A high-strength masonry material based on desulfurized ash and its preparation method

Abstract

The present invention provides a high-strength masonry material based on desulfurized ash, which comprises, by weight parts: 100 parts of modified mixed aggregate; 8-12 parts of masonry binder; 8-15 parts of water; and a water reducing agent accounting for 0.5wt.% - 3wt.% of the total weight of the masonry binder; the modified mixed aggregate is composed of desulfurized ash and aggregate; the masonry binder is composed of steel slag, slag, gypsum and quicklime. The present invention also provides a preparation method of the high-strength masonry material with simple process and easy construction. The high-strength masonry material prepared by the present invention has a 3d compressive strength of not less than 10MPa, and the 14d strength can reach more than 30MPa, meeting the strength grade requirement of autoclaved lime-sand solid bricks MU30 in GB / T11945-2019 national standard. Taking desulfurized ash as the main raw material, it has important significance for realizing resource utilization, reducing land occupation and reducing environmental pollution, and has broad popularization and application prospects.

Description

Technical Field

[0001] The invention belongs to the field of resource utilization of industrial solid wastes, relates to a high-strength masonry material based on desulfurized ash, and also relates to a preparation method of the high-strength masonry material. Background Art

[0002] Desulfurization ash is a solid powder produced by semi-dry desulfurization. Due to the advantages of semi-dry desulfurization process such as low investment, small footprint, low water consumption, low corrosion to equipment, dry by-products, and no wastewater generation, the semi-dry desulfurization process has gradually become the mainstream technology for sintering flue gas desulfurization. Desulfurization ash has also become the third largest solid waste in the steel industry after blast furnace slag.

[0003] Steel slag is industrial waste produced during the steelmaking process in the steel industry. The low comprehensive utilization rate has led to the large-scale storage of steel slag and desulfurization ash, which has an adverse impact on the surrounding water, air, and soil, and poses a great environmental risk and land pressure.

[0004] Masonry materials include sintered ordinary bricks, sintered porous bricks, autoclaved fly ash bricks, autoclaved lime sand bricks, autoclaved aerated concrete bricks and concrete ordinary bricks. High-strength masonry materials have greater demand and better application prospects in construction projects due to their superior mechanical properties. However, conventional high-strength masonry materials often require sintering or steam curing steps during the preparation process, which not only consumes a lot of energy, but also high-density sand and gravel aggregates are usually used in high-strength masonry materials, which will result in heavy masonry and is not conducive to transportation.

[0005] Based on this, providing a high-strength masonry material prepared in collaboration with desulfurization ash and other industrial solid wastes is of great significance for realizing resource utilization, reducing land occupation, and reducing environmental pollution, and is also a technical problem that needs to be solved urgently. Summary of the invention

[0006] One of the objects of the present invention is to provide a high-strength masonry material based on desulfurized ash.

[0007] A second object of the present invention is to provide a method for preparing a high-strength masonry material based on desulfurized ash.

[0008] The technical solution adopted by the present invention to achieve one of the purposes is: to provide a high-strength masonry material based on desulfurized ash, which comprises the following components by weight:

[0009] 100 parts of modified mixed aggregate; 8 to 12 parts of masonry binder; 8 to 15 parts of water; and 0.5 wt.% to 3 wt.% of a water reducing agent accounting for the total weight of the masonry binder;

[0010] The modified mixed aggregate is formed by mixing desulfurized ash and aggregate in a mass ratio of (2-4):(6-8);

[0011] The masonry binder is composed of steel slag, slag, gypsum and quicklime.

[0012] The general idea of a high-strength masonry material provided by the present invention is as follows:

[0013] Desulfurized ash has the characteristics of being porous and loose. Mixing it with masonry aggregate in a certain proportion and making the desulfurized ash evenly adsorbed on the surface of the aggregate can bring the following advantages: First, the desulfurized ash existing on the surface of the aggregate can increase the friction between the aggregates, improve the effect of the masonry aggregate resisting slip and dislocation, and thus improve the overall density and mechanical strength of the masonry material; Second, compared with sand and gravel aggregates, desulfurized ash has the characteristics of low density and light weight. Adding desulfurized ash to replace part of the aggregate can reduce the weight of the high-strength masonry material and reduce the handling and transportation costs of the high-strength masonry material. Third, as a powder material, desulfurized ash is added to the aggregate, which can fill the pores between the aggregates, improve the density of the masonry, reduce the porosity, and is beneficial to improving the compressive strength of the high-strength masonry material. Fourth, there is a certain amount of calcium sulfite in the desulfurized ash. Calcium sulfite is oxidized to form calcium sulfate with a certain amount of micro-expansion. Using the micro-expansion of desulfurized ash to fill the pores between the aggregates in the high-strength masonry material and the volume remaining after the evaporation and drying of water can further increase the compressive strength of the high-strength masonry material. In addition, calcium sulfate or calcium sulfite in the desulfurized ash can also react with slag and steel slag in the masonry binder through hydration to generate ettringite and monosulfate calcium sulfoaluminate. Needle-shaped ettringite and flaky monosulfate calcium sulfoaluminate minerals penetrate and fill the pores between the aggregates, playing a filling role to increase the strength of the masonry material.

[0014] Further, the aggregate includes natural sand and gravel aggregate and / or artificial aggregate.

[0015] Further, the aggregate is composed of primary aggregate and secondary aggregate; preferably, the particle size range of the primary aggregate is 2-5 mm, and the particle size range of the secondary aggregate is 1.25-2 mm.

[0016] Preferably, the mass ratio of the secondary aggregate to the primary aggregate is (1-5):1. In the present invention, aggregates with different particle size ranges are combined with desulfurized ash. Desulfurized ash is used as a particle with a smaller particle size to replace fine aggregate. A good aggregate particle size grading range can promote the pressing effect, and thus improve the compressive strength of the masonry material. At the same time, the composition of the modified mixed aggregate shows a gradient grading, which helps to improve the filling density of the matrix material and further improve the compressive strength of the masonry material.

[0017] Further, the density of the desulfurized ash is 550-900 kg / m 3; Among its components, the proportion of calcium sulfate, calcium sulfite, calcium carbonate and calcium hydroxide is not less than 70 wt.%.

[0018] Preferably, the desulfurized ash is subjected to grinding and screening treatment, and its particle size is not greater than 0.315 mm.

[0019] Further, in the masonry binder, the content of each component is calculated by weight percentage: 15 wt.% - 25 wt.% of steel slag, 40 wt.% - 55 wt.% of slag, 10 wt.% - 25 wt.% of gypsum, and 2 wt.% - 10 wt.% of quicklime.

[0020] Preferably, the preparation method of the masonry binder includes: adding steel slag, slag, gypsum and quicklime into a ball milling system in proportion for mixing and grinding, so that the specific surface area of the mixture is not less than 400 m 2 / kg, thus obtaining the masonry binder. In the above preparation method, under the action of mechanical force, steel slag, slag, gypsum and quicklime can not only realize the double synergistic optimization of the particle size and activity of the mixed abrasive through the "micro grinding ball effect", but also the mixed material grinding can improve the uniformity and hydration activity of the masonry binder and reduce the grinding energy consumption. The masonry binder prepared by the present invention can undergo a hydration reaction in the desulfurized ash environment to generate hydration products such as calcium silicate hydrate, ettringite, monosulfate calcium aluminate, Friedel's salt, etc., and the hydration products will bond the aggregates together to form a stable and high-strength masonry material.

[0021] Further, the water reducing agent is selected from one or a combination of naphthalene-based superplasticizer, amino superplasticizer, polycarboxylate superplasticizer.

[0022] The technical solution adopted by the present invention to achieve the second object is: to provide a preparation method of a high-strength masonry material based on desulfurized ash as described in the first object of the present invention, including the following steps:

[0023] S1. Mix the desulfurized ash and the aggregate evenly to obtain a modified mixed aggregate;

[0024] S2. Add the masonry binder, water and water reducing agent to the modified mixed aggregate, and mix evenly to obtain a masonry cementitious material;

[0025] S3. Press the masonry cementitious material into shape to obtain a high-strength masonry material.

[0026] Further, in step S1, the mixing time is not less than 3 min. During this mixing process, the desulfurized ash and the masonry aggregate are fully contacted by stirring to improve the distribution uniformity of the desulfurized ash and avoid local concentration of the desulfurized ash. Preferably, the mixing time is 3 - 6 min.

[0027] Further, in step S3, the pressure for pressing and forming is 10-25 MPa. Preferably, the pressure for pressing and forming is 20-25 MPa.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The high-strength masonry material based on desulfurized ash provided by the present invention uses a certain proportion of desulfurized ash to replace part of the aggregate as the main raw material. After the porous and loose desulfurized ash is evenly mixed with the masonry aggregate, it can increase the friction between the aggregates and improve the ability of the masonry aggregate to resist slip and dislocation; at the same time, the desulfurized ash has the characteristics of low density and light weight compared with sand and gravel aggregates, which can reduce the weight of the high-strength masonry material and reduce the handling and transportation costs of the high-strength masonry material; further, the desulfurized ash is added to the aggregate as a powder material, which can fill the pores between the aggregates, improve the compactness of the masonry, reduce the porosity, and is beneficial to improving the compressive strength of the masonry material; in addition, the desulfurized ash contains a certain amount of calcium sulfite, and calcium sulfite is oxidized to form calcium sulfate with a certain amount of micro-expansion. The micro-expansion of the desulfurized ash is used to fill the pores between the aggregates and the volume remaining after the evaporation and drying of water in the high-strength masonry material, further increasing the compressive strength of the high-strength masonry material.

[0030] (2) For the high-strength masonry material based on desulfurized ash provided by the present invention, the masonry binder is composed of steel slag, slag, gypsum and quicklime. In the masonry binder, slag and steel slag can undergo a hydration reaction with calcium sulfate or calcium sulfite in the desulfurized ash to generate mineral components such as ettringite and monosulfate calcium sulfoaluminate. The needle-shaped ettringite and flaky monosulfate calcium sulfoaluminate are interspersed and filled into the pores between the aggregates, playing a filling role and increasing the strength of the masonry material.

[0031] (3) For the high-strength masonry material based on desulfurized ash provided by the present invention, the 3-day compressive strength is not less than 10 MPa, and the 14-day strength can reach more than 30 MPa, meeting the strength grade requirements of autoclaved lime-sand solid bricks MU30 in GB / T11945-2019 national standard.

[0032] (4) The preparation method of the high-strength masonry material based on desulfurized ash provided by the present invention has a simple preparation process and is easy to construct. Using desulfurized ash as the main raw material is of great significance for realizing resource utilization, reducing land occupation and reducing environmental pollution, and has broad prospects for popularization and application. Description of the Drawings

[0033] Figure 1 It is a schematic flow chart of a preparation method of a high-strength masonry material based on desulfurized ash provided by the present invention. Detailed Embodiments

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0035] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] The present invention will be further described below in conjunction with specific embodiments, but it is not a limitation of the present invention.

[0037] The main raw materials involved in the embodiments of the present invention and their weight parts are shown in Table 1 below.

[0038] Table 1

[0039]

[0040] In the above table, the density of the desulfurized ash is 550-900 kg / m 3 , in its composition, the proportion of calcium sulfate, calcium sulfite, calcium carbonate and calcium hydroxide is not less than 70 wt.%; the desulfurized ash is sieved, and its particle size <0.315 mm. The aggregate is a mixture of natural sand aggregate and artificial aggregate. Among them, the particle size of the first-class aggregate is 2-5 mm, and the particle size of the second-class aggregate is 1.25-2 mm. In the components of the masonry binder, steel slag, slag, gypsum and quicklime are mixed into powder through a ball mill system, so that the specific surface area of the obtained mixture is not less than 400 m 2 / kg. The water reducing agent is one of naphthalene-based high-efficiency water reducing agent, amino-based high-efficiency water reducing agent and polycarboxylate high-efficiency water reducing agent.

[0041] Example 1

[0042] This example provides a high-strength masonry material based on desulfurized ash, and its preparation method includes the following steps:

[0043] Step 1: By weight, add 30 parts of desulfurized ash and aggregate (17.5 parts of first-class aggregate and 52.5 parts of second-class aggregate) to a stirring system for uniform mixing to form a modified mixed aggregate, and the mixing and stirring time is 4 min;

[0044] Step 2: Add 8 parts of masonry binder (the mass ratio of steel slag, slag, gypsum and quicklime is 20:50:25:5) to the mixture in the stirring system, add 9 parts of water and a water reducing agent during the stirring process, and the addition amount of the water reducing agent is 2.5 wt.% of the masonry binder, and mix evenly to obtain a masonry cementitious material;

[0045] Step 3: Press the masonry cementitious material obtained in Step 2 into shape using a press, with a forming pressure of 20 MPa, to obtain a high-strength masonry material based on desulfurized ash.

[0046] Example 2

[0047] This example provides a high-strength masonry material based on desulfurized ash, and its preparation method includes the following steps:

[0048] Step 1: By weight, add 20 parts of desulfurized ash and aggregates (13.3 parts of primary aggregates and 66.7 parts of secondary aggregates) to a mixing system for uniform mixing to form a modified mixed aggregate, with a mixing time of 5 minutes;

[0049] Step 2: Add 11 parts of masonry binder (the mass ratio of steel slag, slag, gypsum and quicklime is 15:55:20:10) to the mixture in the mixing system, add 15 parts of water and a water reducer during the mixing process, and the addition amount of the water reducer is 0.8 wt.% of the masonry binder, and mix evenly to obtain a masonry cementitious material;

[0050] Step 3: Press the masonry cementitious material obtained in Step 2 into shape using a press, with a forming pressure of 25 MPa, to obtain a high-strength masonry material based on desulfurized ash.

[0051] Example 3

[0052] This example provides a high-strength masonry material based on desulfurized ash, and its preparation method includes the following steps:

[0053] Step 1: By weight, add 40 parts of desulfurized ash and aggregates (30 parts of primary aggregates and 30 parts of secondary aggregates) to a mixing system for uniform mixing to form a modified mixed aggregate, with a mixing time of 4 minutes;

[0054] Step 2: Add 10 parts of masonry binder (the mass ratio of steel slag, slag, gypsum and quicklime is 25:45:20:10) to the mixture in the mixing system, add 10 parts of water and a water reducer during the mixing process, and the addition amount of the water reducer is 1.5 wt.% of the masonry binder, and mix evenly to obtain a masonry cementitious material;

[0055] Step 3: Press the masonry cementitious material obtained in Step 2 into shape using a press, with a forming pressure of 18 MPa, to obtain a high-strength masonry material based on desulfurized ash.

[0056] Example 4

[0057] This example provides a high-strength masonry material based on desulfurized ash, and its preparation method includes the following steps:

[0058] Step 1: By weight, add 30 parts of desulfurized ash and aggregates (23.3 parts of primary aggregates and 46.7 parts of secondary aggregates) to the mixing system for uniform mixing to form modified mixed aggregates, with a mixing time of 4 min;

[0059] Step 2: Add 12 parts of masonry binder (the mass ratio of steel slag, slag, gypsum, and quicklime is 18:52:22:8) to the mixture in the mixing system, add 8 parts of water and a water reducing agent during the mixing process, and the addition amount of the water reducing agent is 3 wt.% of the masonry binder, and mix evenly to obtain masonry cementitious material;

[0060] Step 3: Press the masonry cementitious material obtained in Step 2 into shape using a press, with a forming pressure of 22 MPa, to obtain a high-strength masonry material based on desulfurized ash.

[0061] Example 5

[0062] This example provides a high-strength masonry material based on desulfurized ash. In Step 1 of its preparation method: By weight, add 30 parts of desulfurized ash and ungraded aggregates of 3 - 5 mm to the mixing system for uniform mixing, with a mixing time of 4 min. Other steps are the same as those in Example 4.

[0063] Example 6

[0064] This example provides a high-strength masonry material based on desulfurized ash. In Step 1 of its preparation method: By weight, add 30 parts of desulfurized ash and ungraded aggregates of 1 - 3 mm to the mixing system for uniform mixing, with a mixing time of 4 min. Other steps are the same as those in Example 4.

[0065] Example 7

[0066] This example provides a high-strength masonry material based on desulfurized ash. In Step 2 of its preparation method: Add 12 parts of cement to the mixture in the mixing system, add 8 parts of water and a water reducing agent during the mixing process, and the addition amount of the water reducing agent is 3 wt.% of the cement, and mix evenly to obtain masonry cementitious material. Other steps are the same as those in Example 4.

[0067] Performance test

[0068] The high-strength masonry materials prepared in Examples 1 - 7 are naturally cured at normal temperature and pressure until a certain age, and the compressive strength test is carried out. The relevant results are shown in Table 2 below:

[0069] Table 2

[0070]

[0071] As can be seen from the above table,

[0072] The high-strength masonry materials based on desulfurized ash prepared in Examples 1-7 have good mechanical properties. Their 3-day compressive strength is 7-18 MPa, 14-day compressive strength is 13-36 MPa, and 28-day compressive strength is 16-42 MPa. Compared with Examples 5-7, in Examples 1-4, graded aggregates and self-made masonry binders were used, and the prepared masonry materials have more excellent mechanical properties. Their 3-day compressive strength is 13-18 MPa, 14-day compressive strength is 31-36 MPa, and 28-day compressive strength can reach 35-42 MPa, meeting the strength grade requirements of autoclaved lime-sand solid bricks MU30 in GB / T11945-2019 national standard.

[0073] Furthermore, compared with the preparation methods of conventional high-strength masonry materials, the high-strength masonry materials provided by the present invention use desulfurized ash as the main raw material and do not require complex sintering or steam curing steps. The preparation process is simple, with low energy consumption, which is of great significance for realizing resource utilization, reducing land occupation, and reducing environmental pollution, and has broad promotion and application prospects.

[0074] The above are only the preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be realized that all the equivalent replacements and obvious changes made by using the content of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-strength masonry material based on desulfurized ash, characterized in that By weight parts, it includes the following components: 100 parts of modified mixed aggregate; 8 - 12 parts of masonry binder; 8 - 15 parts of water; and a water reducing agent accounting for 0.5wt.% - 3wt.% of the total weight of the masonry binder; The modified mixed aggregate is formed by mixing desulfurized ash and aggregate in a mass ratio of (2 - 4):(6 - 8); the aggregate is composed of primary aggregate and secondary aggregate in a mass ratio of 1:(1 - 5), the particle size range of the primary aggregate is 2 - 5mm, and the particle size range of the secondary aggregate is 1.25 - 2mm; the desulfurized ash is subjected to grinding and screening treatment, and its particle size is not greater than 0.315mm; In the masonry binder, the content of each component is by weight percentage: 15wt.% - 25wt.% of steel slag, 40wt.% - 55wt.% of slag, 10wt.% - 25wt.% of gypsum, 2wt.% - 10wt.% of quicklime.

2. The high-strength masonry material according to claim 1, characterized in that The aggregate includes natural sand and gravel aggregate and / or artificial aggregate.

3. The high-strength masonry material according to claim 1, characterized in that, The density of the desulfurized ash is 550~900 kg / m 3 ; in its composition, the proportion of calcium sulfate, calcium sulfite, calcium carbonate and calcium hydroxide is not less than 70 wt.%.

4. The high-strength masonry material according to claim 1, characterized in that, The water reducing agent is selected from one or a combination of naphthalene - based superplasticizer, amino - based superplasticizer, polycarboxylate superplasticizer.

5. A method for preparing a high-strength masonry material according to any one of claims 1-4, characterized in that, It includes the following steps: S1. Mix the desulfurized ash and the aggregate evenly to obtain the modified mixed aggregate; S2. Add the masonry binder, water and the water reducing agent to the modified mixed aggregate and mix evenly to obtain the masonry cementitious material; S3. Press - form the masonry cementitious material to obtain the high - strength masonry material.

6. The preparation method according to claim 5, characterized in that, In step S3, the pressure for press - forming is 10 - 25MPa.

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