Cement mortar containing sludge incineration ash and preparation method and application thereof

Abstract

The present invention belongs to the technical field of building materials and solid waste resource utilization, and more specifically, it relates to a cement mortar containing sludge incineration ash and its preparation method and application. Among them, the cement mortar containing sludge incineration ash, by weight, includes: 315-405 parts of cement, 45-135 parts of sludge incineration ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent and 225 parts of water. The raw materials are prepared into mortar, and the compressive strength after curing for 3 days is not less than 20MPa. The sludge incineration ash used is an auxiliary cementitious material with high activity, which can replace slag powder and fly ash in cement mortar in the prior art, and can further replace part of cement, effectively reducing the amount of cement, reducing costs, indirectly reducing carbon emissions, and being beneficial to resource conservation and environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials and solid waste resource utilization, and more specifically relates to a cement mortar containing sludge incineration ash and a preparation method and application thereof. Background Art

[0002] The amount of sludge in rivers, lakes or urban sewage is huge, and contains elements such as nitrogen, phosphorus and heavy metals. The presence of these components will interfere with or hinder the effective utilization and recycling of sludge solid waste. Heavy metals (such as lead, mercury, cadmium, chromium, etc.) in sludge pose a threat to the environment. In the process of resource utilization, how to ensure that these harmful substances do not enter new products or the environment is a major challenge.

[0003] In the existing technology, although there are many methods to treat and utilize sludge solid waste, each method has certain limitations. For example, chemical precipitation may produce a large amount of secondary sludge; physical separation methods are not effective for fine particles; and biological remediation processes take a long time and the effect is unstable. Effective resource recovery technologies often require high investment and operating costs, including equipment purchase, energy consumption, and subsequent maintenance costs.

[0004] If the sludge incineration ash produced by the incineration of riverbed sludge can be used as a raw material for preparing cement mortar, it will not only achieve efficient utilization of solid waste and achieve the goal of energy conservation and emission reduction, but will also greatly reduce the manufacturing cost of mortar. However, if too much solid waste replaces cement, the compressive strength will often fail to meet the requirements. Therefore, how to make the sludge incineration ash have better adaptability in the cement system and improve the early compressive strength of cement mortar has become a difficult problem that technicians in this field need to solve urgently. Summary of the invention

[0005] The purpose of the present invention is to provide a cement mortar containing sludge incineration ash and a preparation method and application thereof, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a cement mortar containing sludge incineration ash, wherein the raw materials include, by weight:

[0008] 315-405 parts of cement, 45-135 parts of sludge incineration ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent and 225 parts of water.

[0009] Furthermore, the particle size distribution of the sludge incineration ash is 0.3 to 100 μm, and the specific surface area is not less than 500 m 2 / kg, loss on ignition is not more than 1.5%.

[0010] The beneficial effect of the above-mentioned sludge incineration ash parameter limitation is: controlling the particle size of the sludge incineration ash within a relatively appropriate range, while avoiding the impact on the technical effect due to large differences in specific surface area.

[0011] Furthermore, the cement is P·I 42.5 silicate cement.

[0012] Furthermore, the fineness modulus of the machine-made sand is 2.7-3.0, the stone powder content is ≤3wt%, and the mud block content is ≤0.5wt%.

[0013] Optionally, the machine-made sand is zone II sand with a fineness modulus of 2.7 to 3.0 and an MB value of less than 1.4.

[0014] The beneficial effect of the above-mentioned machine-made sand parameter limitation is to avoid the influence of the technical effect caused by the large difference in the fineness of the machine-made sand.

[0015] Furthermore, the early strength agent is calcium sulfate and / or sodium sulfate.

[0016] Calcium sulfate introduces Ca 2+ 、SO4 2- It accelerates the hydration of C3S in the induction period and promotes the formation of ettringite. Sodium sulfate can react with the hydration product calcium hydroxide. On the one hand, it consumes the liquid calcium hydroxide to generate sodium hydroxide, increase the alkalinity of the solution, accelerate the hydration of C3S and the formation of ettringite; on the other hand, the extremely fine CaSO4 particles generated by the reaction increase the reaction rate with C3A.

[0017] The 3d compressive strength of the cement mortar containing sludge incineration ash in the present invention is not less than 20MPa.

[0018] The second technical solution of the present invention is to provide a method for preparing the cement mortar containing sludge incineration ash, the steps comprising:

[0019] The cement, sludge incineration ash and early strength agent are mixed and stirred evenly, and then machine-made sand and water are added and mixed evenly to obtain the cement mortar containing sludge incineration ash.

[0020] Furthermore, the stirring time is 30 s and the stirring rate is 140 rpm.

[0021] Furthermore, the mixing rate is 140-285 rpm.

[0022] In the present invention, the mixing is automatically carried out according to the JC / T681-2022 standard.

[0023] The third technical solution of the present invention is to provide an application of the above-mentioned cement mortar containing sludge incineration ash in building materials.

[0024] The present invention discloses the following technical effects:

[0025] The cement mortar of the invention contains loose and porous sludge incineration ash, has good adaptability to the early strength agent, can significantly enhance the early compressive strength of the cement mortar, and the 3d compressive strength is not less than 20MPa.

[0026] The sludge incineration ash used in the present invention is a highly active auxiliary cementitious material, which can replace the slag powder and fly ash in the cement mortar in the prior art, and can further replace part of the cement, effectively reducing the amount of cement, reducing costs, indirectly reducing carbon emissions, and is beneficial to resource conservation and environmental protection.

[0027] The content of phosphorus and heavy metals in sludge incineration ash is relatively high. The scheme of the present invention can solidify heavy metals and reduce the environmental pollution of phosphorus and heavy metals. The present invention performs leaching tests in accordance with the standard "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid and Nitric Acid Method" (HJ / T299-2007). Sludge incineration ash leach 133.311mg / LP, 0.017mg / L Cu and 0.710mg / L Mn in acid solution.

[0028] The cement mortar prepared by the present invention uses a relatively low amount of cement, has a large amount of mineral admixtures, has a low overall cost, can be mass-produced, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 This is the particle size distribution diagram of sludge incineration ash. DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0033] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0034] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0035] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0036] The "parts" in the specific embodiments of the present invention refer to "parts by mass".

[0037] The raw materials and reagents used in the specific embodiments of the present invention are all commercially available products. If they meet the specified specifications, the purchase channel will not affect the realization of the technical effects.

[0038] In a specific embodiment of the present invention, the purity of the early strength agent used is ≥99%; the 28d activity index of the sludge incineration ash used (provided by Shanghai Baoning Environmental Protection Technology Co., Ltd.) is ≥75%, and the specific surface area is not less than 500m 2 / kg, loss on ignition is not more than 1.5%, chemical composition see Table 1, particle size distribution see Figure 1 The standard consistency water consumption of the P·I 42.5 silicate cement used is not more than 26%, and the 28d mortar compressive strength is not less than 42.5MPa; the machine-made sand used is II zone sand with a fineness modulus of 2.7 to 3.0, the stone powder content is ≤3wt%, the mud content is ≤0.5wt%, and the MB value is less than 1.4; the slag powder used is S95 grade, D 50 =10.826μm, chemical composition see Table 2. The fly ash used is Grade I, D 50 =12.870μm, chemical composition see Table 3.

[0039] Table 1

[0040] Components <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[P2O5]]> <![CDATA[Fe2O3]]> CaO MgO Content (wt.%) 40.001 25.949 10.225 7.897 6.111 2.696 Components <![CDATA[SO3]]> <![CDATA[K2O]]> ZnO CuO MnO other Content (wt.%) 2.709 1.801 0.147 0.124 0.212 2.128

[0041] Table 2

[0042] Components CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO Content (wt.%) 34.06 33.8 17.67 9.56 Components <![CDATA[SO3]]> <![CDATA[Na2O]]> other / Content (wt.%) 2.38 0.71 1.82 /

[0043] Table 3

[0044] Components CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> Content (wt.%) 6.1 43 32 3.66 Components MgO <![CDATA[SO3]]> <![CDATA[Na2O]]> other Content (wt.%) 0.9 2.3 0.9 11.14

[0045] Example 1

[0046] Preparation of cement mortar containing sewage sludge incineration ash:

[0047] S1. Raw material preparation: 315 parts of P·I 42.5 silicate cement, 135 parts of sludge incineration ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent (calcium sulfate) and 225 parts of water;

[0048] S2. P·I 42.5 silicate cement, sludge incineration ash and early strength agent are mixed and stirred evenly, poured into a mixing pot for low-speed stirring (30s, 140rpm), and then machine-made sand and water are added. Automatic mixing is performed according to JC / T681-2022 standard. The mixing rate of low-speed mixing is 140rpm, and the mixing rate of fast mixing is 285rpm to obtain cement mortar containing sludge incineration ash.

[0049] Example 2

[0050] Preparation of cement mortar containing sewage sludge incineration ash:

[0051] S1. Raw material preparation: 315 parts of P·I 42.5 silicate cement, 135 parts of sludge incineration ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent (sodium sulfate) and 225 parts of water;

[0052] S2. P·I 42.5 silicate cement, sludge incineration ash and early strength agent are mixed and stirred evenly, poured into a mixing pot for low-speed stirring (30s, 140rpm), and then machine-made sand and water are added. Automatic mixing is performed according to JC / T681-2022 standard. The mixing rate of low-speed mixing is 140rpm, and the mixing rate of fast mixing is 285rpm to obtain cement mortar containing sludge incineration ash.

[0053] Example 3

[0054] Preparation of cement mortar containing sewage sludge incineration ash:

[0055] S1. Raw material preparation: 405 parts of P·I 42.5 silicate cement, 45 parts of sludge incineration ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent (calcium sulfate) and 225 parts of water;

[0056] S2. P·I 42.5 silicate cement, sludge incineration ash and early strength agent are mixed and stirred evenly, poured into a mixing pot for low-speed stirring (30s, 140rpm), and then machine-made sand and water are added. Automatic mixing is performed according to JC / T681-2022 standard. The mixing rate of low-speed mixing is 140rpm, and the mixing rate of fast mixing is 285rpm to obtain cement mortar containing sludge incineration ash.

[0057] Example 4

[0058] Preparation of cement mortar containing sewage sludge incineration ash:

[0059] S1. Raw material preparation: 340 parts of P·I 42.5 silicate cement, 110 parts of sludge incineration ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent (calcium sulfate) and 225 parts of water;

[0060] S2. P·I 42.5 silicate cement, sludge incineration ash and early strength agent are mixed and stirred evenly, poured into a mixing pot for low-speed stirring (30s, 140rpm), and then machine-made sand and water are added. Automatic mixing is performed according to JC / T681-2022 standard. The mixing rate of low-speed mixing is 140rpm, and the mixing rate of fast mixing is 285rpm to obtain cement mortar containing sludge incineration ash.

[0061] Example 5

[0062] Preparation of cement mortar containing sewage sludge incineration ash:

[0063] S1. Raw material preparation: 380 parts of P·I 42.5 silicate cement, 75 parts of sludge incineration ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent (calcium sulfate) and 225 parts of water;

[0064] S2. P·I 42.5 silicate cement, sludge incineration ash and early strength agent are mixed and stirred evenly, poured into a mixing pot for low-speed stirring (30s, 140rpm), and then machine-made sand and water are added. Automatic mixing is performed according to JC / T681-2022 standard. The mixing rate of low-speed mixing is 140rpm, and the mixing rate of fast mixing is 285rpm to obtain cement mortar containing sludge incineration ash.

[0065] Comparative Example 1

[0066] Preparation of cement mortar: (excluding early strength agent and sludge incineration ash)

[0067] S1. Raw material preparation: 450 parts of P·I 42.5 Portland cement, 1350 parts of machine-made sand and 225 parts of water;

[0068] S2. Pour PI 42.5 silicate cement into a mixing pot, then add machine-made sand and water, and automatically mix according to JC / T681-2022 standard. The mixing rate of low-speed mixing is 140 rpm, and the mixing rate of fast mixing is 285 rpm to obtain cement mortar.

[0069] Comparative Example 2

[0070] Preparation of cement mortar containing sludge incineration ash: (without early strength agent)

[0071] S1. Raw material preparation: 315 parts of P·I 42.5 silicate cement, 135 parts of sludge incineration ash, 1350 parts of machine-made sand and 225 parts of water;

[0072] S2. P·I 42.5 silicate cement and sludge incineration ash are mixed and stirred evenly, poured into a mixing pot for low-speed stirring (30s, 140rpm), and then machine-made sand and water are added. Automatic mixing is performed according to JC / T681-2022 standard. The mixing rate of low-speed mixing is 140rpm, and the mixing rate of fast mixing is 285rpm to obtain cement mortar containing sludge incineration ash.

[0073] Comparative Example 3

[0074] Preparation of cement mortar containing sewage sludge incineration ash:

[0075] S1. Raw material preparation: 315 parts of P·I 42.5 silicate cement, 135 parts of sludge incineration ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent (NaNO2) and 225 parts of water;

[0076] S2. P·I 42.5 silicate cement, sludge incineration ash and early strength agent are mixed and stirred evenly, poured into a mixing pot for low-speed stirring (30s, 140rpm), and then machine-made sand and water are added. Automatic mixing is performed according to JC / T681-2022 standard. The mixing rate of low-speed mixing is 140rpm, and the mixing rate of fast mixing is 285rpm to obtain cement mortar containing sludge incineration ash.

[0077] Comparative Example 4

[0078] Preparation of cement mortar containing other mineral admixtures:

[0079] S1. Raw material preparation: 315 parts of P·I 42.5 silicate cement, 45 parts of slag powder, 90 parts of fly ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent (calcium sulfate) and 225 parts of water;

[0080] S2. P·I 42.5 silicate cement, slag powder, fly ash and early strength agent are mixed and stirred evenly, poured into a mixing pot for low-speed stirring (30s, 140rpm), and then machine-made sand and water are added. Automatic mixing is performed according to JC / T681-2022 standard. The mixing rate of low-speed mixing is 140rpm, and the mixing rate of fast mixing is 285rpm to obtain cement mortar containing sludge incineration ash.

[0081] Test example

[0082] The cement mortar prepared in Examples 1 to 5 and Comparative Examples 1 to 4 was poured into a 40 mm × 40 mm × 40 mm mold. After the cement mortar was poured, it was fully vibrated to exhaust the bubbles. After the cement mortar was poured, it was placed in a standard curing box, and the curing temperature was set to 20 ± 2 ° C, and the humidity was greater than 95%. The compressive strength was tested using a press at 3d, 7d, and 28d from the date of preparation, respectively, and the load loading speed was 2.4 kN / s. The results are shown in Table 4.

[0083] Table 4

[0084] sample 3d compressive strength / MPa 7d compressive strength / MPa 28d compressive strength / MPa Fluidity / mm Comparative Example 1 26.7 32.8 42.7 210 Comparative Example 2 9.7 23.5 36.3 163 Comparative Example 3 16.9 25.9 33.7 183 Comparative Example 4 23.1 31.5 41.8 180 Example 1 21.3 30.1 39.0 166 Example 2 22.0 31.2 41.0 174 Example 3 30.2 37.3 46.6 196 Example 4 24.3 33.6 41.7 173 Example 5 26.0 35.3 45.3 185

[0085] It can be seen from the results in Table 4 that Comparative Example 1 is a conventional cement mortar preparation. Comparative Example 1 is used as a control example. In Comparative Example 2, no early strength agent is added, and only sludge incineration ash is used to replace part of the cement for preparation. Its mechanical properties and working performance are significantly reduced, and the 3d compressive strength is reduced by 57%, and the working performance is poor. In Examples 1 to 5, by adding an early strength agent, even if sludge incineration ash is used to replace part of the cement, the early compressive strength and working performance of the cement mortar are significantly improved compared with Comparative Example 2, and the compressive strength of 3d, 7d and 28d is not significantly reduced compared with Comparative Example 1. In Comparative Example 3, the early strength agent is replaced by NaNO2. It can be seen that the 3d strength is improved compared with Comparative Example 2, but it is much lower than Examples 1 and 2, and the 28d strength is even lower than Comparative Example 2. In Comparative Example 4, the sludge incineration ash was replaced by slag powder and fly ash. It can be seen that its 3d and 28d compressive strengths are close to those in Example 1, indicating that calcium sulfate, an early strength agent, has a similar promoting effect on the compressive strength of the sludge incineration ash-cement system and the slag powder-fly ash-cement system at different ages.

[0086] In summary, it can be seen that the present invention uses solid waste-based materials to replace cement in cement mortar, which not only reduces the preparation cost of cement mortar and reduces carbon emissions, but also utilizes early strength agents to improve the early compressive strength of cement mortar, thereby reducing the risk of cracking caused by cement hydration heat.

[0087] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0088] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A cement mortar containing sludge incineration ash, characterized in that: By mass, the raw materials include: 315-405 parts of cement, 45-135 parts of sludge incineration ash, 1350 parts of machine-made sand, 4.5 parts of early strength agent and 225 parts of water.

2. The cement mortar according to claim 1, characterized in that: The cement is P·I 42.5 silicate cement.

3. The cement mortar according to claim 1, characterized in that: The particle size distribution of the sludge incineration ash is 0.3-100 μm, and the specific surface area is not less than 500 m 2 / kg, loss on ignition is not more than 1.5%.

4. The cement mortar according to claim 1, characterized in that: The fineness modulus of the machine-made sand is 2.7-3.0, the stone powder content is ≤3wt%, and the mud block content is ≤0.5wt%.

5. The cement mortar according to claim 1, characterized in that: The early strength agent is calcium sulfate and / or sodium sulfate.

6. The method for preparing cement mortar according to any one of claims 1 to 5, characterized in that the steps include: The cement, sludge incineration ash and early strength agent are mixed and stirred evenly, and then machine-made sand and water are added and mixed evenly to obtain the cement mortar containing sludge incineration ash.

7. The preparation method according to claim 6, characterized in that: The stirring time is 30 s, and the stirring speed is 140 rpm.

8. The preparation method according to claim 6, characterized in that: The mixing speed is 140-285 rpm.

9. Use of the cement mortar according to any one of claims 1 to 5 in building materials.

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