET specific surface area of from 15,000 to 25,000 m 2 /kg and the average particle size is at a level of from 0.1 to 0.2 µm. The amount of silica fume is preferably from 50 to 200 parts by weight, more preferably from 100 to 150 parts by weight, per 100 parts by weight of CA glass. If the amount is outside this range, no adequate quick setting property may sometimes be obtained. The meta-kaolin to be used in the present invention is obtained by calcining kaolinite at a temperature of from 500 to 600°C, whereby the main components SiO 2 and Al 2 O 3 have been made amorphous. The particle size of the meta-kaolin is preferably at a level with a Blaine value of at least 4,000 cm 2 /g, more preferably at least 6,000 cm 2 /g. If the Blaine value is less than 4,000 cm 2 /g, no adequate quick setting property may sometimes by obtained. The blast furnace slag to be used in the present invention is fine powder composed mainly of an aluminosilicate obtained by pulverizing or pulverizing and classifying a vitrified product obtained by quenching with air or water, a molten slag produced as a by-product during the production of pig iron from iron ore by a blast furnace. The blast furnace slag contains CaO, SiO 2 , Al 2 O 3 and MgO and preferably has a ratio of CaO/SiO 2 = 1.15 to 1.25, a ratio of (CaO+MgO)/(SiO 2 +Al 2 O 3 ) = 0.90 to 1.05, Al 2 O 3 being less than 15 wt%, and MgO being less than 5 wt%. The particle size of the blast furnace slag is preferably at a level with a Blaine value of at least 4,000 cm 2 /g, more preferably at least 6,000 cm 2 /g. If the Blaine value is less than 4,000 cm 2 /g, no adequate quick setting property may sometimes be obtained. The amount of the blast furnace slag is preferably from 50 to 200 parts by weight, more preferably from 100 to 150 parts by weight, per 100 parts by weight of CA glass. If the amount is outside this range, no adequate quick setting property may sometimes be obtained. The fly ash to be used in the present invention is the one obtained by collecting, by e.g. an electric dust collector, a spherical product formed by cooling a molten ash, during combustion of fine carbon powder, and it contains at least 60 wt% of SiO 2 and may contain Al 2 O 3 , Fe 2 O 3 and carbon. The particle size of the fly ash is preferably at a level with a Blaine value of from 3,000 to 6,000 cm 2 /g. If the Blaine value is less than 3,000 cm 2 /g, no adequate quick setting property may sometimes be obtained, and even if it exceeds 6,000 cm 2 /g, no further effects may sometimes be expected. The amount of the fly ash is preferably from 50 to 200 parts by weight, more preferably from 100 to 150 parts by weight, per 100 parts by weight of CA glass. If the amount is outside this range, no adequate quick setting property may sometimes by obtained. The total amount of alkali metals in the accelerating agent is preferably at most 0.75 wt% as calculated as sodium oxide (Na 2 O). If the total amount exceeds 0.75 wt%, an alkali-aggregate reaction will take place, which may adversely affect a concrete structure. The particle size of the accelerating agent is not particularly limited, since it depends upon the particular purpose or the method of use, but it is preferably at a level with a Blaine value of from 3,000 to 9,000 cm 2 /g. If the Blaine value is less than 3,000 cm 2 /g, the quick setting property tends to be low, and even if it exceeds 9,000 cm 2 /g, no further effects can be expected. The amount of the accelerating agent is preferably from 5 to 20 parts by weight, more preferably from 8 to 15 parts by weight, per 100 parts by weight of the spraying material comprising cement and the accelerating agent. If the amount is outside this range, no adequate quick setting property may sometimes be obtained. Here, the cement is not particularly limited and may, for example, be various Portland cements such as normal, high early strength and ultra-high early strength Portland cements. Further, it is possible to incorporate to the accelerating agent or the spraying material of the present invention, one or more additives selected from setting adjusting agents, AE agents, water-reducing agents, AE water-reducing agents, fluidizing agents, thickeners, water-holding agents, water-proofing agents, blowing agents, foaming agents, underwater non-separable admixtures such as methylcellulose, anti-freezing agents, rust-proofing agents, colorants (pigments), calcium compounds such as calcium hydroxide, polymer emulsions (latexes), fiber materials such as glass fibers, carbon fibers and steel fibers, and aggregates such as silica sand, natural sand and gravel, within a range not to impair the purpose of the present invention. To prepare the accelerating agent or the spraying material of the present invention, a conventional mixing and stirring apparatus such as an inclined barrel mixer, an omni mixer, a twin-cylinder mixer, a Henshel mixer or a Naughter mixer, may be used. The mixing may be carried out in such a manner that the respective materials are mixed at the time of application, or some or all of such materials may be mixed beforehand. Further, the aging method is not particularly limited, and a commonly employed aging method may be used. For the spraying operation of the spraying material of the present invention, either a dry spraying method or a wet spraying method may be employed. For example, at the time of spraying, using coarse aggregate having the maximum aggregate size of 10 mm, concrete may be blended to have a water/(cement+accelerating agent) ratio of 45% and a fine aggregate ratio of 60%. Further, as a wet spraying method, a spraying method may, for example, be mentioned, wherein water, cement, coarse aggregate and fine aggregate are mixed by a mixer to obtain a concrete, which is then transported under pressure by means of a spraying machine which is capable of transporting concrete under air pressure at a rate of from 10 to 20 m 3 /hr, an accelerating agent is separately transported under pressure by means of a compressor and mixed with the concrete in the vicinity of a nozzle of the spraying machine, followed by spraying. Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to such specific Examples. EXAMPLE 1 CaO material and Al 2 O 3 material, CaO material, Al 2 O 3 material and SiO 2 material, were mixed and melted in an electric furnace at 1,600°C. The melt thereby obtained was quenched by a high pressure air method, followed by pulverization to obtain CA glass and CAS glass having a Blaine value of 5,000 ± 200 cm 2 /g as identified in Table 1. 100 parts by weight of the prepared CA glass, 35 parts by weight of aluminum sulfate α and 125 parts by weight of pozzolanic material 1 ○ were mixed to obtain an accelerating agent. The alkali metal components in this accelerating agent were analyzed. The results are shown in Table 2. This accelerating agent was mixed with cement to obtain a spraying material, whereby the amount of the accelerating agent was 10 parts by weight in 100 parts by weight of the spraying material comprising cement A and the accelerating agent. 700 g of the obtained spraying material and 2,100 g of fine aggregate were blended and dry-mixed for 30 seconds at a low speed by means of a small size table top type mortar mixer. Then, 350 g of water was added thereto, and the mixture was kneaded for 10 seconds at a high speed to obtain cement mortar, whereupon the setting property of the cement mortar was evaluated by a proctor penetration resistance. The results are shown in Table 2. For the purpose of comparison, an experiment was carried out in the same manner as above by using a commercially available accelerating agent instead of the accelerating agent of the present invention. The results are shown also in Table 2. Materials used CaO material: Calcium carbonate, commercial product Al 2 O 3 material: Aluminum oxide, commercial product SiO 2 material: Silicon oxide, commercial product Aluminum sulfate α: Anhydride, Na 2 O eq. 0.04 wt% Pozzolanic material 1 ○: Silica fume, by-product from the production of ferrosilicon, specific gravity 2.20, specific surface area: 21.9 m 2 /g, Na 2 O eq. 1.4 wt% Commercially available accelerating agent: Main component: calcium aluminate, Na 2 O eq. 15.8 wt% Cement A: Normal Portland cement, Blaine value: 3,300 cm 2 /g, Na 2 O eq. 0.48 wt% Fine aggregate: River sand produced in Himekawa, Niigata-ken, Japan, specific gravity: 2.62 Water: City water Measuring methods Alkali metals: Measured by atomic absorption spectroscopy. Alkali metal components other than sodium were also calculated as Na 2 O, and the total amount of alkali metal components was represented by Na 2 O eq. Proctor penetration resistance: The mixture was kneaded in a constant temperature chamber of 20°C, and then it was immediately divided into two layers in formworks and quickly packed while pushing the mortar by a pushing rod, whereupon the proctor penetration resistance was measured every a predetermined period of time after introducing water, by means of a needle having a needle head area of 1/40 in 2 in accordance with ASTM C 403-65 T. CA glass and CAS glass symbol CaO (wt%) Al 2 O 3 (wt%) SiO 2 (wt%) Vitrification ratio (%) a 35 65 0 61 b 45 55 0 95 c 55 45 0 91 d 48 52 0 0 e 62 38 0 0 f 60 35 5 65 g 60 30 10 75 h 50 45 5 91 i 50 40 10 92 j 50 30 20 95 k 45 45 10 95 l 45 40 15 97 m 40 55 5 92 n 40 50 10 93 o 40 45 15 96 p 40 40 20 96 q 40 30 30 96 r 30 60 10 68 s 30 50 20 75 t 30 40 30 73 Test No. CA glass and CAS glass Na 2 O eq. (wt%) Proctor penetration resistance (psi) Notes 1 min 2 min 3 min 5 min 10 min 1-1 1 1.10 240 400 600 1120 1600 Comparative 1-2 a 0.69 1000 2200 3100 4200 - Invention 1-3 b 0.69 1500 2600 3300 4200 - Invention 1-4 c 0.69 1200 2100 2800 4000 - Invention 1-5 d 0.69 600 1100 2000 3300 3800 Comparative 1-6 e 0.69 500 800 1400 2400 3600 Comparative 1-7 f 0.69 1500 2300 2900 4000 - Invention 1-8 g 0.69 1200 2000 3200 4300 - Invention 1-9 h 0.69 1000 1800 2400 4100 - Invention 1-10 i 0.69 1500 2400 4000 - - Invention 1-11 j 0.69 900 1300 2600 4000 - Invention 1-12 k 0.69 800 1500 2800 4100 - Invention 1-13 l 0.69 1800 2500 4600 - - Invention 1-14 m 0.69 1100 1700 3000 4000 - Invention 1-15 n 0.69 1600 2400 4400 - - Invention 1-16 o 0.69 900 1600 2900 4200 - Invention 1-17 p 0.69 1700 2800 4700 - - Invention 1-18 q 0.69 1300 1900 2500 4500 - Invention 1-19 r 0.69 1200 2200 3400 4600 - Invention 1-20 s 0.69 1200 1800 2300 4000 - Invention 1-21 t 0.69 1000 2400 3000 4100 - Invention 1-22 2 15.8 680 880 1520 2100 4600 Comparative EXAMPLE 2 An accelerating agent was prepared by mixing 100 parts by weight of prepared CA glass, 35 parts by weight of aluminum sulfate α and 125 parts by weight of pozzolanic material 2 ○, and the alkali metal components in this accelerating agent were analyzed. The results are shown in Table 3. This accelerating agent was mixed with cement to obtain a spraying material, whereby the amount of the accelerating agent was 10 parts by weight in 100 parts by weight of the spraying material comprising cement A and the accelerating agent. 700 g of the obtained spraying material, 2,100 g of fine aggregate were blended and dry-mixed for 30 seconds at a low speed by means of a small size table top type mortar mixer. Then, 280 g of water was added thereto, and the mixture was kneaded for 10 seconds at a high speed to obtain cement mortar, whereupon the setting property of the cement mortar was evaluated by a proctor penetration resistance. The results are shown in also in Table 3. Material used Pozzolanic material 2 ○: Blast furnace slag, Blaine value: 8,000 cm 2 /g, Na 2 O eq. 0.55 wt% Test No. CA glass and CAS glass Na 2 O eq. (wt%) Proctor penetration resistance (psi) Notes 1 min 2 min 3 min 5 min 10 min 2-1 1 0.44 260 450 700 1300 1800 Comparative 2-2 a 0.29 1100 2400 3400 4600 - Invention 2-3 b 0.29 1700 2900 3600 4600 - Invention 2-4 c 0.29 1400 2300 3100 4400 - Invention 2-5 d 0.29 700 1300 2200 3700 3900 Comparative 2-6 e 0.29 600 900 1600 2700 3800 Comparative 2-7 f 0.29 1700 2600 3200 4400 - Invention 2-8 g 0.29 1400 2200 3600 4700 - Invention 2-9 h 0.29 1100 2000 2600 4300 - Invention 2-10 i 0.29 1700 2700 4400 - - Invention 2-11 j 0.29 1100 1500 2900 4400 - Invention 2-12 k 0.29 1000 2300 4000 - - Invention 2-13 l 0.29 1900 2800 4700 - - Invention 2-14 m 0.29 1300 1900 3300 4400 - Invention 2-15 n 0.29 1800 2700 4500 - - Invention 2-16 o 0.29 1100 2400 4100 - - Invention 2-17 p 0.29 1900 3000 4700 - - Invention 2-18 q 0.29 1500 2100 2800 4700 - Invention 2-19 r 0.29 1400 2600 3700 4800 - Invention 2-20 s 0.29 1400 2000 2500 4400 - Invention 2-21 t 0.29 1100 2600 3300 4500 - Invention EXAMPLE 3 The experiment was carried out in the same manner as in Example 1 except that 100 parts by weight of CA glass as shown in Table 4, aluminum sulfate α as shown in Table 4 and 125 parts by weight of pozzolanic material 1 ○ were used. The results are shown also in Table 4. EXAMPLE 4 The experiment was carried out in the same manner as in Example 2 except that 100 parts by weight of CA glass n, aluminum sulfate α as identified in Table 5 and 125 parts by weight of pozzolanic material 2 ○ were used. The results are shown in Table 5. EXAMPLE 5 The experiment was carried out in the same manner as in Example 1 except that 100 parts by weight of CA glass as identified in Table 6, 35 parts by weight of aluminum sulfate α and 125 parts by weight of pozzolanic materiel as identified in Table 6 were used. The results are shown in Table 6. Materials used Pozzolanic material 3 ○: Meta-kaolin, average particle size: 3.2 µm, Na 2 O eq. 0.30 wt% Pozzolanic material 4 ○: Blast furnace slag, Blaine value: 6,000 cm 2 /g, Na 2 O eq. 0.51 wt% Pozzolanic material 5 ○: Blast furnace slag, Blaine value: 4,000 cm 2 /g, Na 2 O eq. 0.50 wt% Pozzolanic material 6 ○: Fly ash, Blaine value: 4,000 cm 2 /g, Na 2 O eq. 1.40 wt% Test No. CA glass and CAS glass Pozzolanic material Na 2 O eq. (wt%) Proctor penetration resistance (psi) 1 min 2 min 3 min 5 min 10 min 1-3 b 1 ○ 0.69 1500 2600 3300 4200 - 5-1 b 3 ○ 0.16 600 1600 2900 4000 - 5-2 b 2 ○ 0.29 600 1200 2600 3500 4500 5-3 b 4 ○ 0.26 500 1000 2200 3000 4100 5-4 b 5 ○ 0.29 500 1300 2300 3100 4000 5-5 b 6 ○ 0.70 500 1000 2400 3000 4000 1-13 n 1 ○ 0.69 1800 2500 4600 - - 5-6 n 3 ○ 0.16 1000 2000 4100 - - 5-7 n 2 ○ 0.29 800 1500 2500 4800 - 5-8 n 4 ○ 0.26 600 1200 2700 4200 - 5-9 n 5 ○ 0.29 600 1000 2500 4400 - 5-10 n 6 ○ 0.70 500 1100 2700 4000 - Symbol "-" for the proctor penetration resistance indicates that no measurement was made. EXAMPLE 6 The experiment was carried out in the same manner as in Example 2 except that 100 parts by weight of CA glass as identified in Table 7, 35 parts by weight of aluminum sulfate β and 125 parts by weight of pozzolanic material as identified in Table 7 were used. The results are shown in Table 7. Materials used Aluminum sulfate β: 14 to 18 hydrate, first grade reagent, Na 2 O eq. 0.04 wt% Test No. CA glass and CAS glass Pozzolanic material Na 2 O eq. (wt%) Proctor penetration resistance (psi) 1 min 2 min 3 min 5 min 10 min 6-1 b 1 ○ 0.69 1400 1900 2300 4300 - 6-2 b 3 ○ 0.16 900 1600 2500 4200 - 6-3 b 2 ○ 0.29 700 1200 2200 3300 4300 6-4 b 4 ○ 0.26 600 1300 2000 2900 4200 6-5 b 5 ○ 0.29 600 1000 2400 3100 4000 6-6 b 6 ○ 0.70 500 1200 2200 3000 4000 6-7 n 1 ○ 0.69 1700 2300 3500 4400 - 6-8 n 3 ○ 0.16 1200 2000 3400 4200 - 6-9 n 2 ○ 0.29 1000 1700 2600 4000 - 6-10 n 4 ○ 0.26 900 1900 3000 4100 - 6-11 n 5 ○ 0.29 800 1700 2900 4000 - 6-12 n 6 ○ 0.70 600 1100 2500 4000 - Symbol "-" for the proctor penetration resistance indicates that no measurement was made. EXAMPLE 7 The experiment was carried out in the same manner as in Example 1 except that 100 parts by weight of CA glass as identified in Table 8, 35 parts by weight of aluminum sulfate α and pozzolanic material 1 ○ as identified in Table 8 were used. The results are shown in Table 8. EXAMPLE 8 The experiment was carried out in the same manner as in Example 2 except that 100 parts by weight of CA glass n, 35 parts by weight of aluminum sulfate α and pozzolanic material 2 ○ as identified in Table 9 were used. The results are shown in Table 9. EXAMPLE 9 An accelerating agent was prepared in the same manner as in Example 1 using 100 parts by weight of CA glass b, 35 parts by weight of aluminum sulfate α and 125 parts by weight of pozzolanic material 1 ○. Na 2 O eq. in the accelerating agent was 0.69 wt%. The experiment was carried out in the same manner as in Example 1 except that this accelerating agent and cement as identified in Table 10 were used. The results are shown in Table 10. Materials used Cement B: Moderate heat Portland cement, Blaine value: 3,100 cm 2 /g, Na 2 O eq: 0.46 wt% Cement C: High early strength Portland cement, Blaine value: 4,400 cm 2 /g, Na 2 O eq: 0.43 wt% Test No. Cement Proctor penetration resistance (psi) 1 min 2 min 3 min 5 min 10 min 1-3 A 1500 2600 3300 4200 - 9-1 B 1600 2500 3000 3800 4900 9-2 C 1300 2000 2300 3200 4200 Symbol "-" for the proctor penetration resistance indicates that no measurement was made. EXAMPLE 10 An accelerating agent was prepared in the same manner as in Example 2 using 100 parts by weight of CA glass n, 35 parts by weight of aluminum sulfate and 125 parts by weight of pozzolanic material 2 ○. Na 2 O eq. in the accelerating agent was 0.69 wt%. The experiment was carried out in the same manner as in Example 2 except that this accelerating agent and cement as identified in Table 11 were used. The results are shown in Table 11. Test No. Cement Proctor penetration resistance (psi) 1 min 2 min 3 min 5 min 10 min 2-13 A 1900 2800 4700 - - 10-1 B 1800 2500 4400 - - 10-2 C 1400 2100 3600 4600 - Symbol "-" for the proctor penetration resistance indicates that no measurement was made. EXAMPLE 11 An accelerating agent was prepared in the same manner as in Example 1 using 100 parts by weight of CA glass as identified in Table 12, 35 parts by weight of aluminum sulfate α and 125 parts by weight of pozzolanic material 1 ○. Na 2 O eq. in the accelerating agent was 0.69 wt%. The experiment was carried out in the same manner as in Example 1 except that this accelerating agent was used in an amount as identified in Table 12 i.e. parts by weight per 100 parts by weight of the spraying material. The results are shown in Table 12. Test No. CA glass and CAS glass Accelerating agent Proctor penetration resistance (psi) 1 min 2 min 3 min 5 min 10 min 11-1 b 3 1000 1800 2200 2900 4000 11-2 b 5 1400 2400 3200 4200 - 1-3 b 7 1500 2600 3300 4200 - 11-3 b 10 1600 2500 3500 4400 - 11-4 b 15 2400 3500 4100 - - 11-5 n 3 1200 2000 2800 3400 4400 11-6 n 5 1400 2500 3400 4000 - 1-13 n 7 1800 2500 4600 - - 11-7 n 10 1700 3000 4800 - - 11-8 n 15 1800 2800 4700 - - "Accelerating agent" represents parts by weight per 100 parts by weight of spraying material. Symbol "-" for the proctor penetration resistance indicates that no measurement was made. EXAMPLE 12 An accelerating agent was prepared in the same manner as in Example 2 using 100 parts by weight of CA glass n, 35 parts by weight of aluminum sulfate α and 125 parts by weight of pozzolanic material 2 ○. Na 2 O eq. in the accelerating agent was 0.69 wt%. The experiment was carried out in the same manner as in Example 2 except that this accelerating agent was used in an amount as identified in Table 13 i.e. parts by weight per 100 parts by weight of the spraying material. The results are shown in Table 13. Test No. Accelerating agent Proctor penetration resistance (psi) 1 min 2 min 3 min 5 min 10 min 12-1 3 1400 2400 3200 4000 - 12-2 5 1600 2500 4200 - - 2-13 7 1900 2800 4700 - - 12-3 10 2000 2800 4900 - - 12-4 15 2300 3000 4900 - - "Accelerating agent" represents parts by weight per 100 parts by weight of spraying material. Symbol "-" for the proctor penetration resistance indicates that no measurement was made. EXAMPLE 13 Using unit amounts of materials being 360 kg/m 3 of cement A, 1,130 kg/m 3 of fine aggregate, 756 kg/m 3 of coarse aggregate and 162 kg/m 3 of water, an accelerating agent as shown in Table 7 was mixed in an amount of 7 parts by weight in 100 parts by weight of the spraying material, to obtain concrete wherein the maximum aggregate size was 10 mm and the fine aggregate proportion was 60%. This concrete was sprayed to a simulated tunnel having a height of 3.5 m and a width of 3 m by means of a dry spraying machine and a wet spraying machine, whereupon the amount of the concrete fallen in the tunnel was measured, and the rebound ratio was calculated. The results are shown also in Table 14. Material used Coarse aggregate:River gravel produced in Himekawa, Niigata-ken, Japan, specific gravity: 2.66 Measuring method Rebound ratio: The ratio of the rebound amount at the time of spraying of the concrete which fell off without attaching to the simulated tunnel to the amount of the concrete used for spraying. EXAMPLE 14 The experiment was carried out in the same manner as in Example 13 except that an accelerating agent prepared by mixing 100 parts by weight of CA glass n, aluminum sulfate α and pozzolanic material 2 ○ or 3 ○ in an amount as identified in Table 15, was used. The results are shown also in Table 15. Test No. Spraying method Cement Pozzolanic material Na 2 O eq.(wt%) Rebound ratio (%) Notes 14-1 Dry A 2 ○ 125 0.29 13 Invention 14-2 Dry B 2 ○ 125 0.29 21 Invention 14-3 Wet A 2 ○ 125 0.29 10 Invention 14-4 Dry A 3 ○ 125 0.74 23 Invention 14-5 Dry A - 0 0.04 56 Comparative 14-6 Dry A 2 ○ 100 0.30 33 Comparative 14-7 Dry A - 0 15.8 30 Comparative 14-8 Wet A - 0 0.04 30 Comparative "Pozzolanic material" represents parts by weight per 100 parts by weight of CA glass. Symbol "-" for the proctor penetration resistance indicates that no measurement was made. In Test No. 14-6, the aluminum sulfate was not used and in Test No. 14-7, commercially available accelerating agent was used as an accelerating agent. As described in the foregoing, the accelerating agent of the present invention is substantially free from alkali metal components; whereby there will be no adverse effects to the working environment or the surrounding environment, and it presents an excellent quick setting property.

Claims: An accelerating agent which comprises calcium aluminate glass having a Blaine value of from 3,000 to 9,000 cm 2 /g, aluminum sulfate and pozzolanic material as effective components. An accelerating agent which comprises calcium aluminosilicate glass having a Blaine value of from 3,000 to 9,000 cm 2 /g, aluminum sulfate and pozzolanic material as effective components. The accelerating agent according to Claim 1 or 2, wherein the pozzolanic material is at least one member selected from the group consisting of silica fume, meta-kaolin, blast furnace slag and fly ash. A spraying material which comprises cement and the accelerating agent as defined in Claim 1, 2 or 3 as effective components. A spraying concrete which contains the spraying material as defined in Claim 4 as an effective component. A spraying method for a spraying concrete which sprays the spraying concrete as defined in Claim 5.

Inventors: ISHIDA ATSUMU, MIHARA TOSHIO, YANAGIHARA TSUYOSHI, ISHIDA, ATSUMU, MIHARA, TOSHIO, YANAGIHARA, TSUYOSHI, Ishida, Atsumu, Denki Kagaku Kogyo K.K., Mihara, Toshio, Denki Kagaku Kogyo K.K., Yanagihara, Tsuyoshi, Denki Kagaku Kogyo K.K.
Applicants: DENKI KAGAKU KOGYO KK, DENKI KAGAKU KOGYO KABUSHIKI KAISHA
Application year: 1997
Main classification: C04B28
IPC codes: C04B28