Three concrete filled high strength steel tubular columns are compressed by test.A finite element model is established to simulate the experiments and verified.Three design codes are used to calculate the strength of the columns and evaluated.
Experimental and numerical investigations on three large diameter concrete-filled high strength steel tubular (CFHSST) stub columns under axial compression were performed. The three large size steel tubes had the same dimension in the test. The outer diameter was approximately 550mm, the length was approximately 1000mm, and the thickness was approximately 16mm. The steel tubes were made of high strength steel Q550 and filled with C30 concrete. A 40,000kN press machine was adopted to apply the required axial compression to the three specimens. It was found that the load-displacement curves of the three concrete-filled high strength circular steel tubular stub columns were notably close to each other, and the ultimate capacities were approximately 30,000kN. Finite element analysis (FEA) was performed to analyze the stub columns, and the FEA results are consistent with the experimental results. The formulas from three types of design codes were used to calculate the column loading capacity, and the calculation results were compared with the experimental results. The results were close to the experimental results. The EC4 design code gives the most accurate estimations, with discrepancy less than 4% being observed.
Prices varies By State and Location . Due to increased prices on steel, the prices across the country have increased. We are working on updating the website. Call us at 1-800-244-4798 for the latest prices.
Concrete Steel Front Entry Garage 2840 is perfect with some oversized garage doors. Add your own, or get some roll ups, and talk to a rep about vertical sides, or residential for cost savings. Either way this garage is built to last for generations to come. Have something to past on to your grandkids. Lets make it happen! This is just one of the buildings weve done for our customer talk to a building specialist today about customizing yours call us at 1-800-244-4798.
We purchased a metal building in California using big building. We needed as built engineered drawings which did cost extra money and took about a month to make. After we received the drawings we applied for our building permit this was the most frustrating part of anything. Our building department took almost 90 days to accept our permit application. Then we needed to have concrete worked competed the nice thing is there was a detailed foundation page in drawings that we gave to our contractor for foundation work. The bad thing was he was backed up 40 days to be able to get out to us and do the work. Then we had to call and get on schedule and it took about 60 days from then to get the building. They actually finished putting up the building in 2 days the quickest part of the whole dang process. The building looks awesome panels are solid frame and truss system are solid. I'm not sure if everywhere else is that long of a process or just California just be prepared for going through hoops. Big buildings does not actually do permit application that is your responsibility so remember that. Big buildings made everything easy and was super patient throughout the process. Thanks again
The building turned out fantastic so glad we went with big buildings with this project. One thing to be aware of is your deliver time does not start till you actually have your concrete complete this took almost 2 months to complete because of permitting. Once we were on the schedule they gave us a call 1 week before they were going to install a building with a delivery window so they said it would be between 3 days. The install crew finally arrived and they got right after it. It was amazing to watch how fast they put up these structures. Once they finished we were thrilled with the work and paid the remaining balance.
Start to finish Were here, to give you the information you need, so that you can get the metal building of your dreams. From leveling your ground, to coaching on how to deal with your permit office, talking with contractors, or even erecting it yourself. All the way until the day you get the feeling of walking into that wide open building full of opportunity.
A concrete-encased steel pipeline should be calculated for a uniform internal pressure in the ring direction according to the scheme of a multilayer pipeline with consideration of the formation of cracks in the concrete.
In the limit state, limited plastic deformations of the pipeline materials, leading to some redistribution of forces in the rings and to the rational use of metal, are admissible. Here opening of cracks in concrete should not be greater than is allowed by the standards.
P. M. Ermoshkin and V. I. Katkov, Production of large-diameter high-pressure reinforced-concrete pipes, in: Building Materials Industry. Series 3. Precast Reinforced Concrete Industry [in Russian], VNIISM, Moscow, No. 2 (1986).
O. V. Mikhailov, S. A. Berezinskii, O. B. Lyapin, V. V. Lgalov, and N. A. Netsetov, Investigation of deformation of a full-size link of the concrete-encased steel pipeline at the Zagorsk pumped-storage station, Gidrotekh. Stroit., No. 3 (1989).
Technical Report. Assessment of the Seepage Regime and Stress-Strain State of Structures at the Zagorsk Pumped-Storage Station According to Data of On-Site Investigations in 1991 [in Russian], NII Gidroproekt, Moscow (1991).
Reinforced concrete is one of the most ubiquitous building materials in the world. On its own, however, concrete is actually much more brittle than you might expect, and hardly useful in any but a very few limited applications. When reinforced with steel, however, concrete can be used for slabs, walls, beams, columns, foundations, frames, and more.
Concrete is only strong against forces of compression and has low tensile strength and ductility. Reinforcement materials are needed to withstand shear and tensile forces on the concrete. Steel is used because it bonds well with concrete and expands and contracts due to temperature at similar rates.
When you dig deeper into the science of how steel and concrete behave individually, youll quickly see that their properties complement each other in ways that make them uniquely suited to be used together. Their combined properties are beneficial in ways that make reinforced concrete the wonder material responsible for impressive structures, like the Hoover Dam.
Concrete looks extremely strong. Its basically a rock you grow from a powdered formula. In some senses concrete is indeed very strong, but only if pressure is applied in one specific direction. When force is applied in any other direction, as is most often the case for most building applications, concrete is surprisingly brittle.
Concrete is strong against compression forces. This is why it is such a powerful base. Even in ancient times, Roman builders were able to use early forms of concrete (which was not reinforced in any way) for structures such as domes, aqueducts, arenas, and colosseums.
In all of these early examples, concrete was used only in ways that took advantage of concretes strength against compression forces. The weight of the structure only pushed down on the concrete, which pushed the concrete together, and which the concrete could easily support.
The fact that ancient Roman structures such as the Colosseum and the Parthenon have stood for thousands of years is a testament to concretes strength against compression. Even a cylinder made from a cement mix with a lot of water can withstand 1000 pounds (450 kilos) of compression pressure. Other mixes can withstand even more pressure.
When a cylinder made from the same high-water mixture of concrete described above was tested by hanging a weight from it, the sample broke when about 80 pounds (36 kilos) was suspended. This means that concrete is less than 10 percent as strong against tension forces as it is against those of compression.
It may not be immediately obvious why this is a problem for concretes use as a building material. It seems to only indicate that concrete should not be used as a rope. When you look at the internal stresses within the concrete, however, youll see that when there is compression, there is often also tension.
Imagine a horizontal concrete beam, on which pressure is applied down from the top. This would be similar to walking on a concrete 2nd story floor. On the top of the concrete beam, the force is compression, as the concrete is pressed together. On the bottom, however, as the beam bows, the concrete is pulled apart by a force of tension. This is where plain concrete fails.
As we can see, plain concrete is useful if you only apply weight directly down onto it, such as the base of a statue. Modern buildings, however, have to withstand pressure from many types of sources in all types of direction. Without reinforcement, plain concrete will simply fail under these conditions.
When plain concrete fails, it does so suddenly. One moment the concrete is intact, and the next moment, when the force is greater than the concrete can withstand, it crumbles or breaks into pieces. This sudden breaking is known as brittle mode failure.
The main disadvantage of this type of failure is that there are no visual warning signs. Unless you know the specific strength of the material and are actively measuring the amount of stress applied to the material (conditions which are absolutely unfeasible outside of a laboratory setting) there is no way of predicting failure.
Reinforced concrete, on the other hand, experiences ductile mode failure. This means that cracks begin to form before the concrete completely shatters. This is because though the concrete has been stretched further than it can stand alone, the steel rebar still holds the structure together.
If the structure is only subject to compressive forces (such as a slab of flooring) these cracks might not be a big deal. Unless water is likely to infiltrate the crack and undermine the structure by rusting the rebar or expanding the fissure when freezing, the cracks will simply be pressed together by further compression. In other situations, cracks signify the need to repair the area.
As weve learned, plain concrete is only useful in very limited applications because it is strong against compression forces, but weak against tension and shear forces. In order to be as versatile as it is, concrete needs to be reinforced by some material that overcomes these weaknesses. Steel is used to reinforce concrete more often than any other material.
Ductility is a measure of how much deformation a material can undergo before breaking. Concrete has very low ductility. If you twist a chunk of concrete with enough force, it will crumble in your hands. Wood, for example, is somewhat ductile, in that you can bend it a little bit before it will break. Steel, though, is highly ductile. If you bend it, it will simply stay bent.
Steel ductility is useful before the cement is poured because it can be bent into whatever shape will best support the form that is to be poured. Because of this, its easy to create a grid of reinforcing steel rebar in whatever shape is needed by the design of the building.
Steels ductility is also useful once it is a component of the reinforced concrete. When enough force is applied to the structure to deform it, the concrete may crack, but the steel rebar will maintain intact in the deformed shape. Often the steel is still able to support the structure until it can be repaired or replaced.
When solids are heated, the molecules within the materials move faster. These more active atoms take up more space the faster they move, so each molecule, and therefore the material as a whole expands. The opposite happens when a solid is cooled. The net result is that solids expand when heated and shrink in size when cooled.
While this is universally true among solids, it happens at different rates for different materials. In an extremely fortuitous coincidence, steel and concrete have very similar coefficients of thermal expansion. This means that when they are subject to heat (or cold) they expand (or shrink) at essentially the same rate.
If this were not the case, steel would be a poor choice to reinforce concrete. Imagine a corn dog, for example. If when cooked the hot dog doubled in size while the cornbread only grew a little bit, the hot dog would quickly burst through the cornmeal. Conversely, if the cornbread expanded quicker than the hot dog, there would be a large pocket of air around the cooked hot dog.
While either of these scenarios would result in a structurally weak corn dog, this is not what happens in the case of concrete reinforced with steel. The two materials expand and contract at nearly the same rate, ensuring that they stay bonded firmly at any temperature.
The bond between concrete and steel is so strong that reinforced concrete acts as a new, stronger material than simply the combination of concrete and steel. This is further enhanced by creating rebar that has plenty of ridges around which the cement will find solid purchase as it dries.
Because reinforced concrete is used in so many different situations, its often necessary to construct rather elaborate internal frameworks of steel rebar before pouring the cement. Even if the shape isnt unique, the size of the project may require rebar to span lengths far greater than can be feasibly manufactured.
In these scenarios, steel rebar can be welded so that the support is securely where it is needed. Steel is one of the most commonly welded metals as it melts easily without burning through or transferring heat too far from the weld site. This process also doesnt have any negative effects on the properties that make it such a good choice for reinforcing concrete.
Reinforced concrete is made to last for many years, making it a great building material for structures that are meant to last. When the time does come for deconstruction, though, you will be pleased to learn that it is also easy to recycle.
With the proper equipment, it is easy to pulverize reinforced concrete to separate the steel rebar from the concrete. The concrete can be further crushed and reused as part of the mixture of coarse and fine aggregates that make up 60 to 75 percent of cement mix. The steel can be melted down and reformed as new steel rebar to reinforce the next project.
It is rather fortuitous that the metal that has so many advantageous properties for reinforcing concrete is also inexpensive and plentiful. If it were gold or diamonds that had all of these compatible features, it probably wouldnt be as helpful.
As strong as reinforced concrete is, it is still possible for it to crack. While this ductile mode of failure does not immediately result in the structure collapsing (as brittle mode failure would), it is the first phase in a destructive process known as spalling.
1. Because liquid can fill any pocket it is allowed into, it is easy for water to seep into and fill any cracks in the reinforced concrete. If the temperature, then drops below 32 degrees Fahrenheit (0 degrees Celsius) it will freeze.
When water freezes it does so by forming a structure of interlocking ice crystals. These ice crystals take up more space than liquid water molecules, meaning that ice takes up more space than water. This means that as the water freezes, it pushes on the concrete and expands the cracks even wider.
When the ice then melts, the crack is wider, allowing more water to fill the gap, which then freezes to expand even further. This cycle not only physically pushes the concrete apart, but it allows more and more water to penetrate the structure, increasing the amount of damage caused by the other 2 forms of damage.
2. Eventually the cracks will be wide and deep enough for water and air to reach the steel rebar embedded in the reinforced concrete. This exposure can result in the rebar rusting. In the presence of water, oxygen from the air interacts with the iron in the steel to form rust.
The flaky coating on the surface of the rusting rebar does nothing to protect the interior layers of iron from the corrosion process (the way that the formation of a layer of patina prevents the further corrosion of copper surfaces), so the rebar can be continually degraded until it can no longer withstand the tension forces acting on the structure.
A telltale sign that this type of corrosion is happening is if the concrete appears to be stained brown. This color comes from particles of the rust turning the water brown and draining through the cracks in the reinforced concrete.
3. When water infiltrates the reinforced concrete, it can alter the pH balance of the environment and cause chemical reactions within the concrete. This risk is heightened by the fact that on road surfaces and bridges the use of salt to de-ice roads in winter means the infiltrating water is more likely to be highly alkaline.
These alkalines in the water can react with the silica in the concretes aggregates to cause the formation of new crystals. These new crystals take up room and physically force the reinforced concrete apart in the same way that the freezing ice did in example 1. The difference is that the crystals do not melt, so the concrete is pushed apart continuously.
Clearly, it would be better if reinforced concrete isnt allowed to crack. Because steel is so ductile, however, it will stretch or bend, allowing the surrounding concrete to crack. This is, of course, unless something is done to prevent the steel from acting this way.
In order to prevent cracking, steel rebar can be stretched before the cement is poured. This is known as prestressing (or pretensioning) because it adds tension force to the steel before the reinforced concrete is formed. By doing this, the steel then is in a constant state of pulling itself back toward its natural shape, pulling the surrounding concrete inward, a compression force.
The same effect can be achieved by tightening the steel after the concrete has begun to harden. Concrete seems to harden in a matter of hours, but it actually takes about a month to properly cure and continues to harden and strengthen for at least five years after it is poured.
Not only does prestressed and post-stressed concrete result in less cracking, it is actually so much stronger than regular reinforced concrete that smaller and thinner sections of prestressed or post-stressed concrete can carry the same load as unstressed reinforced concrete.
As you look at the specifics of how reinforced concrete works, you may begin to wonder why we are bothering to use concrete in the process at all. Concrete, after all, is only strong against compression forces, whereas steel is strong against:
Plain concrete is not very useful on its own. Its only reinforced concrete, and preferably prestressed (or post-stressed) concrete that is the wonder building material we think of when we picture modern architecture. Since concrete is actually relatively useless without its steel reinforcement, then, why not just build with steel?
As weve seen, when steel is exposed to air and moisture, it rusts. While treatments exist to prevent this oxidation, they require far more maintenance than is feasible. Steel rebar, for example, is often treated before the cement is poured to protect it from the elements, even though it will soon be encased in concrete. Even so, as weve seen, it still can rust.
Concrete, on the other hand, is fairly resistant to corrosion. Cracks must first form, and it often takes several years of water infiltrating, freezing, and refreezing in order to compromise the structural integrity of the reinforced concrete. As long as regular inspections are performed, this gives ample time for the corroding section to be repaired or replaced.
Steel is very heavy and would need to be transported to the construction site in full. Concrete, on the other hand, is about a third as dense as steel, and can be transported in its far lighter composite parts.
The benefits of this is twofold. The first benefit is transportation. Steel would need to be transported to the construction site and then welded together to form the structure. This would be very costly as steel is heavy. Concrete, on the other hand, can be transported much easier as its composite parts, then mixed and poured on site, hardening into the final form.
The second benefit is the weight of the final structure. Because concrete is a third as dense as steel (and even contains as much as 5 to 10 percent trapped air) the total weight of a building made of reinforced concrete is much less than one made entirely of steel. Reinforced concrete is typically about 1 to 4 percent steel, so it ultimately weighs a lot less.
Steel, though relatively cheap and abundant, is a lot more expensive than concrete. It simply makes sense to reinforce concrete with steel because you can get the benefits of steels strength while retaining the low cost and ease of use of concrete.
While the use of early forms of cement have been documented in ancient cultures that date back many thousands of years, it was the ancient Romans who introduced the earliest form of concrete as we know it today. While quarrying limestone for mortar, the Romans accidently discovered a silica and alumina bearing mineral on the slopes of Mount Vesuvius.
When mixed with limestone and burned, it produced a cement that could in turn be mixed with water and sand to produce a mortar which was harder, stronger, and more adhesive than ordinary lime mortar. This mixture could harden under water as well as in the air, much like concrete today. In 2000 BCE the Romans used a type of concrete called pozzolana, which used volcanic ash, to build the Colosseum and Pantheon in Rome.
Then, from about 400 to 1750 CE, there is no evidence of the use of concrete. This effectively became the Dark Ages of concrete, which spanned from the fall of the Roman Empire until an English engineer, John Smeaton, rediscovered how to make hydraulic cement when building a lighthouse in Plymouth, England.
Reinforced concrete was invented and patented by Frenchman Joseph Monier in 1867 CE, but he only applied the technique to cement flowerpots. Reinforced concrete didnt become a widely used building material until twisted rebar and prestressed concrete were developed in the 1880s.
The first concrete road was poured in 1891 in Bellefontaine, Ohio. The Hoover Dam, the biggest concrete structure ever attempted up to that point, was built in 1936. American architect Frank Lloyd Wright built many iconic concrete buildings in the 1950s. Brutalism, an architecture style that emphasized exposed concrete, was popular from the 1950s to the 1970s.
Concrete is an amazing building material that was discovered thousands of years ago, then forgotten. It is an incredibly useful building material because it can be mixed from powder to create stonelike structures of any shape.
Its usefulness is limited, however, by the fact that concrete is only strong against compression forces, and crumbles easily when subject to tension and shear forces. By reinforcing concrete, however, you can create a material that is much stronger than its components. Steel is particularly well suited as reinforcement because it bonds well to concrete and expands at the same rate.
When combined, steel and concrete form a new building material, reinforced concrete. This new material is more useful than either of its individual components on their own because it combines the strength of steel with the ease of use and relative low weight of concrete.
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Concrete and Steel are one of the most common construction materials even in today, Steel Structures Vs Concrete Structures is an attempt to compare advantages and disadvantages of both materials from constriction and maintenance point of view.
Concrete is the second most used material for construction after water in the world. Concrete structure can take compressive stresses very effectively but it cannot take tensile stresses. So the reinforcement is given to concrete where the structure is under the tension load. Concrete is widely used in today construction industry today because of its durability and compatibility. Moreover concrete can be mould in any shape which make it a very useful.
Plain cement concrete is a hardened mass obtained from a mixture of cement, sand, gravel, and water in definite proportion. The concrete structure made by using the plain cement concrete has good compressive strength but very little tensile strength, thus limiting its use in construction. Plain concrete is used where good compressive strength and weight are the main requirement and the tensile stresses are very low. For eg: In roads, concrete blocks for walls, etc
Plain cement concrete has very low tensile strength. To improve the tensile strength of concrete some sort of requirement is needed which can take up the tensile stresses developed in the structure. The most common type of reinforcement is in the form of steel bars which are quite strong in tension. The reinforced concrete has innumerable uses in construction. For eg: in building, flyovers, water tanks, etc.
In ordinary reinforced cement concrete, compressive stresses are taken up by concrete and tensile stresses by steel alone. The concrete below the neutral axis is ignored since it is weak in tension. Although steel takes up the tensile stresses, the concrete in the tensile zone develops minute cracks. The load carrying capacity of such concrete sections can be increased if steel and concrete both are stressed before the application of external loads. This is the concept of prestress concrete.
The prestressed concrete is uses in the structures where tension develops or the structure is subjected to vibrations, impact and shock like girders, bridges, railway sleepers, electric poles, gravity dam, etc.
The material steel, is an alloy of iron and carbon percentage (small percentage) and other elements e.g. silicon, phosphorous and sulphur in varying percentage. Depending upon the chemicals composition, the different types of steel are classified as mild steel, medium carbon steel, high carbon steel, low alloy steel and high alloy steel. The mild steel, medium carbon steel and low alloy steel are generally used for steel structures.
The steel which is used for the manufacture of rolled steel structural, fastenings and other elements for use in structural steel works is called structural steel. Structural steel to be used for building purposes, has been standardized by Indian Standard Institution (I.S.I)I and specification of various qualities are contained in the following standards(as per I.S 800-1984)
The rapid development of urbanization has resulted in the accumulation of a large amount of waste concrete, which not only occupies land resources but also pollutes the air and the environment. Therefore, the recycling of waste concrete has become an important issue that the government needs to solve.
Abandoned concrete blocks are high-quality concrete aggregates which have many advantages. For example, after the buildings are dismantled, the high-quality concrete blocks and silt after crushing and screening can be used as recycled coarse and fine aggregates for concrete. The fine powder can be directly used as the raw material of cement. The concrete prepared from recycled cement and recycled aggregate can enter the next cycle, which realizes zero waste discharge throughout the whole cycle.
Concrete, cement and other wastes in construction waste can be used as building aggregates and recycled brick raw materials after being reasonably crushed, screened and crushed. And the main equipment used for crushing concrete can be divided into two types: traditional fixed crusher and mobile concrete crusher, among which small crushing equipment is favored by users.
Although the compressive strength and hardness of concrete are not high, due to the porosity and the formation type, the concrete has good toughness and can buffer the crushing force, which causes low crushing efficiency. So, what kind of crusher should be selected for concrete crushing? In the process of crushing waste concrete, according to the working principle of more crushing and less grinding, it is necessary to carefully configure the concrete crusher equipment.
Jaw Crusher, also known as concrete crusher, is usually used as the primary equipment for concrete crushing. It is also suitable for metallurgy, mining, construction, chemical, water conservancy and railway sectors, and used as a device for fine and medium crushing of ores and rocks with compressive strength below 250 Mpa.
In recent years, the small jaw crusher has been favored by foreign users because of its small size, easy transportation and installation, low price, and fast profit. The models like PE-150250, PE-200350 and PE-400600 have become the best choice for customers to crush concrete.
After the rough breaking, steel and iron equipment are added to remove the steel bars and iron blocks in the waste concrete, which will eliminate the damage of steel bars and iron blocks to the equipment without affecting the production. Generally, the impact crusher, the fine crushing jaw crusher or the cone crusher is used as the secondary crushing to crush the material to less than 2 cm, and the selected granularity can be basically achieved.
For smaller discharge sizes, a three-stage crusher can be used, for example, the fine crushing crusher or the roller crusher is used to further crush the ore to less than 10 mm. In the actual production, the suitable crusher can be selected according to the size of the concrete block. It can be combined in single or multi-machine operations, both of which have the characteristics of simple operation, strong controllability and high production efficiency.
In the international environment of the crusher industry, besides the traditional jaw crusher, high-efficiency and environmentally-friendly construction concrete crusher will be the trend of future development.
In view of the characteristics of concrete waste, Henan HXJQ Machinery designed a concrete crushing equipment-mobile concrete crusher. The waste concrete after crushing can be used for reinforcing the foundation, producing bricks, cement, etc, not only achieving its values but also solving the issue of land and environment problems, which can be described as two-fold.
The mobile concrete processing station produced by HXJQ Machinery adopts multi-stage combination mode, which includes jaw crusher, impact crusher, cone crusher and vibrating screening equipment, conveyor belt, etc. Generally, the concrete crushing station is composed of a concrete crusher (sand making machine), a screening machine, a feeder, a conveyor belt, a steel frame, a drive system, an electric control system, a motor unit and the like.
The concrete material is sent into the crusher by the feeding equipment, and the crushing machine converts the large concrete into gravel. The finished product which meets the standard is transported by the conveyor belt to the stacking place, and the products which don't meet the standard will be transported by the other conveying belt to the crusher again until it is qualified.
The integrated vibrating screen, feeder and the under-belt conveyor, the vibrating screen and the crusher integrated into the vehicle can reach any position on the working site under any terrain conditions. Thus the mobile concrete crusher has many advantages like reasonable material matching, smooth flow, reliable operation, convenient operation, high efficiency and energy saving.
1. According to the driving way, it is divided into tire type and crawler type: the tire type concrete crushing and sorting machine needs semi-trailer traction to run, while the crawler type can be remotely operated with buttons. Relatively speaking, the latter is more intelligent and the price is more expensive.
2. According to the function, it is divided into crushing type and sand making type: the concrete crushing and screening machine includes a combination of crushing equipment such as jaw crusher, cone crusher and impact crusher. The sand making type is mainly equipped with sand making machine and hammer sanding machine.
The mobile crushing station can prevent and control environmental pollution, improve the ecological environment, and protect natural resources. The size and model can be designed according to the different production needs of users. According to the statistics of the HXJQ machinery, the small mobile crusher is chosen by more foreign users because of its reasonable price, high quality, convenient transition, operation and maintenance.
A project introduction of construction concrete treatment: in October 2018, a customer found HXJQ, and hoped that we could provide him with the complete equipment for breaking construction waste. Our technical manager quickly contacted him and learned that the customer had a large amount of construction waste to be disposed of.
From the perspective of economic foundation and practical operation, the technical manager recommended the fixed crushing station to him and designed a complete set of equipment suitable for his actual needs. In the end, the customer introduced the PE-400600 jaw crusher and PF-1010 impact crusher produced by our company to break the concrete waste. The finished sandstone is used for brick making, roadbed materials, etc., and the separated steel is recycled.
The pretreated concrete with reinforcing steel is sent to the jaw crusher for initial breakage by the conveyor belt, then effectively separated by the iron remover, and sent to the impact crusher for fine crushing. The crushed material is sieved by the vibrating screen. The finished material is output by the conveyor. If the material does not meet the specifications, it will continue to return to the impact crusher and break again.
The development and utilization of waste concrete as a recycled material solves the problems of a large amount of waste concrete treatment and the resulting deterioration of the ecological environment; on the other hand, it can reduce the consumption of natural aggregates in the construction industry, thereby reducing exploitation of the natural sand and gravel, which has fundamentally solved the problem of the depletion of natural aggregates and the destruction of the ecological environment because of the lack of sandstones.
Under this circumstance, the crusher plays an irreplaceable role in the recycling of materials. Whether it is the traditional fixed crusher or the latest mobile crusher, both of them have their own advantages. As long as the size of the stone produced by the equipment can meet the standard, it is a good crusher.
The failure mechanism of the soft roadway was revealed.A reasonable numerical method for concrete-filled steel tubular (CFST) support was proposed.An innovative support technology based on the CFST support was proposed for the soft roadway.
Large deformation control of soft rock roadway is a major challenge for the safety of mining production. Herein, a well-documented case study of a soft rock roadway is presented regarding its large deformation mechanism and the corresponding control technology. The failure characteristics of the studied roadway under the original support scheme were analyzed in detail, and the large deformation mechanism was discussed combining the geological conditions, rock mass properties and the original support scheme. A reasonable numerical method for concrete-filled steel tubular (CFST) support was proposed, and the bearing performance of the inclined-wall arc arch CFST support was analyzed. Then, a modified combined support scheme composed of bolt-cable+mesh+shotcrete and CFST support was proposed and validated by numerical analysis and field application. The results show that there are three main reasons resulting in the large deformation of the background roadway, which are: the contradiction between high in situ stress and broken surrounding rock, the contradiction between high clay mineral composition and poor disintegration resistance, and unreasonable original support scheme with low bearing capacity. The monitoring data obtained from both numerical analysis and field application show that the modified combined support scheme was effective for controlling the large deformation of the studied roadway. This work can provide some helpful guidance for similar projects.