145results about How to "Reduce slump" patented technology

Concrete compositions have a fine-to-coarse aggregate ratio optimized for increased workability with minimal segregation and bleeding. The concrete compositions include at least water, cement, coarse aggregate, and fine aggregate and have a slump of at least 1 inch and a 28-day compressive strength of at least about 1500 psi. Workability is improved by minimizing the viscosity as a function of the aggregate content, while minimizing segregation and bleeding. To improve workability, the concrete compositions include between 45% and 65% fine aggregate and between 35% and 55% coarse aggregate as a function of total aggregate volume. For relatively low strength concrete (1500-4500 psi), the fine aggregate is 55-65% of the total aggregate volume. For medium strength concrete (4500-8000 psi), the fine aggregate is 50-60% of the total aggregate volume. For high strength concrete (>8000 psi), the fine aggregate is 45-55% of the total aggregate volume. Overall workability can be maintained or improved even if slump is decreased.

The invention relates to a novel laser spot welding method, in particular relates to a laser pulse spot welding method for a metal sheet, aiming at solving the problems that in the prior art, the burning loss of the material is high, air holes, cracks and collapse are easy to generate in the laser spot welding process, and particularly the reflectivity of the aluminum alloy material to laser is high so that the stability in the spot welding process is poor. The laser pulse spot welding method for a metal sheet comprises the following specific steps: (1) preprocessing a workpiece to be welded, (2) fixing the workpiece to be welded, and (3) welding by adopting the laser pulse spot welding method. The laser pulse spot welding method for a metal sheet has the advantages of enhancing the welding efficiency, improving the welding spot quality, ensuring good uniformity of the sizes of the welding spots and realizing the spot welding of a plate of moderate thickness by a small-power laser. The laser pulse spot welding method for a metal sheet is mainly used for welding metal materials and particularly used for welding the metal sheet.

The invention relates to a sustainable hybrid pervious concrete pavement structure. The pavement structure comprises a surface layer, a middle layer and a bottom layer from top to bottom; the surface layer and the middle layer are paved by use of pervious concrete different in perviousness coefficient, while the bottom layer is a hardcore bed, and the perviousness coefficients and the porosities gradually increase from the surface layer to the bottom layer; the pervious concrete of the surface layer is composed of the following components in kilograms per cubic meter (kg / m<3>): 300-400kg / m<3> of cement, 1400-1600 kg / m<3> of 5mm-10mm gravel, 2.2-3.25 kg / m<3> of additives and 85-100 kg / m<3> of mixing water; the pervious concrete of the middle layer is composed of the following components in kilometers per cubic meter (kg / m<3>): 280-380kg / m<3> of cement, 1350-1560 kg / m<3> of 10mm-20mm gravel, 2.0-3.0 kg / m<3> of additives and 75-90 kg / m<3> of mixing water. The sustainable hybrid pervious concrete pavement structure is a machined rolled pervious concrete pavement structure; a pyramid perviousness manner is adopted so that the perviousness of the pavement structure is excellent; water holes are not prone to be covered and blocked by dust, and therefore, the service life of the pervious concrete pavement structure is greatly increased.

The invention discloses a preparation method of a high-solid-content ester polycarboxylic acid water reducing agent, which comprises the following steps: (1) mixing polyethyleneglycol monomethyl ether, amino-terminated polyoxypropylene ether, methacrylic acid, a catalyst and a mixed polymerization inhibitor to react to obtain a first mixture; (2) adding unsaturated carboxylate, a cationic monomer and a chain-transfer agent into 70-75 parts of the first mixture, and uniformly mixing to obtain a second mixture; mixing an initiator and acrylic acid to obtain a third mixture; dropwisely adding the third mixture and second mixture into 80-85 parts of the 45-80-DEG C first mixture within 1.5-2 hours, keeping the temperature at 45-80 DEG C to react for 1-1.5 hours, and after the reaction finishes, adding water to regulate the concentration of the system to 80-85%; and (3) adding sodium hydroxide into the material obtained in the step (2) for neutralization to obtain the high-solid-content ester polycarboxylic acid water reducing agent. The method has the advantages of high production efficiency and environment friendliness. The prepared product has excellent properties, and is convenient for storage and line haul.

The invention discloses a sheet forming die and method of a helical cylinder gear. The method comprises the following two major steps: 1) cold and precision forming of a sheet, namely, feeding a metal sheet to be processed between a first concave die and a first convex die, pressing a V-shaped ring blank holder into the metal sheet to be processed, pressing the first convex die into the metal sheet to be processed, keeping the first convex die and a reverse ejecting plate rotating at the same rate and in the same direction until the first convex die is in a certain distance from the first concave die so as to realize the cold and precision forming of the sheet; 2) rotating blanking, namely, blanking to remove the residues together with coating of the metal sheet subjected to the cold and precision forming, so as to obtain the helical cylinder gear. With the adoption of the sheet forming die and method, the cold and precision forming of the helical cylinder gear is realized, the corner collapse is reduced, the highlight zone is expanded, the part quality is improved, and the production cost is decreased.

The invention discloses a wet spraying machine with a sliding foldable arm. The wet spraying machine comprises a frame, a driving cab is arranged on the frame in a left offset manner, a power system is arranged below the frame, an electric control system, an external additive system, a hydraulic system, an air pressure system and a pumping system which is connected with the frame are arranged above the frame, an engineering mechanical chassis is arranged on the frame on the right side of the driving cab, a sliding foldable arm support is arranged on the engineering mechanical chassis, the lower portion of the sliding foldable arm support is connected with a sliding base through bolts, a travelling mechanism is arranged below the sliding base and on a guide rail, and the guide rail is fixed on the frame. By the aid of the wet spraying machine with the sliding foldable arm, one slide, two rotations, four folding and one extension are realized, multidirectional control is realized, dead working angles are eliminated, construction quantity is improved, spraying area is enlarged, labor intensity of workers is reduced since the workers control the spraying device by controlling an operation panel, dust concentration is lowered, and risks to health of construction workers are reduced.

A pumpable watergel explosive composition comprises 10 to 40 wt %, based on the total weight of the pumpable explosive composition, of a continuous liquid phase comprising a solvent, a solubilized chemical sensitizer and a gelling agent and 60 to 90 wt %, based on the total weight of the pumpable explosive composition, of a discontinuous solid phase comprising particulate oxidizer salt particles having interstitial spaces between the salt particles. The watergel explosive composition has a density of 1.05-1.4 g / cc and, a shear thinning rheology such that, when subjected to an external force, the explosive composition has a viscosity sufficiently low to render the watergel explosive composition pumpable. The combination of density and low water content provides energy numbers normally associated with more expensive aluminized formulations.

The invention discloses pervious concrete which is characterized in that the pervious concrete is prepared from the following components in parts by mass: 1500-1600 parts of coarse aggregate, 320-420parts of a cementing material, 105-114 parts of water and 4.5-5.9 parts of a water reducing agent. An anti-corrosion material in the formula has remarkable plasticizing effect, micro-aggregate effect,morphological effect and temperature peak reduction effect, and the mechanical property, abrasion resistance and denudation resistance of the pervious concrete can be improved through the excellent characteristics of the anti-corrosion material itself and the improvement of the continuous grading of the microstructure of the cementing material, so that the durability of the pervious concrete is improved, and the service lifetime of the pervious concrete is prolonged.

The invention discloses a waterproof sealing system for a high-speed railway bridge deck in a severe cold area and a construction method of waterproof sealing system. The waterproof sealing system comprises a protecting wall outside cable duct waterproof system and a between-cable waterproof system and is characterized in that the protecting wall outside cable duct waterproof system comprises a waterproof coating layer and a fiber reinforced concrete protecting layer; the between-cable waterproof system comprises a waterproof coil layer and a fiber reinforced concrete protecting layer. The waterproof sealing system has the advantages that the waterproof coil and C40 fine-stone fiber reinforced concrete are composited to serve as the structure waterproof sealing layer, and the crack resistance and freezing resistance of the concrete are increased; a self-made paving machine is used to perform coil paving to guarantee coil adhering density and increase the effect; a vibration platform isused to perform deck ultrathin glass fiber waterproof concrete pouring, a drainage slope is formed in one step, and cracking after construction is prevented effectively.

The invention provides a lightweight ceramsite concrete and a preparation method thereof. The lightweight ceramsite concrete comprises, by weight, 200-219 parts of medium sand, 462-470 parts of cement, 280-316 parts of cobblestones, 110-116 parts of fly ash, 230-240 parts of super light ceramsite, 230-240 parts of pottery sand, 150-155 parts of water, 8-12 parts of a calcium aluminum sulfate expanding agent and 7.0-9.6 parts of a polycarboxylate superplasticizer. The feeding sequence in the preparation process is changed, sandstones are first added, then cement, fly ash and ceramsite are added, and water and additives are added after the ceramsite and other raw materials are fully and uniformly stirred in order to obtain concrete with good workability; and gravity type mixing of a mixer truck is adopted in the transportation process to prevent the segregation and bleeding phenomena in the transportation process, so the defect of easy segregation of the ceramsite and cement grout is effectively solved. A ratio of all raw materials is optimized to reduce the slump, so the ceramsite difficultly floats up to the surface of concrete, and the defect of the easy segregation of the ceramsite and slurry is avoided.

A new family of concrete admixture additives can be derived from reacting a mixture of olefins / cyclic olefins-maleic anhydride copolymers and methoxy polyethylene glycol amines and / or polyethylene glycol monoalkyl ethers, or a mixture of styrene-maleic anhydride copolymers and methoxy polyethylene glycol amines and / or polyethylene glycol monoalkyl ethers, or a mixture of styrene-olefins / cyclic olefins-maleic anhydride terpolymers and methoxy polyethylene glycol amines and / or polyethylene glycol monoalkyl ethers. These reactions lead to formation of a kind of carboxylic salt containing polymer, which can be used alone in concrete. Only a small amount of this substance is needed to provide excellent water reduction, high concrete flowability and high early strength.

The invention discloses an anti-mud type low-slump-loss polycarboxylic acid water reducing agent and a preparation method thereof, and relates to the technical field of synthesis of concrete admixtures. Specifically, from the effect of a molecular structure and an initial pH value of a reaction system on the performance of a product, during a synthesis process, tartaric acid is selected as an adjusting catalyst of the initial pH value of the reaction system in a kettle, monomers succinic acid monoethyl propionyl oxyethyl ester and 2-allyloxy sodium ethanesulfonate having a special water reducing function, monomers cis-1-propylene phosphonic acid and 2-allyloxy sodium ethanesulfonate having a special anti-mud function, and monomers methoxyethyl acrylate, succinic acid monoethyl propionyl oxyethyl ester and isopentenol polyoxyethylene ether with the molecular weight M of 1400 having a special slump retaining function are introduced; after the reaction is finished, an organic alkali diethanolisopropanolamine is used for neutralizing, and the anti-mud type low-slump-loss polycarboxylic acid water reducing agent is synthesized. The reducing agent has the advantages of low alkali content, fast early strength achieving of concrete, and high strength, can significantly improve the workability and the slump retention of the concrete prepared by high-mud-content aggregates, has relatively good anti-mud ability, and also has the advantages of low gradual loss of newly blended concrete, high strength of hardened concrete, good durability and the like.

The present invention discloses novel fibers for use as secondary reinforcement materials in cementitious composites, which fibers are effective in preventing cracking far better than prior art fibers. Also disclosed are methods of producing the fibers and methods for producing cementitious composite containing the fibers.

The invention relates to a construction structure for constructing a road on a soft soil foundation. The construction structure for constructing the road on the soft soil foundation comprises a crushed-rock layer and a concrete layer which are laid above a soft soil layer in sequence; the construction structure for constructing the road on the soft soil foundation further comprises a plurality oflongitudinal pine piles driven into the soft soil layer; the pine piles are separately lined on the two sides in the length direction of a pavement; the upper ends of the longitudinal pine piles run through the crushed-rock layer and are buried in the concrete layer; and steel reinforcement structures connected with the longitudinal pine piles are buried in the concrete. Through the arrangement, when heavy objects such as pedestrians and vehicles are borne above the concrete layer, the bending resistance of the concrete layer is enhanced through the steel reinforcement structures; and moreover, as the concrete layer and the steel reinforcement structures are connected with the longitudinal pine piles in a supporting and anchoring manner, the crushed-rock layer around a local settlement position bears the pressure load of the concrete layer and the longitudinal pine piles on the two sides bear tensile stress loads on the two sides of the concrete layer when the soft soil foundation under the pavement is locally settled; and therefore, the concrete layer is not easy to collapse or break so that the life and property safeties of the pedestrians on the road are protected.

The present invention relates to a novel flexible composite shotcrete layer support material which comprises the following components in parts by weight: 80-100 parts of cement, 80-120 parts of sands, 100-120 parts of stones, 60-100 parts of rubber particles, 40-60 parts of coal ash, 20-30 parts of hooked end steel fibers, 50-80 parts of water, 6-7 parts of a crosslinking agent, 5-8 parts of an additive, 2-10 parts of polyamic acid resin with a solid content of 10%-25% and 3-5 parts of a 1% silane coupler solution. The prepared shotcrete layer material is greatly improved in compression strength, rupture strength and flexural toughness. The novel flexible composite shotcrete layer support material can be applied to the field of support to surrounding rocks of complex rock layers with characteristics of high stress, soft rock, expansion, flowing deformation, fault structure fracture zones, mining influence and the like or other dynamic pressure tunnel as well as the field of underground engineering of tunnels, subways and the like.

The invention relates to the technical field of concrete preparation, and in particular, relates to a concrete glue reducing agent and a preparation method thereof. The glue reducing agent is composedof the preparation raw materials in parts by weight: 20-30 parts of substituted organic amine and 40-60 parts of water, wherein substituent groups of the substituted organic amine are selected from one or more of ester groups, sulfonic acid groups, carboxylic acid groups and hydroxyl groups. The invention provides the glue reducing agent. The glue reducing agent can be used in concrete, can obviously reduce the cement consumption, avoids the reduction of the concrete strength and slump, effectively reduces the time loss of the concrete, improves the harmony of the concrete, can act together with a water reducing agent and the like, saves the cost while ensuring the physical properties of the concrete, and conforms to JC / T2469-2018.

The invention discloses a cutting and blanking mould for a bar stock, which comprises a base plate, a positioning base, a supporting base, two pull rods, an inclined wedge and two guide pillars, wherein spring bases, push plates and springs are fixed on the two pull rods; a concave mould with an inner hole is fixedly arranged at the upper end of the supporting base; a convex mould cover plate is fixed on one side of the concave mould; a convex mould with the inner hole is slidably arranged between the convex mould cover plate and the concave mould; the convex mould is connected with one of the push plates; a material groove is arranged on the lower part of the convex mould cover plate; a slide block is arranged on an inclined surface of the inclined wedge; a pushing rod, a slide rail cover plate, a slide rail base plate, a rear baffle and a pushing pull rod are arranged around the slide block; the front end of the pushing rod is located in a long slot of the supporting base; a slide base is arranged on the two guide pillars; a withdrawing slot is arranged in the middle of the slide base; the inclined wedge is located in the withdrawing slot; a pushing spring is sleeved on the pushing pull rod; an upper linking plate is connected with the slide rail cover plate; and the slide rail base plate is connected with the other push plate. By using the cutting and blanking mould for the bar stock, the corner collapse phenomenon is greatly reduced, the material loss is reduced, the unloading is conveniently performed and the processing efficiency is high.

The invention discloses a boom system of a wet spraying machine. The boom system of the wet spraying machine comprises a base, a vertical rotary platform, a horizontal rotary platform, a big arm, a medium arm, a small arm, a telescopic arm, a jet device, oil cylinders, a connecting rod, a concrete conveying pipe, a high-pressure air conveying pipe and a hydraulic oil pipe, wherein the base and the vertical rotary platform are connected through a rotary support, the horizontal rotary platform (3) is connected with the vertical rotary platform through a rotary support, the horizontal rotary platform is connected with one end of the big arm in a hinged mode, and the first oil cylinder is arranged between the horizontal rotary platform and the big arm. According to the boom system of the wet spraying machine, bidirectional rotation of the rotary platforms is achieved, bending of the big arm, the medium arm and the small arm, stretching and contraction of the telescopic arm, and bending between the jet device and a rotary motor are achieved, multidirectional control can be easily achieved, the working dead angle is eliminated, the jet area is greatly increased, normal spraying application operation can be carried out on sections, with different sizes, of tunnels, and complex sprayed surfaces of the tunnels, the operating range is wide, efficiency is high, labor intensity of workers is reduced, and concrete construction quality is high.

The invention provides a method for preparing high carbon ferro-chrome by fusible chrome fine ore. The method comprises the following steps that screening is conducted, specifically, raw material chrome fine ore is screened, and chrome fine ore with the granularity being equal to or less than 6 mm and chrome fine ore with the granularity being larger than 6 mm are obtained; pelletizing is prepared, specifically, mixture is obtained after the granularity being equal to or less than 6 mm is evenly mixed with binder, and then the mixture is pressed into the pelletizing; burdening is conducted, specifically, the pelletizing, the chrome fine ore with the granularity being larger than 6 mm, flux and reducing agent are evenly mixed, and then mixture is obtained; and smelting is conducted, specifically, the mixture is placed into a submerged arc furnace to conduct smelting.

The present invention aims at providing a cement admixture having superior water-reducing performance, along with no decrease in slump and slump flow caused by decrease in fluidity of a cement composition over time. A cement admixture is to be provided, which cement admixture comprises two or more members of polycarboxylic acid-based polymers, wherein said cement admixture comprises at least one polycarboxylic acid-based polymer (A) having a constitutional unit represented by the following formula (1): wherein R1 and R2 independently represent a hydrogen atom, an alkyl group with carbon atoms of 1 to 30, an alkenyl group with carbon atoms of 1 to 30, an aryl group with carbon atoms of 6 to 12; A represents an alkylene group with carbon atoms of 1 to 30 or an arylene group with carbon atoms of 6 to 12; a is 0 or 1; OR3 represents an oxyalkylene group with carbon atoms of 2 to 18, wherein each OR3 may be the same or different each other, provided that when OR3 is in a mixed form of two or more members, each OR3 may be added in a block or random form; R4 represents a hydrogen atom or a hydrocarbon group with carbon atoms of 1 to 30; and m represents an average mole number of oxyalkylene groups added and is in the range of 1 to 300; and at least one polycarboxylic acid-based polymer (B) having a constitutional unit represented by the following formula (2): wherein R5 and R6 independently represent a hydrogen atom, a methyl group; x is an integer in the range of 0 to 2 and y is 0 or 1, provided that x and y are not 0 at the same time; OR7 represents an oxyalkylene group with carbon atoms of 2 to 18, wherein each OR7 may be the same or different each other, provided that when OR7 is in a mixed form of two or more members, each OR7 may be added in a block or random form; R8 represents a hydrogen atom or a hydrocarbon group with carbon atoms of 1 to 30; and n represents an average mole number of oxyalkylene groups added and is in the range of 1 to 300.

The invention discloses a slag salvaging cylindrical drill for a drilled pile. The slag salvaging cylindrical drill is characterized in that a cylinder is arranged, a drilling rod is arranged at a neutral axis position of the cylinder, and the top end of the drilling rod penetrates through the top of the cylinder and is provided with a flange disc; the inner part of the cylinder is separated into semi-cylindrical cylinders at two sides by a longitudinal clapboard; a bottom steel beam is arranged at the bottom of the cylinder and is at a position crossing with the bottom edge of the longitudinal clapboard, drilling teeth are arranged on the bottom steel beam at intervals, the bottom steel beam divides the semi-cylindrical cylinders into salvaging bins and storing bins, the salvaging bins are open sectors and the storing bins are sectors of which the bottoms are sealed with steel meshes; and the salvaging bins in the semi-cylindrical bins at two sides are arranged at diagonal positions. According to the invention, the phenomena of pipe plugging, hole collapse and chambered holes in the drilling construction can be effectively reduced, and the construction progress and the safety quality of a pile foundation are ensured.

The invention relates to a method for treating a pickled soft base through industrial residues. The method has the characteristics of being good in treating effect and capable of achieving waste recovery and protecting the environment. According to the technical scheme, the method for treating the pickled soft base through the industrial residues comprises the following steps that (1), staking out in survey is conducted on the levelled pickled soft base to determine stake positions; and (2) nail-shaped bidirectional stirring powder pile spraying construction is conducted, powder during the construction is composed of waste tire rubber powder and an industrial residue curing agent, the components are controlled, by mass, to be 67-73 parts of pickled soil, 17-23 parts of the waste tire rubber powder and 7-13 parts of the industrial residue composite curing agent; the industrial residue composite curing agent is composed of, by mass, 57-63 parts of acetylene sludge, 27-33 parts of flyash and 7-13 parts of excitants; and the excitant is MgO or / and Cao, and maintenance is conducted for seven days.

The invention provides a preparing method for a polycarboxylic admixture and belongs to the field of concrete water reducing agents. According to the admixture, macromonomer methyl allyl polyethenoxy ether and maleic anhydride carry out a polymerization reaction in a redox system, mercapto propionic acid, hydroxyethyl acrylate and fumaric acid are added, branched chains are enlarged by means of the polymerization reaction in deionized water, and side chains are introduced, so that a molecular structure forms a comb-like structure with hydrophily functional groups such as -SH, -OH and -COOH. By controlling the quantity, temperature and time of the raw materials, the dispersing performance of the admixture is good; meanwhile, the phenomenon of bleeding hardening of concrete can be improved. The quantity of admixtures used in the concrete is small, the admixture can have good dispersity while the water reduction effect is improved, duration is long, slump loss is small, and the amount of adopted cement is reduced.

The invention discloses a high section trend wall-type fully mechanized caving mining method for a large inclined super high seam. The method conducts respective mining on a plurality of mining sections in the same section from top to bottom, and the mining process is as follows: first, determination of a coal face: the coal face of a mining section in the current mining section is determined; the coal face is a high section trend wall-type inclined coal face and is the actual mining face; the coal face is divided into a lower section coal face and an upper section coal face above the lower section coal face; and the lower section coal face is a polyline section coal face, and the upper section coal face is a linear section coal face; 2, determination of the height of the section; and 3, coal seam mining: a plurality of coal seam sections are mined respectively. The method of the invention has the advantages of simpleness, reasonable design, simple construction and high-efficiency safe and reliable mining process, and can effectively solve the problems of severe mining difficulty, low safety factor and incapability of efficient mining in the mining process of large inclined super high seam.

The invention discloses a novel concrete. Raw materials of the concrete comprise the following components: Portland cement, coarse sand, medium coarse sand, detritus, water, steel slag, siliceous irontailing powder, gypsum, high-calcium ash, silicon powder, glazed hollow beads, a polycarboxylate superplasticizer, sodium molybdate, sodium nitrite, tin chloride, natural zeolite micropowder, synthetic fibers, an air entraining agent, urea and triethanolamine. The novel concrete disclosed by the invention is reasonable in component and synergic in effect, has high durability such as high strength, high freezing resistance, high impermeability and good corrosion resistance and also has advantages such as noise insulation.

The invention provides a preparation method of a microbial cemented filling material for a coal mine. The preparation method comprises the steps of culture of microorganisms for the coal mine, preparation of a calcium-based chitosan solution, preparation of a urea-calcium-based chitosan solution and preparation of a matrix. A preparation method of the calcium-based chitosan solution comprises heating a 12-15% chitosan-acetic acid solution, carrying out heat preservation, and adding anhydrous calcium chloride until the calcium ion content is 65-90 g / l. According to a preparation method of the matrix, the mass ratio of the coarse aggregate to the fine aggregate is (6-8): (1.4-2.5), and the average specific surface area of the coarse aggregate is 500-1500 m<2> / kg, and the average specific surface area of the fine aggregate is 1500-3000 m<2> / kg. The microbial cemented filling material for coal mine has the advantages of low microbial consumption, high compressive strength, high roof contact rate, small slump and low bleeding rate. The technical problems that an existing microorganism cemented filling material is large in use amount and poor in cemented filling effect are solved.

The invention relates to a preparation and pumping technology of lightweight aggregate concrete. The lightweight aggregate concrete is prepared from water, cement, fly ash, pottery sand, 400-grade ceramsite, a thickening agent, a water reducing agent and an air entraining agent. The preparation and pumping technology is characterized in that original sand and gravels in the concrete are replaced with the pottery sand and the 400-grade ceramsite to serve as new concrete aggregate, so that the apparent density of the concrete can be reduced; the use amounts of the cement, the fly ash and the water in the concrete are increased, wherein the cement and the fly ash are both powder with fine texture and are mixed with the water to serve as an adhesive; meanwhile, the thickening agent and the airentraining agent are added into the adhesive for enhancing the fluidity and cohesion of the concrete, so that pumping is facilitated; in addition, because the materials such as the pottery sand and the ceramsite in the concrete have good heat preservation property, the lightweight aggregate concrete has good thermal insulation effects.

The invention discloses a brushing device of a concrete spraying machine, comprising a first rotary driving piece (30) and a rotary piece (40), wherein one side of the rotary piece (40) is connected with the output end of the first rotary driving piece (30), and the end surface of the other side of the rotary piece (40) is provided with a plurality of eccentric installing positions; a connecting shaft (13) is selectively arranged on one eccentric installing position; and if the connecting shaft (13) is positioned at different eccentric installing positions, included angles between the axis of the connecting shaft (13) and the rotary axis of the rotary piece (40) are different. In addition, the invention also discloses a spraying head assembly of the concrete spraying machine provided with the brushing device. The brushing device and the spraying head assembly with the same can be adjusted to suitable brushing angles according to different spraying surfaces so as to spray concrete, so that the rebound rate of concrete and the caving of uncured concrete are reduced, and further the spraying efficiency of the concrete is improved.

The invention provides an additive for improving carbonization resistance of concrete as well as a preparation method and application of the additive, and belongs to the technical field of concrete. The additive provided by the invention is prepared from the following components in parts by mass: 8-12 parts of mineral substance fine powder, 3-5 parts of silica fume, 10-15 parts of metakaolin, 3-5 parts of methyl silicate, 2-3 parts of an expanding agent, 5-8 parts of a super plasticizer and 6-12 parts of a self-healing expanding fiber anti-crack waterproof agent. Results of the embodiment show that the additive provided by the invention can reduce the internal porosity of concrete by 50% or more, and reduce the number of capillary pores and macropores. The strength of the prepared concrete can be improved by 70% in 3 days, the strength of the prepared concrete can reach the original strength on the 28th day in 7 days, and the strength can be improved by about 20% in 28 days. Energy spectrum analysis before and after concrete carbonization shows that the carbon content of concrete is relatively low even if the concrete is carbonized, which indicates that the additive has very good carbonization resistance.