CN101381217B - A kind of building material product based on the joint action of alkali and CO2 and its preparation method - Google Patents

Abstract

The invention discloses a building material product based on the synergic action between alkali and CO2 and a method for preparing the same, which belongs to the field of silicate building material and product thereof. In the building material product, the fly ash the fineness of which is controlled in the range of between 400 and 600m<2>/Kg and the slag form a mixed powder material, and an aggregate and water glass are added into the mixed powder material for forming so as to obtain a blank, and the blank is subjected to natural curing and carbonization to obtain the building material product. In the invention, the industrial waste slag is used as raw materials, the high-performance silicate product is prepared under the conditions of low alkali and not doping lime and cement clinker, sothat the strength level is high, no scumming phenomenon occurs on the surface of the product, the release quantities of various toxic and harmful ions are far below the threshold value; moreover, thebuilding material product has the advantages of good durability, strong freezeproof and weather resistance capabilities, and is suitable to be the building wall material. The invention has active effect on utilizing waste slag resources, saving energy and reducing emission.

Description

A kind of building material product based on the joint action of alkali and CO2 and its preparation method

technical field

The invention relates to silicate building materials and products, and mainly relates to a new type of wall material prepared by using waste residue, alkali and _CO2 as main raw materials without adding lime.

Background technique

In our country, the use of fly ash, slag and other industrial wastes as cement admixtures and concrete admixtures has become the main way to recycle waste in the cement concrete industry. According to statistics, my country's cement concrete industry consumed 310 million tons of industrial waste in 2006, accounting for 46% of the total comprehensive utilization of industrial waste in the country. From the perspective of reducing CO ₂ emissions, this is equivalent to reducing the production or use of 310 million tons of clinker, and about 1 ton of CO ₂ is emitted per ton of clinker, and the resulting reduction in CO ₂ emissions is about 310 million tons. It can be seen that the use of industrial waste residues as admixtures and admixtures has become the most effective CO ₂ emission reduction measure in the cement concrete industry. Yet, when using industrial waste residue as the auxiliary cementitious material (as mixed materials, admixtures) or as the main raw material of the alkali-activated cementitious material with industrial waste residue at a larger dosage, a certain amount (2% to 50%) must be blended. , or even higher) alkali activator to stimulate the chemical activity of waste residue and promote the rapid development of its gelling performance (called alkali excitation technology). These alkali activators mixed in may cause poor durability (such as alkali aggregate reaction) of concrete structures, and may even cause concrete engineering quality accidents, which restricts the promotion and application of this technology in the cement concrete industry; Alkali activators can also cause problems such as the dissolution of alkali metal ions, surface efflorescence, and high cost of activated cementitious materials, which hinder the practical application of alkali activated cementitious materials made of slag, fly ash, and kaolin. Therefore, a series of problems caused by the incorporation of alkali activators have seriously restricted the role of alkali excitation technology in the field of silicate materials in more effective waste resource utilization and CO ₂ emission reduction.

On the other hand, aluminum and silicate minerals in silicate gelling materials and their hydration products (such as calcium hydroxide) are very easy to chemically react with carbon dioxide dissolved in water during the hydration process (called carbonization). ) to generate calcium carbonate, aluminum glue, and silica gel. For reinforced concrete, carbonization should be avoided as much as possible, because carbonization will cause damage to the dense passivation film on the surface of the steel bar, accelerate the corrosion of the steel bar, and affect the durability of the structure. But for silicate products, carbonization will significantly improve the physical and chemical properties of the products. This improvement is mainly reflected in: the deposition of carbonized products (mainly calcium carbonate) in the pores reduces the porosity of the product and increases the degree of compactness, and correspondingly increases the strength in terms of macroscopic properties; the deposited carbonized products will block Partial pores block the channels for ion migration, thereby wrapping ions in the product and reducing its dissolution. In the context of the global focus on reducing _CO2 emissions, the use of carbonization to prepare materials is of great significance. It can not only modify the material, but also capture a certain amount of CO ₂ . In recent years, people have used carbonization to prepare materials and products using lime, carbide slag, steel slag, etc. as raw materials. However, the carbonization source is not the hydration products of aluminum and silicate minerals, but the calcium hydroxide formed by the mixed lime or the calcium hydroxide contained in the waste residue itself. As we all know, every ton of lime produced will emit about 0.79 tons of CO ₂ in addition to the CO ₂ emitted by fuel, which undoubtedly greatly reduces the significance of reducing emissions of such materials and products. What is even more unfavorable is that due to the high requirement for calcium content, currently only waste slags _such as calcium carbide slag and steel slag can be used as raw materials, and the source of raw materials is very narrow; Concentration and partial pressure) requirements are very strict, and there is also the deficiency that the product is self-heavy. Therefore, the technology of using carbonization to prepare materials and products still needs to make major breakthroughs in raw materials and preparation processes, so as to effectively play the role of this technology in the utilization of waste residues and the capture of CO ₂ .

Both the alkali excitation technology and the carbonization technology are disclosed in patent documents. Patent applications CN1068554 and CN1699253 respectively disclose methods for producing alkali-activated gelling materials using slag and Portland cement clinker, kaolin and steel slag as raw materials, and water glass, sodium sulfate, sodium fluoride, etc. as activators. Patent application CN1699252 Disclosed is an alkali-activated carbonate/slag composite cementitious material with slag and carbonate mineral powder as raw materials and water glass as an activator and a preparation method thereof. Patent application CN101139182 discloses a carbonation curing aerated concrete prepared by absorbing carbon dioxide gas with steel slag and cement as the main materials. The silicate building material product and method in which _CO2 is carbonized gas. However, after searching, there is no patent publication on the preparation technology and related materials and products based on the synergistic effect of alkali and _CO2 based on the use of industrial waste residue, no lime and cement, and no claims related to the core technology in the relevant patents have been retrieved. .

The above-mentioned existing practices and related patents show that the amount of waste slag is increased by simply using the alkali excitation effect (such as increasing the amount of cement admixture, preparing alkali-stimulated cementitious materials, etc.), or simply using carbonization to prepare materials (such as using calcium-containing waste slag, etc.) Preparation of carbonized materials), will not play a more active role in the utilization of waste residue resources, energy saving and emission reduction. Only by giving full play to the respective advantages of the two technologies at the same time (1) the alkali excitation effect promotes the activity of waste residue, the slurry formed by it has excellent structural performance, and the structure itself has a certain degree of alkali metal ion sealing effect, and the resulting product can absorb CO ₂ Advantages such as chemical carbonization; (2) chemical carbonization can enhance the compactness of material structure, improve material performance, and inhibit the dissolution of alkali metal ions; and on this basis, make up for the shortcomings of the two technologies alone (3 ) poor durability of materials caused by alkali excitation effect, high cost caused by high alkali dosage, etc.; The use of industrial waste residues and the use of CO ₂ silicate materials to prepare new technologies with near-zero emissions can effectively amplify the role of alkali excitation and carbonization in waste residue utilization, energy saving and emission reduction.

The present invention is to make full use of the advantages of alkali excitation technology and carbonization technology, and try to avoid the shortcomings of both, to obtain high-performance silicate products with high waste residue utilization, low alkali consumption, no lime and cement, and alkali and CO ₂ The synergistic preparation technology plays a more active role in the utilization of waste residue resources, energy saving and emission reduction.

Contents of the invention

The object of the present invention is to provide a high-performance silicate building material product and its preparation method based on the synergistic effect of alkali and _CO2 , using industrial waste residue as raw material, under the condition of low alkali, no lime and cement clinker.

The building material product based on the synergistic effect of alkali and _CO2 in the present invention is a green body obtained by mixing powder of fly ash and slag components with a fineness controlled in the range of ^400-600m2 /Kg, mixed with aggregate and water glass , and then obtained after natural conservation and carbonization.

Wherein, the mass ratio of fly ash and slag in the mixed powder is 7:3-3:7.

The aggregate is construction sand, coal gangue, phosphorus slag, undisturbed slag and other wastes with a particle size of 0.1-10mm, and the aggregate accounts for 20%-60% of the weight of the mixed powder.

The dosage of the water glass is 5-20% of the weight of the mixed powder.

The green body is a standard brick, porous brick, hollow brick, insulation brick or building block, etc., and the building material products obtained after carbonization are carbonized silicate standard brick, carbonized silicate porous brick, carbonized silicate Wall materials such as hollow bricks, carbonized silicate insulation bricks or carbonized silicate blocks.

The present invention is based on alkali and _CO The preparation method of the building material product of synergy, comprises the following steps:

1) Grinding: Grinding fly ash and slag to the set fineness;

2) Mixing: mix the fly ash and slag evenly according to the ratio requirements;

3) Stirring: add aggregate and water glass to the uniformly mixed powder and stir fully;

4) Injection molding: Immediately inject the fully stirred slurry into a test mold with a set shape to obtain a green body;

5) Curing: naturally curing the green body at room temperature;

6) Carbonization: Put the green body into a carbonization device to carbonize to obtain a product.

Wherein, the gas used in step 6) carbonization is waste gas discharged from fuel combustion and waste gas with high _CO2 content discharged from chemical industry, and its _CO2 concentration is greater than 12%.

Step 6) The temperature of the carbonization device is 50-100°C, the relative humidity is 50-60%, the _CO2 concentration is 20-30%, and the carbonization time is 8-48 hours.

Step 5) The natural curing time is 1 day.

By adopting the above technical scheme, it has been verified that the silicate building material product obtained by the preparation method of the present invention has excellent performance. In the case of low alkali dosage (5%), the strength of the prepared standard brick exceeds MU10 grade; in the case of high alkali dosage (20%), the strength of the body after natural curing can reach 10MPa, After the body is carbonized, its strength exceeds 40MPa; regardless of the amount of alkali, there is no blooming phenomenon on the surface of the product; the dissolution test shows that even when the amount of alkali is 20%, the amount of dissolved alkali (calculated as _Na2O ) is also less than 1% of the total alkali content, and the dissolution rate of various toxic and harmful ions is also far below the limit value. The obtained product has excellent durability, freeze-thaw resistance, and weathering resistance; the size deviation is small, and the appearance quality is excellent.

On the other hand, because the present invention utilizes the strengthening effect of carbonization, it is not necessary to mix a large amount of alkali like the existing preparation technology when preparing products with the same strength, thereby effectively reducing the amount of alkali dissolution at the source of alkali dissolution. The products formed by carbonization will block some pores in the slurry, enhance the compactness of the slurry structure, cut off the migration channels of alkali metal ions to a certain extent, and make them wrap in the reaction products, which further inhibits their dissolution. It can be seen that the low-alkali technology adopted due to the improvement of carbonization on the physical properties of the green body, coupled with the solidification of alkali metal ions by carbonization, forms the innovation of the present invention in inhibiting alkali dissolution.

The invention utilizes the alkali excitation effect to make the industrial waste slag not only produce products that are prone to carbonization under alkaline conditions, but also form a porous slurry structure, so that the carbonization is easier to carry out, and then achieves carbonization without lime and cement (or cement clinker) ) The purpose of preparing high-strength products under the conditions. On the other hand, the alkali excitation effect in the present invention not only provides the carbonization source and the pore channel of chemical carbonization, but also one of the providers of material strength (the other strength provider is the carbonization product of the alkali excitation generation product). This means that on the premise of preparing products with the same strength, the present invention undoubtedly widens the range of carbonization process parameters and reduces the requirement for carbonization depth compared with the existing carbonization technology.

Another characteristic of the present invention is that not only the powder in the raw material is waste residue, but also the function of filler and cement is integrated into one, without adding filler and cement separately. More importantly, the present invention utilizes the characteristics of rapid alkali-induced reaction and the easy reaction of the product with CO ₂ to achieve the purpose of absorbing and capturing CO 2 and effectively utilizing CO ₂ , forming a nearly zero-emission silicate building product The new technology makes a practical and effective contribution to the reduction of CO ₂ emissions.

Detailed ways

The raw materials used in the present invention are composed of fly ash, slag, aggregate, and water glass. After the fly ash and slag are ground, they are mixed evenly in an appropriate proportion, and then mixed with an appropriate proportion of aggregate and water glass to obtain a billet after stirring and molding. The green body is naturally cured and carbonized to obtain the finished product.

The invention uses industrial waste fly ash and slag as main raw materials, and the fineness of the two after grinding is controlled within the range of 400-600m ² /Kg. There is no special requirement on the calcium content of fly ash, and even high calcium fly ash that cannot be used in cement admixtures can also be used as the raw material of the present invention; Yellow-white granules, also known as granulated blast furnace slag, are often simply called slag. The slag used here needs to be processed by grinding, or select commercial slag powder through grinding on the market. In the present invention, the used pulverized fly ash and slag components play two roles in the product production process, that is, the functions of filler and cement. These two effects are reflected in: the fine particles of fly ash and slag fill the gaps and improve the strength of the green body; the gelatinous substance generated by fly ash and slag under the action of alkali excitation cements the material, so that the green body can maintain the set appearance .

The alkali activator used in the present invention is water glass, its quality meets the requirements of "Industrial Sodium Silicate" (GB/T4209-1996), its modulus is 1.6 to 2.2, and its solid content is 35% to 50%. The gas used is the exhaust gas emitted by fuel combustion and the high _CO2 content exhaust gas emitted by the chemical industry, and its _CO2 concentration is greater than 12%.

Aggregate, also known as aggregate, mainly acts as a skeleton. After the product is hardened, the cement will bind the aggregate into a solid whole. The particle size of the aggregate used in the present invention is controlled between 0.1-10 mm, and it can be wastes such as construction sand and stone, coal gangue, phosphorus slag, and slag. The slag selected here is the granulated blast furnace slag formed by quenching the waste slag discharged from the ironmaking blast furnace, which is granular and undisturbed slag.

All of the above starting materials are commercially available.

The silicate building material product of the present invention is obtained by carbonizing a green body made by mixing fly ash, slag powder, aggregate and water glass. Among them, the mass ratio of fly ash to slag powder is between 7:3 and 3:7, the aggregate accounts for 20% to 60% of the weight of the above two powders, and the amount of water glass is 5 to 20%; the body of building material products can be standard bricks, porous bricks, hollow bricks, insulation bricks, blocks, etc., and the products after carbonization can be carbonized silicate standard bricks, carbonized silicate porous bricks, silicon carbide Salt hollow bricks, carbonized silicate insulation bricks, carbonized silicate blocks and other new wall materials.

The preparation method of silicate building material product of the present invention, comprises the following steps:

1. Grinding: Grinding fly ash and slag to the set fineness;

2. Mixing: Mix fly ash and slag evenly according to the ratio requirements;

3. Stirring: Add aggregate and appropriate amount of water glass to the evenly mixed powder and stir thoroughly;

4. Injection molding: Immediately inject the fully stirred slurry into a test mold of a certain shape to obtain a green body;

5. Curing: natural curing of the green body at room temperature;

6. Carbonization: Put the green body into the carbonization device to carbonize to obtain the finished product.

In the above steps, the natural maintenance of the green body at room temperature is to make the mixed water glass exert its stimulating effect, and make the silicon and aluminum minerals in the fly ash and slag react to form a gelling substance that provides strength. Therefore, the green body has a certain initial strength for easy handling, and provides a strength foundation and a precursor structure for the later carbonization treatment.

In the carbonization process, the gas used is the exhaust gas emitted by fuel combustion and the high _CO2 content exhaust gas emitted by the chemical industry, and its _CO2 concentration is greater than 12%. The higher temperature exhaust gas is passed into the carbonization device, and the CO ₂ in the exhaust gas is dissolved in the pore solution of the green body to generate carbonic acid, which is then dissociated into HCO ₃ ^-1 and H ^{+ 1} , and HCO ₃ ^-1 is excited with alkali to produce products and the carbonic acid in the waste residue Minerals react to form calcium carbonate. The generated calcium carbonate is not only one of the strength providers of the product itself, but also deposited in the pores to reduce the porosity of the product and increase the compactness, thereby improving the strength of the product. This dual role of carbonized products ensures that the product has a sufficiently high strength. It is worth noting that the alkali-activated reaction is still going on during the carbonization process, and the reaction rate is often several times or even dozens of times higher under the condition of humid heat than under the condition of normal temperature. This accelerated reaction will continuously generate gelatinous substances, that is, continuously replenish the carbonization source and continuously increase the strength of the green body. It can be seen that the multiple effects of alkali excitation and carbonization are sufficient to ensure high-performance silicate building material products.

The present invention is further illustrated below with specific examples.

Example 1

Take fly ash and slag and grind them to 550m ² /Kg and 550m ² /Kg respectively.

Get 70Kg pulverized coal ash and 30Kg pulverized slag and mix uniformly to obtain powder A-1; Get 60Kg pulverized coal ash and 40Kg pulverized slag and mix uniformly to obtain powder A-2; Get 50Kg ground pulverized coal ash and Mix 50Kg of finely ground slag uniformly to obtain powder A-3; take 40Kg of finely ground fly ash and mix uniformly with 60Kg of finely ground slag to obtain powder A-4; take 30Kg of finely ground fly ash and 70Kg of Material A-5.

In powder A-1, A-2, A-3, A-4, A-5 respectively, add sand (aggregate) 40Kg and water glass (alkali activator) 10Kg (accounting for 40% of powder weight respectively and 10%), fully stirred and shaped to obtain standard brick bodies A-1, A-2, A-3, A-4, A-5 (multiple pieces are prepared for each type), and the green bodies are naturally maintained for 1 day and then placed in temperature Carbonization at 60°C, relative humidity of 50%, and _CO2 concentration of 40% in a carbonization device for 20 hours to obtain carbonized standard bricks A-1, A-2, A-3, A-4, and A-5. The properties of samples A-1, A-2, A-3, and A-4 were tested according to the "Test Method for Wall Bricks" (GBT2542-2003), and the results are shown in Table 1.

Table 1

It is known from Table 1 that under the premise of a certain amount of water glass and carbonization conditions, the strength of the sample in the powder increases gradually with the increase of the amount of slag. However, it is not economical to increase the strength of the sample by increasing the amount of slag, and an appropriate amount of slag should be mixed in production according to the strength requirements. For example, only 30% slag is enough to produce standard bricks of grade MU15. It should be noted that when the amount of water glass and carbonization conditions are changed, the amount of slag obtained in this example is not applicable when producing products of a certain strength level.

Example 2

Grind fly ash and slag to 450m ² /Kg and 450m ² /Kg respectively. According to the weight ratio of 70%:30%, the ground fly ash and the ground slag are evenly mixed to obtain the powder material for use.

Take the same amount of powder (about 2 kg each), and then operate as follows: add aggregate and alkali activator to the powder according to the ratio of sand and water glass to 25% and 5% of the weight of the powder respectively , fully stirred and shaped to obtain the standard brick body B-1; according to the ratio of sand and water glass to 25% and 10% of the powder weight respectively, add aggregate and alkali activator to the powder, fully stir and shape to obtain the standard Brick body B-2; according to the ratio of sand and water glass to 25% and 15% of the powder weight respectively, add aggregate and alkali activator to the powder, fully stir and shape to obtain standard brick body B-3; press Sand and sodium silicate account for 25% and 20% of the weight of the powder respectively. Add aggregate and alkali activator to the powder, fully stir and shape to obtain the standard brick body B-4. Multiple pieces of each type of body are prepared. The green bodies B-1, B-2, B-3, and B-4 were naturally cured for 1 day and then placed in a carbonization device with a temperature of 60°C, a relative humidity of 50%, and _a CO concentration of 20% for carbonization for 20 hours to obtain carbonized Standard bricks B-1, B-2, B-3, B-4. Test the performance of samples B-1, B-2, B-3, and B-4 according to the "Test Method for Wall Bricks" (GBT2542-2003).

The test shows that the dimensional deviation of all samples in the length and width directions is less than 2mm, and the dimensional deviation in the height direction is less than 1mm; all samples have excellent appearance quality, no missing edges, no cracks, no color difference, and no arches; The strength results of the samples are shown in Table 2.

Table 2

Known from Table 2, even if the amount of water glass is as low as 5%, the strength of the sample (B-1) still reaches the MU10 grade after 20 hours of carbonization curing. When the amount of water glass increased to 20%, the compressive strength of the obtained sample (B-4) reached 42MPa, exceeding the MU40 grade of the concrete solid brick. It can be seen that the sample of this example can be made to have sufficient strength after 20 hours of carbonization curing under the condition of mixing 5% to 20% water glass.

Example 3

Take fly ash and slag and grind them to 400m ² /Kg and 550m ² /Kg respectively. The powder is obtained by uniformly mixing the ground fly ash and the ground slag according to the ratio of 60%:40%.

Take powders of the same weight (about 2 kilograms per piece), and then operate as follows: add aggregate and alkali activator to the powder according to the ratio of sand and water glass to 35% and 15% of the weight of the powder respectively , fully stirred and shaped to obtain a standard adobe body C, and the standard adobe body C is prepared into multiple pieces. After one day of natural curing, the multiple green bodies C were placed in a carbonization device with a temperature of 100°C, a relative humidity of 60%, and a _CO2 concentration of 30% for carbonization for 8 hours, 12 hours, 16 hours, 20 hours, 24 hours, and 48 hours respectively. Hours, carbonized standard bricks C-1, C-2, C-3, C-4, C-5, and C-6 were obtained. Test the performance of samples C-1, C-2, C-3, C-4, C-5, and C-6 according to the "Test Method for Wall Bricks" (GBT2542-2003).

The test shows that the dimensional deviation of all samples in the length and width directions is less than 2mm, and the dimensional deviation in the height direction is less than 1mm; all samples have excellent appearance quality, no missing edges, no cracks, no color difference, and no arches; The strength results of the samples are shown in Table 3.

table 3

Known from Table 3, under the condition that the water glass dosage is 15%, along with the prolongation of curing time the intensity of sample increases gradually, but the carbonization curing of too long time (as 48 hours) can not make sample (C- 6) The strength is greatly improved, which shows that there is an optimal carbonization time under a certain amount of water glass and carbonization atmosphere. The optimal carbonization time of this example product is 24 hours.

Example 4

Take fly ash and slag and grind them to 500m ² /Kg and 600m ² /Kg respectively. The powder is obtained by uniformly mixing the ground fly ash and the ground slag according to the ratio of 50%:50%.

Respectively get the same amount of powder (about 1.5 kilograms per block), and then operate as follows: add aggregate and alkali activator to the powder according to the ratio of sand and water glass respectively accounting for 45% and 20% of the weight of the powder, Stir fully and shape to obtain standard adobe body D, and prepare multiple pieces of standard adobe body D. After one day of natural curing, the multi-block green bodies D were carbonized for 12 hours in a carbonization device with a temperature of 60°C, a relative humidity of 50%, and a _CO2 concentration of 20%, 30%, 40%, 50%, and 60%, respectively, to obtain Carbonized standard bricks D-1, D-2, D-3, D-4, D-5. Test the performance of samples D-1, D-2, D-3, D-4, and D-5 according to "Test Method for Wall Bricks" (GBT2542-2003).

The test shows that the dimensional deviations of all samples in the length and width directions are less than 2mm, and the dimensional deviations in the height direction are less than 1mm; the appearance quality of all samples is excellent; the strength results of each sample are shown in Table 4.

Table 4

Known from Table 4, under the condition that the dosage of water glass is fixed as 20% and the carbonization time is fixed as 12 hours, along with the increase of _CO concentration, the strength of the sample increases gradually. When the _CO2 concentration is 20%, the average strength of the sample (D-1) can reach 35MPa; when the _CO2 concentration increases to 30%, the average strength of the sample (D-2) increases to 40MPa; continue to increase CO ₂ concentration, although the average strength of the samples (D-3, D-4, D-5) has increased, but the increase is only 1MPa. This shows that the carbonizable material in this product is almost completely consumed when the _CO2 concentration is 30%, that is, the contribution of carbonization to the strength has reached the maximum value, so the increase in _CO2 concentration shows that the strength increases slowly.

Example 5

Take fly ash and slag, and grind them to 400m ² /Kg and 400m ² /Kg respectively. Mix the ground fly ash and the ground slag uniformly according to the ratio of 40%:60% to obtain the powder.

According to the ratio of sand and water glass respectively accounting for 55% and 15% of the weight of the powder, add aggregate and alkali activator to the powder, fully stir and shape to obtain porous brick body E-1 (length × width × height = 240mm×115mm×53mm), hollow brick body E-2 (length×width×height=290mm×190mm×90mm). According to the proportion that sand and water glass respectively account for 60% and 10% of the weight of the powder, add aggregate and alkali activator to the powder, fully stir and form the hollow block body E-3 (length×width×height= 290mm×290mm×190mm), hollow block body E-4 (length×width×height=390mm×190mm×190mm). Multiple pieces of each type of body are prepared. The porous brick body E-1, the hollow brick body E-2, the hollow block body E-3, and the hollow block body E-4 are naturally cured for 1 day, and then placed in a temperature of 50°C and a relative humidity of 60%. Carbonize in a carbonization device with a _CO2 concentration of 30% for 20 hours to obtain carbonized porous brick E-1, carbonized hollow brick E-2, carbonized hollow masonry E-3, and carbonized hollow block E-4. Test the performance of samples E-1, E-2, E-3, E-4 according to "Test Method for Wall Bricks" (GBT2542-2003).

The test shows that the dimensional deviation of carbonized porous brick E-1 and carbonized hollow brick E-2 in the length and width directions is less than 2mm, and the dimensional deviation in the height direction is less than 1mm; carbonized hollow masonry E-3 and carbonized hollow block E -4 Dimensional deviations in all directions are less than 2mm; all samples have good appearance quality; the strength results of each sample are shown in Table 5.

table 5

Known from Table 5, the average strength of the carbonized porous brick (E-1) obtained in this example is higher, which can reach 18.0MPa; the obtained hollow products (E-2, E-3, E-4) also have sufficient strength.

Example 6

Take fly ash and slag and grind them to 500m ² /Kg and 500m ² /Kg respectively. The powder is obtained by uniformly mixing the ground fly ash and the ground slag according to the ratio of 30%:70%.

According to the ratio of sand and water glass to 30% and 5% of the powder weight respectively, add aggregate and alkali activator to the powder, fully stir and shape to obtain standard brick body F-1 respectively; according to sand and water glass respectively Accounting for 30% and 10% of the powder weight, add aggregate and alkali activator to the powder, fully stir and shape to obtain the standard brick body F-2 respectively; according to sand and water glass respectively accounting for 30% of the powder weight % and 15%, add aggregate and alkali activator to the powder, fully stir and shape to obtain the standard brick body F-3 respectively; according to the ratio of sand and water glass to 30% and 20% of the weight of the powder, respectively , add aggregate and alkali activator to the powder, fully stir and shape to obtain standard brick body F-4 respectively. Multiple pieces of each type of body are prepared. Green bodies F-1, F-2, F-3, and F-4 were naturally cured for 1 day and then placed in a carbonization device with a temperature of 50°C, a relative humidity of 50%, and a _CO2 concentration of 20% for 12 hours to obtain carbonized Bricks F-1, F-2, F-3, F-4. Observe whether the samples F-1, F-2, F-3, and F-4 have a pan-frost phenomenon, and measure the alkali dissolution amount (calculated as Na ₂ O) of the samples F-1, F-2, F-3, and F-4 ) and the dissolved amount of toxic and harmful ions such as chromium, cadmium, arsenic and lead.

The result shows: the surface of sample F-1, F-2, F-3, F-4 all does not have pan-frost phenomenon; When the amount of alkali dissolution is 5% in water glass dosage, the dissolution quantity of sample (F-1) is only 0.1% of the amount of alkali mixed, even when the amount of water glass is increased to 20%, the amount of alkali dissolution of the sample (F-4) is no more than 1%; the dissolution amount of toxic and harmful ions such as chromium, cadmium, arsenic, lead, Far less than the limit value stipulated in "Identification Standards for Hazardous Wastes - Identification of Leaching Toxicity" (GB5085.3-2007). It can be seen that the alkali in the product of this example is completely sealed in the structure, which fully meets the engineering requirements; the dissolution of toxic and harmful ions also fully meets the environmental protection requirements.

Example 7

Take fly ash and slag, and grind them to 600m ² /Kg and 600m ² /Kg respectively. Mix the ground fly ash and the ground slag evenly according to the ratio of 65%:35% to obtain the powder.

According to the ratio of sand and water glass to 50% and 5% of the powder weight respectively, add aggregate and alkali activator to the powder, fully stir and shape to obtain standard brick body G-1 respectively; Accounting for 50% and 10% of the powder weight, add aggregate and alkali activator to the powder, fully stir and shape to obtain the standard brick body G-2 respectively; according to sand and water glass respectively accounting for 50% of the powder weight % and 15%, add aggregate and alkali activator to the powder, fully stir and shape to obtain the standard brick body G-3 respectively; according to the ratio of sand and water glass to 50% and 20% of the weight of the powder, respectively , add aggregate and alkali activator to the powder, fully stir and shape to obtain standard brick body G-4 respectively. Multiple pieces of each type of body are prepared. Green bodies G-1, G-2, G-3, and G-4 were naturally cured for 1 day and then placed in a carbonization device with a temperature of 60°C, a relative humidity of 60%, and a _CO2 concentration of 30% for 16 hours to obtain carbonized Bricks G-1, G-2, G-3, G-4. Test the durability of samples G-1, G-2, G-3, and G-4 in accordance with the "Test Method for Wall Bricks" (GBT2542-2003), that is, freeze-thaw resistance and weathering resistance. Among them, the freeze-thaw resistance is characterized by the strength retention and mass loss of the sample after 15 freeze-thaw cycles, and the weathering resistance is characterized by the 5-hour boiling water absorption.

After freezing and thawing, no cracks, delamination, peeling, missing edges and corners and other frost damage occurred in all samples. The results of the freeze-thaw and 5-hour boiling water absorption tests are shown in Table 6 and Table 7, respectively.

Table 6

It can be seen from Table 6 that, on the basis that samples G-1, G-2, G-3, and G-4 meet the strength grades MU10, MU15, MU30, and MU40 respectively, the samples still retain relatively high strength after freezing and thawing. The freeze-thaw strength loss percentages of the higher strength samples (C-2, C-3, C-4) obtained in this example are all less than 20%, which is less than the 25% specified in the concrete solid brick (GB13544-2000); The freeze-thaw strength retention values of low-strength samples (C-1, C-2) are 10MPa and 15MPa respectively, fully meeting the requirements of autoclaved lime-sand bricks (GB11945-1999) with strength grades M10 and M15 (GB11945-1999 It is stipulated that the freeze-thaw strength retention values of M10 and M15 autoclaved lime-sand bricks shall not be lower than 8MPa and 12MPa respectively). In addition, the highest mass loss of the sample after freezing and thawing is only 1.9%, which is less than the 2% stipulated by autoclaved lime sand brick (GB11945-1999), ordinary fired brick (GB5101-2003) and concrete solid brick (GB13544-2000) 5%. The above shows that the sample obtained in this example has good freeze-thaw resistance.

Table 7

It can be known from Table 7 that the average value of the 5h boiling water absorption of the sample obtained in this example does not exceed 10.3%, which is far less than the minimum value of 18% specified by ordinary fired bricks (GB5101-2003) and the minimum value specified by fired porous bricks (GB13545-2003). The minimum value is 16%, indicating that the sample obtained in this example has good weathering resistance.

Claims (6)

1. A building material product based on the synergistic effect of alkali and _CO2 , which is obtained by mixing fly ash and slag components with fineness controlled in the range of 400-600m ² /Kg, mixed with aggregate and water glass to form The green body is obtained after natural curing and carbonization; The mass ratio of fly ash and slag components in the mixed powder is 7:3～3:7; The aggregate is construction sand, coal gangue, phosphorus slag or undisturbed slag with a particle size between 0.1-10mm, and the aggregate accounts for 20%-60% of the weight of the mixed powder; The dosage of the water glass is 5-20% of the weight of the mixed powder. 2. The building material product according to claim 1, wherein the green body is a standard brick, a porous brick, a hollow brick, an insulating brick or a building block, and the building material product obtained after carbonization is a carbonized silicate standard bricks, carbonized silicate porous bricks, carbonized silicate hollow bricks, carbonized silicate insulating bricks or carbonized silicate blocks. 3. claim 1 or 2 based on alkali and _CO The preparation method of the building material product of synergy, comprises the steps: 1) Grinding: Grinding fly ash and slag to the set fineness; 2) Mixing: mix the fly ash and slag evenly according to the ratio requirements; 3) Stirring: add aggregate and water glass to the uniformly mixed powder and stir fully; 4) Injection molding: Immediately inject the fully stirred slurry into a test mold with a set shape to obtain a green body; 5) Curing: naturally curing the green body at room temperature; 6) Carbonization: Put the green body into a carbonization device to carbonize to obtain a product. 4. preparation method according to claim 3 is characterized in that, step 6) gas used in the carbonization is the exhaust gas of fuel combustion discharge and the high _CO content exhaust gas of chemical industry discharge, and its _CO concentration is greater than 12%. 5. the preparation method according to claim 3 is characterized in that, step 6) carbonization device temperature is 50～100 ℃, relative humidity is 50～60%, _CO Concentration is 20～30%, carbonization time is 8～ 48 hours. 6. The preparation method according to claim 3, characterized in that, step 5) natural curing time is 1 day. the