Corrosion of steel in reinforced concrete
Today I want to continue talking about the durability of concrete, specifically about the corrosion of steel in reinforced concrete. How does it work?...
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Today I want to continue talking about the durability of concrete, specifically about the corrosion of steel in reinforced concrete. How does it work? For what is this? How to avoid it? In this article, you will find everything you need to know about this aspect.
Electrochemical corrosion of the reinforcement
As I have already mentioned, this corrosion occurs through an electrochemical or galvanic mechanism caused by the presence of water and oxygen inside the concrete.
On the other hand, this process is influenced by different factors :
- The characteristics of concrete.
- The 'cover thickness ', ie the distance between the steel bars and the concrete surface.
- The temperature. The higher the temperature, the faster the oxidation process.
- The presence of chlorides, which accelerates the process.
Depassivation of the concrete reinforcement
Generally, the steel in concrete tends to passivate due to the alkalinity given by portlandite or CaOH2 from the hydration of the cement and its alkalis.
However, this passivation can be lost for a number of reasons:
1. CARBONATION
In carbonation, atmospheric CO2 penetrates the air-filled capillaries of the concrete and reacts with calcium hydroxide, giving rise to calcium carbonate. The pH of the concrete must be between 12'5 and 13'5 to properly protect and passivate the reinforcements inside. The presence of calcium carbonate lowers the pH of the medium that surrounds the steel bar to values close to 9, resulting in a more acidic medium than it should and that begins to cause a constant, uniform, and progressive corrosive effect of the steel.
The time required for the penetration front of the CO2 to reach the steel bars depends on the porosity of the concrete, the thickness of the coating of the steel bars, and the humidity of the air.
2. CHLORINE IONS
Chloride ions destroy the passivating layer of the steel in a specific way, giving rise to pitting corrosion that spreads in-depth, being able to section the bars and especially the prestressing wires, which are thinner and with a more delicate crystalline structure. This is why the maximum chloride content is limited to 0.4% in reinforced concrete and 0.2% in prestressed.
In a strict sense, the critical content of chloride s depends on the degree of carbonation of the concrete and the relative humidity of the environment. For corrosion to occur, there must be a significant drop in pH so that the steel remains depassivating, and this drop may be caused by the presence of acidic substances in the concrete.
Measures to avoid the corrosion of the armor
As measures to be taken against the corrosion of steel reinforcements, it is worth highlighting:
- Use good concrete with quality components, with a cement dosage above the minimum and with the maximum water/cement ratio indicated by the instructions.
- Give a suitable coating thickness to the steel bars depending on the environment in which the structure is located and respecting the minimums indicated in the instruction.
Today I bring an article a little more technical than the previous ones but that I think cannot be missing in a blog on this subject. It is concrete, that material that we civil engineers like so much for its excellent resistance properties and relatively low price.
However, as those of you who are involved in the construction world will already know, concrete has a great weakness. The tensile strength of concrete is much lower than its compressive strength, around 10, and limits, in many cases, the use of this material.
How can we alleviate this defect? Here I leave you some brushstrokes of the most common methods to solve this problem so characteristic of concrete.
This article is part of a series on concrete tensile strength. Here you have the other two articles in case you are interested in consulting them:
- Direct tensile tests of concrete
- Indirect tensile tests of concrete
Reinforced concrete
Assembling the concrete is undoubtedly the traditional method par excellence. It is about integrating the properties of "plain" concrete and reinforcing steel. Both materials must work as one, so it is necessary that they be intimately united and interact through the adhesion forces that develop on their contact surfaces.
That is why the surface of the steel must be rough (corrugated steel rods) and the concrete must be vibrated after being placed in the molds.
Steel, unlike concrete, has similar mechanical characteristics both in tension and compression. When faced with tensile stresses, concrete cracks easily, ceasing to resist. The steel prevents collapse from occurring, joining the two "pieces" and resisting those tensions that concrete is unable to resist.
Prestressed concrete
This concept is newer and more complex than that of reinforced concrete. Any beam is subjected to two main loads: its own weight and external loads. As a consequence, some fibers in the section are betrayed and others are compressed.
Due to the characteristics of concrete, the compressed fibers will work properly, on the other hand, the tensile fibers will do so relatively inefficiently (similarly to what happened in the case of reinforced concrete).
To solve this, in the prestressing a state of initial compressive stresses is created in such a way that future tensions are reduced to values that can be assumed by the concrete or simply disappear.
In this way, concrete is subjected to two systems of forces:
- One caused by internal forces caused by prestressing
- Other caused by external loads and own weight
As a final note, it should be noted that the prestressing action is more efficient, it is placed eccentrically with respect to the centroid of the section. But be careful, since an excess of eccentricity could produce the opposite effect and that the concrete would crack on the opposite side only under the force of the prestressing.
Fiber-reinforced concrete
The last method is based on the incorporation of a certain proportion of fibers in the concrete to improve its properties. The fibers improve some characteristics such as toughness, control of the cracking process, and flexural strength.
Therefore, the brittleness of the concrete is reduced and there is a "stitching" effect of the cracks, reducing the opening of the cracks. The most commonly used fibers, in descending order, are steel, glass, and polypropylene.
And this is the most basic of the basics. Without a doubt, an essential in a blog like this. In any case, this is just a contact that I hope will serve the curious or those who are starting in this world.
Tension concrete, how to solve it?
Today I bring an article a little more technical than the previous ones but that I think cannot be missing in a blog on this subject. It is concrete,...
Is there a way to connect a new reinforced concrete slab on an existing reinforced concrete beam, given that the beam doesn't have steel dowels to connect with?
Yes its possible, but I agree with Greville Wood’s answer and genuinely don’t think he is touting for work.
Depends on the loads involved and connecting to the existing set concrete needs specific techniques and materials. Plus you won’t know the reinforcement on the existing beam. It’s a recipe for an expensive mistake.
The safest way is to break back the concrete to establish what reinforcement exists, that way you can physically reconnect to the existing concrete providing it hasn’t degraded or spalled.
The existing concrete will have to be primed and the new concrete replaced, not always easy. The new concrete may have to be polymer modified. That why it is best to check with an engineer.
SNRN 4/07/2021 Admin Bandung Indonesia
Is there a way to connect a new reinforced concrete slab
Is there a way to connect a new reinforced concrete slab on an existing reinforced concrete beam, given that the beam doesn't have steel dowels...
The main principle is that concrete has strong resistance to compression failure therefore it is strong in compression however it is weak in tension resistance to bending that is why steel compensates this weakness hence its strong in tension Having more percentage than the specified will cause the concrete to act as steel structure which is basically is not steel aimed structure besides that the area occupied by more reinforcement will weaken the concrete to act in compression resistance and punching shear and brittle failure may occur especially in the perpendicular structure such as columns at the time of ultimate strength, in conclusion, the standards have undergone plenty of experiences by experts to bring forward simple references for a designer I hope you have gained insight hints.
Rebar or reinforcement is expensive. Using more than recommended will be uneconomical. Moreover, providing adequate spacing between the rebars will be difficult. IS 456:2000 recommends minimum and maximum spacing which has to be fulfilled.
One more disadvantage of providing excess rebar is that the placement of concrete will become difficult. The concrete should be placed uniformly in the framework which would be affected by the presence of excess rebar.
Then the concrete will fail first, which is a brittle material so you will not get any warnings of failure beforehand, which means a sudden failure without warning and it can therefore cause loss of lives… this is a very unwanted situation. The rebar should be below a certain limit so that when the failure will happen, the rebar will start to fail, which is a ductile material so it gives a warning before the collapse and can save lives.
What will happen if we use too much rebar in concrete?
The main principle is that concrete has strong resistance to compression failure therefore it is strong in compression however it is weak in tension resistance...
There is no difference between ‘T’ rebars and ‘H’ rebars, as they both refer to high tensile steel. The letter ‘T’ comes from older codes of practice and ‘H’ is the more modern or current standard. Always use H to avoid confusion with T = Top and B = Bottom. So for example:
5H10 T&B means five 10mm diameter rebars top and five 10mm rebars bottom of the slab or beam. Also you can place two lines above one another as so:
4H16 T
4H25 B
Which would be a common way of showing a beam had different bar sizes top and bottom.
Note that the grade of rebar should be specified in your calculations and drawings using the tensile strength and ductility grade, B500A, B500B and B500C.
What is the difference between T rebars and H rebars?
There is no difference between ‘T’ rebars and ‘H’ rebars, as they both refer to high tensile steel. The letter ‘T’ comes from older codes of practice...
Rather than advising you on which brand of cement to be used, I would advise you on the type of cement to be used because that plays an important role in the quality of construction
For plastering works, use blended cement like PPC or PSC. These cement have less heat of hydration. That means during the cement reaction with water, they produce less heat. Less heat means less cracks on the wall surface. Less cracks and less porosity will decrease any water seepage.
As far as brand is concerned, most of the brands provide cement of good quality these days. You can go with the brand that is locally well known and gives you the best rate. Big brands claim huge premium and it is not worth a value for individual house constructions.
As different stages of construction require different types of cement, Understanding the types of cement, its substitutes, and the availability of local brands should empower you to choose the right cement required for your work thus avoiding any concerns on the availability of cement.
As Cement has a limited shelf life and loses strength over time, cement should be best consumed within a month or at most within two months of its production. The rate at which cement loses its strength depends on the storage conditions.
Which is the best cement used for plastering?
Rather than advising you on which brand of cement to be used, I would advise you on the type of cement to be used because that plays an important role...
That depends on what country you are in. It is specified in different ways. Hopefully, that will come out in other answers, rather than just assuming that we are all in the same plot of land (as is usually the case on Quora). Note also that the way one country does it is not necessarily the best, regardless of how much they puff out their chest or point to their population size.
Grading of Concrete.
Grading of concrete can be defined as the designation of concrete based upon its strength and mix characteristics for its use. In this designation, concrete is graded as M10, M15, M20, M25, and so on, where M specifies the mix and the number corresponds to the strength of concrete after 28 days in N/mm^2. These grades also represent the ratio of aggregates to be used with respect to the cement. Some of these mix ratios are as follows
M10-(1:3:6)
M15-(1:2:4)
M20-(1:1.5:3)
M25-(1:1.2.2.4)
For gaining concrete strengths above M25 design mix has to be prepared as per the standards.
As per IS 456 2000 Concrete Grades are denoted by M10 M15 M20, M25, etc where M refers to Mix and Number stands for the Compressive strength of Mix attained in 28 Days
As per the mix, the density varies, the higher the grade higher the density. As concrete is a versatile structural building material, made by mixing cement, aggregate, and water
The proportions of cement, fine and coarse aggregate are important if satisfactory concrete is to be produced.
here comes the importance of Grading refers to the determination of the particle-size distribution for aggregate (Which includes Fine and Coarse). Grading limits and maximum aggregate size are specified because these properties affect the amount of aggregate used as well as cement and water requirements, workability, pumpability, and durability of concrete.
The strength is derived mainly from the bonding of particle to particle by the hardened cement paste
SNRN 4/04/2021 Admin Bandung Indonesia
What is the grading of concrete?
That depends on what country you are in. It is specified in different ways. Hopefully, that will come out in other answers, rather than just assuming...
Concrete is one of the most used construction materials in the world today. It can be placed in forms to create almost any shape or placed in flat slabs thousands of feet long and inches or feet thick, it can be structural columns and beams supporting tall buildings or bridges, or it can be the hull of a boat that floats underneath the bridge and out to sea.
Concrete is a mixture of cement, usually Portland cement, coarse and fine aggregates (think of coarse as gravel and fine as sand, though other materials may be used). When cement is mixed with water and the appropriate aggregates, it becomes plastic (fluid), and it is placed in forms (molds) to create the shape the user is building. Hydration, a reaction between the dry components of the cement and water causes the concrete to set up, or harden into a stone-like material that is the foundation (literally) of the construction industry today.
Other answers concern themselves with the change in the water to cement ratio if rain occurs before the concrete has set. Having placed and finished concrete for many years, I haven’t seen that happen unless the rain comes while the concrete is being placed. As soon as the concrete has been screeded and bull-floated, the paste is pretty much established, in fact, the process of bull floating is partly to raise paste to the concrete surface. While hard, driving rain or long sustained rainfall may disturb the paste, it doesn’t penetrate through the top layer of the aggregate unless the surface isn't sloped enough for the water to run off.
Ideally, if you expect rain, you will cancel the concrete placement. If you are not able to, then plan on covering the concrete with plastic sheeting as soon as possible after placing and floating the concrete. Uncover the concrete only if it begins to set too hard for adequate finishing, or if the rain passes by. Failing to cover the concrete may allow the cement paste to wash away, leaving very little workable material to finish, but trying to finish the concrete while water is standing on the slab will certainly allow the water to work into the concrete, and this will weaken it.
Keep in mind that the hydration process that causes concrete to set produces heat, so covering the slab while the concrete is wet may cause the set to speed up, and if the concrete remains covered until the concrete begins to set quickly, it will be difficult to achieve an acceptable finish.
What happens if it rains after you pour concrete?
Concrete is one of the most used construction materials in the world today. It can be placed in forms to create almost any shape or placed in flat...
A home's form and exterior construction have a significant impact on its energy quality. The height, width, and depth of the structure are all included in the shape. These are also known as the footprint of a house. The walls, roof, windows, doors, and cladding make up the external frame, also known as the building envelope. A home's footprint and envelope may either make it more energy-efficient or cause it to use more energy. Easy or uncomplicated shapes are more energy-efficient to heat and cool than homes with complex or irregular shapes.
Along with the form and envelope of a house, the location and orientation of a home must also be considered. The home's relationship to the land, the sun, and the wind would have a significant impact on its overall energy performance. The east and west orientations should be carefully considered since these exposures would have a more substantial solar heat gain in hot climates.
To minimize solar heat gain, fewer windows should be installed in east- and west-facing walls. Furthermore, the home's narrowest elevations should face these orientations to minimize wall exposure to the summer sun while allowing the low angle rays of the winter sun to warm the southern exposure when required in cooler climates. Consider the cold prevailing winds and orientation, as well as landscaping and windbreaks, in cold climates.
SNRN 4/04/2021 Admin Bandung Indonesia
Does the structure of the building affect the temperature inside the house?
A home's form and exterior construction have a significant impact on its energy quality. The height, width, and depth of the structure are all included...
Sandcrete is a weak mortar-like building material with little compressive strength and zero tensile strength. I used it in Hollywood in a breakaway wall effect.
Concrete has more cement which is the glue that binds the rock aggregate and sand into concrete. It has lots more compressive strength but still not a lot of tensile strength.
So to make a strong column, vertical steel rods in compression are kept from blowing out with horizontal tension bands. In a horizontal beam or slab, the top chords of steel are in compression, but the bottom ones are being pulled in are in tension. The steel is ductile, which means it can flex with the concrete and it adds that critical tensile strength allowing us to create mighty bridges.
What is the difference between sandcrete and reinforced concrete?
Sandcrete is a weak mortar-like building material with little compressive strength and zero tensile strength. I used it in Hollywood in a breakaway...
Machine excavation and material extraction
Once the stakeout is done, the machine proceeds with the excavation of as much earth as possible.
For this purpose, the total amount of earth to be excavated will be calculated by means of topographic plans and the projection of the new building. This volumetric computation is performed when there is a topographic survey of the terrain under analysis.
Contract and measurement method
The excavation of virgin earth material and the respective extraction and hauling off the ground consist of a single item within the unit price analysis.
The earth excavation contract with the contractor will then be based on the projected volume. This projected volume must be multiplied by a swelling factor according to the type of terrain to be excavated.
- 10% swelling for loose terrain
- 15% for compact sand
- 20% to 25% for clays and clays with gravel
- 30% to 40% for rocky material
- 20% to 70% for demolition debris
Many times when the projected volume is not available, the earth extraction contract is made by machine on the number of dump trucks that leave the land. However, under this model, there is no amount calculated a priori that allows a budget for the work to be made for the excavation item.
Excavation by hand
Excavation by hand is done after all the earth excavated by machine has been removed. This type of excavation (by hand) is carried out for the footings and retaining walls sector.
Although a certain percentage of footing excavation can be done by machine, care must be taken that the machine does not exceed the footing offset depth, since if this happens, the accidentally excavated soil would have to be filled in and compacted, running the risk. that the compacted soil does not remain the same as the naturally consolidated soil.
Although a certain percentage of footing excavation can be done by machine, this excavation must be fully budgeted as if it were by hand. This is because the volume that the machine will help excavate the pit where the footing will go cannot be estimated and in the end, the profiling of the hole must always be done by hand. Therefore, the worst case is adopted, which is that everything is excavated by hand.
Types of excavation by hand
Soft ground excavation
As its name says, it is the excavation of organic soil, sand, or loosely compacted clay.
Hard ground excavation
It consists of the excavation of overconsolidated clay soils or gravelly and rocky soils. This type of excavation is more expensive than the previous one.
Excavation with exhaustion
In cases where the water table is high, and when excavating water must be pumped to allow the workers to work, this pumping must be included in the excavation costs.
Excavation at high depths
There is another type of excavation at high depths where more than one person is already needed to accomplish the job, as well as equipment such as ladders, shirts or rings to support the ground, and even winch, depending on the amount of material to be extracted.
Filling and compacting
Finally, for metric computations, the filling and compaction of the earth must also be measured, referring to the voids to be filled after the foundations have been emptied.
Soil excavation by machine and by hand
Machine excavation and material extractionOnce the stakeout is done, the machine proceeds with the excavation of as much earth as possible.For this purpose,...
It consists of the adaptation of the construction environment to the minimum needs for habitability and work
In this sense, the installation of works is carried out by building temporary environments of different use according to the needs of the construction.
- The most commons are:
- Deposit
- Porter or Caregiver Room
- Bath
- Environment or cover for tools and clothes of Workers
- Perimeter fence
Finishing and improvisation of environments
Most of the time while excavating the land and building the first floor slabs, the environments mentioned above will be highly improvised.
Even at the time of demolishing the old environments prior to the excavation, materials are recovered that can be used to build the environments of the worksite.
When environments are built for the installation of tasks, it is normal to build them on the internal perimeter of the land, since this sector often does not harm the construction of the building.
Bath position
The bathroom is usually accommodated as close as possible to the old chambers of the land, corresponding to the old house or demolished property. This is done to prevent sanitary pipes running through construction and disrupting regular work.
Electrical installations
Electrical installations in the field are usually the elements relegated to the last place in importance, however, it is one of the main inputs in construction.
The cables derived from the electric power meter usually do not have the necessary insulation, or they tend to be routed on the floor and without the necessary support.
A recommended way to have this issue available is through a board like the one shown:
Cost
The Faenas installation could be one of the most difficult items to calculate since it varies according to the type of finish that you want to give it.
The environments can be in the exposed brick partition or in contrast, be huts armed with wood, paint, and all the necessary comforts of an office.
It all depends on the budget you have, the size of the work, and even the factor of how close the offices and logistics area is to the land.
One way of budgeting direct costs for the installation of works could consist of estimating two workers working full time for a week, and adding the amount of material to be used for that purpose.
Construction site preparation
It consists of the adaptation of the construction environment to the minimum needs for habitability and workIn this sense, the installation of works...
What is a rebar coupler?
Rebar couplers are used in reinforced concrete structures to the connection steel bars that replace a normal rebar lap joints. The rebar couplers are very useful for reinforced concrete structure columns and walls. The rebar coupler comprises a piece of rebar furnished with a string, and a coupler sleeve at the correct end as seen toward an establishment. In development joints, rebar couplers can be utilized to supplant all bits of the rebar experiencing the form work. Rebar couplers are utilized for joining rebars with a full tensions capacity. The closures of bars to be joined are furnished with strings, and the bars are joined utilizing a coupler sleeve that moves the power on the rebar across the association.
Type of rebar coupler
What is a rebar coupler?
What is a rebar coupler?Rebar couplers are used in reinforced concrete structures to the connection steel bars that replace a normal rebar lap joints....
There are all sorts of risks associated with construction projects, from natural disasters like fire and wind storms to vandalism, arson, and theft. As a contractor, you have a responsibility to ensure you and your employees are protected with the right types of insurance coverages.
Contractor’s
all-risk coverage, also called builder’s risk coverage, is insurance that
protects the building during its construction. It helps protect against damages
and losses that might occur. Most of the time policies are written to cover the
completed value of the building.
As a
general contractor, you are not always required to obtain this coverage, as the
building owner normally gets it to protect their interests. However,
contractors can be held responsible for any losses that occur due to their or
their employees’ negligence. Therefore, it is a good idea to have some form of
liability insurance along with your own contractor’s all-risk coverage with the
appropriate endorsements, such as:
- Coverage for you and your
employees’ equipment and tools.
- Coverage for leased or rented
equipment.
- Coverage for crane rental, along with riggers and hook liability protection.
Remember, it is your responsibility to make sure you, your employees, and your equipment and tools are adequately insured, no matter what type of coverage the building owner has obtained.
SNRN 2/22/2021 Admin Bandung Indonesia
The Importance of Insurance for Your Construction Project
There
are all sorts of risks associated with construction projects, from natural
disasters like fire and wind storms to vandalism, arson, and theft. As...
The construction area is one that is shockingly inclined to
mishaps because of the high-hazard nature of the work. Working at tallness and
working with incredible hardware makes this kind of work more hazardous than
different occupations.
Did you know, for instance, that 3% of construction laborers
support a business related injury every year – and these details are only the
ones that really get revealed? In 2015/2016 a sum of 43 laborers were lethally
harmed in the construction area (details from HSE).
With figures like these, it's not difficult to see that more
security is required for laborers in this industry and that construction
protection is vital. Just as ensuring laborers in the event that they need to
go on vacation through injury or disease as far as pay, should an extreme
mishap happen, construction obligation protection will cover other fundamental
viewpoints like public risk, items responsibility just as monetary misfortune
and lawful costs.
Picking a decent construction protection strategy and the
proper extra cover is truly significant so don't race into settling on a
choice. You could quickly choose the least expensive cover and afterward
discover when it is past the point of no return that you weren't covered to the
level that you had thought you were. With regards to your wellbeing, choosing
the correct cover is a higher priority than some other part of protection, so
ensure that you work with an expert construction protection supplier like
Tradesman Saver.
Individual mishap cover is basic in this profession, as you
can see from the details, and throughout the span of your vocation, you're
probably going to be needing it because of some type of injury. It likewise
covers you for infection, so you don't need to stress over how you will take
care of the bills on the off chance that you are down and out for some time.
Suppose you broke your wrist playing sport and couldn't work for a while.
Except if you have the applicable protection cover, this could have colossal
monetary implications for you.
In construction, taking out open responsibility cover is
likewise a savvy move. If you somehow managed to be prosecuted for a physical
issue of an individual from the general population, or harm to public property,
the expenses related would be immense. Just as paying your lawful costs, you
would have to pay out remuneration in the event that you are considered to be
at risk. Expenses can undoubtedly run into the large numbers relying upon the
conditions of the case, so it's impossible that your business could bear to
take care of the expenses without protection.
On the off chance that a client endures monetary misfortune,
they may wish to guarantee against you. Once more, this can wind up being
expensive and is undeniably more normal than you may might suspect, so you need
to be taking out a cover that incorporates this.
Kinds of protection Covers in Construction Industry
Different kinds of cover that you can alternatively take out
incorporate business' risk. Regardless of whether you have only one representative,
manager's obligation protection ought to be a need for you. In the event that
your laborer gets harmed while working for you, there are monetary results.
From one side of it, they may set in a pay guarantee against you and relying
upon the earnestness of the injury, expenses could run high. The exact opposite
thing that you need as a business is to question claims with your laborers, so
setting up boss' responsibility will assist with securing your set up and keep
a decent connection with them.
You shouldn't compromise with a protection however when it
comes down to construction protection, you truly can't bear to commit errors.
SNRN 2/22/2021 Admin Bandung Indonesia
Why Is Construction Insurance Important?
The construction area is one that is shockingly inclined to
mishaps because of the high-hazard nature of the work. Working at tallness and
working...
What is the lap length?
It is the length provided to overlap two rebars in order to safely transfer load from one bar to another bar and alternative to this is, to provide mechanical couplers.
What are the general rules for lap length?
For the different diameter of bars
When the bars of different diameters are to be spliced the lap length is calculated considering the smaller diameter bars.
Suppose you are constructing a column, from bottom 20 mm diameter bar is coming and from here 16 mm diameter bar has to be spliced then for calculating lap length 16 mm diameter should be considered and not 20 mm.
What is the minimum lap length?
For direct tension, the straight length of the lapping bar shall not be less than 15d or 20 cm. While in the case of compression lapping should not be less than 24d.
What is the difference between lap length and development length?
Lap length is provided to safely transfer stresses from one bar to another, while development is needed to safely transfer the stresses from steel bar to concrete to make a continuous structure.
Where lap length is provided in column?
The bending moment at the middle portion of the column is zero it means the middle portion of the column is least stressed. Hence, lapping should be provided in the mid-section of the column.
What is Lap Length?
What is the lap length?It is the length provided to overlap two rebars in order to safely transfer load from one bar to another bar and alternative...
The theory is the weight of the earth rest on the heel of the footer of the retaining wall and thus the force downward counteracts the weight of the earth pushing forward on the wall. Wall is then able to retain the earth or medium.
What are the main functional and structural differences between sheet piles and retaining walls?
Talking about structural difference, retaining walls are generally concrete structures which is erected above the ground level and it has backfill on one side(generally), while sheet in sheet piles metal sheets are placed beneath the structure below ground surface in order to increase the drainage length hence avoiding ... They have good driving qualities and are designed to provide the good strength for low weight. The interlocking system facilitates easy positioning of the piles (pitching) and driving, as well as providing a close-fitting joint to form an effective water seal.
What is toe and heel in retaining wall ?
The theory is the weight of the earth rest on the heel of the footer of the retaining wall and thus the force downward counteracts the weight of...
Lapped joints are not always an appropriate means of connecting reinforcing bars. The use of laps
can be time consuming in terms of design and installation and can lead to greater congestion
within the concrete because of the increased amount of rebar used.
Ancon couplers can simplify the design and construction of reinforced concrete and reduce the amount of reinforcement required.
Lapped joints are dependent upon the concrete for load transfer. For this reason any degradation in the integrity of the concrete could significantly affect the performance of the joint. The strength of a mechanical splice is independent of the concrete in which it is located and will retain its strength despite loss of cover as a result of impact damage or seismic event.
The Ancon range of reinforcing bar couplers is the most comprehensive available and includes tapered threaded, parallel threaded and mechanically bolted couplers.
Rebar couplers. Rebar couplers are used in reinforced concrete structures to replace normal rebar lap joints. ... Each rebar coupler consists of a piece of rebar equipped with a thread and coupler sleeve at the right end as viewed in the direction of installation.
All software and resources in the SONATUTS directory are property of their respective authors. All downloadable or viewable content available on SONATUTS is provided as-is. You agree that you bear sole responsibility for your own decisions to download or use any of the software listed.
Reinforcing Bar Couplers
Simplify the design and construction of concreteLapped joints are not always an appropriate means of connecting reinforcing bars. The use of lapscan...
Good design must not only be safe but must aim to save construction costs, time and materials. The following procedures should help to achieve this and an ‘educated’ client will recognize the importance of funding this work with a realistic fee.
1.Decide the Location of Columns & Foundation and Type of Loads Acting on Them
On the building plan, the position of columns and loadbearing walls should be marked, and any other induced loadings and bending moments. The loads should be classified into dead, imposed and wind loadings, giving the appropriate partial safety factors for these loads.
2.Estimate Allowable Bearing Pressure of Soil Using Ground Investigation Report
From a study of the site ground investigation (if available), the strength of the soil at various depths or strata below foundation level should be studied, to determine the safe bearing capacity at various levels. These values – or presumed bearing values (from any standards or codes) in the absence of a site investigation – are used to estimate the allowable bearing pressure.
3.Decide Depth of Foundation
The invert level (underside) of the foundation is determined by either the minimum depth below ground level unaffected by temperature, moisture content variation or erosion – this can be as low as 450 mm in granular soils but, depending on the site and ground conditions, can exceed 1 m – or by the depth of basement, boiler house, service ducts or similar.
4.Calculate Foundation Area
The foundation area required is determined from the characteristic (working) loads and estimated allowable pressure. This determines the preliminary design of the types or combination of types of foundation. The selection is usually based on economics, speed and buildability of construction.
5.Determine Variation in Vertical Stresses
The variation of vertical stress w.r.t depth is determined, to check for possible over-stressing of any underlying weak strata.
6.Calculate Settlement
Settlement calculations should be carried out to check that the total and differential settlements are acceptable. If these are unacceptable then a revised allowable bearing pressure should be determined, and the foundation design amended to increase its area, or the foundations should be taken down to a deeper and stronger stratum.
7.Cost Control
Before finalizing the choice of foundation type, the preliminary costing of alternative superstructure designs should be made, to determine the economics of increasing superstructure costs in order to reduce foundation costs.
8.Consider Time
Alternative safe designs should be checked for economy, speed and simplicity of construction. Speed and economy can conflict in foundation construction – an initial low-cost solution may increase the construction period. Time is often of the essence for a client needing early return on capital investment. A fast-track programmed for superstructure construction can be negated by slow foundation construction.
9.Variation in ground condition
The design office should be prepared to amend the design, if excavation shows variation in ground conditions from those predicted from the site soil survey and investigation.
Design Procedures for a Building Foundation
Good design must not only be safe but must aim to save construction costs, time and materials. The following procedures should help to achieve this...
As we all know that civil engineering can’t be isolated from other engineering fields. For the betterment of human life civil engineering require electrical engineering, architectural engineering. Hence all important aspects of civil engineering are taught as elements of civil engineering in all over the world.
This particular book with title “Basic Civil Engineering” covers all the basic definitions, terminologies and everything related to civil engineering. The book is written in very simple English and is very handy for students to learn civil engineering.
Contents
UNIT - I: CIVIL ENGINEERING MATERIALS 1–70
1 TRADITIONAL MATERIALS 3–32
2 MORTARS 33–38
3 CONCRETE 39–54
4 METALS AS BUILDING MATERIALS 55–58
5 MISCELLANEOUS BUILDING MATERIALS 59–69
UNIT - II: BUILDING CONSTRUCTION 71–136
6 BUILDING PLANNING 73–81
7 FOUNDATIONS 82–91
8 SUPER STRUCTURES 92–127
9 DAMPNESS AND ITS PREVENTION 128–132
10 COST EFFECTIVE CONSTRUCTION TECHNIQUES 133–135
UNIT - III: SURVEYING 137–236
11 INTRODUCTION TO SURVEYING 139–148
12 LINEAR MEASUREMENTS AND CHAIN SURVEYING 149–175
13 COMPASS SURVEYING 176–194
14 PLANE TABLE SURVEYING 195–208
15 LEVEL AND LEVELLING 209–225
16 MODERN TOOLS OF SURVEYING 226–236
UNIT - IV: MAPPING AND SENSING 237–268
17 MAPPING AND CONTOURING 239–246
18 Drawing Contours 246
19 REMOTE SENSING AND ITS APPLICATIONS 266–268
UNIT - V: DISASTER RESISTANT BUILDING 269–287
20 DISASTER RESISTANT BUILDINGS 271–281
21 DISASTER MANAGEMENT AND PLANNING 282–285
22 INDIAN STANDARD CODES 286–287
SNRN 11/06/2020 Admin Bandung Indonesia
Basic Civil Engineering
As we all know that civil engineering can’t be isolated from other engineering fields. For the betterment of human life civil engineering require...
