Green low shrinkage incineration ash-sap cement-based self-leveling mortar

Abstract

The application discloses a kind of green low shrinkage incineration ash-SAP cement-based self-leveling mortar, its composition is: incineration ash 1.94~5.81 parts, Portland cement 21.30~25.18 parts, fly ash 10.62~13.62 parts, river sand 56.10~60.10 parts, superabsorbent resin 0.008~0.016 parts, expanding agent 1.50~1.60 parts, water reducing agent 0.10~0.20 parts, re-dispersible latex powder 0.56~0.60 parts, cellulose ether 0.018~0.020 parts, defoaming agent 0.076~0.078 parts, early strength agent 0.76~0.78 parts;The material replaces part of cement with sludge incineration ash, has the advantages of low carbon environmental protection, cost reduction, realizes the resource utilization of incineration ash, while incorporating SAP to reduce drying shrinkage, so that it has good fluidity, strength and crack resistance, simple method, suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of inorganic non-metallic materials and building environment-friendly materials, and particularly relates to a green low-shrinkage incineration ash-SAP cement-based self-leveling mortar. BACKGROUND

[0002] Self-leveling mortar is a ground material with high fluidity and automatic leveling ability, which is composed of cementitious materials, fine aggregates and admixtures, and has the characteristics of convenient construction, high early strength and good workability. Self-leveling mortar has excellent performance and has been rapidly developed in China. It is suitable for various fields such as schools, hospitals, ships, stores, apartments and office buildings, and has a broad application prospect. However, cement-based self-leveling mortar has self-shrinkage and drying shrinkage. When the shrinkage stress is higher than the cohesion of the self-leveling mortar, surface cracking will occur. Moreover, self-leveling mortar is often used in thin and large-area scenarios, so its crack resistance is particularly important, and it is of great significance to control the shrinkage of self-leveling mortar.

[0003] Sludge incineration is a relatively effective sludge treatment method, which can achieve sludge reduction, inactivation and deodorization. The residue left after sludge incineration is called sludge incineration ash. With the popularization of incineration technology, the amount of incineration ash is increasing. If only landfill or stacking is used, it will occupy a large amount of land resources. Research shows that incineration ash is a solid waste with high sulfur content, which can be used as a substitute for cement in the preparation of cement-based materials. Incineration ash contains a large amount of sulfate, which can react with calcium hydroxide generated during cement hydration to form gypsum, and then form ettringite, which can reduce the shrinkage of the test piece.

[0004] Superabsorbent polymer (SAP) is a high molecular polymer with strong hydrophilic groups, which has strong water absorption and can absorb and store water or water-containing liquid ten times or even one hundred times more than its own mass. Currently, internal curing with superabsorbent polymer is recognized as one of the best methods to reduce the shrinkage of cement-based materials. When superabsorbent polymer is added to concrete or cement mortar, it can release the pre-absorbed water into the surrounding environment, play a moisturizing role, and significantly reduce the shrinkage of cement-based materials. Incineration ash has small particle size, large specific surface area and high water demand. The addition of incineration ash reduces the water demand for cement hydration, so the addition of superabsorbent polymer can supply water for cement hydration and expansion reaction at the same time.

[0005] Traditional cement-based self-leveling mortar in the construction industry uses a large amount of cement and natural sand and stone as the main raw material, which consumes natural resources and causes serious damage to the ecological environment. Therefore, there is an urgent need for a green self-leveling mortar that efficiently utilizes incineration ash, reduces environmental pressure and carbon emissions, reduces costs, and improves the problem of large shrinkage and easy cracking of existing self-leveling mortar. SUMMARY

[0006] In view of the low resource utilization of incineration ash in the prior art, and the defects of the traditional self-leveling mortar such as easy cracking and high cost, the present application aims to improve the resource utilization of incineration ash and reduce the shrinkage of the self-leveling mortar and improve its crack resistance. The method is simple, low in cost, energy-saving and environmentally friendly.

[0007] The technical scheme of the present application is as follows:

[0008] A green low-shrinkage incineration ash-SAP cement-based self-leveling mortar is composed of the following raw materials by weight:

[0009] Incineration ash 1.94-5.81 parts, Portland cement 21.30-25.18 parts, fly ash 10.62-13.62 parts, river sand 56.10-60.10 parts, superabsorbent resin 0.008-0.016 parts, expanding agent 1.50-1.60 parts, water reducing agent 0.10-0.20 parts, redispersible latex powder 0.56-0.60 parts, cellulose ether 0.018-0.020 parts, defoaming agent 0.076-0.078 parts, early strength agent 0.76-0.78 parts;

[0010] During construction, the water-binder ratio of the mortar is 0.43-0.46, preferably 0.45; the water-binder ratio refers to the mass ratio of water to cementitious materials (Portland cement + incineration ash + fly ash).

[0011] The incineration ash used in the present application is sludge incineration ash, a red-brown powder with a high sulfur content (18.53%) and a particle size mainly distributed in 10-100 μm, and a specific surface area of 421 m 2 / kg;

[0012] The fly ash is grade II fly ash;

[0013] The maximum particle size of the river sand is 1.18 mm;

[0014] The superabsorbent resin is pre-absorbed with water and then participates in mixing and stirring, with a water absorption rate of 207.7 g / g;

[0015] The expanding agent is a HCSA type concrete expanding agent;

[0016] The water reducing agent is a polycarboxylic acid type high-performance water reducing agent;

[0017] The redispersible latex powder is a copolymer of vinyl acetate and ethylene;

[0018] The cellulose ether is a hydroxypropyl methyl cellulose ether;

[0019] The defoaming agent is a mineral oil and polyethylene glycol containing defoaming agent;

[0020] The early strength agent is a calcium formate early strength agent.

[0021] The technical principle of the present application is that:

[0022] The sludge incineration ash used in the present application has the characteristics of high sulfur content, and the sulfate can react with calcium hydroxide to generate dihydrate gypsum, which further reacts with C3A to generate ettringite, thereby reducing shrinkage. In addition, SAP has a synergistic effect with incineration ash in the system of the present application, which promotes the generation of ettringite. The shrinkage-reducing effect of the composite is greater than that of single-doped incineration ash and single-doped SAP.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] 1) The incineration ash-SAP cement-based self-leveling mortar provided by the present application uses incineration ash obtained after sludge incineration to replace part of the cement, which can consume solid waste such as incineration ash, reduce the amount of cement, reduce carbon dioxide emissions, and promote the development of green and low-carbon cement-based self-leveling mortar.

[0025] 2) The incineration ash-SAP cement-based self-leveling mortar provided by the present application can reduce the dry shrinkage of the self-leveling mortar by compounding incineration ash with high sulfur content and high water absorption resin to replace part of the cement. During the cement hardening process, the sulfate in the incineration ash reacts with the Ca(OH)2 generated by the hydration reaction to generate dihydrate gypsum, which further reacts with C3A in the cement to generate ettringite, thereby reducing shrinkage and preparing a self-leveling mortar with excellent crack resistance, which improves the limitations of the application of self-leveling mortar in engineering.

[0026] 3) The incineration ash-SAP cement-based self-leveling mortar provided by the present application has part of the cement replaced by incineration ash, which is low in cost and suitable for industrialized production. For example, using a scheme of compounding 10% incineration ash to replace cement and 0.04% high water absorption resin, the cost can be reduced by 35.1%.

[0027] 4) The incineration ash-SAP cement-based self-leveling mortar provided by the present application has part of the cement replaced by incineration ash, which can effectively reduce the environmental impact of cement-based self-leveling mortar. For example, the global warming potential, acidification potential and eutrophication potential are reduced by 7.5%, 3.0% and 3.3%, respectively. DETAILED DESCRIPTION

[0028] The present application will be further described below through specific examples, but the scope of protection of the present application is not limited thereto.

[0029] The incineration ash used in the application is sludge incineration ash obtained by incinerating sludge in Hangzhou. The sludge is pretreated by using an acidifying agent and a flocculating agent to improve the dewatering capacity of the sludge, and then the pretreated sludge is subjected to plate-frame pressurized filtration dewatering. After the two steps of pretreatment and pressurized dewatering, the water content in the sludge can be greatly reduced. Finally, the dewatered sludge is incinerated at high temperature (about 850 DEG C), and the red-brown powder has a high sulfur content of 18.53%, and the particle size is mainly distributed in 10-100 mu m, and the specific surface area is 421 m 2 / kg.

[0030] The fly ash is II-grade fly ash.

[0031] The river sand has a maximum particle size of 1.18 mm.

[0032] The superabsorbent resin is produced by Shengli Oilfield Chang'an Holding Group Co., Ltd., and has a mesh size of 120-180, and is saturated with water in advance before participating in mixing and stirring, and has a water absorption rate of 207.7 g / g.

[0033] The expanding agent is HCSA type concrete expanding agent produced by Jiangsu Subo Technology Co., Ltd., and has a specific surface area of 374 m2 / kg.

[0034] The water reducing agent is 400P polycarboxylic acid type high-performance water reducing agent produced by Jiangsu Subo Technology Co., Ltd., and is a white solid powder, and has a water reducing rate of > 35%.

[0035] The redispersible latex powder is Vinnapas RE5044N produced by Wacker Company in Germany, which is a copolymer of vinyl acetate and ethylene.

[0036] The cellulose ether is hydroxypropyl methyl cellulose ether produced by Shanghai Chenqi Chemical Technology Co., Ltd., and has a viscosity of 400 mPa·s.

[0037] The defoaming agent is Mingling P803 defoaming agent, which contains mineral oil and polyethylene glycol defoaming agent, and has an active substance of > 65% and a pH value of 72.

[0038] The early strength agent is calcium formate early strength agent produced by Shanghai Titan Science and Technology Co., Ltd.

[0039] The performance test method of the mortar of the application is as follows:

[0040] The fluidity test is carried out according to the method of JC / T985-2017 "Cement-based self-leveling mortar for ground", and the fluidity of the sample is tested. The test mold is: Φ = 30 ± 0.1 mm, h = 50 ± 0.1 mm hollow cylinder. The flowability test mold is placed in the center of the glass plate (area greater than 300 mm x 300 mm) to ensure that the cement mortar will not flow out of the glass plate during the flow process. Before testing, the surface of the glass plate must be smooth, clean and free of obvious water stains. If the surface of the glass plate is dry, a wet towel should be used to wet the surface of the glass plate. Pour the stirred cement mortar into the mold, fill the mold without excessive filling, and after 2 s, lift the mold vertically by about 10 cm to let the mortar fall freely. Record the diameter of the sample in two perpendicular directions after 4 min, and take the average to obtain the initial fluidity of the sample. Let the sample stand for 20 min and test the 20 min fluidity.

[0041] The flexural and compressive strength tests should be carried out according to GB / T 17671-2021 "Cement mortar strength test method (ISO method)", using a planetary mixer to stir the mortar, and pouring the freshly stirred mortar into a triple test mold without vibration. The test piece is cured at 23℃±2℃ and 50%±5% relative humidity for 24h, and then demolded and cured to the corresponding age before testing the flexural and compressive strength. The sample size for flexural strength test is 40mm x 40mm x 160mm, and the loading rate is 50N±l0 N / s. The test block size for compressive strength test is 40mm x 40mm x 40mm, and the loading rate is 2.4KN / s±0.2KN / s

[0042] The drying shrinkage test is carried out according to the method of JC / T985-2017 "Cement-based self-leveling mortar for ground", the shrinkage mold is removed, a layer of release agent is evenly coated, then the shrinkage head is fixed at the fixed position at both ends of the mold, and the distance between the shrinkage head and the end face of the test piece is about 8mm. The mortar mold is poured into a size of 10mm x 40mm x 160mm, and after curing for 24h under standard test conditions (temperature 23℃±2℃, relative humidity 50%±5%), it is taken out, the test direction is marked, and the initial length is measured. Then the sample is placed under standard test conditions for 27d, then taken out, and the length is measured according to the test direction.

[0043] Example 1 (complex addition of incineration ash and 0.02% SAP)

[0044] A green low-shrinkage incineration ash-SAP cement-based self-leveling mortar and its preparation method, the raw material composition of which is:

[0045]

[0046] The self-leveling mortar is prepared according to the above-mentioned mass ratio, and water is added for fully stirring according to a total water-binder ratio of 0.45, wherein the high water-absorbing resin is pre-absorbed with 200 g / g of water, and the remaining water is added during stirring, and the self-leveling mortar is constructed after being stirred uniformly.

[0047] The basic performance of the formula is as follows: 20 min fluidity 132 mm, 1d flexural strength 2.2 MPa, 1d compressive strength 8.1 Mpa, 3d flexural strength 3.8 MPa, 3d compressive strength 19.4 MPa, 28d flexural strength 6.1 MPa, 28d compressive strength 33.4 MPa, 90d flexural strength 7.5 MPa, 90d compressive strength 35.1 MPa, 28d dry shrinkage -898.14 με.

[0048] Example 2 (complex mixing of incineration ash and 0.04% SAP)

[0049] A green low-shrinkage incineration ash-SAP cement-based self-leveling mortar and a preparation method thereof, the raw material composition of which is as follows:

[0050]

[0051]

[0052] The self-leveling mortar is prepared according to the above-mentioned mass ratio, and water is added for fully stirring according to a total water-binder ratio of 0.45, wherein the high water-absorbing resin is pre-absorbed with 200 g / g of water, and the remaining water is added during stirring, and the self-leveling mortar is constructed after being stirred uniformly.

[0053] The basic performance of the formula is as follows: 20 min fluidity 132 mm, 1d flexural strength 2.2 MPa, 1d compressive strength 8.1 Mpa, 3d flexural strength 3.8 MPa, 3d compressive strength 19.4 MPa, 28d flexural strength 6.1 MPa, 28d compressive strength 33.4 MPa, 90d flexural strength 7.5 MPa, 90d compressive strength 35.1 MPa, 28d dry shrinkage -898.14 με.

[0054] Comparative Example 1 (no addition of SSA and SAP group)

[0055]

[0056] The self-leveling mortar is prepared according to the above-mentioned mass ratio, and water is added for fully stirring according to a total water-binder ratio of 0.45, wherein the high water-absorbing resin is pre-absorbed with 200 g / g of water, and the remaining water is added during stirring, and the self-leveling mortar is constructed after being stirred uniformly.

[0057] The basic performance of the formulation is: 20 min fluidity 146 mm, 1 d flexural strength 2.9 MPa, 1 d compressive strength 10.2 Mpa, 3 d flexural strength 4.9 MPa, 3 d compressive strength 22.6 MPa, 28 d flexural strength 7.4 MPa, 28 d compressive strength 36.6 MPa, 90 d flexural strength 8.4 MPa, 90 d compressive strength 39.7 MPa, 28 d dry shrinkage -1 118.54 με.

[0058] Comparative Example 2 (only SSA is added)

[0059]

[0060] The self-leveling mortar is prepared according to the above specified mass ratio, and water is added for fully stirring according to the total water-binder ratio of 0.45, and then construction is performed.

[0061] The basic performance of the formulation is: 20 min fluidity 133 mm, 1 d flexural strength 2.3 MPa, 1 d compressive strength 8.6 Mpa, 3 d flexural strength 4 MPa, 3 d compressive strength 20.6 MPa, 28 d flexural strength 6.5 MPa, 28 d compressive strength 34 MPa, 90 d flexural strength 7.8 MPa, 90 d compressive strength 36.4 MPa, 28 d dry shrinkage -1099.52 με.

[0062] Comparative Example 3 (only 0.02% SAP is added)

[0063]

[0064] The self-leveling mortar is prepared according to the above specified mass ratio, and water is added for fully stirring according to the total water-binder ratio of 0.45, and then construction is performed.

[0065] The basic performance of the formulation is: 20 min fluidity 140 mm, 1 d flexural strength 3.3 MPa, 1 d compressive strength 10.6 Mpa, 3 d flexural strength 5.2 MPa, 3 d compressive strength 22.9 MPa, 28 d flexural strength 8.2 MPa, 28 d compressive strength 37.4 MPa, 90 d flexural strength 8.9 MPa, 90 d compressive strength 40.3 MPa, 28 d dry shrinkage -1099.52 με.

[0066] Comparative Example 4 (only 0.04% SAP is added)

[0067]

[0068] According to the quality ratio specified above, the self-leveling mortar is prepared, and water is added for fully stirring according to the total water-binder ratio of 0.45, wherein the superabsorbent resin is pre-water-absorbed by 200 g / g, and the remaining water is added during stirring, and the self-leveling mortar is constructed after being stirred uniformly.

[0069] The basic performance of the formula is as follows: 20 min fluidity 133 mm, 1d flexural strength 3 MPa, 1d compressive strength 9.5 MPa, 3d flexural strength 4.9 MPa, 3d compressive strength 22.4 MPa, 28d flexural strength 7.2 MPa, 28d compressive strength 34.7 MPa, 90d flexural strength 8 MPa, 90d compressive strength 37.3 MPa, 28d dry shrinkage -1048.55 με.

[0070] The incineration ash replaces 10% of cement, and the water demand of the cement-based self-leveling mortar is increased, and the superabsorbent resin is added in a pre-water-absorbed manner, so that the 20 min fluidity of the self-leveling mortar is reduced, but the 20 min fluidity still meets the performance requirements of the cement-based self-leveling mortar for ground.

[0071] The incineration ash replaces 10% of cement, and the flexural and compressive strengths of the cement-based self-leveling mortar are reduced, and the flexural strength is reduced more than the compressive strength. When the superabsorbent resin is added alone, the flexural and compressive strengths of the cement-based self-leveling mortar are reduced with the increase of the content. When the SSA replaces 10% of cement and is mixed with 0.02% and 0.04% of the superabsorbent resin, respectively, the strengths of the self-leveling mortar at different ages are reduced to different degrees compared with the single mixing. However, the flexural and compressive strengths of the self-leveling mortar mixed with the incineration ash alone, the superabsorbent resin alone and the two meet the standard requirements.

[0072] When the incineration ash replaces 10% of cement, the dry shrinkage of the cement-based self-leveling mortar is reduced by 15.8%; when the superabsorbent resin is added alone, the dry shrinkage is reduced by 1.7% and 6.3%, respectively. When the incineration ash replaces 10% of cement and is mixed with the superabsorbent resin, the dry shrinkage is reduced by 19.7% and 26.0%, respectively, and the reduction effect is significantly higher than that of the single mixing of the two. The reduction effect of the mixed mixing is higher than the superposition of the reduction effect of the single mixing of the two. Therefore, the incineration ash replacing 10% of cement and the superabsorbent resin have a synergistic effect.

[0073] In summary, the self-leveling mortar of the application greatly improves the shrinkage reduction effect while meeting the performance standard requirements, and realizes the resource utilization of the incineration ash, which has wide practical significance.

Claims

1. A green, low-shrinkage incinerator ash-SAP cement-based self-leveling mortar, characterized in that, It consists of the following raw materials in parts by weight: Incineration ash 1.94–5.81 parts, silicate cement 21.30–25.18 parts, fly ash 10.62–13.62 parts, river sand 56.10–60.10 parts, superabsorbent resin 0.008–0.016 parts, expanding agent 1.50–1.60 parts, water-reducing agent 0.10–0.20 parts, redispersible latex powder 0.56–0.60 parts, cellulose ether 0.018–0.020 parts, defoamer 0.076–0.078 parts, early strength agent 0.76–0.78 parts; in, The incineration ash is municipal sludge incineration ash, with a sulfur content of 18.53%, a particle size distribution of 10–100 μm, and a specific surface area of ​​421 m². 2 / kg; The superabsorbent resin is pre-absorbed with water before being mixed and stirred, with a water absorption ratio of 207.7 g / g; The expansive agent is an HCSA type concrete expansive agent.

2. The green low-shrinkage incinerator ash-SAP cement-based self-leveling mortar as described in claim 1, characterized in that, The water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

3. The green low-shrinkage incinerator ash-SAP cement-based self-leveling mortar as described in claim 1, characterized in that, The redispersible latex powder is a copolymer of vinyl acetate and ethylene.

4. The green low-shrinkage incinerator ash-SAP cement-based self-leveling mortar as described in claim 1, characterized in that, The cellulose ether is hydroxypropyl methylcellulose ether.

5. The green low-shrinkage incinerator ash-SAP cement-based self-leveling mortar as described in claim 1, characterized in that, The defoamer is a defoamer containing mineral oil and polyethylene glycol.

6. The green low-shrinkage incinerator ash-SAP cement-based self-leveling mortar as described in claim 1, characterized in that, The early strength agent is calcium formate.

7. The green low-shrinkage incinerator ash-SAP cement-based self-leveling mortar as described in claim 1, characterized in that, During construction, the water-cement ratio of the mortar should be 0.43 to 0.46.

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