Dry-mixed mortar prepared by dry-processing recycled aggregate of full concrete and preparation method thereof

Abstract

The present invention provides a dry-mixed mortar prepared by dry-processing all-concrete recycled aggregate and a preparation method thereof, and relates to the technical field of building materials. The dry-mixed mortar comprises the following components by weight: 10-20 parts of cement, 3-10 parts of active fillers, 75-85 parts of recycled aggregates, 0.01-0.06 parts of water-retaining thickeners, 0.002-0.006 parts of air entraining agents, 0.025-0.075 parts of water reducers, and 1-2 parts of lubricants. In the technical scheme provided by the present invention, the main raw materials used are recycled aggregates obtained from concrete construction waste, and the preparation method of the recycled aggregates does not require drying and wet modification, and the process is simple and energy consumption is low. Moreover, there is no need to add other aggregates such as natural sand, which can not only greatly improve the utilization rate of recycled concrete solid waste, but also be more green and environmentally friendly, and avoid the shortage of natural sand resources and the limitation of difficult mining. The other raw materials used are all conventional products on the market, and the raw materials are easy to obtain and low in cost. After the prepared dry-mixed mortar is sealed and stored for 30 days, the product properties do not change significantly.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a dry-mix mortar prepared by dry-processing all-concrete recycled aggregate and a preparation method thereof. Background Art

[0002] In recent years, with the advancement of my country's urbanization process and the development of new rural construction, a large number of old buildings have been demolished and new construction projects have generated a large amount of construction waste. At the same time, natural sand, as a non-renewable resource, is limited in its mining. Currently, it faces two major problems: shortage of natural sand resources and accumulation of construction waste. Replacing natural sand with solid waste recycled concrete aggregate as building aggregate not only solves the problem of high aggregate cost, but also reduces the damage to the ecological environment caused by the mining of natural sand resources and the pollution of the environment caused by solid waste. Therefore, recycling solid waste concrete and turning waste into treasure has significant environmental, social and economic benefits.

[0003] Due to its unique composition and structure, recycled concrete aggregate contains a lot of adsorbed water. Direct use will cause a series of problems such as agglomeration and hardening of dry-mixed mortar products. Especially in bulk ordinary dry-mixed mortar, due to the good sealing and poor air permeability of bulk tanks, the moisture of recycled aggregate cannot evaporate freely and is easily absorbed by cement and other cementitious materials, causing bulk dry-mixed mortar to agglomerate in bulk silos, resulting in a series of problems such as poor material discharge, inability to store for a long time, and reduced strength, which seriously affect the normal use of the product. In addition, the crushing index and water absorption rate of recycled coarse aggregate are high, and the particle shape is flaky. The mortar prepared with it generally has problems such as large consistency loss, poor workability, and poor construction.

[0004] In the prior art, there are usually two countermeasures to this problem: on the one hand, the recycled concrete aggregate is dried to reduce its moisture content, but this process requires special drying equipment and causes a significant increase in costs; on the other hand, the recycled aggregate is mixed with other aggregates with lower moisture content to control the overall moisture content of the aggregate, but this approach will limit the dosage of recycled aggregate, resulting in limited large-scale application.

[0005] Chinese patent CN 114591049 A discloses a method for preparing green mortar using construction waste. The invention reduces the water absorption rate of aggregates by mixing discarded clay bricks and concrete, crushing and screening them, adding organic silicon waterproofing agent to soak and modify them, and then drying them. Then, the green mortar is prepared by mixing with cement, fly ash, quartz sand, water reducer, retarder, binder, and water. The mortar prepared by this method can solve the problem of large consistency loss caused by high water absorption rate of recycled aggregates, but the method requires soaking, modifying and drying the recycled aggregates, which is a relatively complex process, and there is a wet process. In addition, the drying time is long, resulting in a long production cycle of the product. At the same time, the cellulose ether used is a non-conventional product on the market and needs to be customized separately, which further increases the difficulty of product production. In addition, some natural quartz sand needs to be added, which is not conducive to the environmental protection concept of reducing natural sand mining. When using recycled aggregates in the prior art, it is usually necessary to add some additional natural sand to improve product performance. The reasons are: on the one hand, it is to control the moisture content of the dry-mixed mortar aggregate; on the other hand, because the natural sand aggregate has a round particle size and a good particle shape, it can improve the workability of ordinary dry-mixed mortar.

[0006] Therefore, how to develop and design a dry, low-energy method to prepare recycled aggregate that can be preserved for a long time, and a method for preparing dry-mixed mortar using this as raw material without compounding natural sand, is a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0007] The purpose of the present invention is to provide a dry-mixed mortar prepared by dry-processing all-concrete recycled aggregate, wherein the main raw material used is recycled aggregate obtained from concrete construction waste, and no natural sand is added; and the preparation method of the recycled aggregate does not require drying and wet modification, and the process is simple and the energy consumption is low; the other raw materials used are all conventional products on the market, and the raw materials are easy to obtain and low in cost.

[0008] To achieve the above-mentioned object, the present invention provides a dry-mixed mortar prepared by dry-processing recycled aggregate of full concrete, which comprises the following components in parts by weight: 10-20 parts of cement, 3-10 parts of active filler, 75-85 parts of recycled aggregate, 0.01-0.06 parts of water-retaining thickener, 0.002-0.006 parts of air-entraining agent, 0.025-0.075 parts of water-reducing agent, and 1-2 parts of lubricant.

[0009] In a preferred embodiment, the recycled aggregate is prepared by the following method:

[0010] S1 mixes concrete construction waste and anti-caking agent evenly, crushes, removes impurities and sieves to obtain graded recycled aggregates with nominal particle sizes of 3-5mm, 1.18-3mmmm, 0.6-1.18mm and 0-0.6mm respectively;

[0011] S2 is calculated according to the aggregate fineness modulus calculation formula (1), and the cumulative screen residue percentages A1, A2, A3, A4, A5, and A6 are calculated;

[0012]

[0013] Where: M x ——fineness modulus;

[0014] A1, A2, A3, A4, A5, A6 - cumulative percentage of residue on square sieves of 4.75mm, 2.36mm, 1.18mm, 0.60mm, 0.30mm, 0.15mm, respectively;

[0015] S3 controls the fineness modulus of aggregate to M x =2.3-3.0, and the recycled aggregate is obtained by determining the proportion of each grade of particle size.

[0016] In a preferred embodiment, in step S1, the mass ratio of the concrete construction waste to the anti-caking agent is 1:(0.02-0.06).

[0017] In a preferred embodiment, in step S1, the anti-caking agent includes one or more of sodium sulphate, sodium thiosulfate, attapulgite, zeolite, lime lime, and tricalcium phosphate.

[0018] In a preferred embodiment, the cement is 32.5-52.5 grade Portland cement or ordinary Portland cement.

[0019] In a preferred embodiment, the active filler is one or more of fly ash, mineral powder, and silica ash.

[0020] In a preferred embodiment, the water-retaining thickener includes one or more of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose;

[0021] The air entraining agent includes one or more of rosin-based air entraining agents, alkylbenzene sulfonate-based air entraining agents, lignin salt-based air entraining agents, salts of protein substances, fatty acids, resin acids and their salts;

[0022] The water reducer is a naphthalene-based or polycarboxylate water reducer;

[0023] The lubricant is one or more of graphite and talcum powder.

[0024] Another object of the present invention is to provide a method for preparing dry-mixed mortar by dry-processing recycled aggregate of all concrete, wherein the raw materials of the dry-mixed mortar are all powders, which are convenient for storage, transportation and use, and have no special requirements for production equipment and process during preparation, and can be prepared using existing mortar production lines, which is particularly suitable for large-scale industrial production. Moreover, after the prepared product is sealed and stored for one month, the product performance has no obvious change.

[0025] To achieve the above object, the present invention provides a method for preparing dry-mix mortar by dry processing of recycled aggregate of full concrete, which specifically comprises the following steps:

[0026] Weigh all raw materials by weight and mix them evenly; add water to the raw material powder and stir to obtain the product.

[0027] In a preferred embodiment, the mass ratio of the powder to water is 1:(0.15-0.18).

[0028] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0029] 1) The technical solution provided by the present invention can achieve 100% use of recycled concrete as aggregate for dry-mixed mortar, without the need to add other aggregates such as natural sand. This can not only greatly improve the utilization rate of recycled concrete solid waste, but also be more green and environmentally friendly, avoiding the limitations of shortage of natural sand resources and difficulty in mining.

[0030] 2) In the technical solution of the present invention, the recycled aggregate used can be directly applied to ordinary dry-mixed mortar after crushing, removing impurities and grading concrete waste without going through drying and wet processes. The preparation process does not require special drying and wet modification equipment, which can optimize equipment technology, reduce production costs, avoid dependence on equipment and production conditions during the processing process, and expand the application method of concrete waste.

[0031] 3) The scheme of the present invention can effectively solve a series of quality problems caused by the high moisture content of recycled aggregate in concrete and the easy agglomeration of bulk dry-mixed mortar, and can increase the feeding speed of bulk dry-mixed mortar products, extend the storage time of bulk dry-mixed mortar, and improve product stability, thereby obtaining high-quality dry-mixed mortar.

[0032] 4) The solution of the present invention can effectively solve the problems of high water absorption rate of recycled aggregate and high consistency caused by poor particle shape, and has excellent workability and construction performance, with small consistency loss. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with specific implementation methods, but it should be understood that the protection scope of the present invention is not limited by the specific implementation methods.

[0034] The embodiment of the present invention provides a method for preparing ordinary dry-mixed mortar with all-concrete recycled aggregate that does not require drying or modification, thereby solving the problem of wet modification, drying and other operations required for preparing dry-mixed mortar from construction waste in the prior art, simplifying the process flow, shortening the time for preparing mortar, and improving work efficiency; and the prepared mortar can be stored for a long time without changing its performance.

[0035] In addition, in the present invention, firstly, an anti-caking agent is added to the recycled aggregate in concrete to absorb the free water therein, thereby effectively controlling the moisture content of the aggregate. Secondly, an air-entraining agent is added to introduce tiny bubbles into the mixed mortar to improve the workability of the product, thereby allowing the recycled aggregate to be used directly without compounding with natural sand, thereby avoiding dependence on natural sand.

[0036] The technical solution in the present invention is to solve the above problems, and the overall idea is as follows:

[0037] The invention provides a dry-mixed mortar prepared by dry-processing all-concrete recycled aggregate. The dry-mixed mortar comprises the following components by weight: 10-20 parts of cement, 3-10 parts of active filler, 75-85 parts of recycled aggregate, 0.01-0.06 parts of water-retaining thickener, 0.002-0.006 parts of air entraining agent, 0.025-0.075 parts of water reducing agent and 1-2 parts of lubricant.

[0038] In a preferred embodiment, the total weight of the components is 100 parts.

[0039] In a preferred embodiment, the recycled aggregate is prepared by the following method:

[0040] S1 mixes concrete construction waste and anti-caking agent evenly, crushes, removes impurities and sieves to obtain graded recycled aggregates with nominal particle sizes of 3-5mm, 1.18-3mmmm, 0.6-1.18mm and 0-0.6mm respectively;

[0041] S2 is calculated according to the aggregate fineness modulus calculation formula (1), and the cumulative screen residue percentages A1, A2, A3, A4, A5, and A6 are calculated;

[0042]

[0043] Where: M x ——fineness modulus;

[0044] A1, A2, A3, A4, A5, A6 - cumulative percentage of residue on square sieves of 4.75mm, 2.36mm, 1.18mm, 0.60mm, 0.30mm, 0.15mm, respectively;

[0045] S3 controls the fineness modulus of aggregate to M x=2.3-3.0, and the recycled aggregate is obtained by determining the proportion of each grade of particle size.

[0046] In a preferred embodiment, before step S1, a pretreatment step is also included, specifically: crushing the concrete construction waste to a particle size of less than 50 mm.

[0047] In a preferred embodiment, in step S1, the mass ratio of the concrete construction waste to the anti-caking agent is 1:(0.02-0.06).

[0048] In a preferred embodiment, in step S1, the anti-caking agent includes one or more of sodium sulphate, sodium thiosulfate, attapulgite, zeolite, lime lime, and tricalcium phosphate.

[0049] In a preferred embodiment, in step S1, the crushing method can be a conventional method known to those skilled in the art, such as using a jaw crusher; the impurity removal method can be a conventional method known to those skilled in the art, and its purpose is to remove impurities such as iron components such as steel bars in concrete. Therefore, the impurity removal method used can be adsorbed by an electromagnet. The screening method can be a conventional method known to those skilled in the art, such as using a vibrating screening machine, as long as aggregates of corresponding particle sizes can be obtained.

[0050] Because the iron component contained in concrete waste will cause the powder to agglomerate near the steel bars after being prepared into aggregate, resulting in uneven strength distribution of the mortar. Therefore, when using recycled concrete to prepare aggregate, it is necessary to carry out a decontamination step and then classify it.

[0051] In a preferred embodiment, the cement is 32.5-52.5 grade Portland cement or ordinary Portland cement.

[0052] In a preferred embodiment, the active filler is one or more of fly ash, mineral powder, and silica ash.

[0053] In a preferred embodiment, the water-retaining thickener includes one or more of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose;

[0054] The air entraining agent includes one or more of rosin-based air entraining agents, alkylbenzene sulfonate-based air entraining agents, lignin salt-based air entraining agents, salts of protein substances, fatty acids, resin acids and their salts;

[0055] The water reducer is a naphthalene-based or polycarboxylate water reducer;

[0056] The lubricant is one or more of graphite and talcum powder.

[0057] In a preferred embodiment, the anti-caking agent, water-retaining thickener, air-entraining agent, water-reducing agent, and lubricant are all powders.

[0058] In the design formula of the present invention, the anti-caking agent used is a powder with large surface area, high specific volume, fine particles, and part of which has microporous properties. By absorbing moisture or being extremely hydrophilic, it absorbs part of the free water in the concrete construction waste, reduces the content of free water in the mortar, and slows down the caking caused by cement absorbing water. The anti-caking agent is first mixed with the concrete construction waste, and then crushed and classified, so that the anti-caking agent and the concrete construction waste particles are fully mixed, and the moisture absorption effect is better. In addition, the present invention classifies the concrete construction waste particles, and determines the reasonable ratio of each level of particle size by controlling the fineness modulus, so that the concrete construction waste forms a recycled aggregate with reasonable coarseness and fineness. The obtained recycled aggregate has good stability and is not easy to agglomerate, so that it can be prepared with other raw materials to obtain a dry mixed mortar with excellent mechanical properties and processing properties.

[0059] In addition, in the formula of the present invention, by adding a lubricant, the fluidity of the dry powder of the finished dry-mixed mortar can be improved, and the anti-clogging effect can be achieved, so that the recycled aggregate can be directly prepared into bulk ordinary dry-mixed mortar without drying. Furthermore, the lubricant can also solve the quality problem of bulk products caused by high moisture content of recycled aggregates, resulting in poor material discharge and inability to store for a long time.

[0060] In the dry-mixed mortar formula of the present invention, the addition of an air-entraining agent can form a large number of tiny closed bubbles in the mixed mortar. The ball effect can reduce the friction resistance between aggregate particles, improve the problem of poor construction performance due to the poor particle shape of the recycled aggregate, and enhance the workability. At the same time, a large number of microbubbles block or block the capillary water seepage channels in the mortar, reducing the adsorption of water by the recycled aggregate, so that there is enough free water to ensure the workability of the mortar, improve the problem of large loss of mortar consistency, and comprehensively enhance the performance of the mortar.

[0061] Finally, the active filler added in the present invention, although it does not have hydraulic properties alone, can form a hydraulic compound after mixing with cement and water at room temperature, which can improve product strength, reduce cement usage, and improve mortar mechanical properties.

[0062] In a preferred embodiment, the dry-mixed mortar can be used as plaster mortar, masonry mortar and floor mortar through different dosage ratios, all of which meet the national standards for corresponding mortar products.

[0063] In a preferred embodiment, when the dry-mixed mortar is used as masonry mortar, it includes the following components by weight: 15 parts of cement, 4 parts of active filler, 5 parts of 3-5mm particle size recycled aggregate, 30 parts of 1.18-3mm particle size recycled aggregate, 44 parts of 0.6-1.18mm particle size recycled aggregate, 0.02 parts of water-retaining thickener, 0.002 parts of air entraining agent, 0.025 parts of water reducer, and 2 parts of lubricant;

[0064] The prepared dry-mix masonry mortar has a water retention rate of 94.5% in 1 day, an initial consistency of 75 mm, and a consistency loss rate of 8.9% in 2 hours.

[0065] In a preferred embodiment, when the dry-mixed mortar is used as plaster mortar, it includes the following components by weight: 17 parts of cement, 3 parts of active filler, 7 parts of 3-5mm particle size recycled aggregate, 43 parts of 1.18-3mm particle size recycled aggregate, 28 parts of 0.6-1.18mm particle size recycled aggregate, 0.04 parts of water-retaining thickener, 0.004 parts of air entraining agent, 0.035 parts of water reducer, and 2 parts of lubricant;

[0066] The prepared dry-mixed plaster mortar has a water retention rate of 95.2% in 1 day, an initial consistency of 95 mm, and a consistency loss rate of 9.6% in 2 hours.

[0067] In a preferred embodiment, when the dry-mixed mortar is used as floor mortar, it includes the following components by weight: 19 parts of cement, 3 parts of active filler, 13 parts of 3-5 mm particle size recycled aggregate, 45 parts of 1.18-3 mm particle size recycled aggregate, 18 parts of 0.6-1.18 mm particle size recycled aggregate, 0.15 parts of water-retaining thickener, 0.004 parts of air entraining agent, 0.055 parts of water reducer, and 2 parts of lubricant;

[0068] The prepared dry-mixed floor mortar has a water retention rate of 94.2% in 1 day, an initial consistency of 51 mm, and a consistency loss rate of 9.6% in 2 hours.

[0069] Another object of the present invention is to provide a method for preparing dry-mixed mortar by dry processing of recycled aggregates of all concrete, wherein the raw materials of the dry-mixed mortar used are all powders, which are convenient for storage, transportation and use, and have no special requirements on production equipment and processes during preparation. It can be prepared using an existing mortar production line, and is particularly suitable for large-scale industrial production.

[0070] To achieve the above object, the present invention provides a method for preparing dry-mix mortar by dry processing of recycled aggregate of full concrete, which specifically comprises the following steps:

[0071] Weigh all raw materials by weight and mix them evenly; add water to the raw material powder and stir to obtain the product.

[0072] In a preferred embodiment, the mass ratio of the powder to water is 1:(0.15-0.18).

[0073] In a preferred embodiment, the water adding and stirring conditions can adopt conditions known to those skilled in the art. Preferably, the water adding and stirring speed is above 280 rpm, more preferably, the water adding and stirring speed is 280-1000 rpm, and the water adding and stirring time is 60-120 s.

[0074] The technical solution of the present application is described in detail below through specific embodiments:

[0075] Unless otherwise specified, the technical means used in the present invention are conventional means well known to those skilled in the art, and the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The reagents used in the present invention are analytically pure unless otherwise specified.

[0076] In the embodiments of the present invention, the rosin-based air-entraining agent used is model NA392, and its manufacturer is Jiuding Chemical; the alkylbenzene sulfonate air-entraining agent used is specifically sodium dodecylbenzene sulfonate, its model is SDBS, and its manufacturer is Jiangsu Pules Biotechnology Co., Ltd.; the naphthalene-based water reducer used is model UBM-I, and its manufacturer is Tianjin Baoming.

[0077] In the present invention, parts by weight may be μg, mg, g, kg or other weight units known in the art, or multiples thereof, such as 1 / 10, 1 / 100, 10 times, 100 times or the like.

[0078] Example 1

[0079] A method for preparing dry-mix masonry mortar DM-M10 by dry processing of all-concrete recycled aggregates comprises the following steps:

[0080] 1. Preparation of recycled aggregate: concrete construction waste with a particle size of less than 50mm is used as raw material. The construction waste is mixed with sodium thiosulfate anti-caking agent in a mass ratio of 77:2, and then directly subjected to crushing and impurity removal processes, and then sieved to prepare graded recycled aggregates with different particle sizes such as 3-5mm, 1.18-3mm, 0.6-1.18mm, and 0-0.6mm.

[0081] 2. According to the grading of recycled aggregates of different particle sizes after classification, and based on the calculation formula of aggregate fineness modulus, when the fineness modulus of aggregate is adjusted to Mx=2.3, the combination of recycled aggregates of each particle size is determined as follows: 5 parts of 3-5mm particle size, 30 parts of 1.18-3mm particle size, 44 parts of 0.6-1.18mm particle size, and a total of 79 parts of recycled aggregates of each level.

[0082] 3. Weigh the following raw materials in parts by weight: 15 parts of slag silicate cement PSA32.5, 4 parts of mineral powder, 5 parts of 3-5mm recycled aggregate, 30 parts of 1.18-3mm recycled aggregate, 44 parts of 0.6-1.18mm recycled aggregate, 0.02 parts of hydroxypropyl methylcellulose (viscosity 100000mPa.s), 0.002 parts of alkylbenzene sulfonate air entraining agent, 0.025 parts of naphthalene water reducer, and 2 parts of graphite. Mix all the components evenly in a mixer and set aside.

[0083] 4. Mix the evenly mixed powder and water in a cement mortar mixer at a mass ratio of 1:0.17 for 120 seconds to prepare an anti-caking ordinary dry-mixed masonry mortar with all-recycled concrete as aggregate that does not require drying.

[0084] In this embodiment, cement type 32.5 is combined with aggregates prepared from fully recycled concrete waste, and no natural sand is added to prepare M10 strength grade mortar. According to the test standard for dry-mixed mortar in GB / T 25181-2019 "Premixed Mortar", the test results are shown in Table 1. After testing, all technical indicators meet the national standard requirements, and the product performance has basically not changed after being sealed for 1 month, and there is no caking after being sealed for 3 months.

[0085] Table 1 Preparation of dry-mix masonry mortar by dry treatment of recycled aggregates of all concrete

[0086]

[0087] Example 2

[0088] A method for preparing dry-mixed plaster mortar DP-M20 by dry processing of all-concrete recycled aggregates comprises the following steps:

[0089] 1. Preparation of recycled aggregate: concrete construction waste with a particle size of less than 50mm is used as raw material. The construction waste is mixed with attapulgite anti-caking agent in a mass ratio of 75:3, and then directly subjected to crushing and impurity removal processes, and then sieved to prepare graded recycled aggregates with different particle sizes such as 3-5mm, 1.18-3mm, 0.6-1.18mm, and 0-0.6mm.

[0090] 2. According to the grading of recycled aggregates of different particle sizes after classification, and based on the calculation formula of aggregate fineness modulus, when the fineness modulus of aggregate is adjusted to Mx=2.5, the combination of recycled aggregates of each particle size is determined as follows: 7 parts of 3-5mm particle size, 43 parts of 1.18-3mm particle size, 28 parts of 0.6-1.18mm particle size, and a total of 78 parts of recycled aggregates of each level.

[0091] 3. Weigh the following raw materials in parts by weight: 17 parts of ordinary Portland cement PO 42.5, 3 parts of fly ash, 7 parts of 3-5mm particle size recycled aggregate, 43 parts of 1.18-3mm particle size recycled aggregate, 28 parts of 0.6-1.18mm particle size recycled aggregate, 0.04 parts of hydroxypropyl methylcellulose (viscosity 100000mPa.s), 0.004 parts of rosin-based air entraining agent, 0.035 parts of naphthalene-based water reducer, and 2 parts of talc. Mix all the components evenly in a mixer and set aside.

[0092] 4. Mix the evenly mixed powder and water in a cement mortar mixer at a mass ratio of 1:0.18 for 120 seconds to prepare an anti-caking ordinary dry-mixed plaster mortar with all-recycled concrete as aggregate that does not require drying.

[0093] The test was carried out in accordance with the testing standards for dry-mixed mortar in GB / T 25181-2019 "Premixed Mortar". The results are shown in Table 2. After testing, all technical indicators meet the national standard requirements, and the product performance has basically not changed after being sealed for 1 month, and there is no caking after being sealed for 3 months.

[0094] Table 2 Preparation of dry-mixed plaster mortar using recycled aggregate from full concrete by dry method

[0095]

[0096] Example 3

[0097] A method for preparing dry-mixed floor mortar DS-M20 by dry processing of all-concrete recycled aggregates comprises the following steps:

[0098] 1. Preparation of recycled aggregate: concrete construction waste with a particle size of less than 50mm is used as raw material. The construction waste is mixed with zeolite anti-caking agent in a mass ratio of 73:3, and then directly subjected to crushing and impurity removal processes, and then sieved to prepare graded recycled aggregates with different particle sizes such as 3-5mm, 1.18-3mm, 0.6-1.18mm, and 0-0.6mm.

[0099] 2. According to the grading of recycled aggregates of different particle sizes after classification, and based on the calculation formula of aggregate fineness modulus, when the fineness modulus of aggregate is adjusted to Mx=2.7, the combination of recycled aggregates of each level of particle size is determined as follows: 13 parts of 3-5mm particle size, 45 parts of 1.18-3mm particle size, 18 parts of 0.6-1.18mm particle size, and a total of 76 parts of recycled aggregates of each level.

[0100] 3. Weigh the following raw materials in parts by weight: 19 parts of ordinary Portland cement PO 42.5, 3 parts of mineral powder, 13 parts of 3-5mm particle size recycled aggregate, 45 parts of 1.18-3mm particle size recycled aggregate, 18 parts of 0.6-1.18mm particle size recycled aggregate, 0.015 parts of hydroxypropyl methylcellulose (viscosity 100000mPa.s), 0.004 parts of sodium dodecylbenzene sulfonate air entraining agent, 0.055 parts of naphthalene-based water reducer, and 2 parts of talc. Mix all the components evenly in a mixer and set aside.

[0101] 4. Mix the evenly mixed powder and water in a cement mortar mixer at a mass ratio of 1:0.17 for 120 seconds to prepare an anti-caking ordinary dry-mixed floor mortar with drying-free fully recycled concrete as aggregate.

[0102] The test was carried out in accordance with the testing standards for dry-mixed mortar in GB / T 25181-2019 "Premixed Mortar". The results are shown in Table 3. After testing, all technical indicators meet the national standard requirements, and there is no caking after being sealed and placed for 3 months.

[0103] Table 3 Preparation of dry-mixed floor mortar using recycled aggregate from all-concrete by dry method

[0104]

[0105] Comparative Example 1

[0106] Compared with Example 1, the only difference is that when preparing the recycled aggregate, no sodium thiosulfate anti-caking agent is added, all of it is concrete construction waste, and the resulting recycled aggregates of various particle sizes are matched as follows: 5 parts of 3-5mm particle size, 30 parts of 1.18-3mm particle size, 44 parts of 0.6-1.18mm particle size, and a total of 79 parts of recycled aggregate prepared from all concrete construction waste.

[0107] The remaining methods and dosages are exactly the same as those in Example 1.

[0108] The test was carried out in accordance with the testing standard for dry-mixed mortar in GB / T 25181-2019 "Premixed Mortar", with the test results shown in Table 4 after 1 day and 30 days of sealing.

[0109] Table 4 Preparation of dry-mix masonry mortar using recycled aggregate from full concrete by dry method

[0110]

[0111] It can be seen from Table 4 that due to the lack of anti-caking agent, the initial product performance has a slight decline. At the same time, after one month of sealed storage, the water in the recycled aggregate is absorbed by the cement, causing the product to agglomerate. At the same time, due to partial hydration, the initial consistency of the product increases, and the water retention rate and strength are significantly reduced, and the product performance declines.

[0112] Comparative Example 2

[0113] Compared with Example 1, the only difference is that no graphite is added when preparing the dry-mixed mortar, and the rest of the method and dosage are exactly the same as those in Example 1.

[0114] Since the product does not contain lubricant, its dry powder has poor fluidity. During the first use of bulk products, the dry powder material is not discharged smoothly or even not discharged. It is necessary to manually knock on the tank body and vibrate the material, which is not conducive to application.

[0115] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A dry-mix mortar prepared by dry processing of recycled aggregate of full concrete, characterized in that: The composition includes the following components by weight: 10-20 parts of cement, 3-10 parts of active filler, 75-85 parts of recycled aggregate, 0.01-0.06 parts of water-retaining thickener, 0.002-0.006 parts of air entraining agent, 0.025-0.075 parts of water reducing agent, and 1-2 parts of lubricant; Wherein, the recycled aggregate is prepared according to the following method: S1 mixes concrete construction waste and anti-caking agent evenly, crushes, removes impurities and sieves to obtain graded recycled aggregates with nominal particle sizes of 3-5mm, 1.18-3mm, 0.6-1.18mm and 0-0.6mm respectively; S2 is calculated according to the aggregate fineness modulus calculation formula (1), and the cumulative screen residue percentage is calculated. , , , , , ; Formula (1) Where: —— fineness modulus; , , , , , ——the cumulative percentage of residue on the square hole sieves of 4.75mm, 2.36mm, 1.18mm, 0.60mm, 0.30mm and 0.15mm respectively, %; S3 controls the fineness modulus of aggregate to M x =2.3-3.0, determine the proportion of each level of particle size to obtain the recycled aggregate; In step S1, the mass ratio of the concrete construction waste to the anti-caking agent is 1:(0.02-0.06); the anti-caking agent includes one or more of sodium sulphate, sodium thiosulfate, attapulgite, zeolite, lime lime, and tricalcium phosphate.

2. The dry-mix mortar prepared by dry-processing recycled aggregate of full concrete according to claim 1, characterized in that: The cement is 32.5-52.5 grade silicate cement or ordinary silicate cement.

3. The dry-mix mortar prepared by dry-processing recycled aggregate of full concrete according to claim 1, characterized in that: The active filler is one or more of fly ash, mineral powder and silica ash.

4. The dry-mix mortar prepared by dry-processing recycled aggregate of full concrete according to claim 1, characterized in that: The water-retaining thickener includes one or more of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose; The air entraining agent includes one or more of rosin-based air entraining agents, alkylbenzene sulfonate-based air entraining agents, lignin salt-based air entraining agents, salts of protein substances, fatty acids, resin acids and their salts; The water reducer is a naphthalene-based or polycarboxylate water reducer; The lubricant is one or more of graphite and talcum powder.

5. The method for preparing the dry-mixed mortar according to any one of claims 1 to 4, comprising the following steps: Weigh all raw materials by weight and mix them evenly; add water to the raw material powder and stir to obtain the product.

6. The method for preparing dry-mixed mortar according to claim 5, characterized in that: The mass ratio of the powder to water is 1:(0.15-0.18).

Images