WO2022041374A1

WO2022041374A1 - Modification material for low-quality aggregate and treatment method

Info

Publication number: WO2022041374A1
Application number: PCT/CN2020/117739
Authority: WO
Inventors: 王玲; 王振地; 姚燕
Original assignee: 中国建筑材料科学研究总院有限公司
Priority date: 2020-08-27
Filing date: 2020-09-25
Publication date: 2022-03-03
Also published as: CN111978056A

Abstract

The present application pertains to the technical field of building materials, and specifically relates to a modification material for a low-quality aggregate and a treatment method. The modification material for a low-quality aggregate provided in the present application comprises the following components in percentage by mass: 46-50% of cement; 10-15% of a mineral admixture; 2-5% of an active powder; 0.2-0.6% of a water reducing agent; 0.001-0.004% of a viscosity adjusting agent; 0-3.2% of an expansion agent; 0-0.12% of an air-entraining agent; and 0-0.0007% of a defoaming agent. The modification material provided in the present application can achieve effective filling and coating modification of a low-quality aggregate by means of the combined actions of the components and the adjustment of the amounts thereof, and especially can effectively adjust the surface tension and viscosity of the modification material and coordinatively optimize the pore immersion amount and the shell coating thickness by means of the combined actions of the cement, the active powder, and the viscosity adjusting agent in specific amounts. The combined use of the inorganic and organic components can promote secondary hydration/chemical bonding of a slurry layer, and improve the strength of the interface between the aggregate and the slurry layer. After the modification treatment, the cylinder compressive strength of the aggregate is increased by 40% or more, the crushing value is reduced by 30% or more, and the water absorption rate in 24 hours is reduced by 15% or more.

Description

A kind of modified material and processing method of low-quality aggregate

cross reference

This application claims the priority of the Chinese patent application filed on August 27, 2020 with the application number 202010879703.1 and the invention titled "A Modified Material of Low-Quality Aggregate and Its Processing Method", the entire contents of which are approved by Reference is incorporated in this application.

technical field

The application belongs to the technical field of building materials, and specifically relates to a modified material of low-quality aggregate and a processing method.

Background technique

With the continuous advancement of my country's marine development strategy, the amount of infrastructure construction in offshore islands or coastal areas has increased significantly. As an important part of concrete raw materials, ordinary river sand and gravel resources are extremely scarce on offshore islands, and are transported from the mainland. The raw materials of sand and gravel will greatly increase the construction cost and prolong the construction period. On the premise of not destroying the local ecological environment, the use of abandoned coral reefs and sand on the island reefs as raw materials to prepare coral aggregate concrete can not only save natural sand and gravel resources, reduce transportation costs, shorten the construction period, but also effectively meet the requirements of deep-sea development and It is of great practical significance and extremely high application value to meet the needs of development projects in areas far from the coastline.

Coral reef aggregates have large porosity, strong water absorption, low strength, and high content of harmful ions. Direct use in concrete preparation will cause many problems such as poor workability, low strength, uncoordinated strength development before and after, and insufficient durability, which seriously restricts its performance. Application in offshore and island reef engineering construction.

With the rapid development of infrastructure construction and real estate market, more and more buildings are newly built and rebuilt every year, and a large amount of construction waste will be generated in the process of new construction and reconstruction, which has a great impact on the environment. At present, the annual construction waste generated has reached 2 billion tons, and it is increasing year by year; on the other hand, the annual consumption of concrete exceeds 8 billion cubic meters, and the demand for sand and gravel aggregates reaches 13 billion tons, and the natural aggregate resources are seriously lacking. , the resulting economic, social and environmental problems have become increasingly prominent. Crushing and sorting waste concrete as recycled aggregate can not only effectively utilize waste resources, but also save natural sand and gravel resources, and solve the problem of environmental damage caused by lack of natural aggregate and mining.

Compared with natural aggregates, recycled aggregates have lower strength and higher crushing index values; they have multiple edges and corners, and a layer or part of hardened slurry is attached to the surface, which has higher porosity and forms a complex multiple interface structure inside the concrete. , which makes the durability problem of recycled concrete more prominent. At present, its application is limited to a certain extent. In order to broaden its application field and improve its utilization rate, it must first be surface treated to achieve multiple interface strengthening and performance improvement.

At present, the treatment methods for low-quality aggregates such as coral aggregates and recycled aggregates mainly include mechanical modification and chemical modification. Mechanical modification is to improve the particle shape and surface roughness of low-quality aggregates through mechanical action; chemical modification is to soak and dry low-quality aggregates with inorganic or organic materials, and use the filling and film-forming effects of slurry. , reduce the water absorption of low-quality aggregates and improve the strength of aggregates.

However, these methods still have certain drawbacks and have not yet been applied on a large scale. Mechanical modification cannot precisely control the modification effect, consumes high energy and produces a large amount of waste powder; chemical modification is still in the experimental research stage, and conventional inorganic materials cannot enter the pores of low-quality aggregates, and the flow of polymer materials The properties and film-forming properties are good, but the compatibility with cement concrete materials is not good, and the modification effect is limited. In addition, the modification of coral aggregates generally starts from the two aspects of pore filling and surface coating. Filling and coating are realized by selecting different modified materials, but due to the selected filling and coating modified materials The difference in performance will introduce a new interface, resulting in poor treatment effect; if the same modified material is used for filling and coating treatment, due to the different performance requirements of the modified material for filling and coating, it is difficult to achieve both. Effective filling and wrapping. Therefore, chemical modification materials and methods for porous low-quality aggregates such as coral aggregates and recycled aggregates have yet to be developed.

SUMMARY OF THE INVENTION

Therefore, the technical problem to be solved by the present application is to overcome the defects in the prior art that the modified materials and modification methods for porous and low-quality aggregates cannot simultaneously realize the effective filling of pores and surface coating, thereby providing a low-grade aggregate. Modified materials and processing methods of high-quality aggregates.

To this end, the application provides the following technical solutions:

The present application provides a modified material for low-quality aggregates, comprising the following components by mass percentage:

Cement 46-50%;

Mineral admixture 10-15%;

Active powder 2-5%;

Water reducing agent 0.2-0.6%;

Viscosity modifier 0.001-0.004%;

Expanding agent 0-3.2%;

Air-entraining agent 0-0.12%;

Defoamer 0-0.0007%.

Further, the modified material of the low-quality aggregate comprises the following components by mass percentage:

Cement 47-49%;

Mineral admixtures 12-13%;

Active powder 2-4%;

Water reducing agent 0.3-0.5%;

Viscosity modifier 0.001-0.004%;

Expanding agent 2.3-3.0%;

Air-entraining agent 0.05-0.08%;

Defoamer 0.0002-0.0005%.

Further, in the modified material of the low-quality aggregate, the balance is water; preferably, the amount of water is 30.5-36.3%.

Further, the active powder is at least one of nano-silicon dioxide and polymer rubber powder;

Preferably, the active powder is composed of nano-silicon dioxide and polymer rubber powder, and the mass ratio of the two is 1:2.

Further, the density of the viscosity modifier is 0.98-1.02 g/mL, and the pH is 7.5-10.0;

Preferably, the viscosity modifier is Rheoplus420 high-performance viscosity modifier produced by BASF China Co., Ltd.

Further, the mineral admixture is at least one of fly ash, mineral powder, silica fume, metakaolin, and limestone powder.

Preferably, the mineral admixture is composed of fly ash, mineral powder, and metakaolin, and the mass ratio is 3:3:2.

Further, the cement is at least one of Portland cement and aluminate cement;

The water reducing agent is at least one of a polycarboxylic acid series water reducing agent and a naphthalene series water reducing agent; preferably, the water reducing rate of the water reducing agent is not less than 30%;

The expansion agent is at least one of calcium sulfoaluminate type expansion agent and calcium oxide type expansion agent;

The air-entraining agent is at least one of rosin-type air-entraining agent and saponin-type air-entraining agent;

The defoamer is at least one of a silicone-based defoamer or a modified polyether-based defoamer.

The present application also provides a method for processing low-quality aggregates, comprising the following steps:

The low-quality aggregates are soaked in water glass, dried and used for later use;

Put the immersed low-quality aggregates into the immersion container, use modified materials for modification treatment under vacuum and/or pressurized conditions, spread the low-quality aggregates, and naturally cure for 18-24 hours at high temperature and high pressure Steam for 4-12h and cool.

Further, the modified material is the modified material of the above-mentioned low-quality aggregate provided by the application.

Further, the modification step is to inject the modified material under vacuum conditions, stir for 1-4 minutes, and continue stirring for 2-6 minutes under high pressure conditions;

Preferably, the vacuum condition is 2-5 kPa, and the high pressure condition is 0.2-0.5 MPa.

Further, the conditions of the high-temperature and high-pressure steam curing are as follows: the temperature is 60-80° C. and the pressure is 1-2 MPa.

Further, the mass ratio of the modified material to the low-quality aggregate is 1:0.2-0.35.

The low-quality aggregates include coral aggregates and regenerated aggregates, wherein the regenerated aggregates are derived from waste concrete blocks, and can be mixed in a certain proportion after crushing and grading.

There is no special requirement for cement type in this application. Specifically, Portland cement can be selected from six grades of 42.5, 42.5R, 52.5, 52.5R, 62.5, 62.5R, and aluminate cement can be selected from CA-50, CA- 60, CA-70, CA-80 four types.

The polymer rubber powder includes vinyl acetate-ethylene copolymer rubber powder, acrylic rubber powder, ethylene and vinyl chloride and vinyl laurate ternary copolymer rubber powder, vinyl acetate and ethylene and higher fatty acid vinyl ester ternary copolymer rubber powder And one or more of vinyl acetate and higher fatty acid vinyl ester copolymer rubber powder.

The technical solution of the present application has the following advantages:

1. The modified material of low-quality aggregate provided by this application includes the following components by mass percentage: cement 46-50%; mineral admixture 10-15%; active powder 2-5%; water reduction 0.2-0.6% of adhesive; 0.001-0.004% of viscosity modifier; 0-3.2% of expansion agent; 0-0.12% of air-entraining agent; 0-0.0007% of defoamer. The modified material provided by this application, through the coordination between the components and the adjustment of the dosage, the fluidity of the modified material is ≥ 260mm; Coating modification, especially through the combination of a specific amount of cement, active powder and viscosity modifier, can effectively adjust the surface tension and viscosity of the modified material. The thickness of the surface shell, and at the same time, the immersion filling of the aggregate pores and the modification of the shell coating are realized, which improves the overall treatment effect of the aggregate; the combined use of inorganic and organic components promotes the secondary hydration/chemical bonding of the slurry layer and improves the bone quality. The strength of the interface between the material and the slurry layer.

The modified material of the low-quality aggregate provided by the present application can improve the modification effect of the aggregate and enhance the mixing performance of the concrete by further optimizing and adjusting the dosage of each component. Among them, the addition of the expansion agent can compensate for the volume shrinkage during the formation of the cementitious material, ensure the strength and compactness of the slurry, and at the same time play the role of optimizing the interface between the slurry and the aggregate.

In the modified material of low-quality aggregates provided by this application, the active powder is composed of nano-silica and polymer rubber powder, and the mass ratio of the two is 1:2. It can further enhance the filling and modification effect of modified materials on the pores and surfaces of low-quality aggregates, and improve the surface treatment effect.

In the modified material of low-quality aggregate provided by the application, the viscosity modifier has a density of 0.98-1.02 g/mL and a pH of 7.5-10.0; preferably, the viscosity modifier is a polycarboxylic acid type viscosity reducer . By selecting a viscosity modifier with specific properties and composition, the cohesiveness and fluidity of the slurry can be synergistically optimized to ensure the effect of impregnation and coating.

In the modified material of low-quality aggregate provided by the present application, the mineral admixture is composed of fly ash, mineral powder, and metakaolin, and the mass ratio is 3:3:2. The overall water absorption and workability of the slurry can be adjusted by selecting mineral admixtures with specific compositions and proportions. The mineral admixtures and cement together build a dense and corrosion-resistant cementitious material system, reducing the heat of hydration and reducing the Cement consumption, saving costs while increasing the durability and long-term strength of the material.

2. The method for treating low-quality aggregates provided by this application includes the following steps: soaking the low-quality aggregates with water glass, drying, and preparing for use; placing the soaked low-quality aggregates in a dipping container, Under vacuum and/or pressurized conditions, modified materials are used for modification treatment, and the low-quality aggregates are spread out, naturally cured for 18-24 hours, high-temperature and high-pressure steam curing for 4-12 hours, and cooled. In the treatment method provided by the present application, first soaking the low-quality aggregate with water glass solution can form a layer of colloidal film on the surface of the aggregate, which acts as a coupling with the subsequent treatment material, so that the gap between the aggregate and the slurry of the modified material is formed. Has a good interface transition area. The vacuum impregnation process can ensure that the slurry and the aggregate are fully infiltrated, so that the slurry can more fully fill the aggregate pores, and the pressurized stirring can make the modified material slurry enter deeper into the aggregate pores, improve the degree of pore filling and the second At the same time, it can also improve the compactness of the shell layer and the overall strength of the aggregate. The processing method for low-quality aggregates provided by the present application can achieve effective filling of aggregate pores and surface coating by only one-step processing of a single modified material, which is easy to operate and avoids the need for step-by-step processing of multiple modified materials. Introduce a new interface, which affects the processing effect.

For the treatment method of low-quality aggregates provided in this application, the modified materials provided in this application are selected for treatment, and the modified materials with specific composition and proportion provided in this application are used in conjunction with a specific treatment method. After modification treatment, A sufficient amount of modified material is filled in the pores of the low-quality aggregate, and a coating layer with a thickness of 0.7-1.5mm is formed on the surface of the low-quality aggregate, so that the cylinder compressive strength of the treated aggregate is increased by more than 40%. The crush value is reduced by more than 30%, and the 24h water absorption rate is reduced by more than 17%.

In the method for treating low-quality aggregates provided by the present application, the conditions of the high-temperature and high-pressure steam curing are: temperature 60-80° C., pressure 1-2 MPa, and time 8-12 h. High-temperature autoclave curing can improve the hydration degree of cement and mineral admixtures in surface treatment materials, improve the microstructure and compactness of the slurry, and improve the overall performance of the treated aggregate.

In the method for processing low-quality aggregates provided by the present application, the mass ratio of the modified material to the low-quality aggregates is 1:0.2-0.35, and by limiting the mass ratio of the two, the modification of the low-quality aggregates can be further improved Effect.

Description of drawings

In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the accompanying drawings that need to be used in the description of the specific embodiments or the prior art will be briefly introduced below. The drawings are some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is the SEM photograph of the bonding situation between the aggregate surface and the coating layer after the treatment in Example 5 of the application;

2 is an optical microscope photo of the coral aggregate cross-section after the treatment in Example 5 of the application.

detailed description

The following examples are provided for a better understanding of the present application, and are not limited to the best embodiments, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by combining with the features of other prior art shall fall within the protection scope of the present application.

Those who do not specify specific experimental steps or conditions in the examples can be carried out according to the operations or conditions of conventional experimental steps described in the literature in this field. The reagents or instruments used without the manufacturer's indication are all conventional reagent products that can be obtained from the market.

Example 1

The present embodiment provides a method for processing low-quality aggregates, comprising the following steps:

The composition of the modified material:

Portland cement 52.5R 50kg; mineral admixture 12.5kg; active powder 5kg; water reducing agent 0.6kg; 3kg metakaolin, 4kg limestone, 2.5kg silica fume; the active powder is nano-silica; the water reducing agent is ZY-700 polycarboxylate water reducing agent produced by CNBM Zhongyan Technology Co., Ltd.; the viscosity adjusting agent is BASF Rheoplus420 high performance viscosity modifier produced by China Co., Ltd.

The processing steps are as follows: 1) 20 kg of cleaned coral aggregates are soaked in 50 kg of water glass solution with a mass fraction of 30% for 4 hours and taken out, and dried for later use; 2) the modified materials are weighed according to the above proportions, and each component is weighed. 3) Put the coral aggregate to be treated into the impregnation container, inject the modified material, vacuumize, stir for 1min under the vacuum condition of 5kPa, and then stir under the high pressure condition of 0.2MPa for 2min; 4) The obtained coral aggregates after dipping and coating treatment were spread out to avoid cementation with each other, and were naturally cured for 24 hours, and then steamed at high temperature and high pressure for 4 hours. Cool to room temperature.

Example 2

The composition of the modified material:

Portland cement 52.5R 50kg; mineral admixture 15kg; active powder 2kg; water reducing agent 0.2kg; Metakaolin, 4kg limestone; active powder is nano-silica; water reducing agent is ZY-700 polycarboxylate water reducing agent produced by CNBM Zhongyan Technology Co., Ltd.; viscosity adjusting agent is Ningbo Zhongshuike Chemical Technology Co., Ltd. The SK-420 viscosity modifier produced by the company.

The processing steps are as follows: 1) soak 35 kg of the cleaned coral aggregate with 50 kg of water glass solution with a mass fraction of 5% for 5 hours, take it out, and dry it for later use; 2) weigh the modified materials according to the above proportions, and mix the components 3) put the coral aggregate to be treated into the dipping container, inject the modified material slurry, and then stir 6min under the high pressure condition of 0.5MPa; 4) the coral aggregate after the obtained dipping and coating treatment Spread out to avoid cementation between each other, and naturally cure for 18h, and then high-temperature and high-pressure steam curing for 12h. The pressure of high-temperature and high-pressure steam curing is 2MPa, the temperature is 60 °C, and then cooled to room temperature.

Example 3

The composition of the modified material:

Aluminate cement CA-60 46kg; mineral admixture 13kg; active powder 4kg; water reducing agent 0.5kg; viscosity modifier 3g, expansion agent 3.2kg, air entraining agent 0.08kg, defoamer 7g, add water to 100kg, wherein the mineral admixture is composed of 5kg fly ash, 4kg metakaolin, 4kg silica fume; the active powder is nano-silicon dioxide; the water reducing agent is ZY-700 type produced by CNBM Zhongyan Technology Co., Ltd. Polycarboxylate water reducing agent; the viscosity modifier is Rheoplus420 high-performance viscosity modifier produced by BASF China Co., Ltd.; the expansion agent is ZY-UEA II type expansion agent produced by CNBM Zhongyan Technology Co., Ltd.; The air agent is SX rosin air-entraining agent produced by Shanxi Sunmusi Building Materials Chemical Co., Ltd.; the defoamer is an organosilicon defoamer.

The processing steps are: 1) 25kg of cleaned coral aggregates are soaked in 50kg of water glass solution with a mass fraction of 20% for 4.5h and taken out, and dried for later use; 2) the modified materials are weighed according to the above proportions, and each group 3) put the coral aggregate to be treated into the dipping container, then inject the modified material slurry, vacuumize, and stir for 4min under the condition that the vacuum degree is 2kPa; 4) the obtained dipping coating is processed The coral aggregates were spread out to avoid cementation between each other, and were naturally cured for 20 hours, and then steamed at high temperature and high pressure for 8 hours. The pressure of high temperature and high pressure steam curing was 1.5MPa, the temperature was 70 °C, and then cooled to room temperature.

Example 4

The composition of the modified material:

Portland cement 42.5R 49kg; mineral admixture 14kg; active powder 4kg; water reducing agent 0.3kg; Among them, the composition of the mineral admixture is 5kg fly ash, 4kg metakaolin, 4kg silica fume, 1kg mineral powder; the active powder is vinyl acetate-ethylene copolymer rubber powder; the water reducing agent is CNBM Zhongyan Technology Co., Ltd. The ZY-700 type polycarboxylate water reducing agent produced; the viscosity modifier is Rheoplus420 high-performance viscosity modifier produced by BASF China Co., Ltd.; the expansion agent is ZY-UEA II produced by CNBM Zhongyan Technology Co., Ltd. Expansion agent; the air-entraining agent is SX rosin type air-entraining agent produced by Shanxi Sunmus Building Materials Chemical Co., Ltd.; the defoamer is a silicone type defoamer.

The processing steps are: 1) soak 30kg of the cleaned coral aggregate with 60kg of water glass solution with a mass fraction of 20% for 4.5h, take it out, and dry it for later use; 3) Put the coral aggregate to be treated into the impregnation container, inject the modified material, vacuumize, stir for 2min under the vacuum condition of 3kPa, and then stir under the high pressure condition of 0.4MPa for 4min; 4 ) Spread out the obtained coral aggregates after dipping and coating treatment to avoid mutual bonding, and naturally cure for 20 hours, and then steam at high temperature and high pressure for 6 hours, wherein the pressure of high temperature and high pressure steam curing is 1.5 MPa, and the temperature is 65 ° C , and then cooled to room temperature.

Example 5

The composition of the modified material:

Portland cement 42.5R 48kg; Mineral admixture 13kg; Active powder 4kg; , among them, the composition of the mineral admixture is 4.9kg fly ash, 3.2kg metakaolin, 4.9kg mineral powder; the active powder composition is 1.3kg nano-silica from Zhongke Detong (Beijing) Technology Co., Ltd., Germany 2.7kg of 5010N type rubber powder produced by Wacker Chemicals; ZY-700 type polycarboxylate water reducer as water reducing agent; Rheoplus420 high-performance viscosity modifier produced by BASF China Co., Ltd. for viscosity modifier; the expansion agent It is ZY-UEA II type expansion agent; the air-entraining agent is SJ-2 saponin type air-entraining agent produced by Lvsheng Biotechnology Co., Ltd.; the defoamer is a polyether defoamer.

The processing steps are as follows: 1) 25 kg of cleaned coral aggregates are soaked in 50 kg of water glass solution with a mass fraction of 18% for 3 hours, and then taken out, and dried for later use; 2) the modified materials are weighed according to the above proportions, and each component is weighed. 3) Put the coral aggregate to be treated into the impregnation container, inject the modified material, vacuumize, stir for 3min under the vacuum condition of 4kPa, and then stir under the high pressure condition of 0.3MPa for 3min; 4) The obtained coral aggregates after dipping and coating treatment were spread out to avoid cementation with each other, and were naturally cured for 20 hours, and then steamed at high temperature and high pressure for 8 hours. Then cool to room temperature.

Fig. 1 is a SEM photograph of the bonding situation between the surface of the aggregate and the coating layer after the treatment of the present embodiment. It can be seen from the figure that the thickness of the coating layer is about 1.3mm, and the interface between the cement hydration product of the coating layer material and the coral aggregate is The structure is dense and the interface is well bonded.

Figure 2 is an optical microscope photo of the cross-section of the coral aggregate after the treatment in this example. It can be seen from the figure that the coating material and the aggregate are densely combined, and the slurry has a good filling effect in the pores inside the aggregate.

Example 6

The composition of the modified material:

Portland cement 42.5R 49kg; Mineral admixture 12kg; Active powder 3kg; Water reducing agent 0.4kg; Among them, the composition of the mineral admixture is 4.5kg fly ash, 3kg metakaolin, 4.5kg mineral powder; the active powder composition is 1kg nano-silica from Zhongke Detong (Beijing) Technology Co., Ltd., Wacker Chemicals, Germany The 5010N type rubber powder produced by the company is 2kg; the water reducing agent is ZY-700 type polycarboxylate water reducing agent; the viscosity modifier is Rheoplus420 high-performance viscosity modifier produced by BASF China Co., Ltd.; the expansion agent is ZY-UEA Type II expansion agent; the air-entraining agent is SJ-2 saponin-type air-entraining agent produced by Lvsheng Biotechnology Co., Ltd.; the defoamer is a polyether defoamer.

The processing steps are as follows: 1) 25 kg of cleaned coral aggregates are soaked in 55 kg of water glass solution with a mass fraction of 18% for 4 hours and taken out, and dried for later use; 2) the modified materials are weighed according to the above proportions, and each component is 3) Put the coral aggregate to be treated into the impregnation container, inject the modified material, vacuumize, stir for 3min under the vacuum condition of 4kPa, and then stir under the high pressure condition of 0.3MPa for 3min; 4) The obtained dipped and coated coral aggregates were spread out to avoid cementation with each other, and were naturally cured for 20 hours, and then steamed at high temperature and high pressure for 5 hours. Then cool to room temperature.

Example 7

The composition of the modified material:

Portland cement 42.5R 48kg; Mineral admixture 13kg; Active powder 4kg; , among them, the composition of mineral admixture is 4.9kg fly ash, 4.9kg metakaolin, 3.2kg mineral powder; the composition of active powder is 2.7kg nano-silica from Zhongke Detong (Beijing) Technology Co., Ltd., Germany 1.3kg of 5010N type rubber powder produced by Wacker Chemicals; ZY-700 type polycarboxylate water reducer as water reducing agent; Rheoplus420 high performance viscosity modifier produced by BASF China Co., Ltd. for viscosity modifier; the expansion agent It is ZY-UEA II type expansion agent; the air-entraining agent is SJ-2 saponin type air-entraining agent produced by Lvsheng Biotechnology Co., Ltd.; the defoamer is a polyether defoamer.

The processing steps are: 1) The cleaned recycled aggregate (the recycled aggregate is derived from waste concrete blocks, and the waste concrete blocks are broken into two grades of 5-10mm and 10-20mm, according to (5-10mm): (10 : 20mm)=4:6 ratio mixed into continuous grades) 25kg is soaked in 50kg of water glass solution with a mass fraction of 18% for 3h and taken out, and dried for use; 2) Weigh the modified materials according to the above proportions, put 3) Put the regenerated aggregate to be treated into the impregnation container, inject the modified material, vacuumize, stir for 3 minutes under the vacuum condition of 4kPa, and then stir for 3 minutes under the high pressure condition of 0.3MPa; 4) Spread out the obtained regenerated aggregate after impregnation and coating treatment to avoid mutual bonding, and naturally cure for 20 hours, and then steam at high temperature and high pressure for 8 hours, wherein the pressure of high temperature and high pressure steam curing is 1.5 MPa, and the temperature is 75 °C and then cooled to room temperature.

Comparative Example 1

This comparative example provides a method for processing low-quality aggregates, comprising the following steps:

The composition of the modified material:

Portland cement 42.5R 48kg; mineral admixture 13kg; water reducing agent 0.4kg; viscosity modifier 3g, expansion agent 2.8kg, air-entraining agent 0.06kg, defoamer 4g, add water to make up to 100kg, among which, mineral admixture The composition of the mixture is 4.9kg fly ash, 3.2kg metakaolin, 4.9kg mineral powder; the water reducing agent is ZY-700 type polycarboxylate water reducing agent; the viscosity adjusting agent is Rheoplus420 high-performance viscosity produced by BASF China Co., Ltd. Modifier; the expansion agent is ZY-UEA II type expansion agent; the air-entraining agent is SJ-2 saponin type air-entraining agent produced by Lvsheng Biotechnology Co., Ltd.; the defoamer is polyether Defoamer.

Comparative Example 2

The composition of the modified material:

Portland cement 42.5R 48kg; active powder 4kg; water reducing agent 0.4kg; viscosity modifier 3g, expansion agent 2.8kg, air entraining agent 0.06kg, defoamer 4g, add water to make up to 100kg, among which, active powder The composition is 1.3kg of nano-silicon dioxide from Zhongke Detong (Beijing) Technology Co., Ltd., 2.7kg of 5010N type rubber powder produced by German Wacker Chemical Company; the water reducing agent is ZY-700 type polycarboxylate water reducing agent; The adhesive is Rheoplus420 high-performance viscosity modifier produced by BASF China Co., Ltd.; the expansion agent is ZY-UEA II type expansion agent; the air-entraining agent is SJ-2 type saponins produced by Lvsheng Biotechnology Co., Ltd. Air-entraining agent; the defoamer is a polyether defoamer.

Comparative Example 3

The composition of the modified material:

Portland cement 42.5R 48kg; mineral admixture 13kg; active powder 4kg; The composition of the mixture is 4.9kg of fly ash, 3.2kg of metakaolin, and 4.9kg of mineral powder; the active powder is composed of 1.3kg of nano-silica from Zhongke Detong (Beijing) Technology Co., Ltd., produced by German Wacker Chemical Company 2.7kg of 5010N type rubber powder; the water reducing agent is ZY-700 type polycarboxylate water reducing agent; the expansion agent is ZY-UEA II type expansion agent; the air-entraining agent is produced by Lvsheng Biotechnology Co., Ltd. SJ-2 type saponin air-entraining agent; the defoamer is a polyether defoamer.

Experimental example

The coral aggregates and recycled aggregates treated in Examples 1-7 and Comparative Examples 1-3 of the present application and the untreated coral aggregates and recycled aggregates were tested. The test items included the coating layer of the modified aggregate. Thickness, pore filling amount, cylinder compressive strength, crush value, porosity, water absorption and water-soluble chloride ion content, as well as the fluidity and viscosity of the modified slurry, etc. The specific test methods and results are as follows.

1. Coating Thickness and Pore Filling Test

The treated aggregate is cut and observed under an optical microscope or a scanning electron microscope to obtain the thickness of the surface coating layer, and the average value of 10 aggregates is used as the value of the coating layer thickness. The mass of the aggregate before and after treatment was tested, and the percentage of mass increment was calculated as the pore filling value.

2. Cylinder compressive strength test

Refer to GB/T 17431.2 Lightweight aggregate and its test method Part 2: Lightweight aggregate test method to test the compressive strength of coral aggregate cylinder.

3. Crush value test

Test according to the method in GB/T 14685 Construction Pebble and Crushed Stone.

4. Porosity test

The porosity is measured by the drainage method, that is, a certain amount of aggregate is randomly selected, and the aggregate sample is placed in a vacuum saturated equipment for vacuum saturation. The vacuum degree is maintained at 1-5kPa, and the continuous saturation time is 4h. The functional aggregate sample was taken out, and its water retention mass M _s was weighed, accurate to 0.1 g.

Place the water container on the electronic scale, bind the functional aggregate with a string, and hang the rope over the water container to keep the functional aggregate submerged by the water in the container, and not sink to the bottom or contact the container wall. The actual volume V of the aggregate was obtained from the difference between the electronic weighing readings before and after the addition of the material.

All the aggregates were put into an oven, the oven temperature was adjusted to 105°C, and the drying was continued for 48h. The sample was taken out of the oven, cooled to room temperature under natural conditions, and its mass M _d was weighed, accurate to 0.1 g. The porosity is calculated according to the following formula,

5. Water absorption test

Test with reference to the methods in JGJ 52 Standard for Sand and Stone Quality and Inspection Methods for Ordinary Concrete.

6. Slurry fluidity test

Measure the fluidity of the slurry according to GB/T 8077-2012.

7. Slurry viscosity test

In the experiment, a digital rotational viscometer was used to prepare the slurry according to the proportion. The pure slurry mixer was used to stir at a slow speed for 1 min, and then quickly stir for 2 min. It was quickly injected into the viscosity test sample barrel to test its performance under the condition of a rotating speed of 60 r/min. Viscosity value, test temperature is 20 ℃.

8. Water-soluble chloride ion content test

Test with reference to the "chloride ion content test in sand" method in JGJ 52 Standard for Sand and Stone Quality and Inspection Methods for Ordinary Concrete.

Table 1

It can be seen from the data in the table that after the coral aggregate is treated with the slurry prepared in the present application, the compressive strength of the aggregate cylinder is significantly increased and the crushing value is greatly reduced, indicating that the slurry and the treatment method can improve the strength of the porous coral aggregate. The effect is obvious; the aggregate porosity, water absorption and water-soluble chloride ion content are all reduced, which can effectively improve the workability of low-quality aggregate concrete.

The data of Example 5 compared with Comparative Example 1 shows that the addition of active powder can increase the compactness of the surface coating layer and the thickness of the surface slurry coating layer of the treated aggregate, thereby increasing the cylinder compressive strength and reducing the crushing value. , the porosity, water absorption and water-soluble chloride ion content of coral aggregates were significantly reduced after adding active powder.

The data of Example 5 compared with Comparative Example 2 shows that the addition of mineral admixtures can adjust the properties of the slurry, such as fluidity and viscosity (in Comparative Example 2, the water-to-binder ratio is too large, and the slurry is seriously bleeding and cannot be tested) , thereby affecting the thickness of the coating layer and the amount of pore filling, thereby affecting the compactness and overall performance of the surface hydration products. Adding an appropriate amount of mineral admixtures can not only save material costs, but also further synergistically optimize the slurry properties, thereby affecting the treatment effect of aggregates.

The data of Example 5 compared with Comparative Example 3 shows that the addition of the viscosity modifier can effectively reduce the viscosity of the slurry and increase the fluidity of the slurry, thereby effectively increasing the amount of pore filling, thereby affecting the modification effect of the aggregate.

From the effect of Example 7, after the recycled aggregate is treated with the material of the present application, the crush value, porosity and water absorption of the aggregate all decrease, indicating that the aggregate strength increases after the treatment, and the need for preparing concrete increases. The reduction of the water amount and the reduction of the adsorption rate of the admixture will help to improve the strength of the recycled aggregate concrete and enhance the workability of the recycled aggregate concrete.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation manner. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. However, the obvious changes or changes derived from this are still within the protection scope created by the present application.

Claims

A modified material of low-quality aggregate, characterized in that it comprises the following components by mass percentage:

Cement 46-50%;

Mineral admixture 10-15%;

Active powder 2-5%;

Water reducing agent 0.2-0.6%;

Viscosity modifier 0.001-0.004%;

Expanding agent 0-3.2%;

Air-entraining agent 0-0.12%;

Defoamer 0-0.0007%.
The modified material of low-quality aggregate according to claim 1, is characterized in that, comprises the following components by mass percentage:

Cement 47-49%;

Mineral admixtures 12-13%;

Active powder 2-4%;

Water reducing agent 0.3-0.5%;

Viscosity modifier 0.001-0.004%;

Expanding agent 2.3-3.0%;

Air-entraining agent 0.05-0.08%;

Defoamer 0.0002-0.0005%.
The modified material of low-quality aggregate according to claim 1 or 2, wherein the balance is water; preferably, the amount of water is 30.5-36.3%.
The modified material of low-quality aggregate according to claim 1 or 2, wherein the active powder is at least one of nano-silica and polymer rubber powder;

Preferably, the active powder is composed of nano-silicon dioxide and polymer rubber powder, and the mass ratio of the two is 1:2.
The modified material for low-quality aggregates according to claim 1 or 2, wherein the viscosity modifier has a density of 0.98-1.02 g/mL, and a pH of 7.5-10.0;

Preferably, the viscosity modifier is Rheoplus420 high-performance viscosity modifier produced by BASF China Co., Ltd.
The modified material of low-quality aggregate according to claim 1 or 2, wherein the mineral admixture is at least one of fly ash, mineral powder, silica fume, metakaolin, and limestone powder;

Preferably, the mineral admixture is composed of fly ash, mineral powder, and metakaolin, and the mass ratio is 3:3:2.
The modified material of low-quality aggregate according to any one of claims 1-6, wherein the cement is at least one of Portland cement and aluminate cement;

The water-reducing agent is at least one of a polycarboxylic acid-based water-reducing agent and a naphthalene-based water-reducing agent; preferably, the water-reducing rate of the water-reducing agent is not less than 30%;

The expansion agent is at least one of calcium sulfoaluminate type expansion agent and calcium oxide type expansion agent;

The air-entraining agent is at least one of rosin-type air-entraining agent and saponin-type air-entraining agent;

The defoamer is at least one of a silicone-based defoamer or a modified polyether-based defoamer.
A method for processing low-quality aggregates, comprising the following steps:

The low-quality aggregates are soaked in water glass, dried and used for later use;

Put the immersed low-quality aggregate into the dipping container, use the modified material for modification treatment under vacuum and/or pressurization conditions, spread the low-quality aggregate, and naturally cure for 18-24 hours under high temperature and high pressure. Steam for 4-12h and cool.
The method for processing low-quality aggregates according to claim 8, wherein the modified material is the modified material of low-quality aggregates according to any one of claims 1-7.
The method for treating low-quality aggregates according to claim 8 or 9, wherein the modification step is as follows: injecting modified materials under vacuum conditions, stirring for 1-4 min, and continuing to stir under high pressure conditions for 2- 6min;

Preferably, the vacuum condition is 2-5 kPa, and the high pressure condition is 0.2-0.5 MPa.
The method for treating low-quality aggregates according to claim 8 or 9, characterized in that, the conditions of the high-temperature and high-pressure steam curing are as follows: the temperature is 60-80° C. and the pressure is 1-2 MPa.
The method for treating low-quality aggregates according to any one of claims 8-11, wherein the mass ratio of the modified material to the low-quality aggregates is 1:0.2-0.35.