High-performance lightweight aggregate for lightweight ultra-high performance concrete and method for preparing the same

Abstract

The application provides a high-performance light aggregate for light super high performance concrete and a preparation method thereof, the aggregate comprises the following components in percentage by weight: copper tailing slag 30-40%, lithium slag 25-35%, red mud 10-20%, pyrite cinder 5-15%, titanium ore slag 3-8%, calcium carbonate 1-3%, and magnesium carbonate 1-3%. The application further discloses a preparation method of the high-performance light aggregate for light super high performance concrete. The high-performance light aggregate is prepared by drying, uniformly mixing, grinding, granulating, aging, balling and high-temperature firing of industrial solid wastes, such as copper tailing slag, lithium slag, red mud, pyrite cinder and titanium ore slag, and calcium carbonate and magnesium carbonate, and is applied to light super high performance concrete, so that the strength, volume stability and durability of the light super high performance concrete are improved, and the preparation cost of the light super high performance concrete is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete, and particularly relates to a high-performance lightweight aggregate for lightweight ultra-high performance concrete and a preparation method thereof. BACKGROUND

[0002] Compared with conventional ultra-high performance concrete (UHPC), lightweight ultra-high performance concrete (LUHPC) uses lightweight aggregate as aggregate, which can reduce the self-weight of concrete structure by 20-30%, and due to the internal curing effect of water absorption and release of porous lightweight aggregate, the shrinkage rate is also greatly reduced, and the volume stability is greatly improved, but the strength and durability are also excellent. However, lightweight ultra-high performance concrete requires lightweight aggregate to have high cylinder compressive strength, low apparent density and bulk density, and high water absorption rate, and the commonly used lightweight aggregate ceramic sand is usually difficult to unify in these three aspects. Therefore, it is urgent to develop a high-performance lightweight aggregate for lightweight ultra-high performance concrete, which can further reduce the apparent density and shrinkage rate of concrete while ensuring its strength and improve its durability.

[0003] With the rapid industrialization development of China, the total amount of bulk solid waste is also increasing year by year, and there are more than ten kinds of solid waste with a cumulative accumulation of hundreds of millions of tons or annual emissions of hundreds of millions of tons, such as iron tailings slag, copper tailings slag, molybdenum tailings slag, lithium slag, pyrite cinder, red mud and the like. A large amount of industrial solid waste is accumulated or treated in the form of landfill, and the comprehensive utilization rate is low, and the potential value cannot be fully tapped, which causes long-term pollution to the soil and environment. If some solid waste with potential hydration characteristics is appropriately selected to prepare the high-performance lightweight aggregate required by LUHPC, the comprehensive performance of LUHPC can be further improved, the utilization rate of industrial solid waste can be greatly improved, the cost can be reduced, and the environment can be protected. SUMMARY

[0004] The present application provides a high-performance lightweight aggregate for lightweight ultra-high performance concrete and a preparation method thereof, which has good strength, volume stability and durability, and also reduces the preparation cost of LUHPC.

[0005] The technical scheme of the present application is a high-performance lightweight aggregate for lightweight ultra-high performance concrete, which comprises the following components in percentage by weight: copper tailings slag 30-40%, lithium slag 25-35%, red mud 10-20%, pyrite cinder 5-15%, titanium slag 3-8%, calcium carbonate 1-3%, and magnesium carbonate 1-3%.

[0006] Further, the copper tailings slag contains SiO2 70-75%, Al2O3 10-12%, Fe2O3 3-6%, CaO 2-4%, MgO 2-4%, K2O+Na2O 3-8%, CuO 0.1-0.3%, MnO 0.05-0.1%, and the rest is other impurities.

[0007] Further, the lithium residue has SiO2 content of 60-65%, Al2O3 content of 18-24%, Fe2O3 content of 0.5-1.0%, CaO content of 2-4%, MgO content of 0.2-0.4%, TiO2 content of 0.1-0.2%, and the rest is other impurities.

[0008] Further, the red mud has SiO2 content of 16-18%, Al2O3 content of 18-24%, Fe2O3 content of 18-24%, CaO content of 14-18%, MgO content of 1-3%, K2O+Na2O content of 1-3%, TiO2 content of 3-5%, and the rest is other impurities.

[0009] Further, the pyrite cinder has SiO2 content of 40-45%, Al2O3 content of 32-38%, Fe2O3 content of 6-9%, CaO content of 3-6%, MgO content of 0.1-0.3%, K2O+Na2O content of 0.3-0.5%, TiO2 content of 3-6%, and the rest is other impurities.

[0010] Further, the titanium ore slag has SiO2 content of 18-24%, Al2O3 content of 18-24%, CaO content of 22-28%, MgO content of 5-10%, Fe2O3 content of 3-6%, TiO2 content of 14-18%, and the rest is other impurities.

[0011] Further, the purity of the calcium carbonate and magnesium carbonate is ≥99.0%.

[0012] The application also relates to a preparation method of the high-performance lightweight aggregate, which comprises the following steps:

[0013] S1, drying raw materials to constant weight respectively, uniformly mixing according to the proportion, and ball milling into powder;

[0014] S2, performing aging treatment on the powder after adding water, and then preparing into spherical green bodies and drying;

[0015] S3, performing high-temperature firing on the spherical green bodies obtained in S2, respectively keeping at 250-350 DEG C, 550-650 DEG C and 850-950 DEG C for 0.6-1.5 h respectively and keeping at 1100-1300 DEG C for 1-3 h, and then cooling to room temperature, and sieving to obtain the high-performance lightweight aggregate for lightweight super-high-performance concrete.

[0016] Further, the powder is sieved through a 200-mesh sieve after ball milling in S1, and the undersize is taken; the water adding amount is 6-10% of the mass of the powder in S2, and the aging time is 24-36 h.

[0017] Further, in S3, the temperature rising rate is 3 DEG C / min and the temperature falling rate is 8 DEG C / min during high-temperature firing; and the spherical particles with a diameter of 0.15-4.75 mm are taken out after sieving.

[0018] The present application has the following advantages:

[0019] (1) Compared with the commonly used light aggregate ceramic sand, the high-performance light aggregate for light-weight ultra-high performance concrete has higher cylinder compressive strength, lower apparent density and bulk density, and higher water absorption, can further reduce the apparent density of the LUHPC, i.e. the self-weight of the concrete structure, and the 28d compressive strength, flexural strength and axial compressive strength are all greatly improved, and the 90d shrinkage rate is also greatly reduced, and the volume stability is better.

[0020] (2) The present application comprehensively utilizes the chemical properties of various industrial solid wastes, deeply studies the influence mechanism of main chemical components SiO2, Al2O3, Fe2O3, CaO, MgO, K2O+Na2O on the performance of light aggregate, and optimizes the component ratio and preparation method, thereby fundamentally solving the contradiction between the apparent density, bulk density, water absorption and cylinder compressive strength of the traditional light aggregate. The appropriate SiO2 and Al2O3 in the prepared light aggregate can promote the generation of more mullite, which is beneficial to improve the cylinder compressive strength of the light aggregate, and the contribution of SiO2 to the strength is greater than that of Al2O3; at the same time, appropriate amounts of SiO2, Al2O3, CaO and MgO are beneficial to the control of liquid phase viscosity and the formation of micro-connected pores during high-temperature firing, and when the content is too high, the liquid phase viscosity is too high, which is not conducive to the formation of micro-connected pores, and the water absorption of the light aggregate is reduced, and when the content is too low, the liquid phase viscosity is too low, and the expansion gas is easy to escape, and the water absorption of the light aggregate is increased; on the contrary, too high content of K2O+Na2O will significantly reduce the high-temperature liquid phase viscosity, which is not conducive to the expansion of the light aggregate and the formation of micro-connected pores, and too low content will increase the firing temperature, which is high in energy consumption; Fe2O3 is both a fluxing agent and a foaming agent, and O2 will be released at a high temperature above 1000 DEG C, but too high content will increase the firing temperature, which is high in energy consumption. Finally, the apparent density and bulk density are not only related to the chemical composition of the light aggregate, and the increase of the content of SiO2, Al2O3 and Fe2O3 is beneficial to the increase of the density of the light aggregate, and the increase of the content of CaO, MgO and K2O+Na2O will relatively reduce the density of the light aggregate, and at the same time, the density is also related to the porosity, and the more the porosity, the lower the density, the more the large connected pores, the lower the density, and the lower the strength, but the higher the water absorption, so it needs to be considered in balance.

[0021] (3) The high-performance light aggregate for light-weight ultra-high performance concrete of the present application uses a large amount of industrial solid waste as raw material, fully develops the potential value of the solid waste, greatly improves the comprehensive utilization rate, and is also conducive to reducing the cost of LUHPC and protecting the environment. Moreover, the preparation process is simple and easy to popularize. DETAILED DESCRIPTION

[0022] Embodiments of the present application will be described in detail below with reference to Examples, but those skilled in the art will understand that the following Examples are for illustrative purposes only and should not be construed as limiting the scope of the present application.

[0023] The raw materials involved in the following Examples and Comparative Examples were analyzed for their specific components as follows.

[0024] The main chemical components of copper tailings slag were SiO2 content of 72.39%, Al2O3 content of 11.62%, Fe2O3 content of 4.49%, CaO content of 2.81%, MgO content of 2.42%, K2O+Na2O content of 5.41%, CuO content of 0.14%, MnO content of 0.08%, and the rest were other impurities.

[0025] The main chemical components of lithium slag were SiO2 content of 63.20%, Al2O3 content of 21.00%, Fe2O3 content of 0.98%, CaO content of 3.32%, MgO content of 0.39%, TiO2 content of 0.15%, and the rest were other impurities.

[0026] The main chemical components of red mud were SiO2 content of 17.33%, Al2O3 content of 21.09%, Fe2O3 content of 21.93%, CaO content of 16.32%, MgO content of 1.89%, K2O+Na2O content of 2.67%, TiO2 content of 4.69%, and the rest were other impurities.

[0027] The main chemical components of pyrite cinder were SiO2 content of 43.65%, Al2O3 content of 35.50%, Fe2O3 content of 7.63%, CaO content of 4.73%, MgO content of 0.24%, K2O+Na2O content of 0.39%, TiO2 content of 4.43%, and the rest were other impurities.

[0028] The main chemical components of titanium slag were SiO2 content of 21.82%, Al2O3 content of 20.14%, CaO content of 25.56%, MgO content of 8.25%, Fe2O3 content of 4.05%, TiO2 content of 16.78%, and the rest were other impurities.

[0029] Calcium carbonate and magnesium carbonate were obtained from a commercial channel.

[0030] Example 1

[0031] The preparation method of the high-performance lightweight aggregate for lightweight ultra-high performance concrete provided in this example is as follows:

[0032] (1) The copper tailings slag, lithium slag, red mud, pyrite slag, titanium slag, calcium carbonate and magnesium carbonate were dried in an oven at 105℃ to constant weight.

[0033] (2) Add 30% copper tailings, 35% lithium slag, 20% red mud, 5% pyrite slag, 6% titanium slag, 2% calcium carbonate and 2% magnesium carbonate by weight percentage to the mixer and stir until evenly mixed.

[0034] (3) Add the mixed material to a ball mill for grinding. After grinding for 12 hours, pass the mixture through a 200-mesh sieve to obtain the mixed powder.

[0035] (4) Add 8% by mass of deionized water to the mixed powder for granulation and aging. After aging for 30 hours, use a pelletizing machine to form spherical blanks and dry them in an oven at 105℃ until constant weight.

[0036] (5) The dried spherical green bodies were placed in a muffle furnace for high-temperature firing, with a heating rate of 3℃ / min. The green bodies were held at 300℃, 600℃, and 900℃ for 1 hour each, and at 1200℃ for 2 hours. Finally, the cooling rate was controlled at 8℃ / min. After cooling to room temperature, spherical particles with a diameter of 0.15-4.75mm were screened out, which became the high-performance lightweight aggregate LA-1 for lightweight ultra-high-performance concrete. Its apparent density was measured to be 1329 kg / m³. 3 The bulk density is 708 kg / m³ 3 The water absorption rate is 16.78%, and the compressive strength of the cylinder is 6.65 MPa.

[0037] Example 2

[0038] The preparation method of high-performance lightweight aggregate for lightweight ultra-high performance concrete provided in this embodiment is as follows:

[0039] (1) The copper tailings slag, lithium slag, red mud, pyrite slag, titanium slag, calcium carbonate and magnesium carbonate were dried in an oven at 105℃ to constant weight.

[0040] (2) Add 32% copper tailings, 32% lithium slag, 18% red mud, 8% pyrite slag, 4% titanium slag, 3% calcium carbonate and 3% magnesium carbonate by weight percentage to the mixer and stir until evenly mixed.

[0041] (3) The uniformly mixed copper tailings slag, lithium slag, red mud, pyrite slag, titanium slag, calcium carbonate and magnesium carbonate are added to a ball mill for grinding. After grinding for 12 hours, the mixture is passed through a 200-mesh sieve to obtain mixed powder.

[0042] (4) Add 7% by mass of deionized water to the mixed powder for granulation and aging. After aging for 24 hours, use a pelletizing machine to form spherical blanks and put them into an oven at 105℃ to dry to constant weight.

[0043] (5) Put the dried spherical blank into the muffle furnace for high-temperature firing, control the heating rate to be 3℃ / min, and keep the temperature at 300℃, 600℃ and 900℃ for 1h respectively and at 1200℃ for 2h, finally control the cooling rate to be 8℃ / min, sieve out the spherical particles with a diameter of Φ0.15-4.75mm after cooling to room temperature, which are high-performance lightweight aggregates LA-2 for lightweight super high-performance concrete, and the apparent density thereof is measured to be 1332kg / m 3 , the bulk density is 714kg / m 3 , the water absorption is 16.65%, and the cylinder compressive strength is 6.71MPa.

[0044] Example 3

[0045] The preparation method of the high-performance lightweight aggregate for lightweight super high-performance concrete provided in the embodiment is as follows:

[0046] (1) Dry copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate respectively in a 105℃ oven to constant weight;

[0047] (2) Add the dried 35% copper tailings slag, 30% lithium slag, 15% red mud, 10% pyrite cinder, 5% titanium slag, 2.5% calcium carbonate and 2.5% magnesium carbonate by weight percentage into a mixer and stir to mix uniformly;

[0048] (3) Put the mixed copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate into a ball mill for grinding, and sieve out the mixed powder through a 200-mesh sieve after grinding for 14h;

[0049] (4) Add 8% deionized water by mass fraction to the mixed powder for granulation and aging, and use a ball making machine to make spherical blank after aging for 30h, and put the spherical blank into a 105℃ oven to dry to constant weight;

[0050] (5) Put the dried spherical blank into the muffle furnace for high-temperature firing, control the heating rate to be 3℃ / min, and keep the temperature at 300℃, 600℃ and 900℃ for 1h respectively and at 1200℃ for 2h, finally control the cooling rate to be 8℃ / min, sieve out the spherical particles with a diameter of Φ0.15-4.75mm after cooling to room temperature, which are high-performance lightweight aggregates LA-3 for lightweight super high-performance concrete, and the apparent density thereof is measured to be 1337kg / m 3 , the bulk density is 721kg / m 3 , the water absorption is 16.89%, and the cylinder compressive strength is 6.75MPa.

[0051] Example 4

[0052] The preparation method of the high-performance lightweight aggregate for lightweight ultra-high performance concrete provided in the embodiment is as follows:

[0053] (1) The copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were dried to constant weight in an oven at 105°C respectively;

[0054] (2) The dried copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were added into a mixer in percentages by weight, and stirred and mixed uniformly;

[0055] (3) The uniformly mixed copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were added into a ball mill for grinding, and the mixed powder was obtained by sieving through a 200-mesh screen after grinding for 12 hours;

[0056] (4) Deionized water in a mass fraction of 9% was added to the mixed powder for granulation and aging, and the spherical green body was prepared by a ball making machine after aging for 36 hours, and was placed into an oven at 105°C for drying to constant weight;

[0057] (5) The dried spherical green body was placed into a muffle furnace for high-temperature firing, the heating rate was controlled to be 3°C / min, and the temperature was kept at 300°C, 600°C and 900°C for 1 hour respectively and at 1200°C for 2 hours, and finally the cooling rate was controlled to be 8°C / min, and the spherical particles with a size of Φ0.15-4.75 mm were sieved out after cooling to room temperature, which were the high-performance lightweight aggregate LA-4 for lightweight ultra-high performance concrete, and the apparent density, the bulk density, the water absorption and the cylinder compressive strength thereof were measured to be 1334 kg / m 3 , 716 kg / m 3 , 16.96% and 6.72 MPa respectively.

[0058] Example 5

[0059] The preparation method of the high-performance lightweight aggregate for lightweight ultra-high performance concrete provided in the embodiment is as follows:

[0060] (1) The copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were dried to constant weight in an oven at 105°C respectively;

[0061] (2) The dried copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were added into a mixer in percentages by weight, and stirred and mixed uniformly;

[0062] (3) The uniformly mixed copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were added into a ball mill for grinding, and the mixed powder was obtained by sieving through a 200-mesh screen after grinding for 16 hours;

[0063] (4) Add 6% deionized water to the mixed powder by mass fraction to granulate and stale, and after 24h of stale, use a ball making machine to make spherical green bodies, and put them into an oven at 105℃ to dry to constant weight;

[0064] (5) Put the dried spherical green bodies into a muffle furnace for high-temperature firing, control the heating rate to be 3℃ / min, and keep the temperature at 300℃, 600℃ and 900℃ for 1h respectively and at 1200℃ for 2h, finally control the cooling rate to be 8℃ / min, and after cooling to room temperature, sieve out the spherical particles with a diameter of Φ0.15-4.75mm, which are high-performance lightweight aggregates LA-5 for lightweight super high performance concrete, and the apparent density is measured to be 1342kg / m 3 , the bulk density is 728kg / m 3 , the water absorption is 16.57%, and the cylinder compressive strength is 6.79MPa.

[0065] Example 6

[0066] The preparation method of the high-performance lightweight aggregate for lightweight super high performance concrete provided in this embodiment is as follows:

[0067] (1) Dry copper tailings, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate in a 105℃ oven to constant weight respectively;

[0068] (2) Add 37% dried copper tailings, 27% lithium slag, 12% red mud, 12% pyrite cinder, 8% titanium slag, 1% calcium carbonate and 3% magnesium carbonate by weight percentage into a mixer to mix and stir uniformly;

[0069] (3) Put the uniformly mixed copper tailings, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate into a ball mill for grinding, and after 14h of grinding, sieve out the mixed powder through a 200-mesh sieve;

[0070] (4) Add 10% deionized water to the mixed powder by mass fraction to granulate and stale, and after 36h of stale, use a ball making machine to make spherical green bodies, and put them into an oven at 105℃ to dry to constant weight;

[0071] (5) Put the dried spherical green bodies into a muffle furnace for high-temperature firing, control the heating rate to be 3℃ / min, and keep the temperature at 300℃, 600℃ and 900℃ for 1h respectively and at 1200℃ for 2h, finally control the cooling rate to be 8℃ / min, and after cooling to room temperature, sieve out the spherical particles with a diameter of Φ0.15-4.75mm, which are high-performance lightweight aggregates LA-6 for lightweight super high performance concrete, and the apparent density is measured to be 1340kg / m 3 , the bulk density is 725kg / m 3, a water absorption of 17.04%, and a cylinder compressive strength of 6.77 MPa.

[0072] Example 7

[0073] The preparation method of the high-performance lightweight aggregate for lightweight ultra-high performance concrete provided in this example is as follows:

[0074] (1) The copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate, and magnesium carbonate were dried to constant weight in an oven at 105°C, respectively;

[0075] (2) The dried 40% copper tailings slag, 25% lithium slag, 10% red mud, 15% pyrite cinder, 5% titanium slag, 2% calcium carbonate, and 3% magnesium carbonate were added to a mixer in a weight percentage and stirred and mixed uniformly;

[0076] (3) The uniformly mixed copper tailings slag, lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate, and magnesium carbonate were added to a ball mill for grinding. After grinding for 16 h, the mixed powder was sieved through a 200-m screen to obtain a mixed powder;

[0077] (4) Deionized water with a mass fraction of 7% was added to the mixed powder for granulation and aging. After aging for 24 h, a ball machine was used to form spherical green bodies, which were then placed in an oven at 105°C and dried to constant weight;

[0078] (5) The dried spherical green bodies were placed in a muffle furnace for high-temperature firing. The heating rate was controlled at 3°C / min, and the temperature was maintained at 300°C, 600°C, and 900°C for 1 h each and at 1200°C for 2 h. Finally, the cooling rate was controlled at 8°C / min. After cooling to room temperature, the spherical particles with a diameter of Φ0.15-4.75 mm were sieved out, which were the high-performance lightweight aggregate LA-7 for lightweight ultra-high performance concrete. The apparent density was measured to be 1349 kg / m 3 , the bulk density was 732 kg / m 3 , the water absorption was 16.70%, and the cylinder compressive strength was 6.83 MPa.

[0079] Comparative Example 1

[0080] Referring to the preparation method of Example 3, the difference is that copper tailings slag is not used. The specific preparation method is as follows:

[0081] (1) The lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate, and magnesium carbonate were dried to constant weight in an oven at 105°C, respectively;

[0082] (2) The dried 65% lithium slag, 15% red mud, 10% pyrite cinder, 5% titanium slag, 2.5% calcium carbonate, and 2.5% magnesium carbonate were added to a mixer in a weight percentage and stirred and mixed uniformly;

[0083] (3) The mixed lithium slag, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were added into a ball mill for grinding. After grinding for 14 h, the mixed powder was obtained by passing through a 200 mesh screen;

[0084] (4) Deionized water with a mass fraction of 8% was added to the mixed powder for granulation and aging. After aging for 30 h, the spherical green body was prepared by a ball making machine, and was placed into an oven at 105°C to dry to constant weight;

[0085] (5) The dried spherical green body was placed into a muffle furnace for high-temperature sintering. The heating rate was controlled at 3°C / min, and the temperature was kept at 300°C, 600°C and 900°C for 1 h respectively, and at 1200°C for 2 h. Finally, the cooling rate was controlled at 8°C / min. After cooling to room temperature, the spherical particles with a diameter of 0.15-4.75 mm were obtained by sieving, which were the lightweight aggregate. The apparent density was 1462 kg / m 3 , the bulk density was 789 kg / m 3 , the water absorption was 12.37%, and the cylinder compressive strength was 6.58 MPa.

[0086] Comparative Example 2

[0087] The preparation method of Reference Example 3 was referred, except that lithium slag was not used. The specific preparation method was as follows:

[0088] (1) The copper tailings, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were dried to constant weight in an oven at 105°C;

[0089] (2) The dried copper tailings, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were mixed in a mixer at a weight percentage of 65%, 15%, 10%, 5%, 2.5% and 2.5% respectively;

[0090] (3) The mixed copper tailings, red mud, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were added into a ball mill for grinding. After grinding for 14 h, the mixed powder was obtained by passing through a 200 mesh screen;

[0091] (4) Deionized water with a mass fraction of 8% was added to the mixed powder for granulation and aging. After aging for 30 h, the spherical green body was prepared by a ball making machine, and was placed into an oven at 105°C to dry to constant weight;

[0092] (5) The dried spherical green body was placed into a muffle furnace for high-temperature sintering. The heating rate was controlled at 3°C / min, and the temperature was kept at 300°C, 600°C and 900°C for 1 h respectively, and at 1200°C for 2 h. Finally, the cooling rate was controlled at 8°C / min. After cooling to room temperature, the spherical particles with a diameter of 0.15-4.75 mm were obtained by sieving, which were the lightweight aggregate. The apparent density was 1462 kg / m 3, the bulk density is 822 kg / m 3 , the water absorption is 10.54%, and the cylinder compressive strength is 6.83 MPa.

[0093] Comparative Example 3

[0094] The preparation method of Example 3 is referred to, except that red mud is not used, and the specific preparation method is as follows:

[0095] (1) Copper tailings slag, lithium slag, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were dried to constant weight in a 105°C oven, respectively;

[0096] (2) The dried 35% copper tailings slag, 30% lithium slag, 25% pyrite cinder, 5% titanium slag, 2.5% calcium carbonate and 2.5% magnesium carbonate were added to the mixer in percentage by weight and stirred and mixed uniformly;

[0097] (3) The uniformly mixed copper tailings slag, lithium slag, pyrite cinder, titanium slag, calcium carbonate and magnesium carbonate were added to the ball mill for grinding, and after grinding for 14 h, the mixed powder was obtained by passing through a 200 mesh sieve;

[0098] (4) 8% deionized water by mass fraction was added to the mixed powder for granulation and aging, and after aging for 30 h, the spherical green body was formed by using a ball making machine, and was placed in a 105°C oven for drying to constant weight;

[0099] (5) The dried spherical green body was placed in a muffle furnace for high temperature firing, the heating rate was controlled at 3°C / min, and the temperature was kept at 300°C, 600°C and 900°C for 1 h respectively and at 1200°C for 2 h, and finally the cooling rate was controlled at 8°C / min, and after cooling to room temperature, the spherical particles of Φ0.15-4.75 mm were selected by sieving, which were the lightweight aggregate, and the apparent density was measured to be 1554 kg / m 3 , the bulk density is 867 kg / m 3 , the water absorption is 6.95%, and the cylinder compressive strength is 7.32 MPa.

[0100] Comparative Example 4

[0101] The preparation method of Example 3 is referred to, except that pyrite cinder is not used, and the specific preparation method is as follows:

[0102] (1) Copper tailings slag, lithium slag, red mud, titanium slag, calcium carbonate and magnesium carbonate were dried to constant weight in a 105°C oven, respectively;

[0103] (2) The dried 35% copper tailings slag, 30% lithium slag, 25% red mud, 5% titanium slag, 2.5% calcium carbonate and 2.5% magnesium carbonate were added to the mixer in percentage by weight and stirred and mixed uniformly;

[0104] (3) The mixed copper tailings, lithium slag, red mud, titanium slag, calcium carbonate and magnesium carbonate are added into a ball mill for grinding. After grinding for 14 hours, the mixed powder is obtained by passing through a 200-mesh screen;

[0105] (4) 8% deionized water by mass fraction is added to the mixed powder for granulation and aging. After aging for 30 hours, the granulated body is made by a ball making machine, and is placed in an oven at 105°C to dry to constant weight;

[0106] (5) The dried granulated body is placed in a muffle furnace for high-temperature firing. The heating rate is controlled at 3°C / min, and the temperature is kept at 300°C, 600°C and 900°C for 1 hour respectively, and at 1200°C for 2 hours. Finally, the cooling rate is controlled at 8°C / min. After cooling to room temperature, the spherical particles with a diameter of 0.15-4.75 mm are screened out, which are the lightweight aggregate. The apparent density is measured to be 1281 kg / m 3 , the bulk density is 673 kg / m 3 , the water absorption is 21.76%, and the cylinder compressive strength is 5.28 MPa.

[0107] Comparative Example 5

[0108] The commercially available lightweight aggregate ceramic sand is measured to have an apparent density of 1487 kg / m 3 , a bulk density of 804 kg / m 3 , a water absorption of 8.16%, and a cylinder compressive strength of 6.19 MPa.

[0109] Implementation effect verification

[0110] The high-performance lightweight aggregate prepared in Examples 1-7 and Comparative Examples 1-5 are used for lightweight ultra-high performance concrete test. The mixing ratio of LUHPC used is: P.Ⅱ52.5 cement 700 kg / m 3 , silica fume 200 kg / m 3 , microbeads 150 kg / m 3 , lightweight aggregate 580 kg / m 3 , steel fiber 196 kg / m 3 , mixing water 176 kg / m 3 , water reducing agent 21 kg / m 3 .

[0111] Before the test, the lightweight aggregate is pre-wetted to saturation face dry, and the pre-wetting water of the lightweight aggregate is deducted from the mixing water when stirring to ensure that the water-cement ratio of the mixture is unchanged. The slump, spread and apparent density thereof are tested according to GB / T 50080-2016 Standard Test Methods for Properties of Fresh Ordinary Concrete, the 28d compressive, flexural and axial tensile strengths thereof are tested according to GB / T 50081-2019 Standard Test Methods for Mechanical Properties of Ordinary Concrete, and the 90d shrinkage thereof is tested according to GB / T 50082-2009 Standard Test Methods for Long-term Properties and Durability of Ordinary Concrete.

[0112] The specific test results are shown in Table 1.

[0113] Table 1

[0114]

[0115]

[0116] As can be seen from Table 1, compared with Comparative Examples 1-3, the high-performance lightweight aggregate prepared in Example 3 applied to lightweight ultra-high-performance concrete not only has good fluidity, low apparent density, but also has high 28d compressive, flexural and axial tensile strengths, and low shrinkage; compared with Comparative Example 4, although the apparent density and 90d shrinkage of Example 3 are higher, the workability, 28d compressive, flexural and axial tensile strengths are higher, which is more in line with the comprehensive performance requirements of lightweight ultra-high-performance concrete, such as large fluidity, lightweight, high strength and low shrinkage; compared with the commercially available lightweight aggregate ceramic sand of Comparative Example 5, the high-performance lightweight aggregate prepared in Examples 1-7 applied to lightweight ultra-high-performance concrete not only reduces the apparent density of the concrete, i.e. the structural self-weight, but also greatly improves the 28d compressive, flexural and axial tensile strengths, and greatly reduces the 90d shrinkage, and has better volume stability.

[0117] The above examples are only for illustrating the technical ideas and characteristics of the present application, and the content is only the preferred embodiments of the present application, but the protection scope of the present application is not limited to this. Within the technical scope disclosed in the present application, equivalent changes or improvements according to the technical solutions and inventive concept of the present application should be covered in the protection scope of the present application.

Claims

1. A high-performance lightweight aggregate for lightweight ultra-high-performance concrete, characterized in that, The composition comprises, by weight percentage: 30-40% copper tailings slag, 25-35% lithium slag, 10-20% red mud, 5-15% pyrite cinder, 3-8% titanium ore slag, 1-3% calcium carbonate, and 1-3% magnesium carbonate; wherein the pyrite cinder contains 40-45% SiO2, 32-38% Al2O3, 6-9% Fe2O3, 3-6% CaO, 0.1-0.3% MgO, 0.3-0.5% K2O+Na2O, and 3-6% TiO2, with the remainder being other impurities; wherein the copper tailings slag contains 70-75% SiO2, 10-12% Al2O3, 3-6% Fe2O3, 2-4% CaO, 2-4% MgO, 3-8% K2O+Na2O, 0.1-0.3% CuO, and 0.05-0.1% MnO. The lithium slag contains 60-65% SiO2, 18-24% Al2O3, 0.5-1.0% Fe2O3, 2-4% CaO, 0.2-0.4% MgO, and 0.1-0.2% TiO2, with the remainder being other impurities. The red mud contains 16-18% SiO2, 18-24% Al2O3, 18-24% Fe2O3, 14-18% CaO, 1-3% MgO, 1-3% K2O+Na2O, and 3-5% TiO2, with the remainder being other impurities. The titanium slag contains 18-24% SiO2, 18-24% Al2O3, 22-28% CaO, 5-10% MgO, 3-6% Fe2O3, and 14-18% TiO2, with the remainder being other impurities. The preparation of high-performance lightweight aggregates includes the following steps: S1. Dry the raw materials separately to constant weight, mix them evenly according to the ratio, and then ball mill them into powder; S2. The powder is aged with water, then formed into spherical blanks and dried. The spherical green bodies obtained from S3 and S2 are fired at high temperatures, and held at 250~350℃, 550~650℃ and 850~950℃ for 0.6~1.5h respectively, and then held at 1100~1300℃ for 1~3h. After cooling to room temperature, they are sieved to obtain high-performance lightweight aggregate for lightweight ultra-high performance concrete.

2. The high-performance lightweight aggregate according to claim 1, characterized in that: The purity of the calcium carbonate and magnesium carbonate is ≥99.0%.

3. The high-performance lightweight aggregate according to claim 1, characterized in that: In S1, the material is ball-milled and then passed through a 200-mesh sieve. The material passing through the sieve is collected. In S2, the amount of water added is 6-10% of the powder mass, and the aging time is 24-36 hours.

4. The high-performance lightweight aggregate according to claim 1, characterized in that: During high-temperature firing in S3, the heating rate is controlled at 3℃ / min and the cooling rate at 8℃ / min; spherical particles with a diameter of 0.15-4.75mm are taken during sieving.

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