CN109534745B - Preparation method of low-alkali silicic acid reaction-expanded high-doping-amount waste crushed glass self-compacting concrete - Google Patents
Preparation method of low-alkali silicic acid reaction-expanded high-doping-amount waste crushed glass self-compacting concrete Download PDFInfo
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- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
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- C08B37/0024—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid beta-D-Glucans; (beta-1,3)-D-Glucans, e.g. paramylon, coriolan, sclerotan, pachyman, callose, scleroglucan, schizophyllan, laminaran, lentinan or curdlan; (beta-1,6)-D-Glucans, e.g. pustulan; (beta-1,4)-D-Glucans; (beta-1,3)(beta-1,4)-D-Glucans, e.g. lichenan; Derivatives thereof
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- C08B37/003—Chitin, i.e. 2-acetamido-2-deoxy-(beta-1,4)-D-glucan or N-acetyl-beta-1,4-D-glucosamine; Chitosan, i.e. deacetylated product of chitin or (beta-1,4)-D-glucosamine; Derivatives thereof
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Abstract
The invention relates to a preparation method of low-alkali silicic acid reaction expansion high-dosage waste crushed glass self-compacting concrete. Firstly, degrading, deacylating, carboxylating, intramolecular dehydrating and the like natural chitin high polymer to prepare a polylactic acid alkali silicate reaction inhibitor solution; and mixing the waste crushed glass fine aggregate covered by the polylactic acid alkali silicate reaction inhibitor instead of river sand fine aggregate into the self-compacting concrete to prepare the high-mixing-amount waste crushed glass self-compacting concrete with low alkali silicate reaction expansion. The addition of the polylactic acid alkali silicate reaction inhibitor effectively inhibits the alkali silicate reaction in the high-doped waste crushed glass self-compacting concrete. The high-content waste crushed glass self-compacting concrete prepared by the method has better working performance and durability and good volume stability compared with the traditional self-compacting concrete, further expands the application range of waste glass, and can generate good technical, economic, social and environmental benefits.
Description
Technical Field
The invention relates to the field of novel building materials, in particular to a preparation method of low-alkali silicic acid reaction expansion high-content waste crushed glass self-compacting concrete.
Background
Since the twenty-first century, with the progress of urbanization and the increase of infrastructure construction speed worldwide, the consumption and usage of high-performance concrete materials as the most widely used building materials have been increasing. Self-compacting concrete is an important component of high performance concrete material, because of it has that the mobility is strong, the filling nature is good, stable not segregation, need not the vibration and only rely on self gravity can reach fully closely knit state, and the work progress is simple, easy operation, and it is fast to pour, practices thrift the manual work, can shorten advantages such as construction period. Has been widely applied to large-volume structural concrete and reinforcing engineering with complex shapes, such as high-rise buildings, ports and docks, submarine tunnels, sea-crossing bridges, island engineering and the like.
The traditional self-compacting concrete mainly comprises cement, mineral admixture, coarse aggregate, fine aggregate and a high-efficiency water reducing agent. The fine aggregate is an important component for forming the self-compacting concrete, and the fine aggregate in the single self-compacting concrete accounts for 50-60% of the total volume of the concrete. The preparation of the self-compacting concrete needs to use a large amount of natural river sand fine aggregate, which causes the price of the fine aggregate to continuously rise, and meanwhile, the blind mining of the natural river sand fine aggregate also causes great negative influence on the ecological environment of China. More importantly, the self-compacting concrete prepared by using the natural river sand fine aggregate can obtain enough fluidity only by adding more high-efficiency water reducing agents, so that the self-compacting concrete has higher raw material cost than common high-performance concrete. These have limited the widespread use of self-compacting concrete in civil engineering structures. The method for preparing the self-compacting concrete by using the crushed solid wastes such as the waste glass, the tires, the shells, the coconut shells, the oil palm shells and the like as the artificial fine aggregate is a good method for solving the problems. The technology not only expands the source of the fine aggregate in the self-compacting concrete, but also reduces the use amount and the dependence degree of the natural river sand fine aggregate. Meanwhile, a large amount of solid waste is consumed, and the negative influence on the surrounding environment caused by accumulation of the solid waste is avoided.
Relevant researches at home and abroad show that the waste crushed glass is an artificial fine aggregate with clear application prospect. The waste crushed glass is used for replacing natural river sand fine aggregate and is added into the self-compacting concrete, so that the flowing property of the self-compacting concrete can be obviously improved, and the use amount of the high-efficiency water reducing agent for preparing the self-compacting concrete and the cost of the fine aggregate raw material are reduced. However, the ratio of the waste crushed glass fine aggregate to the natural river sand fine aggregate in the self-compacting concrete is too high, and the problems of large alkali silicate reaction expansion of the self-compacting concrete, poor volume stability of the self-compacting concrete and the like can occur. Generally, the proportion of the waste crushed glass in the self-compacting concrete to replace the natural river sand fine aggregate is strictly controlled below 30 percent, which restricts the wide application of the waste crushed glass fine aggregate in the self-compacting concrete material.
Aiming at the problems of low consumption of waste crushed glass, large alkali silicate reaction expansion, poor volume stability and the like in the current waste crushed glass self-compacting concrete, some researchers at home and abroad try to add lithium salt into the waste crushed glass self-compacting concrete to inhibit the long-term alkali silicate reaction expansion, but the lithium salt alkali silicate reaction inhibitor is added to obviously increase the production cost of the waste crushed glass self-compacting concrete.
Disclosure of Invention
The invention aims to provide a preparation method of low-alkali silicic acid reaction expansion high-dosage waste crushed glass self-compacting concrete. The prepared high-doped waste crushed glass self-compacting concrete has better working performance and durability and good volume stability compared with the traditional self-compacting concrete, thereby expanding the application range of waste glass.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a preparation method of low-alkali silicic acid reaction-expanded high-content waste crushed glass self-compacting concrete comprises the following steps:
1) weighing chitin high polymer and water in proportion, putting into a reaction container with a stirring device and a reflux device, raising the temperature to 85-90 ℃, and stirring the mixture at an accelerated speed to uniformly disperse the chitin high polymer into the water to form a uniform suspension solution;
2) slowly dripping the mixed solution of potassium permanganate and hydrogen peroxide at the temperature of 85-90 ℃, finishing the addition within 45-60 minutes, reacting at the temperature of 90-95 ℃ for 7-8 hours, and degrading the chitin high polymer into chitin oligomer;
3) cooling the chitin oligomer solution to 65-70 ℃, adding a sodium hydroxide solution, keeping stirring for 16 hours, and removing acetyl in the chitin oligomer to generate a chitosan oligomer containing amino, hydroxyl and hydroxymethyl groups;
4) keeping the temperature of the reaction system at 65-70 ℃, adding a sodium hypochlorite solution into the chitosan oligomer solution, adjusting the pH of the solution to 9-10, raising the temperature of the system to 90-95 ℃, and stirring for 24 hours to form a clear chitosan oligomer solution containing carboxyl;
5) reducing the temperature of the reaction solution to 35-40 ℃, adding a small amount of butyltin dehydrating agent into the oligomer containing carboxyl, hydroxyl and hydroxymethyl chitosan, raising the system temperature to 140-145 ℃ to carry out intramolecular dehydration for 6-10 hours, and obtaining a viscous polylactic acid alkali silicate reaction inhibitor;
6) sorting, cleaning and airing the waste glass, then crushing the waste glass, and sieving the crushed waste glass through a 5mm square hole sieve to obtain crushed waste glass fine aggregate, and removing impurities and crushed waste glass particles with irregular shapes;
7) putting the crushed waste glass fine aggregate into a viscous polylactic acid alkali silicate reaction inhibitor solution, and soaking for 6-8 hours at the temperature of 35-40 ℃ to cover a layer of polylactic acid film on the surface of the crushed waste glass fine aggregate; airing and crushing the waste glass fine aggregate in the air, and sealing for later use;
8) putting cement, fly ash, treated crushed waste glass fine aggregate, river sand fine aggregate and coarse aggregate into a container with a stirrer in proportion, and dry-mixing for several minutes at a certain stirring speed; then adding mixing water doped with the polycarboxylic acid high-efficiency water reducing agent, and continuously stirring for a few minutes; finally, continuously mixing the waste crushed glass self-compacting concrete slurry for several minutes at a higher stirring speed;
9) detecting the initial slump flow of the freshly-mixed waste crushed glass self-compacting concrete, and ensuring that the working performance of the waste crushed glass self-compacting concrete meets the requirement;
10) pouring the freshly-mixed waste crushed glass self-compacting concrete into a test mold, and maintaining for 24 hours; after 1 day, the sample was removed from the test mold and placed in a standard curing bath for curing to a specified age.
The mass ratio of the chitin high polymer to the water in the step 1) is as follows: 1:2.8-1:3.2.
The preparation of the mixed solution of potassium permanganate and hydrogen peroxide in the step 2) is as follows: the weight ratio of the potassium permanganate with the purity of 99.5 percent to the hydrogen peroxide with the weight percentage concentration of 35 percent is 1: 3; the mass ratio of the mixed solution of potassium permanganate and hydrogen peroxide to the chitin polymer solution is 2: 1; degrading the chitin high polymer into chitin oligomer, and controlling the weight average molecular weight of the chitin oligomer to be between 0.6 and 0.8 ten thousand.
And 3) controlling the deacylation degree of the chitosan oligomer molecules to be more than 95%.
Adding sodium hypochlorite solution into the chitosan oligomer solution in the step 4) according to the following amount: the mass ratio of the chitosan oligomer solution to the sodium hypochlorite solution with the weight percentage concentration of 40% is 1:0.85-1: 0.95; the content of carboxyl in the chitosan oligomer molecule is controlled to be 5.2-6.0%.
And 5) adding the butyl tin dehydrating agent in an amount of 0.05-0.055% of the chitosan oligomer solution containing carboxyl according to mass percent.
In the step 7), the mass ratio of the crushed waste glass fine aggregate to the viscous polylactic acid alkali silicate reaction inhibitor solution is 1:2.
In the step 8), the proportion of the cement, the fly ash, the fine aggregate and the coarse aggregate is as follows: the cementing material (cement and fly ash) comprises fine aggregate, coarse aggregate and water, wherein the coarse aggregate comprises (0.9-1.1) to (1.48-1.53) to (2.32-2.40) to (0.32-0.39), the mass proportion of the fly ash substituted for the cement is 20%, the mass proportion of the treated crushed waste glass fine aggregate substituted for the natural river sand fine aggregate is 50-70%, and the stirring speed is as follows: 30-40 revolutions per minute; the adding amount of the polycarboxylic acid high-efficiency water reducing agent is 0.4 percent of the using amount of the cementing material, and the polycarboxylic acid high-efficiency water reducing agent is calculated by mass percent; the faster stirring speed is: 60-70 r/min.
Step 9) the initial slump flow requirement is 250-270 mm.
Step 10) pouring the freshly mixed waste crushed glass self-compacting concrete into test molds of 100mm multiplied by 100mm, 100mm multiplied by 400mm, phi 100mm multiplied by 50mm and 70mm multiplied by 285mm, and placing the test molds in an environment with the temperature of 25 ℃ and the humidity of 55-65% for curing for 24 hours; after 1 day, the sample was removed from the test mold and placed in a standard curing water bath at 20 ℃ and a humidity of 90. + -. 5% for curing to a prescribed age.
After the curing is finished, the compressive strength, the flexural strength, the water absorption and the alkali silicate reaction expansion value of the hardened and abandoned crushed glass self-compacting concrete are measured in a specified age.
The invention carries out modification treatment on natural chitin high polymer to synthesize low molecular weight polylactic acid alkali silicate reaction inhibitor, and uses the polylactic acid alkali silicate reaction inhibitor to carry out covering treatment on the surface of waste crushed glass fine aggregate to prepare the high-performance self-compacting concrete with low alkali silicate reaction expansion and over 50 percent of waste crushed glass fine aggregate mixing amount. The invention firstly uses strong oxidant to degrade chitin high polymer molecules into chitin low polymers. Then, under the conditions of high temperature and strong alkali, the chitin oligomer is subjected to deacylation reaction. And then under the action of sodium hypochlorite, performing carboxylation reaction on the chitosan oligomer to obtain the chitosan oligomer containing hydroxyl, hydroxymethyl and carboxyl groups. And finally, under the condition that a dehydrating agent exists, heating carboxyl and hydroxyl in the chitosan oligomer molecule to generate intramolecular dehydration, thus preparing the polylactic acid alkali silicate reaction inhibitor. And soaking the waste crushed glass fine aggregate in the polylactic acid alkali silicate reaction inhibitor for a period of time to cover a layer of polylactic acid film on the surface of the waste crushed glass fine aggregate. The treated waste crushed glass fine aggregate replaces a certain proportion of river sand fine aggregate and is added into the self-compacting concrete. The high-content waste crushed glass self-compacting concrete prepared by the method has the characteristics of good flowing property and mechanical property, low alkali silicate expansion and the like. In addition, the polylactic acid alkali silicate reaction inhibitor is prepared by modifying the natural chitin high molecular material, so that the application field of the natural chitin high molecular material is widened, and the raw material cost for preparing the alkali silicate reaction inhibitor in the waste crushed glass self-compacting concrete is obviously reduced. The polylactic acid alkali silicate reaction inhibitor covers the surface of the crushed glass fine aggregate to form a film, so that the dissolution speed of silicon dioxide in the waste crushed glass is slowed down, and the alkali silicate reaction incidence rate of the waste crushed glass in the self-compacting concrete is effectively inhibited. The self-compacting concrete prepared by the invention uses a large amount of waste crushed glass fine aggregates, and avoids the problems that the waste glass treated by the traditional landfill method needs to occupy a large amount of land and seriously pollutes the surrounding environment. The waste crushed glass fine aggregate which is treated by being covered by the polylactic acid-alkali silicate reaction inhibitor is added into the self-compacting concrete, so that the use cost of the high-efficiency water reducing agent and the alkali silicate reaction inhibitor can be obviously reduced, and meanwhile, the prepared high-doped waste crushed glass self-compacting concrete has better working performance, durability and volume stability than the traditional self-compacting concrete. The waste crushed glass fine aggregate treated by the polylactic acid alkali silicate reaction inhibitor prepared by the chitin high polymer is added into the self-compacting concrete, thereby producing good technical, economic, social and environmental benefits.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention obtains the polylactic acid alkali silicate reaction inhibitor by degrading, deacetylating, carboxylating and intramolecular dehydrating natural chitin high polymer, and the polylactic acid alkali silicate reaction inhibitor is covered on the surface of the crushed glass fine aggregate, so that the alkali silicate reaction in the high-doped waste crushed glass self-compacting concrete can be effectively inhibited.
(2) The chitin high polymer has wide raw material sources and low market price. Compared with the traditional lithium salt alkali silicate reaction inhibitor, under the same effect of inhibiting alkali silicate reaction, the cost of the alkali silicate reaction inhibitor can be saved by 2.4 yuan only when one cubic high-content waste crushed glass self-compacting concrete is produced.
(3) The natural chitin is used as a raw material for preparing the alkali silicate reaction inhibitor, the utilization efficiency of the chitin polymer material is improved, and the application field of the chitin natural polymer material is expanded.
(4) Compared with the traditional self-compacting concrete using natural fine aggregate, the proportion of the artificial fine aggregate of the waste crushed glass in the high-doping waste crushed glass self-compacting concrete prepared by the invention is as high as 50-70%, and the use cost of the raw material of the fine aggregate can be saved by more than 8.6 yuan per cubic meter of the high-doping waste crushed glass self-compacting concrete.
(5) The waste crushed glass fine aggregate has lower water absorption, and the dosage of the polycarboxylic acid high-efficiency water reducing agent can be reduced by adding the high-dosage crushed glass fine aggregate into the self-compacting concrete under the condition of keeping the flowability of the self-compacting concrete unchanged. The use cost of the polycarboxylic acid high-efficiency water reducing agent can be saved by 0.8 yuan per cubic meter of the self-compacting concrete.
(6) Comprehensively considering, the cost of various raw materials can be saved by 10 ten thousand yuan by producing the high-content waste crushed glass self-compacting concrete every year.
(7) The method uses the waste crushed glass fine aggregate to replace the natural river sand fine aggregate to prepare the high-content waste crushed glass self-compacting concrete, consumes a large amount of waste glass, and avoids the problems that the waste glass treated by the traditional landfill method needs to occupy a large amount of land and seriously pollutes the surrounding environment.
(8) The polylactic acid alkali silicate reaction inhibitor prepared by the modified chitin high polymer is added into the high-doping waste crushed glass self-compacting concrete, so that alkali silicate reaction expansion in the waste glass self-compacting concrete can be effectively inhibited, the mechanical property, durability and volume stability of the waste crushed glass self-compacting concrete are obviously improved, and the application range of the waste crushed glass self-compacting concrete is further expanded.
Drawings
FIG. 1: a flow chart of preparing low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete.
FIG. 2: Control-SCC, Li2CO3SCC, PA-SCC self-compacting concrete slump flow changes over time.
FIG. 3: Control-SCC, Li2CO3Compressive strength of SCC, PA-SCC self-compacting concrete.
FIG. 4: Control-SCC, Li2CO3And the rupture strength of SCC and PA-SCC self-compacting concrete.
FIG. 5: Control-SCC, Li2CO3SCC, PA-SCC self-compacting concrete water absorption.
FIG. 6: Control-SCC, Li2CO3SCC, PA-SCC self-compacting concrete alkali silicate reaction expansion values.
Detailed Description
The present invention will be further described with reference to the following specific examples. In the embodiment of the invention, the technical scheme of the invention is adopted to prepare the cubic meter of low-alkali silicic acid reaction expanded high-doping-amount waste crushed glass self-compacting concrete, and the performance of the cubic meter of low-alkali silicic acid reaction expanded high-doping-amount waste crushed glass self-compacting concrete is compared with the performance of a high-doping-amount waste crushed glass self-compacting concrete sample which is not doped with a lithium alkali silicate reaction inhibitor and a high-doping-amount waste crushed glass self-compacting concrete sample which is doped with a lithium alkali silicate reaction inhibitor under the same mixing ratio.
1. Preparation of polylactic acid alkali silicic acid reaction inhibitor by using chitin high polymer
1.1 degradation of chitin Polymer
245-250kg chitin high polymer (weight average molecular weight of 41.19 ten thousand) and 750-755kg water were weighed into a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser tube. The temperature is raised to 85-90 ℃ and the mixture is stirred at an accelerated rate to form a homogeneous suspension. Keeping the temperature of the suspension solution at 85-90 ℃, slowly dripping 2000-2050kg of mixed solution of potassium permanganate and hydrogen peroxide, wherein the ratio of the potassium permanganate (with the purity of 99.5%) to the hydrogen peroxide (with the weight percentage concentration of 35%) in the mixed solution is 1:3 (weight ratio), finishing adding the mixed solution after 45-60 minutes, and reacting for 7-8 hours at the temperature of 90-95 ℃. The weight average molecular weight of the chitin oligomer is controlled to be between 0.6 and 0.8 ten thousand.
1.2 preparation of amino-containing chitosan oligomer 650-670kg of the semi-clarified chitin oligomer solution was cooled to 65-70 deg.C, 330-335kg of sodium hydroxide solution (concentration 50%) was added, and the reaction temperature was controlled at 65-70 deg.C and stirred for 16 hours to form a uniform, clarified amino-containing chitosan oligomer solution (concentration 30-35%). And measuring the acetylation degree of the product by an alkali method, and controlling the deacetylation degree in the chitosan oligomer molecules to be more than 95%.
1.3, the temperature of the reaction system is kept between 65 and 70 ℃ in the carboxylation of the chitosan oligomer, 900 and 910kg of sodium hypochlorite solution (the weight percentage concentration is 40 percent) is added into 1000 and 1150kg of chitosan oligomer solution containing amino, the pH value of the solution is adjusted to between 9 and 10, the temperature of the system is increased to between 90 and 95 ℃, and the solution is continuously stirred for 24 hours to form clear chitosan oligomer solution containing carboxyl. The content of carboxyl in the chitosan oligomer molecule is controlled to be 5.2-6.0%.
1.4, preparing polylactic acid alkali silicate reaction inhibitor, reducing the temperature of the reaction solution to 35-40 ℃, adding 0.5kg of butyl tin dehydrating agent into 1000-1050kg of carboxyl-containing chitosan oligomer solution, raising the temperature of the system to 140-145 ℃ for intramolecular dehydration, and strongly stirring for 6-10 hours at the temperature. The viscosity of the clarified chitosan oligomer solution containing carboxyl is increased continuously, and finally the viscous polylactic acid alkali silicate reaction inhibitor is obtained.
2. Preparation and treatment of crushed waste glass fine aggregate
Sorting, cleaning, airing and crushing the waste white glass beverage bottles, and then screening the crushed waste glass fine aggregates through a 5mm square hole screen to remove impurities and irregular waste glass fine aggregate particles. Controlling the size of the crushed waste glass fine aggregate to be less than 5mm and analyzing the particle size distribution of the crushed waste glass fine aggregate. Then, 415-420kg of crushed waste glass fine aggregate is placed into 830-850kg of viscous polylactic acid alkali silicate reaction inhibitor solution (solid/liquid ratio is 1:2), and the crushed waste glass fine aggregate is soaked for 6-8 hours at the temperature of 35-40 ℃, so that a layer of polylactic acid film is covered on the surface of the crushed waste glass fine aggregate. And finally, airing the treated waste glass fine aggregate in the air and sealing for later use.
3. Preparation of high-doping-amount waste crushed glass self-compacting concrete
3.1 proportion of self-compacting concrete
The method aims to prepare the C50 high-strength self-compacting concrete with the 28d strength of 50MPa of the hardened concrete. The cement used in the invention is conch ordinary portland cement (P.O 42.5.5), and the fly ash is first-grade fly ash of Nanjing Huaneng power plant. Two kinds of fine aggregates are used, one is natural river sand fine aggregate, and the fineness modulus of the river sand fine aggregate is 2.46. The modulus of fineness of the treated waste glass fine aggregate is 3.22. The coarse aggregate is in primary composition (5-25 mm). The high-efficiency water reducing agent is a polycarboxylic acid high-efficiency water reducing agent (PCA) of Jiangsu institute of architectural science. The water for mixing is drinking water. The self-compacting concrete is prepared from coarse aggregate, fine aggregate, cementing material (cement and flyash), water1.56:1:0.66: 0.23. The dosage of the cementing material in the self-compacting concrete of the waste crushed glass with high doping amount of one cubic meter is 460kg/m3The proportion of the fly ash to the cement is 20 percent, and the dosage of the fine aggregate is 693.81kg/m3The proportion of crushed waste glass fine aggregate replacing natural river sand fine aggregate is 60 percent, the sand rate is 39 percent, and the mixing amount of the polycarboxylic acid high-efficiency water reducing agent (PCA) is 0.4 percent of the total amount of the cementing material. Self-compacting concrete (PA-SCC) treated by waste glass fine aggregate and doped with polylactic acid-alkali-silicic acid reaction inhibitor is taken as a reference sample, and Li is not doped2CO3Waste glass self-compacting concrete (Control-SCC) and Li-doped2CO3Self-compacting concrete sample (Li)2CO3SCC) as control. The initial slump flow of the self-compacting concrete is controlled to be 250-270 mm. The mixing proportion of the three groups of C50 high-strength self-compacting concrete is shown in Table 1.
3.2 preparation and curing of self-compacting concrete
370kg of cement of 350-. 1.80-1.85kg of polycarboxylic acid water reducing agent and 160-165kg of stirring water are fully mixed and added into a container, and stirring is continued for 2 minutes at the stirring speed of 30 revolutions per minute. In order to avoid the self-compacting concrete slurry from being laminated at the bottom of the container, the concrete slurry is manually stirred for 1-2 times by using an iron shovel. The self-compacting concrete slurry was then mixed for 2 minutes at a mixing speed of 60 rpm. And taking a small amount of newly-mixed self-compacting concrete slurry to carry out initial slump flow detection. Then pouring part of newly-mixed PA-SCC self-compacting concrete into test molds of 100mm multiplied by 100mm and 100mm multiplied by 400mm to prepare 24 samples, and detecting the compressive strength and the flexural strength of the self-compacting concrete for 3, 7, 28 and 90 d. Preparing 12 pieces of phi 100mm x 50mmAnd (3) detecting the water absorption of the compact concrete sample for 3, 7, 28 and 90 days, and pouring other newly-mixed PA-SCC self-compact concrete into a test mould of 70mm multiplied by 285mm to detect the alkali silicate reaction expansion values of different ages. And finally, covering the test mould filled with the PA-SCC self-compacting concrete by using a wet gunny bag, placing the test mould indoors (the temperature is 25 ℃, and the humidity is 55-65%), removing the PA-SCC self-compacting concrete sample from the test mould after 24 hours, and placing the test mould in the environment (the temperature is 20 ℃, and the humidity is 90 +/-5%) for curing until the test age. Preparation of the same amounts of Control-SCC, Li under the same conditions2CO3SCC self-compacting concrete samples, comparative experiments were carried out.
And 4.1, measuring the performances of three groups of self-compacting concrete, including initial slump flow, slump flow retention, compressive strength, breaking strength, water absorption and alkali silicate reaction expansion values (figures 2-6).
FIG. 2 shows that the high-doped waste glass fine aggregate self-compacting concrete treated by the polylactic acid alkali silicate reaction inhibitor is not doped with Li2CO3The high-doped waste glass self-compacting concrete is doped with Li2CO3The initial slump flow and slump flow retention of the high-dosage waste glass self-compacting concrete. As can be seen from FIG. 2, the self-compacting concrete with high content of waste glass fine aggregate treated by adding the polylactic acid-alkali-silicate reaction inhibitor has higher content than that of the self-compacting concrete without adding Li under the same content of the polycarboxylate superplasticizer2CO3The high-doped waste glass self-compacting concrete is doped with Li2CO3The high-dosage waste glass self-compacting concrete has higher initial slump flow and better slump flow retention.
FIG. 3 shows the self-compacting concrete treated with poly (lactic acid-alkali-silicate) reaction inhibitor and high-doped waste glass fine aggregate, without Li addition2CO3The high-doped waste glass self-compacting concrete is doped with Li2CO3The compressive strength of the self-compacting concrete with high-content waste glass fine aggregate is developed. As can be seen from FIG. 3, the self-compacting concrete doped with the high content of waste glass fine aggregate treated with the polylactic acid-alkali silicate reaction inhibitor has a higher degree of strength than the concrete not doped with Li2CO3The high-doped waste glass fine aggregate self-compacting concrete and the doped Li2CO3The high-doping-amount waste glass fine aggregate self-compacting concrete has higher long-term compressive strength.
As shown in FIG. 4, the self-compacting concrete treated by the polylactic acid alkali silicate reaction inhibitor and containing high-content waste glass fine aggregate is not added with Li2CO3The high-doped waste glass fine aggregate self-compacting concrete and the doped Li2CO3The high-doping-amount waste glass fine aggregate self-compacting concrete has the advantage of developing the breaking strength. As can be seen from FIG. 4, the self-compacting concrete treated with high content of waste glass fine aggregate doped with the polymeric emulsion acid-base-silicic acid reaction inhibitor has better performance than the concrete without Li2CO3The high-doped waste glass fine aggregate self-compacting concrete and the doped Li2CO3The self-compacting concrete with high content of waste glass fine aggregate has higher long-term rupture strength.
As shown in FIG. 5, the self-compacting concrete treated by the polylactic acid alkali silicate reaction inhibitor and containing high-content waste glass fine aggregate is not added with Li2CO3The high-doped waste glass fine aggregate self-compacting concrete and the doped Li2CO3The water absorption of the self-compacting concrete with high-content waste glass fine aggregate develops. As can be seen from FIG. 5, the self-compacting concrete doped with the high content of waste glass fine aggregate treated with the polylactic acid-alkali silicate reaction inhibitor has a higher degree of strength than the concrete not doped with Li2CO3The high-doped waste glass fine aggregate self-compacting concrete and the doped Li2CO3The self-compacting concrete with high content of waste glass fine aggregate has lower long-term water absorption.
As shown in FIG. 6, the self-compacting concrete treated by the polylactic acid alkali silicate reaction inhibitor and containing high-content waste glass fine aggregate is not added with Li2CO3The high-doped waste glass fine aggregate self-compacting concrete and the doped Li2CO3The alkali silicate reaction expansion value of the self-compacting concrete with high doping amount of waste glass fine aggregate. As can be seen from FIG. 6, the self-compacting concrete doped with the high content of waste glass treated with the PLA pH-silicic acid reaction inhibitor has higher performance than the concrete not doped with Li2CO3High-doped waste glassSelf-compacting glass concrete and Li-doped concrete2CO3The high-doped waste glass self-compacting concrete has lower alkali silicate reaction expansion value.
The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention in any way, and any person skilled in the art can make any simple modification, equivalent replacement, and improvement on the above embodiment without departing from the technical spirit of the present invention, and still fall within the protection scope of the technical solution of the present invention.
Claims (10)
1. A preparation method of low-alkali silicic acid reaction-expanded high-doping-amount waste crushed glass self-compacting concrete is characterized by comprising the following steps of: the method comprises the following steps:
1) weighing chitin high polymer and water in proportion, putting into a reaction container with a stirring device and a reflux device, raising the temperature to 85-90 ℃, and stirring the mixture at an accelerated speed to uniformly disperse the chitin high polymer into the water to form a uniform suspension solution;
2) slowly dripping the mixed solution of potassium permanganate and hydrogen peroxide at 85-90 deg.C for 45-60min, reacting at 90-95 deg.C for 7-8 hr to degrade the chitin high polymer into chitin oligomer;
3) cooling the chitin oligomer solution to 65-70 ℃, adding a sodium hydroxide solution, keeping stirring for 16 hours, and removing acetyl in the chitin oligomer to generate chitosan oligomer molecules containing amino, hydroxyl and hydroxymethyl groups;
4) keeping the temperature of the reaction system at 65-70 ℃, adding a sodium hypochlorite solution into the chitosan oligomer solution, adjusting the pH of the solution to 9-10, raising the temperature of the system to 90-95 ℃, and stirring for 24 hours to form a clear chitosan oligomer solution containing carboxyl;
5) reducing the temperature of the reaction solution to 35-40 ℃, adding a small amount of butyltin dehydrating agent into the oligomer containing carboxyl, hydroxyl and hydroxymethyl chitosan, raising the system temperature to 140-145 ℃ to carry out intramolecular dehydration for 6-10 hours, and obtaining a viscous polylactic acid alkali silicate reaction inhibitor;
6) sorting, cleaning and airing the waste glass, then crushing the waste glass, and sieving the crushed waste glass through a 5mm square hole sieve to obtain crushed waste glass fine aggregate, and removing impurities and crushed waste glass particles with irregular shapes;
7) putting the crushed waste glass fine aggregate into a viscous polylactic acid alkali silicate reaction inhibitor solution, and soaking for 6-8 hours at the temperature of 35-40 ℃ to cover a layer of polylactic acid film on the surface of the crushed waste glass fine aggregate; airing and crushing the waste glass fine aggregate in the air, and sealing for later use;
8) putting cement, fly ash, treated crushed waste glass fine aggregate, river sand fine aggregate and coarse aggregate into a container with a stirrer in proportion, and dry-mixing for several minutes at a certain stirring speed; then adding mixing water doped with the polycarboxylic acid high-efficiency water reducing agent, and continuously stirring for several minutes; finally, continuously mixing the waste crushed glass self-compacting concrete slurry for several minutes at a higher stirring speed;
9) detecting the initial slump flow of the freshly-mixed waste crushed glass self-compacting concrete, and ensuring that the working performance of the waste crushed glass self-compacting concrete meets the requirement;
10) pouring the freshly-mixed waste crushed glass self-compacting concrete into a test mold, and maintaining for 24 hours; after 1 day, the sample was removed from the test mold and placed in a standard curing bath for curing to a specified age.
2. The method for preparing the low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete according to claim 1, which is characterized in that: the mass ratio of the chitin high polymer to the water in the step 1) is as follows: 1:2.8-1:3.2.
3. The method for preparing the low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete according to claim 1, which is characterized in that: the preparation of the mixed solution of potassium permanganate and hydrogen peroxide in the step 2) is as follows: the weight ratio of the potassium permanganate with the purity of 99.5 percent to the hydrogen peroxide with the weight percentage concentration of 35 percent is 1: 3; the mass ratio of the mixed solution of potassium permanganate and hydrogen peroxide to the chitin polymer solution is 2: 1; degrading the chitin high polymer into chitin oligomer, and controlling the weight average molecular weight of the chitin oligomer to be between 0.6 and 0.8 ten thousand.
4. The method for preparing the low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete according to claim 1, which is characterized in that: and 3) controlling the degree of deacylation in the chitosan oligomer molecules to be more than 95%.
5. The method for preparing the low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete according to claim 1, which is characterized in that: adding sodium hypochlorite solution into the chitosan oligomer solution in the step 4) according to the following amount: the mass ratio of the chitosan oligomer solution to the sodium hypochlorite solution with the weight percentage concentration of 40% is 1:0.85-1: 0.95; the content of carboxyl in the chitosan oligomer molecule is controlled to be 5.2-6.0%.
6. The method for preparing the low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete according to claim 1, which is characterized in that: and 5) adding the butyl tin dehydrating agent in an amount of 0.05-0.055% of the chitosan oligomer solution containing carboxyl according to mass percent.
7. The method for preparing the low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete according to claim 1, which is characterized in that: in the step 7), the mass ratio of the crushed waste glass fine aggregate to the viscous polylactic acid alkali silicate reaction inhibitor solution is 1:2.
8. The method for preparing the low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete according to claim 1, which is characterized in that: in the step 8), the proportion of the cement, the fly ash, the fine aggregate and the coarse aggregate is as follows: the cementing material (cement and fly ash) comprises fine aggregate, coarse aggregate and water, wherein the coarse aggregate comprises (0.9-1.1) to (1.48-1.53) to (2.32-2.40) to (0.32-0.39), the mass proportion of the fly ash substituted for the cement is 20%, the mass proportion of the treated crushed waste glass fine aggregate substituted for the natural river sand fine aggregate is 50-70%, and the stirring speed is as follows: 30-40 revolutions per minute; the adding amount of the polycarboxylic acid high-efficiency water reducing agent is 0.4 percent of the using amount of the cementing material, and the polycarboxylic acid high-efficiency water reducing agent is calculated by mass percent; the faster stirring speed is: 60-70 r/min.
9. The method for preparing the low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete according to claim 1, which is characterized in that: step 9) the initial slump flow requirement is 250-270 mm.
10. The method for preparing the low alkali silicic acid reaction expanded high-content waste crushed glass self-compacting concrete according to claim 1, which is characterized in that: step 10) pouring the freshly mixed waste crushed glass self-compacting concrete into test molds of 100mm multiplied by 100mm, 100mm multiplied by 400mm, phi 100mm multiplied by 50mm and 70mm multiplied by 285mm, and placing the test molds in an environment with the temperature of 25 ℃ and the humidity of 55-65% for curing for 24 hours; removing the sample from the test mold after 1 day, and maintaining in a standard maintenance water tank with temperature of 20 deg.C and humidity of 90 + -5% for a specified age; after the curing is finished, the compressive strength, the flexural strength, the water absorption and the alkali silicate reaction expansion value of the hardened and abandoned crushed glass self-compacting concrete are measured in a specified age.
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