Since Lanling slashed it with a wind blade, that dragon-like thing has never appeared, although Lanling said that the thing was a cave newt, but the ancient bluebird still had palpitations, because it was just a glimpse at the time, but it was found that it was still too much like a dragon, which was unforgettable.

Seeing that the ancient bluebird looked like this, Lanling didn't say anything, but just stayed by the side of the ancient bluebird, always paying attention to the surrounding environment, for fear that something abnormal would happen again.

But the cave seemed to be quiet like this, and there was no more problem, and the two of them fell down like this, and the ancient bluebird didn't remember how long they had descended, so they kept going down slowly like this.

Finally, the ancient bluebird saw the bottom of the cave: "We are in the end!" ”

Hearing the surprise cry of the ancient blue bird, Lan Ling also nodded, ready to deal with emergencies that could occur at any time, and the first one fell to the ground.

The ancient bluebird also landed at the bottom of the cave, but found that the ground at the bottom of the cave was actually full of sand.

Sand refers to tiny stone grains, or things shaped like sand. It is also a metaphor for imperfect flaws. On August 19, 2019, the British journal Nature recently published a commentary saying that sand and gravel are being mined faster than their natural recovery. Chinese name 沙子 foreign name sa

d Pinyin shā zǐ 注 音 ㄕㄚ ㄗㄧ Explanation Fine stone grains Main component silica (SiO₂) Functions Manufacture of cement, glass and electronic products Table of Contents 1 Word Concept ▪ Basic Information ▪ Citations and Explanations 2 Basic Meanings 3 Identification Methods 4 Uses 5 Reduction Word ConceptsEdit Basic Information Sand [sa].

d] refers to the pellets with a particle size of 0.074~2mm that are washed by rain or rolled from rocks after rock weathering. There are many types of sand, including river sand, sea sand, metal sand, natural sandstone pulverized sand, and so on. To say that a little off, there is also an abrasive cloth. The main component of common river sand is silica (SiO₂). Sand generally contains a small amount of soil, and the soil content is limited by the grade of the building. The apparent density of construction sand is greater than 2500kg/m³, and the loose bulk density is greater than 1350kg/m³. Sand is one of the main constituent materials of concrete and mortar, and is a bulk material for civil engineering. Sand is generally divided into two categories: natural sand and artificial sand. Rock particles formed by natural conditions (mainly rock weathering) with a particle size of less than 5mm are called natural sand. Artificial sand is made of crushed rock, which is generally not used due to its high cost and many flakes and powders. According to its different origins, natural sand can be divided into river sand, sea sand and mountain sand. The surface of mountain sand is rough, the particles are angular and angular, the sand content is high, the content of organic impurities is also more, and the quality is poor. The surface of sea sand and river sand is smooth, but the salt content of sea sand is high, which has a certain impact on concrete and mortar, and river sand is relatively clean and widely used. The coarseness of sand refers to the average coarseness of sand grains of different particle sizes mixed together. There are usually coarse sand, medium sand, and fine sand. The particle gradation of sand refers to the ratio of sand size particles. As can be seen in the figure, if it is sand of the same thickness, the void is the largest [Fig. (a)], and the void is reduced when the sand with two particle sizes is matched [Fig. (b)], and the sand with three particle sizes is matched with the void is smaller [Fig. (c)]. It can be seen that the porosity of the sand depends on the degree of collocation of the particle size of the sand at all levels. Graded sand can not only save cement, but also improve the compactness and strength of concrete and mortar. The thickness of the sand is expressed by the fineness modulus Mx. The larger the fineness modulus, the coarser the sand. According to the size range of fineness modulus, the sand is divided into coarse sand, medium sand, fine sand and extra-fine sand. When configuring concrete, medium sand should be preferred. When coarse sand is used, the sand rate should be increased and sufficient cement dosage should be maintained; When fine sand is used, it is advisable to reduce the sand rate appropriately. The sand used for masonry mortar should meet the technical property requirements of concrete sand. Due to the thin mortar layer, the maximum particle size of the sand should be limited. For the sand used in rubble masonry, the maximum particle size should be less than one-quarter to one-fifth of the thickness of the mortar layer. For brick masonry, it is advisable to use medium sand, and the particle size shall not be greater than 2.5mm. For smooth plastering and grouting, fine sand should be used. Citations and explanations 1. The sixth chapter of "The Legend of Children's Heroes": "Although the fierce monk is fierce, he is also a flesh man. The fleshy man's eyes were probably worse than rubbing a piece of sand into it, and it hurt him so much that he 'ouched' and fell backwards with a clatter. Yang Mo's "Song of Youth" Part 1, Chapter 3: "Her hair was stained with a lot of fine sand, but she didn't feel it at all. 2. Refers to something shaped like sand. Such as: iron sand. 3. A metaphor for imperfect flaws. For example, there is no room for sand in my eyes. Basic meaningEdit After weathering, the rock is carried by the wind or water current, and the small mass is taken away to form the soil - plain, and the medium mass is taken away when the wind speed or flow speed The photographer takes a photomicrograph of the sand particles at 250 times magnification [1] Reduce the urine deposition to form a sandy beach (the soil should be carried farther away when the carrier velocity drops, and the gravel is deposited in advance), and the large mass remains in place to continue weathering. In the end, it becomes soil, and that's how the soil on earth is formed. Of course, there are also phenomena of magma erupting to form rocks, although there are still far fewer volcanoes in the 21st century than in ancient times. The sand used in the 21st century is transported from the sand field, where the sand gathers. The most common composition of sand is silica, usually in the form of quartz, which is chemically stable and hard enough to resist weathering. The main component of sand is silicon dioxide (SiO2), and the density of silica is 2.65g/cm^3, that is, 2.65t/m^3. Sand is made up of minerals and tiny rock fragments. Rock chips are rocks that have been eroded and weathered. The composition of the sand varies from place to place, depending on the source and conditions of the local rocks. [1] In inland (e.g., desert) and non-tropical coastal (e.g., sandy) environments, the most common component of sand is silicon (silica SiO2). Typically, silicon exists in the form of quartzite. Feldspar sandstone is a type of sand or sandstone with a high content of feldspar (aluminum silicate) and is usually formed by weathering and erosion of nearby granite. The fine white sand found in coral reefs is above-ground corals (limestone) that can pass through the digestive system of parrot fish. In some places, the sand contains magnetite, clay, chlorite, glauconite, or gypsum. Magnetite-rich sand has a deep black color. Sand containing chlorite and glauconite is generally green in color. The gypsum dunes at the White Sands National Museum in New Mexico are world-famous for their white color. In some areas, the sand layer contains garnet and other corrosion-resistant minerals, such as some gem ores. Identification methodEdit To determine the quality of the sand particle gradation, it is necessary to do a sieving test. The sieve test shows 2 different types of results. 1. Clearly know the cumulative sieve surplus percentage of each sieve. Second, fineness modulus. Both of these results were obtained by comparing or calculating the cumulative sieve remainder percentages. For the screening test, it is necessary to pass through a 9.5mm sieve and take about 500g for the test. Set sieve 4.75 2.36 1.18 0.6 0.3 0.15 0.075 and sieve bottom. Fineness modulus algorithm Fineness modulus: M = (A2.36 + A1.18 + A0.6 + A0.3 + A0.15-5A4.75) / (100-A4.75) where A0.15 and A0.3~~~A4.75 are the cumulative sieve residue percentage on the corresponding sieve. So as to obtain the fineness modulus, you can determine whether it is the initial sand, or the middle sand, fine sand, and the construction site is used in the middle sand. Coarse sand 3.7-3.1 medium sand 3.0-2.3 fine sand 2.2-1.7, from which the sand is determined, and then look at the grading range. The sand under the microscope is also based on whether the cumulative sieve percentage of each sieve is within the range required by the specification. Sand, mostly artificially made, or artificially polished from some stones, the particles are relatively larger, the fullness is stronger, and you can clearly feel the presence of particles in your hand. The main purpose of making sand is to sharpen tools, make noises, or to use it as a timer. The sand is also ground by stone, but the grains of sand are polished by the forces of nature over thousands of years, and are extremely fine and soft, suitable for some soft products. The biggest difference is that the sand is different colors and different types of sand in different places. If you hold a handful of sand on your hand, you won't feel the particles, but if you bathe with sand, it can have a noticeable effect on removing dead skin cells from the surface of the skin and smoothing the skin. So, sand has many uses. The sand has a single variety and a rough appearance, and no more useful advantages have been found other than grinding. Usageedit Sand (sand) has a wide range of uses: in addition to being used in construction, road construction, filtration, breeding and beautification, and as a smelting speed-up agent, it is also the main material for making glass, which contains silicon elements, and in addition to sand pits in sports, it can also be used as a sandbag for boxing and a sandbag for flood control. In daily life, it exerts the charm of cleanliness: factory workers wash their hands and feet with sand sand, wash wine bottles, porcelain, metal utensils, jade, silverware, etc. Bright, smooth metal, wood sandpaper! In addition, volcanic ash or hot spring mud is a pet used by beauty children! It is also indispensable to make porcelain, and it is also used for salt-baked chicken in cooking, if there is organic oil on the ground, the oil is paved with sand, and it is cleaned up as soon as it is sprinkled with sand, and it is used to clean up traffic accidents, and the sand bombs used for hunting, and the sand bags used in the past have sand, and the sandbags are used on the battlefield and the raking field, and the sandbags are used for many purposes. The last funeral of the dead: Sasha is also it. On August 19, 2019, a recent review published in the British journal Nature said that sand and gravel have been mined faster than their natural recovery. Sand and gravel are already the most mined raw materials, with about 32 billion to 50 billion tonnes of sand used worldwide each year, mainly to make cement, glass and electronics. Although deserts cover 20% of the Earth's land surface, the sand in them is too smooth to use. The vast majority of angular sand suitable for industrial use comes from rivers – which occupy less than 1% of the Earth's area.

Sand (mainly SiO2), mostly artificially made, or artificially polished from some stones, the particles are relatively larger, the fullness is stronger, and the presence of particles can be clearly felt in the hand. Chinese name Sand Composition SiO2 Formation Artificial Manufacturing Function Sand is a material for building decoration Table of Contents 1 Features 2 Uses 3 Density FeaturesEdit Sand is also ground for stone, or used as a building material. However, the sand grains are polished by the forces of nature over thousands of years, and are extremely fine and soft, suitable for some soft products, or as building decoration materials, or for aquaculture. Artificially manufactured sand is mostly used for process decoration or special performance of the roasting medium - granular roasted sand. The biggest difference is that the sand is different colors and different types of sand in different places. If you hold a handful of sand on your hand, you won't feel the particles, but if you bathe with sand, it can have a noticeable effect on removing dead skin cells from the surface of the skin and smoothing the skin. UsageEdit The main purpose of making sand is to sharpen tools, make noises, or to use as a timer. Sand is a material for architectural decoration. Sand is a new thing in handicrafts. Sand is an indispensable medium in the roasting industry. Sand is the raw material for the production of optical fibers. Sand is the main material that makes up concrete and mortar. Its main functions are: (1) In concrete, it can be combined with cement molecules, increase the diffusion area of cement molecules, and enhance the hydration of cement after forming cement slurry. (2) Fill the gaps between the stone particles, and play the role of skeleton together with the stones, so as to improve the compactness and strength of the concrete. (3) It has a certain lubricating effect and improves the workability of concrete mixture. (4) In the process of cement hydration, the heat of cement hydration is effectively reduced, and the cracks of cement are inhibited when the volume of physical and chemical reactions changes. (5) It plays the role of aggregate in all kinds of mortar, and can effectively save cementing materials. (6) It can be used as a cushion in expansive soil, frozen soil and other undesirable soil layers, which plays a protective role. So, sand has many uses. And what about sand? In the past, it was a single variety, rough appearance, floating dust and debris, and it was generally regarded as an impurity, which could only be used as a foil or tool for finer things. Pad the fish tank and sprinkle the walls. There are also those used to fry goods... And so on Specially processed sand is widely used, glass sand is used to make glass products decorative materials, iron sand is used for concrete and other weight-like counterweights, round particles are used for fried sand and fried goods, quartz sand glass raw materials, Maifan stone water purification filter material... etc. Density editing Building material bulk density: sand bulk density is generally 1300–1600Kg/m3 (related to moisture content) Stone bulk density is generally 1500–1800Kg/m3 (related to stone material) Sand bulk density is commonly used 1.28t/m3 Stone bulk density is commonly used 1.48t/m3 bulk density (Bulk De

The weight per unit volume of a bulk material in its natural packing state is called bulk density. It can be expressed by the following formula: ρ = m/V formula: ρ0′ - bulk density (kg/m3); m - mass of the material (kg); V0′ - Stacked volume of material (m3). The volume of a loose material in its natural state refers to the total volume including both the pores inside the particles and the voids between the particles. When determining the bulk density of a bulk material, the mass of the material refers to the mass of the material in a container of a certain volume, and its bulk volume refers to the volume of the container used. If it is calculated by the volume of the compacted solid, it is called the compact packing density.

Sand and gravel, which refers to a loose mixture of sand grains and crushed stone. In geology, the mineral or rock particles with a particle size of 0.074~2mm are called sand, and those with a particle size greater than 2mm are called gravel or breccia (the difference between the two is that the degree of rounding is different, and the details can be seen in the entry conglomerate and sandstone). If the gravel in the sand is mostly gravel, it is called gravel. There are also people who refer to sandstone as sandstone in daily life. Chinese name Shashi Foreign name Sa

d Mineral detritus Main quartz, feldspar Cementation Calcareous, siliceous, irony, argillaceous Large and small particle size of 0.074~2mm Loose mixture of defined sand and gravel Table of Contents 1 Introduction ▪ Composition ▪ Characteristics ▪ Uses 2 Causes 3 Relevant regulations 4 Precautions 5 Latest trends ▪ Graded sand and gravel ▪ Cushion layer Composition Composition Sand (3 photos) Composition Mineral detritus: mainly quartz, feldspar. Rock detritus: related to the type of rock outcropping in the surrounding environment of the field or upstream of the river. Cementation: There is also cementation in the rock, and the cementation of different sandstones is different, and the common ones are calcareous, siliceous, irony, argillaceous, etc. Characteristics Different sand and gravel structures are quite different, some particles have uniform coarseness, and some are of different sizes; Some of the sand and gravel have good roundness of the debris, and some of the sand and gravel have sharp edges and corners of the debris. Sand and gravel is a loose substance, but its particles are generally hard, and in the surface environment, the chemical properties are stable. For sandstone, its resistance to weathering is generally strong, especially the silicified quartz sandstone, which is harder than granite. Uses Because of its good hardness and stable chemical properties, sand and gravel are often widely used as high-quality building materials and concrete raw materials in houses, roads, highways, railways, engineering and other fields. As for sandstone, since ancient times, it has been an important building material for large-scale buildings, rock carvings, interior decoration, and garden courtyard construction. GenesisEdit Natural causes: In nature, rocks are broken and separated into particles of different sizes through weathering, denudation and other surface actions. Under the action of water, wind, glaciers, etc., these particles are transported and accumulated, forming a layer of sand and gravel. The sand and gravel layers formed before the Quaternary period (2 million to 3 million years ago) basically formed rocks, that is, various sandstones, conglomerates, etc. The Quaternary period formed during the Quaternary period is not consolidated into rocks, that is, all kinds of sand gravel, gravelly sand, sandy gravel, etc., or Quaternary loose deposits. Naturally occurring sand and gravel, also known as natural sand. Artificial causes: The material made by human beings crushing stones through sand making machines and other equipment is called machine-made sand. Relevant regulationsEdit The quality of sand and gravel products must be qualified, and should be tested before use, and there must be a factory quality certificate and test sheet. Before use, sampling tests should be carried out according to the different varieties, specifications, origins and batches. The required test items of sand include sieve analysis, mud content, and mud block content. The mandatory test items of crushed stone include sieve analysis, mud content, mud content, needle and flake particle content, and crushing index. For the sand and gravel used to prepare concrete with special requirements, the corresponding project test needs to be done. [1] In any of the following cases, such as imported sand and gravel, sand and gravel without factory certificate, sand and gravel with doubts about the quality of sand and gravel, and used in load-bearing structures, must be retested, and the concrete should be re-tested. Unqualified sand and gravel shall not be used. For those who need to take certain technical treatment measures before use, they should first meet the technical requirements and be signed and approved by the relevant technical person in charge before they can be used. The factory certificate of sand and gravel products shall be provided to the user by the quality inspection department of the manufacturer to prove that the quality of its products has reached the specified indicators. Its main contents include: the date of delivery, the seal of the inspection department, the number of the certificate, the variety, the specification, the quantity, the particle gradation, the density, the mud content and other data and conclusions. [1] The data clerk shall collect, sort out and verify the factory quality certificate and test report of the sand and gravel in a timely manner. The quality certificate and test report should be clear, complete, accurate and true, and should not be omitted or filled in incorrectly, and there should be no outstanding matters, and should not be altered, forged, damaged or withdrawn at will. If the batch is large and the factory certificate provided is small, a copy (such as a copy) can be made for future reference, and the original certificate number, storage unit, copy time, and should be signed by the copying person and stamped by the copying unit. In the remarks column on the sand and gravel quality certificate, the construction unit shall fill in the name and location of the use project. [1] PrecautionsEdit The factory quality certificate and test report of sand and gravel should be consistent with the physical evidence between the physical objects. The factory quality certificate must be stamped by the manufacturer's quality inspection department, and the test report must be signed by the relevant personnel of the testing unit and stamped by the unit. The user must carefully check whether the measured values in the factory quality certificate and test report are in line with the standards specified in the specification. The test number should be included in the test report to facilitate verification and verification of the relevant information of the laboratory. There should be a clear conclusion in the test report, and the signature and seal should be complete. For the unqualified test report, the qualified test report or processing report of the double test piece retest shall be attached, and the unqualified test report shall not be withdrawn or destroyed. [1] The construction materials related to the sand and gravel factory quality certificate and test report also include construction organization design, technical disclosure, negotiation records, construction logs, concrete and mortar mix ratio application forms and notices, concrete and mortar test block compressive strength reports and other construction test data, hidden inspection records, quality acceptance records, as-built drawings, etc., so the certificate and test report should not only be consistent with the actual project and location used, but also should be consistent with the above construction data. [1] Latest TrendsEdit During the "Twelfth Five-Year Plan" development period, China's economic development is still in a period of important strategic opportunities. China's market demand pattern has not changed with domestic demand as the main body, industrialization, informatization, urbanization, marketization, internationalization of the "five" development goals for the future development of the sand and gravel industry of building materials provides a huge market space, China's economy will continue to maintain a steady and rapid growth during the "Twelfth Five-Year Plan" period. During the "Twelfth Five-Year Plan" period, the country will also invest heavily in infrastructure, construction demand is still very strong, and the total market demand for major building materials products continues to grow. Forecast for the future development of the building materials industry: the growth rate of the whole industry is moderate, the industrial structure is further optimized, and the economic benefits bottomed out in 2012, and the annual growth of the building materials industry is expected to be 10%. These new development characteristics of the building materials industry not only provide new opportunities for the development of the sand and gravel industry, but also face the severe challenges of the transformation of the industry structure. It is expected that by 2020, the domestic demand for sand and gravel products will be 16 billion tons, and the average annual growth rate of industrial added value and total profit will be more than 10%. Development trend: 1. Rapid reduction of natural sand resources After years of mining, natural sand resources are rapidly decreasing, and natural sand has been nearly exhausted in some areas. In order to protect river embankments and dams and protect the ecological balance, all localities will increase the river limit and strictly prohibit mining. Natural sand resources are becoming increasingly tight, and the price continues to rise, which will rise to more than 100 yuan/cubic meter. 2. The construction of machine-made sand production base has a strong development momentum With the requirements of infrastructure construction technology and the development of high-tech, there are higher requirements for the quantity and quality of sand and gravel. At present, entrepreneurs around the country are very optimistic about the development prospects of the sand and gravel industry and the business opportunities for the development and utilization of mineral resources, and have invested in the construction of large and medium-sized sand and gravel production bases. Their intermediaries have injected new impetus for the development of the sand and gravel industry and become a new force to promote the high-quality and high-level development of the sand and gravel industry. A number of large- and medium-sized machine-made sand and gravel production bases with strength, high level and standardized management in the industry will be built and put into operation one after another. 3. The enterprise management of the sand and gravel industry has been strengthened The enterprise management of the sand and gravel industry has been strengthened, and the small and substandard sand mining plants have been forcibly closed within a time limit, and the integration, merger and reorganization have been vigorously implemented, so as to become bigger and stronger. Driven by national policies and development strategies such as the extension of the industrial chain, the survival of the fittest in the industry is conducive to the improvement of the overall scale of the industry and the development of industrialization. To this end, the implementation plan of standardized mining design and industrial production process will become an important measure for the formalization and development of the industry. 4. Industrial upgrading and extension of the industrial chain On the basis of eliminating and closing the production capacity of the backward traditional sand and gravel mining industry, the industrial chain will be extended. Such as: commercial mixing, cement products, fine powder, ultra-fine powder and other products. Under the premise of improving production technology and product standards and raising the threshold for entering the industry, moderate development according to market capacity will be the embodiment of the mature, stable and well-won cycle development of the industry. Improving the resource allocation capacity and the efficiency of resource utilization in the production process, forming multi-level and diversified international trade and cooperation, increasing the international market share and improving international competitiveness will be the focus and foothold of improving the development level of the industry. 5. Scientific and technological progress and harmonious development The sand and gravel industry will be an important support point for leading the development of the industry in terms of scientific and technological innovation, technological progress, upgrading the scale of the industry and accelerating the transformation of the structural development mode. Take energy conservation, emission reduction and the development of circular economy as the main focus of industry development and progress, realize the synchronous development of green environmental protection and harmonious society, and realize the transformation and upgrading of the industry. Some domestic colleges and universities, such as Tsinghua University, Beijing Institute of Civil Engineering and Architecture, Tongji University, Nanjing University of Technology, South China University of Technology, Jimei University and many other scientific research institutes, have carried out in-depth research in this field. According to the "Twelfth Five-Year Development Plan for Building Materials Industry" organized by the Ministry of Industry and Information Technology and the "Twelfth Five-Year Plan" developed by the China Building Materials Federation, the China Sand and Gravel Association has formulated the "Twelfth Five-Year" development plan for the sand and gravel industry. The "Twelfth Five-Year Plan" development plan objectives of the sand and gravel industry: 1. Establish a stable, large-scale and modern sand and gravel industry supply base All parts of the country according to the reasonable layout of the establishment of sand and gravel production demonstration bases, industrial scale in the annual output of more than 1 million tons of sand and gravel large and medium-sized stable production enterprises and supply bases. In the whole industry, we will build dozens of "green environmental protection" demonstration enterprises with an annual output of 10 million tons. 2. Comprehensive utilization of renewable resources Research and develop the comprehensive utilization of renewable resources (such as waste rock, tailings, construction waste, etc.), and build supporting downstream products to reduce transportation costs and environmental impact. The total amount of solid waste in the comprehensive utilization and co-disposal of sand and gravel industry increased by 600 million tons compared with 2010. 3. Implement the industry access system and formulate corresponding standards Formulate the "Mechanism Sand and Gravel Industry Production Quasi-person System" and related series of standards, raise the quasi-person threshold, and strive to integrate the sand and gravel industry into the development track of the country's industrialized circular economy. 4. Promote the construction and development of green mines Implement green production methods, while mining, while regreening, so that the sand and gravel industry has become the main force of land reclamation and greening, and by promoting the construction and development of green mines, the scientific mining methods, environmental protection of production processes, intensive resource utilization, and standardization of enterprise management have been realized. Energy conservation and emission reduction, the development of circular economy. 5. Improve the overall level of crushed stone production technology and equipment In accordance with the national standards for sand and gravel products, improve the technical level of mechanical sand and gravel production. The level of the main gravel equipment and the whole machine equipment is close to or basically reaches the world's advanced level. 6. Carry out the establishment of an enterprise credit system Advocate the industry to stress creditworthiness and reputation, and carry out efforts to establish an enterprise credit system. Strive to establish the industry's credit system during the "Twelfth Five-Year Plan" period and play a role in the development and progress of the industry. Form a new pattern of international management of science, industry and trade integration and services, and improve the development of science, industry and trade. The market share and influence of the divination. Graded Sand Graded Sand and Gravel (G

aded sa

d) refers to the mixed materials used for basic or other purposes after mixing in a certain proportion, and its ratio is different according to the specific engineering design. If the design is not specified, reference can be made to the quota. According to the size, it can be divided into coarse sand, medium sand and fine sand. Cushion grading Natural grading refers to even sand and gravel. The artificial grading mix ratio is gravel (20mm-40mm): natural sand: water = 9.11: 4.97: 3 The graded gravel cushion should be dense and stable, and its particle size grading range meets the following table: The above two gradations are cushion layers The first one stipulates that the diameter of all particles cannot be greater than 50mm, in order to better meet the degree of compaction, it is recommended to choose the first one! In addition, in order to prevent frost heave and wet softness, attention should be paid to controlling the content and plasticity index of less than 0.5mm fine material. Graded gravel is sometimes used as a cushion called graded gravel cushion, and its graded gravel requires a particle size between 5-40mm, of which 25-40mm content is not less than 50%

Silica Sand Editor Discuss The main raw material for making glass, simply put, is silicon-containing sand, general sand contains silicon, and generally sand with more silicon content is a good raw material for making glass. Chinese name silica sa foreign name silica sa

d Uses The main raw material for making glass Good raw material Sand with a lot of silicon content is a good raw material for making glass Flat Pull Method In 1908, the Americans invented the "flat pull method" Table of Contents 1 Introduction 2 Development Introduction Edit Glass technology has experienced a history of more than 5,000 years, and it was not until the 20th century that glass became an industrial material and developed rapidly. In 1908, the Americans invented the "flat drawing method", and in 1910, the Belgians invented the "slotted vertical upward quotation method", which freed the production of flat glass from the blowing method that relied on heavy manual labor (see Ref. [1], p. 530). In 1924, the Pittsburgh Flat Glass Company (now PRG Company (1)) invented the vertical introduction method, which greatly improved the efficiency of glass production, and its impact was no less than the impact of the assembly line on the automobile industry (2). 1959 Pilki, England

gto

Company (3) invented the floating glass production process, which became a general process for the manufacture of high-quality flat glass. With the development of physics, chemistry and other disciplines, the composition and characteristics of glass have been gradually understood, which has created conditions for the research and development of glass and large-scale production. Today, people can not only use high-quality silica sand to produce optical glass, special glass, crystalline glass, medium-quality silica sand to produce flat glass, and secondary sand to produce colored glass, but also to research and develop and produce all kinds of special glass according to the needs of national defense and economic construction. Development China is a major glass producer, and its glass output ranks among the top in the world. The development of China's glass industry can be traced back to the Yaohua Glass Factory (the predecessor of China Yaohua Glass Group Corporation), which was established in Qinhuangdao in 1922. In 1971, Luoyang Glass Factory (now Luoyang Float Glass Group Company) invented the "Luoyang Float Technology", which created a new era of China's national glass industry. At present, China's glass and glass products industry (including architectural glass products industry, industrial technology glass manufacturing industry, optical glass manufacturing industry, glass instrument manufacturing industry, daily glass manufacturing industry, glass insulation container manufacturing industry and other glass and glass products industry) has developed into an industrial sector with relatively complete products. The national daily glass output is about 60,000 doors in 1999), the production capacity of flat glass of key enterprises has exceeded 200 million weight boxes (2000), and the output of flat glass has ranked first in the world for 13 consecutive years. In 2000, the total industrial output value of the glass and glass products industry (all state-owned and non-state-owned industrial enterprises with annual product sales revenue of more than 5 million yuan, the same below) was 42.829 billion yuan (constant price in 1990), an increase of 7.9% over the previous year, and the average annual employment in 2000 decreased by 5.8% over the previous year. , a decrease of 9.1 percent over 1998, initially showing the effect of reducing the number of employees in state-owned enterprises and increasing efficiency. Since the reform and opening up, foreign direct investment has played an important role in promoting the development of China's glass and glass products industry. In 2000, the proportion of state capital, Hong Kong, Macao and Taiwan capital and foreign capital was 51.8%, 21.0% and 27.2% respectively, showing the important position of foreign direct investment in China's glass and glass products industry. Compared with 1998, the state capital increased by 2.2 per cent, while the share of Hong Kong, Macao, Taiwan and foreign capital decreased by 2.0 per cent and 0.2 per cent respectively. On the basis of relevant research [2~3], this paper will analyze the international competitiveness of China's glass and glass products industry from three aspects: competitive strength, competitive potential and competitive environment.

Sea sand, as the name suggests, is sand and gravel in the sea. As the second largest marine mineral after oil and gas, sea sand has many uses, one of the most important uses is as a raw material for engineering construction, especially for large-scale land reclamation. Because the salt chloride ions in the sea sand will erode the steel bars, bringing potential safety hazards to the project. Therefore, as early as August 2004, the Ministry of Construction issued the "Opinions on Strict Management of Sea Sand for Construction". Chinese name Haisha Foreign name Sea sa

d Substance Sand and gravel in the sea Raw materials for engineering construction Nature Marine Minerals Hanyu Pinyin: hǎi shā Table of Contents 1 Explanation ▪ Marine Mineral Resources ▪ Another name for salt 2 Classification ▪ Construction ▪ Industry ▪ Ironmaking 3 Uses ▪ Glass sand ▪ Foundry sand ▪ Thermal insulation sand ▪ Grinding sand 4 Price skyrocketing ▪ Cause ▪ Governance 5 Latest policy 6 Building hazards ▪ Unqualified sea sand ▪ Illegal use of sea sand Explanation and editing Marine mineral resources It is widely used in urban construction. Sea sand is becoming the second largest marine mineral after oil and gas. Sea sand refers to the sand that has been eroded by seawater and has not been desalinated, mostly from the junction of seawater and rivers. Because the sea sand contains chloride ions, if this component exceeds the standard, it will have a serious corrosive effect on the steel bar when used in engineering construction after concrete mixing. To this end, in August 2004, the Ministry of Construction issued an "Opinions on the Strict Management of Sea Sand for Construction", which mentioned that the process of sea sand mining, desalination treatment, concrete mixing and other processes have strict regulations, and the sea sand used in construction projects must be specially desalined, if it is to be used, in reinforced concrete, the chloride ion content of sea sand should not be greater than 6 parts per 10,000. If we take 300 kg of cement as an example, then the content of chloride ions in concrete cannot be higher than 0.18 kg. Another name for salt Ming Li Shizhen's "Compendium of Materia Medica, Jinshi Five, Salt": "Fangshi calls salt as sea sand." According to the use, sea sand can be divided into the following types: Construction More than 90% of the total global production of sea sand is used as construction and civil engineering materials for sand making machines, of which 45% is used as concrete fine bone materials. In addition, about 20 percent of the sea sand is used for paving the roadbed, about 20 percent is used as land reclamation filler, and the remaining 15 percent is used for asphalt concrete. In Taiwan, since there is no complete sea sand survey, the plan for the use of sea sand and the relevant material specifications have been formulated, so except for some illegal mining and dredging of sea sand in harbor channels for civil engineering and construction projects, the existing sea sand development plans are all for land reclamation. In the case of the Changbin Industrial Zone, for example, it is estimated that more than 160 million tonnes of sea sand fill will be required by the time it is completed in 1998. The Yunlin Outlying Island Basic Industrial Zone requires up to 600 million cubic meters of landfill. Land reclamation activities are taking place in other coastal areas, and the demand for sea sand is set to increase significantly. Industrial industrial sea sand can be divided into silica sand, calcareous sand and heavy sand in terms of composition, although the output only accounts for about 10% of the total sea sand use, but it is extremely widely used. Ironmaking Iron-containing sea sand, obtained by magnetic separation. It is used in ironmaking and steelmaking. Such as Indonesian sea sand. There are four different names for different purposes. Glass sand Glass sand is the main raw material used in the manufacture of glass, and its particle size specification can refer to the standards of the American Ceramic Society, and the composition varies according to the type of finished product. For the purest optical glass, the silica content of silica sand must be greater than 99.8%, while the content of alumina and iron oxide must be less than 0.1% and 0.02% respectively. Foundry sand is used in the manufacture of steel and alloys of cast copper, lead and iron. The properties required for silica sand include adhesion, thermal insulation and permeability. Thermal sand is often used as a raw material for the manufacture of silicon bricks and tiles. Abrasive sand is mainly composed of quartz sand, which is used for sawing stone, glass grinding, metal polishing and sandblasting. Required characteristics include clean, hard, consistent particle size, and angular edges.