CN106186930A - Haydite manganese carbonate mine tailing concrete and preparation method thereof - Google Patents

Abstract

The invention discloses a ceramsite manganese carbonate tailings concrete and a preparation method thereof. The ceramsite manganese carbonate tailings concrete includes water, cement, ceramsite, manganese carbonate tailings and natural river sand. In terms of mass ratio, water:cement : Ceramsite: Manganese carbonate tailings: Natural river sand = 1: 1.78～2.01: 0.50～1.32: 1.70～3.53: 3.12～3.52. The present invention combines the current situation of tailings produced by manganese ore with characteristics in Guangxi. In addition to cement and water, ceramsite and manganese carbonate tailings are used as coarse aggregates, and natural sand is used as fine aggregates to make ceramsite manganese carbonate tailings concrete. The use of industrial waste in the field of construction realizes the recycling of resources and ensures the required strength of masonry structures. The concrete of the invention is environmentally friendly, light in weight, and has good thermal insulation performance, can save energy in building structures, effectively reduce building loads, improve the thermal insulation performance of building walls, and improve the comfort of living rooms.

Description

Ceramsite manganese carbonate tailings concrete and preparation method thereof

technical field

The invention belongs to the technical field of building materials, and in particular relates to a ceramsite manganese carbonate tailings concrete and a preparation method thereof.

Background technique

With the comprehensive and rapid development of the political economy, my country's construction industry is also moving forward with a momentum that cannot be underestimated, which has caused the use of natural aggregates to increase year by year. In the past, a large number of clay bricks were used in walls, causing serious damage to the land. , the relevant departments have issued relevant regulations prohibiting the use of clay bricks, but the extensive use of non-renewable raw materials cannot solve the problems faced in the implementation of sustainable development strategies after all, which forces the public to turn their attention to the recycling of resources. Since the reform and opening up, the use of cement and aggregate in my country has increased by 21.45 times and 15.6 times respectively. According to relevant reports, high-quality natural aggregates are close to depletion in some areas. In order to meet the demand for construction gravel, many mountains have been destroyed. From large-scale mining to severe damage to the ecological environment, how to deal with resource shortages and continue to implement sustainable development strategies will become the focus of today's world. From the perspective of recycling resources, saving natural aggregates, and promoting the coordinated development of the ecological environment, it is of great practical significance to study and utilize industrial waste instead of natural gravel to turn waste into treasure.

With the rapid development of economy and technology, the pace of human exploration of high-rise and super-high-rise has never slowed down, and the height of skyscrapers has been constantly refreshed. If these buildings all use light aggregate hollow blocks as non-load-bearing structures, this will help reduce the building's self-weight , It will be of great significance to reduce the requirements on the bearing capacity of the foundation, reduce the production cost, and optimize the structural design. Lightweight wall panels account for a considerable proportion of the use of wall materials in foreign buildings, of which 64% are in Japan, 42% in the United States, 49% in Poland, 47% in Germany, and only 26% in my country, which is much lower than other countries. nation. The hollow block made of ceramsite and manganese carbonate tailings as coarse aggregate has the light weight and low cost of lightweight aggregate concrete, and also has good thermal insulation performance, which responds to a certain extent for energy saving and reduction. platoon call.

Many developed countries, due to the shortage of minerals or the needs of national strategies, have set their sights on lower-grade manganese ore. By combining advanced technology with actual production, the recycling and reuse of manganese carbonate tailings is no longer a Utopian talk, by strictly controlling costs and maximizing benefits, a large-scale production line has been formed, but in our country, work in this area is still quite lacking.

my country is one of the countries rich in manganese ore. The reserves of manganese ore rank among the top in the world. It has been proven to be about 6.4 tons, ranking fourth in the world after South Africa, Ukraine and Gabon. The distribution of manganese ore in China is very uneven, mainly concentrated in Yunnan, Sichuan, Hunan, Hubei, Guangxi and other provinces (autonomous regions), of which Guangxi accounts for about 38.6%, Hunan accounts for about 18.5%, and Guizhou accounts for about 13.1%. Although there are many reserves of manganese ore resources in my country, the proportion of high-grade manganese ore is relatively small, mainly showing the characteristics of poor, fine and miscellaneous. The average grade of manganese ore is about 22%. There are almost no international commodity-grade rich ores in China. It also only accounts for 6.4% of the national reserves. At present, high-grade manganese ore is mostly used in domestic manganese smelting, while low-grade manganese ore can only be discarded as tailings because it does not meet the requirements. Due to immature technology and high cost, low-grade manganese ore can only be piled up for storage temporarily For future needs. Although this issue has attracted the attention of many scholars, due to technical problems and the cost of putting into production, the utilization of manganese carbonate tailings is still very small. The current application is mainly for recovery and purification, including the use of relevant chemical methods to convert low-grade manganese ore. Precipitation of metal manganese and preparation of potassium manganate, but no related application of manganese carbonate tailings has been found in the construction field. According to investigations, with the accumulation of time, low-grade manganese ore has piled up into mountains, which will inevitably bring about cost and safety issues. Therefore, effective use of low-grade manganese ore will avoid waste of resources and ease the pressure on land and safety management.

With the rapid development of civil engineering, the proportion of building energy consumption in the total energy consumption of society is increasing. According to statistics, the heating energy consumption per unit building area in my country is equivalent to 3 to 4 times that of developed countries under the same climate conditions. , Rational use of resources, reduction of energy consumption for heating and heating, and improvement of energy-saving technology for building exterior walls will become important goals of building energy conservation in my country.

For this reason, many scholars have carried out relevant research on building exterior wall materials. Jiang Zhiping, Zhang Maoliang, etc. found through the research on ceramsite concrete lightweight self-insulating blocks that the compressive strength of the hollow blocks of the new material reached MU5. Building energy-saving requirements; for small hollow blocks, the porosity is closely related to the use and performance of materials. Therefore, Teng Chao, Yang Qi, Peng Hong, etc. used the limited solvent method to study the coupled heat transfer process of hollow blocks Through simulation, the effects of ceramsite concrete porosity, shape of holes, number of rows of holes and staggered holes on the thermal resistance of hollow blocks are analyzed, and a method for optimizing the structure of holes is proposed. The "Code for Thermal Engineering Design of Civil Buildings" only involves the thermal calculation parameters of a single material, while the relevant thermal calculation parameters for multi-row concrete hollow blocks of composite materials are blank. According to the method, the composite material is divided into a single material, and the relevant thermal performance parameters of the multi-row hole hollow block are calculated, which provides a certain degree of reference for the future design of this new material.

In order to pursue the lower heat transfer coefficient of lightweight aggregate concrete and achieve better thermal insulation performance, many scholars will add lighter materials to ceramsite concrete, such as Wang Qingxuan, Shi Yunxing, Qu Tiejun and others in ceramsite concrete. Foam was added to the model, and by comparing the calculated value with the actual value, it was found that the two are relatively consistent, with a difference of only 2.1%, which proves that the thermal insulation performance of the new material is significantly better than that of the traditional material, and the thermal resistance considering the geometric correction factor is also given. Calculation formula, which refers to the condition of composite flat walls, and considers the multi-dimensionality of the heat transfer effect of blocks; Wang Jinyan used recycled aggregates instead of natural aggregates to study the performance of ceramsite concrete and its hollow block masonry , the hollow blocks with recycled aggregate replacement rate of 70% and 100% meet the building energy-saving requirements of heat transfer coefficient K≤1.5W/(m ² ·k), D≥3.0, and can be classified as self-insulation materials; Wang Wenjie in Polyphenylene particles and regenerated sand were added to the ceramsite concrete, and it was made into a hollow block. The mechanical properties and thermal insulation properties of the material were studied, and good results were obtained.

A new type of concrete is developed by using lightweight and environmentally friendly ceramsite and manganese carbonate tailings coarse aggregate, and it is made into a new type of hollow block with low apparent density and good thermal insulation performance, which is in line with my country's building energy saving and wall requirements The relevant regulations of the Office of Material Reform conform to the current trend of green buildings. Manganese carbonate tailings are the industrial waste residue left after manganese carbonate smelting. The tailings are used in the construction field to replace natural gravel as coarse aggregate, which achieves the purpose of protecting the mountain, saving natural resources and resource recycling. Sustainable Development Strategy.

Contents of the invention

In view of this, the present invention aims to solve the problems that the demand for concrete is constantly increasing, and the existing industrial waste residues are difficult to handle, difficult to recycle, and pollute the environment. A ceramsite manganese carbonate tailings concrete and a preparation method thereof are provided.

In order to solve the above technical problems, the present invention discloses a ceramsite manganese carbonate tailings concrete, including water, cement, ceramsite, manganese carbonate tailings and natural river sand, in terms of mass ratio, water: cement: ceramsite: carbonic acid Manganese tailings: natural river sand = 1: 1.78-2.01: 0.50-1.32: 1.70-3.53: 3.12-3.52.

Preferably, the ceramsite manganese carbonate tailings concrete has a mass ratio of water: cement: ceramsite: manganese carbonate tailings: natural river sand=1:1.89:0.89:2.67:3.31.

The invention also discloses a preparation method of the above-mentioned ceramsite manganese carbonate tailings concrete, comprising the following steps:

(1) Pre-wetting of ceramsite: sieve ceramsite by particle size, clean surface impurities, dry, soak for 24 hours, then spread out ceramsite and air-dry naturally until there is no obvious flowing water on the surface;

(2) Mixing: Mix the pre-wetted ceramsite with one-half of the cement and stir for 30 seconds, so that the surface of the ceramsite absorbs enough cement, and then evenly infiltrate one-half of the water, stirring for one minute, so that the cement water The surface of the ceramsite is evenly covered with cement mortar. During this process, pay attention to keep the mixer rotating in the same direction at all times, and do not reverse it, otherwise the phenomenon of ceramsite breakage will be increased;

Then pour manganese carbonate tailings, natural river sand and another 1/2 cement, stir for 30 seconds, then add the remaining 1/2 water and stir for 2 minutes to obtain a concrete mixture;

(3) Forming: the concrete mixture is injected into a mold;

(4) Curing: Moisture-retaining curing is carried out to the formed concrete.

Further, the forming step adopts the method of secondary mold loading, which specifically includes:

(1) Install the mold for the first time, fill the concrete mixture to two-thirds of the height of the mold, vibrate for 5 seconds, insert and pound with a trowel along the periphery of the mold, so that there is no honeycomb pockmark around the test piece Condition, to ensure that the junction of the mixture and the mold is dense;

(2) Install the mold for the second time, make the concrete mixture higher than the mold, vibrate for 5 seconds, smooth the upper surface of the mold with a trowel, and apply a little pressure so that the protruding ceramsite does not exceed the height of the mold ;

(3) 1 hour after the mold is installed, use a trowel to wipe back and forth to further make the protruding ceramsite not higher than the height of the test mold, so that the surface of the trowel is smooth and smooth.

Further, the maintenance step specifically includes: using natural maintenance, watering after 5-6 hours of molding, watering once every 6 hours, when the temperature is higher than 20°C, covering the surface of the block with a plastic film for heat preservation and moisturizing treatment .

Further, in the mixing step, in terms of mass ratio, water: cement: ceramsite: manganese carbonate tailings: natural river sand=1:1.89:0.89:2.67:3.31.

Compared with prior art, the present invention can obtain and comprise following technical effect:

1) The present invention combines the current situation of Guangxi characteristic manganese ore tailings production. In addition to the cement and water components used in traditional concrete, ceramsite and manganese carbonate tailings are used as coarse aggregates, and natural sand is used as fine aggregates. The ceramsite manganese carbonate tailings concrete can use regional industrial waste in the construction field, and realize the recycling of resources, and this kind of ceramsite manganese carbonate tailings concrete can ensure the required strength of the masonry structure.

2) The ceramsite manganese carbonate tailings concrete of the present invention is environmentally friendly and light in weight, has good thermal insulation performance, can save energy in building structures, effectively reduce building loads, improve the thermal insulation performance of building walls, and improve Room comfort. It will have a place in the field of green buildings, meet the requirements of "environmental protection and energy saving" in the field of construction, and have good economic and social benefits.

3) The present invention uses industrial waste residues as raw materials, which is beneficial to realize the reuse of industrial waste residues, saves land occupation, reduces the pollution of industrial waste residues, reduces the damage of waste residues to the natural environment, saves the exploitation of natural resources, and is conducive to alleviating the disposal of a large amount of industrial waste residues problems and growing resource problems. It is conducive to promoting the sustainable development of resources and the environment, fundamentally solving the problems existing in my country's industrial waste residues, and at the same time establishing and improving a comprehensive industrial waste residue disposal system suitable for my country's actual conditions. In addition, it has also promoted my country's scientific and technological progress, economic construction, environmental and social development, all of which have important theoretical significance and practical value.

Of course, implementing any product of the present invention does not necessarily need to achieve all the technical effects described above at the same time.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is the relationship diagram between water-cement ratio and compressive strength in the embodiment of the present invention;

Fig. 2 is the relation figure of apparent density and ceramsite substitution rate in the embodiment of the present invention;

Fig. 3 is the relationship diagram of cube compressive strength and ceramsite substitution rate in the embodiment of the present invention;

Fig. 4 is a relation diagram between axial compressive strength and cube compressive strength in the embodiment of the present invention;

Fig. 5 is LC 0 stress-strain curve figure in the embodiment of the present invention;

Fig. 6 is LC 30 stress-strain curve figure in the embodiment of the present invention;

Fig. 7 is LC50 stress-strain curve figure in the embodiment of the present invention;

Fig. 8 is the stress-strain graph of LC 70 in the embodiment of the present invention;

Fig. 9 is a graph showing the relationship between the peak strain and the substitution rate of ceramsite in the embodiment of the present invention.

detailed description

The implementation of the present invention will be described in detail below with reference to the drawings and examples, so as to fully understand and implement the implementation process of how to use technical means to solve technical problems and achieve technical effects in the present invention.

Example

1. Materials

1.1 Ceramsite

The shale ceramsite produced by Guangxi Huagui Ceramic Products Co., Ltd. is selected. The ceramsite has excellent properties of low density, high cylinder compressive strength, high softening coefficient, large porosity, frost resistance and alkali-aggregate reaction. Considering that ceramsite should be used in small hollow blocks of lightweight aggregate concrete, too large particle size is not conducive to the forming quality of the test block, so the ceramsite is screened and the ceramsite with a particle size of 5-10mm is selected. After the screened ceramsite is manually cleaned and dried, it is tested for bulk density, apparent density, cylinder compressive strength, and 24h water absorption. The specific results are shown in Table 1-4.

Table 1 Bulk density of ceramsite

Table 2 Apparent density of ceramsite

Table 3 ceramsite cylinder compressive strength

Table 4 Ceramsite 24-hour water absorption

1.2 Manganese carbonate tailings

Select the manganese carbonate tailings left over from manganese smelting by the Daxin Manganese Mine Branch of CITIC Dameng Mining Co., Ltd., with a particle size of 4-6mm and a grade of 2%-3%. In accordance with the relevant regulations of GB/T 15229-2011 and JGJ 52-2006, and because the raw materials belong to smelting tailings and contain more sediment impurities, the samples were sieved with a 1mm aperture sieve, rinsed repeatedly, and dried for later use. For the basic physical and mechanical properties of manganese carbonate tailings, its apparent density, water content, 24h water absorption and crushing index are mainly measured, as shown in Table 5-8.

Table 5 Apparent Density of Manganese Carbonate Tailings

Table 6 Moisture content of manganese carbonate tailings

Table 7 Crushing index of manganese carbonate tailings

Table 8 24-hour water absorption rate of manganese carbonate tailings

1.3 Natural river sand

Natural river sand was used as fine aggregate. In order to reduce the influence of other factors on the water-cement ratio and strength, related impurities such as shells were filtered with a sieve of corresponding aperture before the test, and the fine aggregate was fully dried for future use. The fineness modulus of the sample was measured as 2.7 in accordance with the relevant provisions of the "Code for Design of Concrete Structures" GB 50010-2010, which belongs to medium-coarse sand, and the particle gradation meets the requirements. The screening results are shown in Table 9:

Table 9 Cumulative sieve residue of test sand

Mesh size(mm) 5 2.5 1.25 0.63 0.315 0.16 Fineness modulus Cumulative sieve rate 10.3 25.9 39.0 60.4 89.5 97.9 2.9

1.4 Cement and water

Conch brand ordinary Portland cement P.O42.5 produced by Fusui Xinning Conch Cement Co., Ltd. is used, and the water used in the mixing process and maintenance is tap water.

2. Preparation of ceramsite manganese carbonate tailings concrete

The preparation method of ceramsite manganese carbonate tailings concrete comprises the following steps:

(1) Pre-wetting of ceramsite: sieve ceramsite by particle size, clean surface impurities, dry, soak for 24 hours, then spread out ceramsite and air-dry naturally until there is no obvious flowing water on the surface;

(2) mixing:

①Put the pre-wetted ceramsite and one-half of the cement in the pre-wet mixer and mix for 30 seconds, so that the surface of the ceramsite absorbs enough cement, and then evenly infiltrates one-half of the water, and stirs for one minute. As a result, the cement is hydrated and the surface of the ceramsite is evenly covered with cement mortar. During this process, pay attention to keep the mixer rotating in the same direction at all times, and do not reverse it, otherwise the phenomenon of ceramsite breakage will be increased;

② Pour the manganese carbonate tailings, natural river sand and the other half of the cement into the mixer, stir for 30 seconds, then add the remaining half of the water and stir for two minutes to obtain a concrete mixture.

The ratio of water, cement, ceramsite, manganese carbonate tailings and natural river sand is shown in Table 10.

Table 10 Mixing ratio of ceramsite manganese carbonate tailings concrete materials

(3) Forming by the method of secondary mold loading:

① For the first mold loading, fill the concrete mixture to two-thirds of the mold height, vibrate for 5 seconds, insert a trowel along the mold around the mold, so that there is no honeycomb pockmark around the specimen, Make sure that the junction between the mixture and the mold is dense.

②For the second mold loading, make the concrete mixture higher than the mold, vibrate for 5 seconds, smooth the upper surface of the mold with a trowel, and apply a little pressure so that the protruding ceramsite does not exceed the height of the mold.

③ 1 hour after the mold is installed, use a trowel to wipe back and forth to further make the protruding ceramsite not higher than the height of the test mold, so as to ensure that the surface of the test block is smooth and smooth.

(4) Conservation: Use outdoor natural conservation, water after 5-6 hours of molding, and water every 6 hours. When the temperature is higher than 20°C, cover the surface of the block with a plastic film for heat preservation and moisturizing treatment.

According to the mix ratio in Table 10, 12 groups of ceramsite manganese carbonate tailings concrete cube test blocks were made, with 3 in each group, a total of 36 cube test blocks. The production process and maintenance time of the test pieces are strictly in accordance with the national standards. After curing, use YZ-2000A hydraulic pressure testing machine for compressive strength test.

Classify the obtained data, and analyze the change law of strength with water-cement ratio under the same substitution rate, as shown in Figure 1. It can be seen from Figure 1 that the strength of ceramsite manganese carbonate tailings concrete decreases with the increase of water-cement ratio. The larger the water-cement ratio, the less the amount of cement, the lower the strength of the formed cement mortar, and the smaller the elastic modulus. However, the code stipulates that in non-load-bearing walls, the minimum strength grade of hollow blocks is MU3.5, According to the literature, the strength of the hollow block made of it can be calculated from the compressive strength of the cube. The specific formula is as follows: R _B =(0.9577-1.129K)×R.

Among them: R _B is the 28-day compressive strength (MPa) of the small hollow block; K is the hollow ratio of the small hollow block; R is the cubic compressive strength (MPa) of the concrete standard specimen.

The above-mentioned hollow block is a standard single-row hole hollow block, and the hollow ratio is about 52% through test calculation, so as long as the cubic compressive strength exceeds 10MPa, it can meet the requirements of the new specification. From the perspective of environmental protection and energy saving, the water-cement ratio of 0.45 can not only meet the requirements of non-load-bearing walls, but also reduce the use of cement. When the ratio is 0.45, the dosage of each component is as shown in Table 11.

Table 11 Amount of ceramsite manganese carbonate tailings concrete

3. Performance test of ceramsite manganese carbonate tailings concrete

3.1 Workability and apparent density test and analysis

Workability and apparent density are important indicators for evaluating the physical properties of ceramsite manganese carbonate tailings concrete. Workability includes fluidity, cohesiveness, and water retention. The quality of workability is an important factor to measure whether the concrete meets the requirements of use. At present, there is only a specific method to determine the fluidity. The cohesion and water retention are mainly observed by the naked eye. This test uses the slump method to determine Measure the fluidity of ceramsite manganese carbonate tailings concrete. The apparent density is the mass per unit volume of the concrete mixture after compaction, and is the key to determine the use of the new ceramsite manganese carbonate tailings concrete. Therefore, the ceramsite manganese carbonate tailings concrete test blocks with different ceramsite substitution rates The mass per unit volume further illustrates the advantages of the new material, and then classifies its use. The specific slump and apparent density test results are shown in Table 12.

The physical properties of table 12 ceramsite manganese carbonate tailings material mixture

Numbering LC 0 LC 30 LC 50 LC 70 Slump (mm) 89 80 71 60 Apparent density (kg/m ³ ) 2180 1980 1820 1760

According to the analysis in Table 12, it can be seen that: (1) With the increase of the substitution rate of ceramsite, the content of manganese carbonate tailings decreases, and the slump gradually decreases. On the one hand, because the apparent density of ceramsite is small, the bulk density of the mixture is small , and the cement mortar is added to make the mixture more viscous and the slump value is smaller. The degree value is larger. (2) With the increase of ceramsite substitution rate, the apparent density of ceramsite manganese carbonate tailings concrete gradually decreases. As the ceramsite substitution rate changes from 0% to 70%, the apparent density of concrete decreases by 9%, 8% and 3% respectively, indicating that with the increase of ceramsite substitution rate, the apparent density of concrete decreases tends to gentle. When the ceramsite replacement rate is 50% and 70%, the apparent density of the new ceramsite manganese carbonate tailings concrete is less than 1950kg/m ³ , which belongs to lightweight aggregate concrete. Now the relationship between the apparent density and the substitution rate of ceramsite is fitted, and the relationship between the apparent density and the substitution rate of ceramsite is shown in Figure 2.

3.2 Cube compressive strength test

According to the optimal water-cement ratio of 0.45 obtained by the trial mix, and according to the specific mix ratio, standard cube specimens with different ceramsite substitution rates were poured, with side lengths of 150mm×150mm×150mm, 3 for each group, 4 groups in total. After 28 days of curing in the standard curing room, use the YZ200A200T press to carry out the cube compressive strength test. Comparing and analyzing the three compressive strength data of each group, if the maximum and minimum values are not more than 15% of the middle value, it meets the requirements. The results of the cubic compressive strength test are shown in Table 13.

The crack development and final failure form of ceramsite manganese carbonate tailings concrete are not much different from those of ordinary concrete. During the loading process, the specimen is compressed vertically by the constraints of the loading end and forced to expand horizontally.

When the replacement rate is 0%, as the load increases, the stress of the ceramsite manganese carbonate tailings concrete increases gradually, and the horizontal deformation of the specimen also increases gradually. During the loading process, the peeling of the cement mortar first appeared on the surrounding surfaces, and a few vertical cracks appeared on the four vertical surfaces, and then extended upward or downward, and some vertical cracks also gradually extended to the corners of the specimen. end, and then form a figure-of-eight crack connected upside down. As the load continues to increase, the figure-eight cracks gradually expand inward, and the excessive deformation causes the concrete in the middle to expand outward and gradually peel off, and the specimen eventually evolves into a quadrangular pyramid failure form that connects upside down. Since the particle size of manganese carbonate tailings is small, that is, the concrete coarse aggregate is small, the failure interface when the specimen is damaged is basically cement mortar, and there is almost no damage to the manganese carbonate tailings aggregate, which also verifies to a certain extent The strength of manganese carbonate tailings concrete is lower than that of conventional concrete under the same mix ratio.

When the replacement rate is 30% to 70%, due to the addition of ceramsite, it is different from the failure interface of manganese carbonate tailings concrete. The failure of ceramsite manganese carbonate tailings concrete is basically the failure of ceramsite, which leads to the failure of the specimen. Analyzing the reason, it is because the ceramsite has a porous structure, the interior is not dense, and its strength and rigidity are lower than that of cement mortar. When the ceramsite is under pressure, it accumulates energy and makes a "squeak" sound. When the stress is greater than the compressive strength of the ceramsite, the internal ceramsite is destroyed, the energy is released instantaneously, and the specimen is destroyed. Because of its many internal pores, there is a large deformation when it is compressed to failure, so the strain of ceramsite manganese carbonate tailings concrete after failure is much larger than that of manganese carbonate tailings concrete.

Table 13 cube compressive strength test results

The relationship between the compressive strength of the cube and the substitution rate of ceramsite was fitted, and the linear relationship shown in Figure 3 was obtained.

It can be seen from Table 13 and Figure 3 that: (1) With the increase of ceramsite substitution rate and the decrease of manganese carbonate tailings content, the strength of concrete gradually decreases. The strength of concrete is greatly affected by the strength of lightweight aggregate particles. Therefore, before the lightweight aggregate concrete is subjected to pressure and reaches the limit state, the lightweight aggregate first breaks and breaks due to its low strength. When the material damage evolves into interface damage , the concrete reaches the limit state of its bearing capacity and fails. Through the analysis, it is obtained that the strength of ceramsite is much lower than that of cement mortar, and the surface is rough, with many fine holes and large specific surface area, so the interface between ceramsite and cement mortar has strong bonding force and is not easy to produce initial cracks. Although the ceramsite is pre-wetted before pouring, the water absorption and return characteristics of lightweight aggregate in cement mortar enable concrete to play a "self-curing" role during curing, which improves the interface strength to a certain extent. In addition, because the elastic modulus of ceramsite is small, the strain generated by the same stress is larger than that of cement mortar, so the concrete test block will produce slight damage sound and large deformation during the loading process, so the damage of concrete is basically ceramic. Granular aggregates are destroyed prior to the bonding interface.

(2) The compressive strength of concrete made of manganese carbonate tailings as coarse aggregate is lower than that of ordinary concrete. Although the manganese carbonate tailings concrete mixture has good workability, and the strength of coarse aggregate is not much different from that of ordinary crushed stone, due to its small particle size, the damage is material damage and interface damage, and the compressive strength is lower than that of ordinary concrete.

(3) The slope of the straight line between 0% and 30% of the ceramsite substitution rate is the largest, that is, the addition of ceramsite to the manganese carbonate tailings concrete makes the strength drop greatly, and the decline rate is about 33.9%. With the increase of the ceramsite substitution rate , the decline trend of cubic compressive strength tends to be stable and gentle, mainly because at this time the ceramsite manganese carbonate tailings concrete is finally destroyed due to the destruction of ceramsite.

3.3 Axial compressive strength test

Compared with the cubic compressive strength, the axial compressive strength is more in line with engineering practice, so an accurate understanding of the axial compressive strength of new materials is of great significance for its application. According to the determined water-cement ratio and mix ratio, pour prism standard test blocks with a side length of 150mm×150mm×300mm, 3 for each group, 4 groups in total. After 28 days of standard curing, according to GB/T 50081-2002, the axial compressive strength test was carried out using the instrument RMT-201 in the structure laboratory of Guangxi University.

When the cube specimen is under compression, due to the existence of the "hoop effect", the compressive strength deviates from the real situation, that is, it is larger than the real value. The research shows that the farther away from the loading end, the smaller the "hoop effect". When the distance exceeds This effect can be ignored when the side length of the specimen is 0.866 times, so in order to eliminate this deviation and make the test value reflect the actual situation more truly, the axial compressive strength is used as a reference index in our country, but in actual engineering, consider For the convenience of the production process and the saving of materials, the axial compressive strength of the prism is directly converted by measuring the compressive strength of the cube. Therefore, the conversion relationship between the cubic compressive strength and the axial compressive strength of the ceramsite manganese carbonate tailings concrete is studied. very important.

In this experiment, four groups of ceramsite manganese carbonate tailings concrete with different substitution rates were tested. Due to the addition of ceramsite, the new type of ceramsite manganese carbonate tailings concrete showed better deformation ability in the process of compression failure. The sound of being compressed, the specimen undergoes a large deformation and then fails. Before the prism bears the pressure and reaches the failure load, a small amount of vertical fine cracks appear around the prism. With the gradual increase of the ceramsite substitution rate, the visible cracks on the surface of the specimen appear later and later. When the pressure is greater than the failure load, The original cracks gradually lengthened and widened, and many cracks parallel to the direction of gravity appeared and developed rapidly, and finally penetrated and caused interface failure. By observing the broken prism, it can be found that:

When the replacement rate is 0%: the compressive failure process of the manganese carbonate tailings concrete prism is similar to that of ordinary concrete. When the stress is small, micro-cracks are generated at the joint of mortar and aggregate due to the concentration of tensile stress. As the load increases, the micro-cracks continue It develops, forming visible cracks parallel to the load direction, splitting occurs inside the specimen, oblique cracks form, and finally connects to form a through-joint failure, which belongs to inclined plane shear failure. By observing the four damaged surfaces, it is found that some only form a complete vertical crack on the surface, and some have more cracks, forming a typical figure-eight damage connected upside down. Generally speaking, there are cracks on all four surfaces The presence.

When the replacement rate is 30%: due to the unavoidable floating phenomenon of different degrees of ceramsite in the process of pouring and curing, the cracks of the prism mainly appear in the weak area of the concrete when the prism is destroyed, that is, the upper part of the specimen during pouring, and the lower part of the prism. Portions are less. Different from the replacement rate of 0%, as the load increases, the floating ceramsite is compressed and accumulates energy, and is crushed when the stress is greater than its strength. As the pressure continues to increase, microcracks appear in the cement mortar near the crushed ceramsite, and the cracks develop in the weak area until failure. The failure form is different from 0%, which is longitudinal splitting failure.

When the replacement rate is 50% and 70%: the failure form is not much different from that of the ceramsite replacement rate of 30%. Due to the increase of the ceramsite substitution rate, the phenomenon of ceramsite being crushed in the weak area of the concrete is more obvious, and longitudinal splitting damage is more prominent.

The axial compressive strength and cubic compressive strength are compared, as shown in Table 14. The ratio of axial compressive strength to cubic compressive strength of ceramsite manganese carbonate tailings concrete in this test is between 0.9 and 1.0, which meets the requirements.

Table 14 Axial compressive strength test results

The axial compressive strength of ceramsite manganese carbonate tailings concrete was correlated with the cubic compressive strength, and the linear relationship shown in Figure 4 was obtained.

From Table 14 and Figure 4, it can be seen that the ratio of concrete axial compressive strength to cubic compressive strength is closely related to the coarse aggregate used, including the particle size and strength of the coarse aggregate. For ordinary concrete, the research on this ratio has been relatively mature. Among them, the ratio of concrete using natural gravel as coarse aggregate is about 0.82, while the ratio of lightweight aggregate concrete is about 0.93. For ceramsite concrete, due to the different types of ceramsite, the ratio of the axial compressive strength to the cubic compressive strength is between 0.9 and 1.0, and the factors that cause the ratio change generally include the following aspects:

(1) When the concrete is formed and vibrated, the density of ceramsite is smaller than that of other materials, and it is more likely to appear floating phenomenon. Different vibrating processes cause different degrees of ceramsite floating, and the uniformity of the mixture is also different. During the loading process, the specimen is more likely to be damaged on the weak side.

(2) During the test, the error caused by the centering method of the specimen before loading is unavoidable, and eccentric compression is more likely to occur instead of axial compression.

(3) During the forming process of the test piece, the difference in the test mold causes the surface flatness of the test piece and the parallelism of the loaded ends to be different, and there is a certain deviation.

3.5 Compressive stress-strain test

The full stress-strain curves of the new ceramsite manganese carbonate tailings concrete specimens with four kinds of ceramsite substitution rates are shown in Figure 5-8. Due to the addition of ceramsite in the manganese carbonate tailings concrete, the stress-strain curve of the new material concrete It is also different from ordinary concrete.

According to the stress-strain full curve test results, it can be seen that:

1) 0%: The full stress-strain curve of concrete with 0% ceramsite substitution rate, that is, manganese carbonate tailings concrete, is similar to that of ordinary concrete, and has gone through several stages: ① From zero point to proportional limit load point: the process The relationship between stress and strain is basically a straight line, the slope is almost constant, and the stress at the proportional limit load is about 40% of the peak stress; ②From the proportional limit load point to the peak stress point: the slope of the curve decreases rapidly at this stage, when it reaches the peak When the stress is high, the slope of the curve is 0; ③From the peak stress point to the inflection point: the absolute value of the slope increases gradually at this stage, the stress drops sharply, and the strain increases slowly; ④From the inflection point to the end: the stress in the previous stage decreases Small but the strain increases rapidly, and the later stress is gradually maintained in a certain range, and the strain continues to increase.

30% to 70%: The specimens with the three substitution rates have also gone through the above stages, but due to the addition of ceramsite, when the stress exceeds the peak stress, the stress decline rate is obviously faster than that of ordinary concrete, and the decline rate increases with The increase of the content of ceramsite increases, and the curve becomes steeper.

2) As the replacement rate of ceramsite increases, the inflection point in the descending section of the stress-strain curve of the new material concrete becomes less obvious, and some even do not exist. The reason is analyzed, because the structure of ceramsite is a porous structure. When the load When the ultimate load of the ceramsite is reached, the horizontal deformation increases, and the energy accumulated by the ceramsite is released instantaneously, resulting in the accelerated development of cracks on the surface of the specimen.

3) Comparing the rising section of the stress-strain curve of each ceramsite substitution rate, it can be seen that the elastic stage of the 0% specimen is more obvious and lasts longer. With the increase of ceramsite substitution rate, this stage gradually becomes The gain is not obvious and the duration is shortened, because the content of ceramsite has a very important influence on the axial compressive strength. When the applied load is greater than the ultimate load of ceramsite, the ceramsite will collapse and fail, making the growth of strain faster than that of stress. Fast, destroying the original same growth rate.

4) Peak stress and peak strain

Theoretically, the strain corresponding to the peak stress is called the peak strain. The stress-strain curve of ceramsite manganese carbonate tailings concrete is different from ordinary concrete in the ascending section and descending section. Since the coarse aggregate of new material concrete includes ceramsite and manganese carbonate tailings, the dosage is different, and the corresponding The peak stress and peak strain of the new material are also different, so it is of great significance to study the difference between the peak stress and peak strain of the new material and ordinary concrete. The peak stress and peak strain of the new material concrete are shown in Table 15.

Table 15 Concrete peak stress and peak strain

Numbering Apparent density (kg/cm ³ ) Peak stress (MPa) Peak strain (×10 ^-3 ) LC 0 2180 33.1 2.0384 LC 30 1980 21.2 2.1828 LC 50 1820 16.7 2.3318 LC 70 1760 11.1 2.4329

It can be seen from Table 15 that with the increase of the replacement rate of ceramsite and the decrease of the content of manganese carbonate tailings, the apparent density of the new material concrete gradually decreases, the peak stress gradually decreases and the decline is large, and the peak strain Gradually increase and are larger than ordinary concrete. The peak strain of ordinary concrete is about 1.8×10 ^-3 ~ 2×10 ^-3 , and the peak strain of the new material increases by 7.28%, 14.88%, 22.73%, and 28.05% respectively, and the growth rate is close to a linear relationship. The relationship between the substitution rate of ceramsite is shown in Figure 9.

The present invention combines the present situation of tailings produced by characteristic manganese mines in Guangxi. In addition to the cement and water components used in traditional concrete, ceramsite and manganese carbonate tailings are used as coarse aggregates, and natural sand is used as fine aggregates. After trial preparation, a new type of pottery is prepared. Granular manganese carbonate tailings concrete can use regional industrial wastes in the construction field, truly realize the recycling of resources, and this kind of ceramsite manganese carbonate tailings concrete can ensure the strength required by the masonry structure. The ceramsite manganese carbonate tailings concrete of the present invention is environmentally friendly, light in weight, and has good thermal insulation performance. comfort. It will have a place in the field of green buildings, meet the requirements of "environmental protection and energy saving" in the field of construction, and have good economic and social benefits.

The present invention uses industrial waste residues as raw materials, which is beneficial to realize the reuse of industrial waste residues, saves land occupation, reduces the pollution of industrial waste residues, reduces the damage of waste residues to the natural environment, saves the exploitation of natural resources, and is beneficial to alleviate the disposal of a large amount of industrial waste residues and A growing resource problem. It is conducive to promoting the sustainable development of resources and the environment, fundamentally solving the problems existing in my country's industrial waste residues, and at the same time establishing and improving a comprehensive industrial waste residue disposal system suitable for my country's actual conditions. In addition, it has also promoted my country's scientific and technological progress, economic construction, environmental and social development, all of which have important theoretical significance and practical value.

For example, certain terms are used in the description and claims to refer to specific components or methods. Those skilled in the art should understand that different regions may use different terms to refer to the same component. The description and claims do not use the difference in name as a way to distinguish components. As mentioned throughout the specification and claims, "comprising" is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The following descriptions in the specification are preferred implementation modes for implementing the present invention, but the descriptions are for the purpose of illustrating the general principles of the present invention, and are not intended to limit the scope of the present invention. The scope of protection of the present invention should be defined by the appended claims.

It should also be noted that the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a good or system comprising a set of elements includes not only those elements but also includes items not expressly listed. other elements of the product, or elements inherent in the commodity or system. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the article or system comprising said element.

The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the forms disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various Various other combinations, modifications, and environments can be made within the scope of the inventive concept described herein, by the above teachings or by skill or knowledge in the relevant field. However, changes and changes made by those skilled in the art do not depart from the spirit and scope of the present invention, and should all be within the protection scope of the appended claims of the present invention.

Claims (6)

1. a haydite manganese carbonate mine tailing concrete, it is characterised in that include water, cement, haydite, manganese carbonate mine tailing and natural river Sand, by quality ratio, described water: cement: haydite: manganese carbonate mine tailing: natural river sand=1:1.78～2.01:0.50～1.32: 1.70～3.53:3.12～3.52.

2. haydite manganese carbonate mine tailing concrete as claimed in claim 1, it is characterised in that by quality ratio, described water: water Mud: haydite: manganese carbonate mine tailing: natural river sand=1:1.89:0.89:2.67:3.31.

3. the preparation method of a haydite manganese carbonate mine tailing concrete, it is characterised in that comprise the following steps:

(1) haydite is prewetted: haydite is carried out particle diameter screening, clean surface impurity, dry after, soak 24h, then by described haydite Spread natural air drying existence without obvious circulating water to surface out；

(2) mixing: by the described haydite after pre-wetted treatment and the cement mixing and stirring 30 seconds of 1/2nd, the most uniformly penetrate into two / mono-water, stirs one minute, is subsequently poured into manganese carbonate mine tailing, natural river sand and another 1/2nd cement, stirs 30 seconds, then limit Add residue 1/2nd waterside to stir two minutes, obtain concrete mix；

(3) molding: described concrete mix is injected mould molding；

(4) maintenance: the described concrete after molding is protected tide maintenance.

4. the preparation method of haydite manganese carbonate mine tailing concrete as claimed in claim 3, it is characterised in that described forming step Use the method that secondary is die-filling, specifically include:

(1) the most die-filling, described concrete mix is filled at 2/3rds of mold height, vibrate 5s, uses trowel edge Described mould surrounding plugs and pounds, and makes test specimen surrounding there is not the situation of voids and pits；

(2) the most die-filling, make described concrete mix exceed described mould, vibrate 5s, with trowel at described die surface The most floating, and the haydite making to highlight of exerting pressure is less than described mold height；

(3) after die-filling 1h, smear pressure back and forth with trowel, make prominent haydite be not higher than described die trial height further, make to smear pressure surface and put down Whole smooth.

5. the preparation method of haydite manganese carbonate mine tailing concrete as claimed in claim 4, it is characterised in that described curing step Particularly as follows: use natural maintenance, water after molding 5～6h, watered once every 6 hours, when temperature is higher than 20 DEG C, building Block surface covered with plastic film carries out heat and moisture preserving process.

6. the preparation method of haydite manganese carbonate mine tailing concrete as claimed in claim 5, it is characterised in that described blend step In, water by quality ratio: cement: haydite: manganese carbonate mine tailing: natural river sand=1:1.89:0.89:2.67:3.31.