A high-activity modified volcanic rock powder admixture and preparation method thereof

Abstract

The invention discloses a high-activity modified volcanic rock powder admixture and a preparation method thereof. The high-activity modified volcanic rock powder admixture is made of the following raw materials in parts by weight: 120-180 parts of volcanic rock powder, 20-40 parts of slag powder, 3-7 parts of quicklime powder, 5-18 parts of desulfurized gypsum, 3-5 parts of sulphoaluminate cement clinker and 0.4-1.2 parts of grinding aid. The invention compounds volcanic rock powder, slag powder, quicklime powder, desulfurized gypsum, sulphoaluminate cement clinker and grinding aid. Through modification, the activity index of the volcanic rock powder can be stably increased to more than 70%, and can reach more than 85% at most, which is better than the activity index of Class II fly ash for concrete. The modified volcanic rock powder can be used as a mixed material to be directly mixed with powder materials such as ground clinker, gypsum, etc. to prepare volcanic ash silicate cement, and can also completely replace the current Class II fly ash as an admixture for concrete preparation, and the effect reaches and is better than the effect of the original Class II fly ash.

Description

Technical Field

[0001] The invention relates to the technical field of cement-based material development, and in particular to a high-activity modified volcanic rock powder admixture and a preparation method thereof. Background Art

[0002] In the production of cement, a portion of original fly ash needs to be added as an admixture to adjust the cement grade and reduce manufacturing costs. In the process of concrete preparation, air-selected fly ash of grade II and above is often used as an admixture to reduce production costs, reduce the early hydration heat of cement, and improve durability. my country's thermal power companies have gradually reduced the use of coal fuel, resulting in an increasingly tight supply of fly ash. With the development of modern concrete technology, the role of fly ash has evolved from simple cost control to a key component for improving material performance, so there is an urgent need to find alternative materials for fly ash.

[0003] my country has a vast territory with rich volcanic rock resources and a large number of volcanic tailings. However, due to the low content of crystal minerals in these ores, their development and utilization value is limited. Currently, they are only used as filter materials in the field of water treatment. However, volcanic rocks undergo high-temperature melting and rapid cooling during the process of diagenesis, and the rock mass contains a certain amount of amorphous components, the main chemical components of which include SiO 2 、Al 2 O 3 and CaO, which are highly consistent with the main components of fly ash. Therefore, in theory, through scientific treatment processes, volcanic rock is expected to become an active material to replace fly ash in cement production and concrete preparation.

[0004] However, existing domestic and foreign studies have shown that the activity index of volcanic rock powder after conventional grinding is usually only between 40% and 50%, which is far below the standard required for industrial application. Using traditional activation methods, its activity improvement is still limited, and it is difficult to achieve effective replacement of fly ash. Therefore, developing more efficient modification and activation technologies to improve the activity of volcanic rock powder is of great significance for promoting its application in cement and concrete production. Summary of the invention

[0005] In view of the above-mentioned prior art, the purpose of the present invention is to provide a highly active modified volcanic rock powder admixture and a preparation method thereof. Through modification, the activity index of the volcanic rock powder can be stably increased to more than 70%, and can reach a maximum of more than 85%, which is better than the activity index of Class II fly ash for concrete. The modified volcanic rock powder can be used as a mixed material to be directly mixed with ground clinker, gypsum and other powder materials to prepare volcanic ash silicate cement, and can also completely replace the current Class II fly ash as an admixture for the preparation of concrete, and the effect is the same as and better than the original Class II fly ash.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a highly active modified volcanic rock powder admixture, which is made from the following raw materials in parts by weight: 120-180 parts of volcanic rock powder, 20-40 parts of slag powder, 3-7 parts of quicklime powder, 5-18 parts of desulfurized gypsum, 3-5 parts of sulphoaluminate cement clinker and 0.4-1.2 parts of grinding aid.

[0008] Preferably, the grinding aid is prepared by mixing sodium hexametaphosphate and sodium lactate in a mass ratio of (1-3): (1-3).

[0009] Preferably, the volcanic rock powder consists of the following chemical components in mass percentage:

[0010] SiO 2 35%~50%,Al 2 O 3 12%~18%, Fe 2 O 3 8%~12%, CaO 7%~13%, MgO 5%~7%, K 2 O 1%~3%, Na 2 O 2%~4%, SO 3 0%~1%, the balance is inevitable impurities.

[0011] Preferably, the slag powder is S95 grade slag powder with a specific surface area of ​​420-450m 2 / kg.

[0012] Preferably, the mass content of CaO in the quicklime powder is ≥90%, and the specific surface area is 300-330m 2 / kg.

[0013] As a preference, SO in the desulfurized gypsum 3 Mass content ≥35%, specific surface area 200~250m 2 / kg.

[0014] Preferably, the basicity coefficient of the sulphoaluminate cement clinker is 0.9-1.0, and the aluminum-sulfur ratio is 3.5-4.0.

[0015] The second aspect of the present invention provides a method for preparing the above-mentioned highly active modified volcanic rock powder admixture, comprising the following steps:

[0016] (1) drying the volcanic rock powder and adding a grinding aid to grind it to obtain ultrafine volcanic rock powder;

[0017] (2) mixing sulphoaluminate cement clinker and desulfurized gypsum accounting for 7.5% to 12.5% ​​of the mass of the sulphoaluminate cement clinker and grinding to obtain sulphoaluminate cement powder;

[0018] (3) The ultrafine volcanic rock powder, slag powder, quicklime powder, remaining desulfurized gypsum and sulphoaluminate cement powder are uniformly mixed to obtain a highly active modified volcanic rock powder admixture.

[0019] Preferably, in step (1), the drying temperature is 100-105°C, and the drying time is 30-45 min; the grinding speed is 45-55 r / min, and the grinding time is 50-60 min.

[0020] The third aspect of the present invention provides the use of the above-mentioned high-activity modified volcanic rock powder admixture in the preparation of cement or concrete.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention compounds volcanic rock powder, slag powder, quicklime powder, desulfurized gypsum, sulphoaluminate cement clinker and grinding aids. S95 grade slag powder is selected to participate in the secondary hydration of the modified volcanic rock powder and slowly release the active silicon and aluminum components required for the hydration of the modified volcanic rock powder; quicklime powder can stimulate the depolymerization of the glass structure in the slag powder and volcanic rock powder and provide the calcium components required for the hydration of the active silicon and aluminum components; desulfurized gypsum is an industrial byproduct and can provide the SO required in the hydration process of the modified volcanic rock powder. 4 2- ions, stimulating the active Al in volcanic rock powder 2 O 3 The dissolution and hydration of sulphoaluminate cement clinker can stimulate the depolymerization of the glass structure in slag powder and volcanic rock powder and provide the sulfur components required for the hydration of active aluminum phase components to form ettringite (AFt); sulphoaluminate cement clinker can quickly generate a large number of fine AFt grains in the early stage of hydration of cementitious materials, provide the crystal nuclei required for the hydration of volcanic rock powder in cementitious materials to form AFt, increase the expansion components in the hardened body of cementitious materials, and by adjusting the content of sulphoaluminate cement clinker, the shrinkage resistance of cementitious materials in the later stage of hydration can be accurately adjusted; in addition, grinding aids are added during the grinding process. Sodium hexametaphosphate plays a grinding aid role in the ultrafine grinding process of volcanic rocks, eliminates the agglomeration of ultrafine particles, and prevents sedimentation and water seepage in concrete mixtures, effectively improving the workability of the mixture; sodium lactate can stimulate the depolymerization and hydration of the silicon-aluminum network in the modifier slag powder and volcanic rocks during the hydration process of modified volcanic rock powder; the activity index of volcanic rock powder is significantly improved through the synergistic effect between the modifier and the grinding aid.

[0023] 2. Through modification, the activity index of volcanic rock powder can be stably increased to more than 70%, and can reach more than 85% at the highest, which is better than the activity index of Class II fly ash for concrete. The modified volcanic rock powder can be used as a mixed material to be directly mixed with powder materials such as ground clinker and gypsum to prepare volcanic ash silicate cement, and can also completely replace the current Class II fly ash as an admixture for concrete preparation, and the effect reaches and is better than the effect of the original Class II fly ash. The present invention solves the problem of shortage of fly ash for cement and concrete caused by the cancellation of coal burning in thermal power plants, and also solves the problem of shortage of active concrete admixtures in areas rich in volcanic rock resources, reduces carbon emissions in the cement concrete manufacturing process, and improves the performance of concrete. The P.P32.5 and P.P42.5 grade cements prepared by using the high-activity modified volcanic rock powder material of the present invention can meet the index requirements of the current national standards. The C30 and C50 concretes prepared by replacing Class II fly ash in the same proportion can reach and be better than the indexes of the fly ash reference sample in terms of mixing performance, mechanical properties and durability. Moreover, without adding an expansion agent, the characteristics of the modified volcanic rock powder admixture can significantly reduce the shrinkage rate of the hardened specimen and effectively improve the anti-cracking performance of the concrete material in the later stage of hydration. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 : XRD analysis of mineral composition of volcanic rocks. DETAILED DESCRIPTION

[0025] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0026] As mentioned in the background technology, the activity index of volcanic rock powder after conventional grinding is usually only between 40% and 50%, which is far below the standard required for industrial application. Using traditional activation methods, its activity improvement is still limited, making it difficult to effectively replace fly ash.

[0027] Based on this, the inventors used composite grinding aids and modifiers to mechanically activate and compositely modify volcanic rocks. Volcanic rocks are rich in silicon and aluminum components and have a high glass content. Theoretically, they should have high volcanic ash activity. However, the silicon and aluminum components in the volcanic ash need to consume a large amount of calcium and sulfur components to form hydration products C-(A)-SH and AFt during the hydration process. At the same time, the volcanic ash reaction process is a slow process and requires an alkaline excitation process. In addition, in the process of generating hydration products, the nucleation of hydration products requires a high energy barrier. When the number of nuclei in the system is small, it is difficult to overcome this barrier and a large number of nuclei will appear. Therefore, this study adds a small amount of sulfoaluminate cement clinker to provide the AFt nuclei required in the hydration process and accelerate the excitation and hydration process of the volcanic ash. The addition of slag powder is to supplement the active silicon and aluminum components in the early system. Combined with quicklime and gypsum, two activating materials, it provides AFt to the cement paste through hydration reaction, and also provides a large number of dispersed C-(A)-SH nuclei, which helps to generate hydration products from the oligomers released after the disintegration of the volcanic ash glass in the later stage of hydration, thereby improving the gelling activity of the modified volcanic rock powder hydration system.

[0028] The present invention uses a composite grinding aid and a modifier to compositely modify volcanic rock, so that the activity of low-activity volcanic rock is significantly improved. All activity indexes in the embodiments are greater than 70%, and the highest example sample MP2-3 has a 28d strength activity index of 87.5%, which can be used as an active admixture for cement production and concrete preparation. The modified high-activity volcanic rock powder can be used as an active admixture for cement production and concrete preparation, thereby solving the shortage of fly ash admixtures.

[0029] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0030] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0031] The volcanic rock powder used in the present invention is made by grinding volcanic rock by itself. The volcanic rock is purchased from Lingshou County Rongsheng Building Materials Co., Ltd., with a specification of 50-100 mm. From the XRD diagram of the volcanic rock, it can be seen that the main mineral components in the volcanic rock powder are potassium feldspar, sodium feldspar, dicalcium silicate and magnetite ( Figure 1 ).

[0032] The slag powder used in the present invention was purchased from Sanhe Tianlong New Building Materials Co., Ltd. and was S95 grade slag powder with a specific surface area of ​​420-450m 2 / kg.

[0033] The quicklime powder used in the present invention was purchased from Zibo Wanpu New Materials Co., Ltd. The model is C1 type quicklime, the mass content of CaO in the quicklime powder is ≥90%, and the specific surface area is 300~330m 2 / kg.

[0034] The desulfurized gypsum used in the present invention is purchased from Douhe Power Plant of Datang International Power Generation Co., Ltd. The model is secondary. 3 Mass content ≥35%, specific surface area 200~250m 2 / kg.

[0035] The sulphoaluminate cement clinker used in the present invention is purchased from Tangshan Polar Bear Building Materials Co., Ltd., with a basicity coefficient of 0.9-1.0 and an aluminum-sulfur ratio of 3.5-4.0.

[0036] Example 1: Preparation of highly active modified volcanic rock powder admixture:

[0037] (1) After drying the volcanic rock, a grinding aid of 0.3% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1; the drying temperature is 100°C and the drying time is 40 minutes;

[0038] The ultra-fine volcanic rock powder was obtained by grinding with a Ø500×500mm cement test mill for 52 minutes, with a specific surface area of ​​612m 2 / kg;

[0039] (2) mixing sulphoaluminate cement clinker and desulfurized gypsum in a mass ratio of 10:1 and grinding them to obtain sulphoaluminate cement powder;

[0040] (3) Ultrafine volcanic rock powder, slag powder, quicklime powder, desulfurized gypsum and sulphoaluminate cement powder were mixed uniformly in a mass ratio of 160:24:4:8:4 to obtain a highly active modified volcanic rock powder admixture, which was recorded as MP1-1.

[0041] Example 2: Preparation of highly active modified volcanic rock powder admixture:

[0042] (1) After drying the volcanic rock, a grinding aid of 0.3% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1; the drying temperature is 100°C and the drying time is 40 minutes;

[0043] The ultra-fine volcanic rock powder was obtained by grinding with a Ø500×500mm cement test mill for 52 minutes, with a specific surface area of ​​612m 2 / kg;

[0044] (2) mixing sulphoaluminate cement clinker and desulfurized gypsum in a mass ratio of 10:1 and grinding them to obtain sulphoaluminate cement powder;

[0045] (3) Ultrafine volcanic rock powder, slag powder, quicklime powder, desulfurized gypsum and sulphoaluminate cement powder were mixed uniformly in a mass ratio of 150:30:5:11:4 to obtain a highly active modified volcanic rock powder admixture, which was recorded as MP1-2.

[0046] Example 3: Preparation of highly active modified volcanic rock powder admixture:

[0047] (1) After drying the volcanic rock, a grinding aid of 0.3% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1; the drying temperature is 100°C and the drying time is 40 minutes;

[0048] The ultra-fine volcanic rock powder was obtained by grinding with a Ø500×500mm cement test mill for 52 minutes, with a specific surface area of ​​612m 2 / kg;

[0049] (2) mixing sulphoaluminate cement clinker and desulfurized gypsum in a mass ratio of 10:1 and grinding them to obtain sulphoaluminate cement powder;

[0050] (3) Ultrafine volcanic rock powder, slag powder, quicklime powder, desulfurized gypsum and sulphoaluminate cement powder were mixed uniformly in a mass ratio of 140:36:6:11:4 to obtain a highly active modified volcanic rock powder admixture, which was recorded as MP1-3.

[0051] Example 4: Preparation of highly active modified volcanic rock powder admixture:

[0052] (1) After drying the volcanic rock, a grinding aid of 0.5% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1; the drying temperature is 100°C and the drying time is 40 minutes;

[0053] The ultra-fine volcanic rock powder was obtained by grinding with a Ø500×500mm cement test mill for 70 minutes, with a specific surface area of ​​807m 2 / kg;

[0054] (2) mixing sulphoaluminate cement clinker and desulfurized gypsum in a mass ratio of 10:1 and grinding them to obtain sulphoaluminate cement powder;

[0055] (3) Ultrafine volcanic rock powder, slag powder, quicklime powder, desulfurized gypsum and sulphoaluminate cement powder were mixed uniformly in a mass ratio of 160:24:4:8:4 to obtain a highly active modified volcanic rock powder admixture, which was recorded as MP2-1.

[0056] Example 5: Preparation of Highly Active Modified Volcanic Rock Powder Admixture:

[0057] (1) After drying the volcanic rock, a grinding aid of 0.5% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1; the drying temperature is 100°C and the drying time is 40 minutes;

[0058] The ultra-fine volcanic rock powder was obtained by grinding with a Ø500×500mm cement test mill for 70 minutes, with a specific surface area of ​​807m 2 / kg;

[0059] (2) mixing sulphoaluminate cement clinker and desulfurized gypsum in a mass ratio of 10:1 and grinding them to obtain sulphoaluminate cement powder;

[0060] (3) Ultrafine volcanic rock powder, slag powder, quicklime powder, desulfurized gypsum and sulphoaluminate cement powder were mixed uniformly in a mass ratio of 150:30:5:11:4 to obtain a highly active modified volcanic rock powder admixture, which was recorded as MP2-2.

[0061] Example 6: Preparation of Highly Active Modified Volcanic Rock Powder Admixture:

[0062] (1) After drying the volcanic rock, a grinding aid of 0.5% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1; the drying temperature is 100°C and the drying time is 40 minutes;

[0063] The ultra-fine volcanic rock powder was obtained by grinding with a Ø500×500 cement test mill for 70 minutes, with a specific surface area of ​​807m 2 / kg;

[0064] (2) mixing sulphoaluminate cement clinker and desulfurized gypsum in a mass ratio of 10:1 and grinding them to obtain sulphoaluminate cement powder;

[0065] (3) Ultrafine volcanic rock powder, slag powder, quicklime powder, desulfurized gypsum and sulphoaluminate cement powder were mixed uniformly in a mass ratio of 140:36:6:11:4 to obtain a highly active modified volcanic rock powder admixture, which was recorded as MP2-3.

[0066] Comparative Example 1:

[0067] (1) The volcanic rock was dried and ground with a Ø500×500mm cement test mill for 70 minutes at a drying temperature of 100°C for 40 minutes to obtain a specific surface area of ​​668 m 2 / kg of volcanic rock powder, recorded as comparison sample C1.

[0068] Comparative Example 2:

[0069] (1) The volcanic rock was dried and ground with a Ø500×500mm cement test mill for 85 minutes at a drying temperature of 100°C for 40 minutes to obtain a specific surface area of ​​805 m 2 / kg of volcanic rock powder;

[0070] (2) mixing sulphoaluminate cement clinker and desulfurized gypsum in a mass ratio of 10:1 and grinding them to obtain sulphoaluminate cement powder;

[0071] (3) Volcanic rock powder, slag powder, quicklime powder, desulfurized gypsum and sulphoaluminate cement powder were mixed evenly in a mass ratio of 140:36:6:11:4 to obtain a modified volcanic rock powder admixture, which was recorded as reference sample C2.

[0072] The difference between this comparative example and Example 6 is that no grinding aid is added, and the specific surface area of ​​the volcanic rock powder is kept consistent by increasing the grinding time.

[0073] Comparative Example 3:

[0074] (1) After drying the volcanic rock, a grinding aid of 0.5% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1; the drying temperature is 100°C and the drying time is 40 minutes;

[0075] Grind with Ø500×500 cement test mill for 70 min to obtain a specific surface area of ​​807m 2 / kg of modified volcanic rock powder, recorded as comparison sample C3.

[0076] The difference between this comparative example and Example 6 is that no modifier (slag powder, quicklime powder, desulfurized gypsum and sulphoaluminate cement powder) is added.

[0077] Comparative Example 4:

[0078] (1) After drying the volcanic rock, a grinding aid of 0.5% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1; the drying temperature is 100°C and the drying time is 40 minutes;

[0079] Grind with Ø500×500 cement test mill for 70 min to obtain a specific surface area of ​​807m 2 / kg of modified volcanic rock powder, recorded as comparison sample C3.

[0080] (2) Ultrafine volcanic rock powder, slag powder and desulfurized gypsum were mixed evenly in a mass ratio of 140:36:11 to obtain a comparative sample C4.

[0081] The difference between this comparative example and Example 6 is that sulphoaluminate cement powder and quicklime powder are omitted in the modifier.

[0082] Comparative Example 5:

[0083] (1) After drying the volcanic rock, a grinding aid of 0.5% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1; the drying temperature is 100°C and the drying time is 40 minutes;

[0084] The ultra-fine volcanic rock powder was obtained by grinding with a Ø500×500 cement test mill for 70 minutes, with a specific surface area of ​​807m 2 / kg;

[0085] (2) Ultrafine volcanic rock powder, slag powder, quicklime powder and desulfurized gypsum were mixed evenly in a mass ratio of 140:36:6:11 to obtain a highly active modified volcanic rock powder admixture, which was recorded as comparison sample C5.

[0086] The difference between this comparative example and Example 6 is that the sulphoaluminate cement powder is omitted.

[0087] Comparative Example 6:

[0088] (1) After drying the volcanic rock, a grinding aid of 0.5% by weight of the volcanic rock is added, wherein the grinding aid is a mixture of sodium hexametaphosphate and sodium lactate in a mass ratio of 1:1;

[0089] The ultra-fine volcanic rock powder was obtained by grinding with a Ø500×500 cement test mill for 70 minutes, with a specific surface area of ​​807m 2 / kg;

[0090] (2) mixing sulphoaluminate cement clinker and desulfurized gypsum in a mass ratio of 10:1 and grinding them to obtain sulphoaluminate cement powder;

[0091] (3) Ultrafine volcanic rock powder, slag powder, desulfurized gypsum and sulphoaluminate cement powder were mixed uniformly in a mass ratio of 140:36:11:4 to obtain a comparative sample C6.

[0092] The difference between this comparative example and Example 6 is that quicklime powder is omitted.

[0093] Test Example 1:

[0094] The activity indexes of the highly active modified volcanic rock powder admixtures prepared in Examples 1-6 and the modified volcanic rock powders prepared in Comparative Examples 1-6 were measured.

[0095] Test method:

[0096] (1) Preparation of reference samples:

[0097] Take 4750 g of Portland cement clinker and 250 g of desulfurized gypsum and grind them with a Ø500×500 cement test mill for 30 min to obtain a specific surface area of ​​350±15m 2 / kg of benchmark sample B1.

[0098] (2) According to the standard "Test method for strength of cement mortar (ISO method)" (GB / T 17671-2020), the prepared reference sample B1 was used to prepare mortar strength specimens. After 24 hours, the specimens were demolded and cured under standard curing conditions (20±2℃, 95%±5% relative humidity). The compressive strength at 3d and 28d was measured as the benchmark strength value for calculating the activity index of volcanic rock powder.

[0099] (3) According to the standard "Test Method for Activity of Industrial Waste Slag for Cement Admixture" (GB / T 12957-2005), the high-activity modified volcanic rock powder admixture prepared in Examples 1-6 and the modified volcanic rock powder prepared in Comparative Examples 1-5 were uniformly mixed with the reference sample B1 at a mass ratio of 3:7 to prepare mortar strength test specimens, which were demoulded after curing for 24 hours and continued to be cured under standard curing conditions (20±2°C, 95%±5% relative humidity). The compressive strength at 3d and 28d was measured, and the activity index of the high-activity modified volcanic rock powder admixture prepared in Examples 1-6 and the modified volcanic rock powder prepared in Comparative Examples 1-6 was calculated using the 28d compressive strength of the reference sample B1 as the reference value. The test results are shown in Table 1.

[0100] Table 1 Activity test intensity values ​​and activity index of each sample

[0101]

[0102] As shown in Table 1, in Examples 1-3 of the present invention, 0.3% of the mass of the volcanic rock powder was added to the volcanic rock powder by grinding aid and the mixture was ground for 52 min. The specific surface areas of the prepared high-activity modified volcanic rock powder admixtures MP1-1, MP1-2 and MP1-3 were all 612 m 2 / kg, the activities were 71.6%, 74.3% and 78.2% respectively; Example 4-6: 0.5% of the mass of volcanic rock powder was added to the volcanic rock powder and ground for 70 minutes. The specific surface area of ​​the prepared high-activity modified volcanic rock powder admixture was 807m 2 / kg, the activity index of the modified volcanic rock powder was further improved. The activity indexes of the prepared high-activity modified volcanic rock powder admixtures MP2-1, MP2-2 and MP2-3 were 76.8%, 81.8% and 87.5%, respectively.

[0103] In Comparative Example 1, conventional grinding was performed without adding grinding aids and any modifiers, and the activity index of the prepared volcanic rock powder comparative sample C1 was only 47.4%; in Comparative Example 2, the grinding time of the volcanic rock powder was extended to 85 minutes without adding grinding aids, and the grinding time was extended by 21.4%, and the specific surface area of ​​the fineness similar to that of Example 6 was obtained. Then, by adding all the modifiers, the activity index of the volcanic rock powder was increased to 68%, and the activity index was increased by 20.6% compared with C1; in Comparative Example 3, the volcanic rock was ground for 70 minutes with the addition of grinding aids, and the specific surface area was 807m 2 / kg of ground volcanic rock powder, without adding other modifiers, its activity index reached 54.6%, compared with C1, the grinding efficiency was increased by 20.8%, and the activity index was increased by 7.2%; Comparative Example 4 ground volcanic rock for 70 minutes under the condition of adding grinding aids, and obtained a specific surface area of ​​807m 2 / kg of ground volcanic rock powder, when other modifiers without quicklime and sulphoaluminate cement powder were added, its activity index reached 65.6%, which was 18.2% higher than that of C1, but 21.9% lower than that of Example 6; Comparative Example 5 added quicklime powder on the basis of Comparative Example 4, and its activity index reached 67.1%, which was 1.5% higher than that of C4; Comparative Example 6 added sulphoaluminate cement powder on the basis of Comparative Example 4, and its activity index reached 69.3%, which was 3.7% higher than that of C4; Example 6 added quicklime and sulphoaluminate cement powder on the basis of Comparative Example 4, and its activity index reached 87.5%, which was 21.9% higher than that of C4; By comparison, it can be seen that on the basis of Comparative Sample C4, the activities of Comparative Samples C5 and C6 increased by 1.5% and 3.7% respectively, totaling 5.2%. In Example 6, in which quicklime powder and sulphoaluminate cement powder were added to the comparative sample C4, the activity was increased by 21.9% compared with the comparative sample, indicating that there was a significant synergistic effect between quicklime powder and sulphoaluminate cement powder.

[0104] Test Example 2: Effect of Highly Active Modified Volcanic Rock Powder Admixture on Concrete Performance and Mechanical Strength

[0105] In order to further evaluate the effect of modified ground volcanic rock powder as an admixture on the performance and mechanical strength of concrete, the high-activity modified volcanic rock powder admixture prepared in Example 6 was used to replace Class II fly ash in the same proportion to prepare C30 and C50 concretes. The mixing performance and mechanical properties of the concretes were tested and the test results are shown in Tables 2 to 5.

[0106] Table 2 Proportion scheme of C30 concrete prepared by replacing fly ash with modified volcanic rock powder

[0107]

[0108] Table 3 Proportion scheme of C50 concrete prepared by replacing fly ash with modified volcanic rock powder

[0109]

[0110] Table 4 Performance and strength results of C30 concrete mixture prepared by replacing fly ash with modified volcanic rock powder

[0111]

[0112] Table 5 Performance and strength results of C50 concrete mixture prepared by replacing fly ash with modified volcanic rock powder

[0113]

[0114] It can be seen from the test results in Tables 2 to 5 that the mixing performance and mechanical properties of C30 and C50 concrete prepared by replacing Class II fly ash with modified ground volcanic rock powder in the same proportion can reach and exceed the indicators of the fly ash reference sample.

[0115] In order to explore the influence of modified volcanic rock powder on the cracking performance of concrete materials, the relatively moderate SF3002 and SP3002 in the C30 concrete mix ratio in the previous table and the relatively moderate SF5002 and SP5002 pure paste ratio in the C50 concrete mix ratio were selected, and they were numbered SFJ3002, SPJ3002, SFJ5002 and SPJ5002 respectively. The cracking performance was evaluated using a square and round cracking mold. The test results are shown in Table 6.

[0116] Table 6 Cracking test results of modified volcanic rock powder replacing fly ash paste

[0117]

[0118] It can be seen from the test results in Table 6 that, without adding an expansion agent, the shrinkage rate of concrete can be significantly reduced by adding modified volcanic rock powder as an admixture, effectively improving the anti-cracking performance of concrete materials in the later stage of hydration.

[0119] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A highly active modified volcanic rock powder admixture, characterized in that: The method is prepared from the following raw materials in parts by weight: 120-180 parts of volcanic rock powder, 20-40 parts of slag powder, 3-7 parts of quicklime powder, 5-18 parts of desulfurized gypsum, 3-5 parts of sulphoaluminate cement clinker and 0.4-1.2 parts of grinding aid; The grinding aid is prepared by mixing sodium hexametaphosphate and sodium lactate in a mass ratio of (1-3): (1-3); The volcanic rock powder has the following chemical components in mass percentage: composition: SiO2 35%~50%, Al2O3 12%~18%, Fe2O3 8%~12%, CaO 7%~13%, MgO 5%~7%, K2O 1%~3%, Na2O2%~4%, SO3 0%~1%, and the balance are inevitable impurities.

2. The highly active modified volcanic rock powder admixture according to claim 1, characterized in that: The slag powder is S95 grade slag powder with a specific surface area of ​​420~450m 2 / kg.

3. The highly active modified volcanic rock powder admixture according to claim 1, characterized in that: The mass content of CaO in the quicklime powder is ≥90%, and the specific surface area is 300~330m 2 / kg; the SO3 mass content in the desulfurized gypsum is ≥35%, and the specific surface area is 200~250m 2 / kg.

4. The highly active modified volcanic rock powder admixture according to claim 1, characterized in that: The basicity coefficient of the sulphoaluminate cement clinker is 0.9-1.0, and the aluminum-sulfur ratio is 3.5-4.

0.

5. The method for preparing the highly active modified volcanic rock powder admixture according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) drying the volcanic rock powder and adding a grinding aid to grind it to obtain ultrafine volcanic rock powder; (2) mixing sulphoaluminate cement clinker and desulfurized gypsum accounting for 7.5% to 12.5% ​​of the mass of the sulphoaluminate cement clinker and grinding to obtain sulphoaluminate cement powder; (3) The ultrafine volcanic rock powder, slag powder, quicklime powder, remaining desulfurized gypsum and sulphoaluminate cement powder are uniformly mixed to obtain a highly active modified volcanic rock powder admixture.

6. The preparation method according to claim 5, characterized in that: In step (1), the drying temperature is 100-105°C and the drying time is 30-45 minutes.

7. The preparation method according to claim 5, characterized in that: In step (1), the grinding speed is 45 to 55 r / min, and the grinding time is 50 to 60 min.

8. Use of the highly active modified volcanic rock powder admixture according to any one of claims 1 to 4 in the preparation of cement or concrete.

Images