4 Factors affecting the strength of concrete

4 Factors affecting the strength of concrete

CivilWork       Comment   

In construction, concrete is a composite building material made from a combination of aggregate and cement binder. The most common form of concrete is Portland cement concrete, which consists of mineral aggregates (usually gravel and sand), cement and water. In the world of construction, concrete has a vital role. Concrete construction is the building structure of a building. The strength of concrete construction is the backbone of the building or not. Then what are the concrete compilers themselves and what factors affect their strength?

The following is an explanation of the factors that influence the strength of a concrete structure.

1. Cement content

The more cement material you will use, the stronger and better reinforced concrete construction will be produced. The use of cement is directly proportional to the strength of concrete construction.

2. Water Content

The more water you use, the worse the construction of the concrete. Although in the construction of lightweight concrete construction, if water is used a lot, the construction of concrete is easier to do and the work becomes lighter. The key is to use as little water as possible, just so that a mixture of concrete construction can be done (can be transported, casted, compacted and finished).

3. Water Mixture and Cement Material or Cement Air Fakor

The higher the ratio of the mixture of water and cement materials, the concrete construction will be even worse. To improve the quality of concrete construction, the house must reduce the ratio of water and cement materials.

The water and cement material is the ratio between the weight of water compared to the weight of cement material. If we symbolize water with W, and we symbolize the cement material with C then the formula is FAS = W / C, where the density of water is 1 kg / liter, and the density of cement material is 3150 kg / m3 (required American Standard Testing and Material).

4. Aggregate (Sand and coral)

A mixture that is too much sand even though it will make the concrete smooth but its strength is slightly reduced, when compared to a normal mixture. The strength of the concrete will decrease if the mixing uses molen for too long. Conversely, if concrete consists of a lot of coral, concrete construction will be rough but its strength becomes better when compared to concrete that uses more sand.

4 Grouping and Types of Concrete in Indonesia

4 Grouping and Types of Concrete in Indonesia

CivilWork       Comment   

4 Grouping and Types of Concrete in Indonesia

Concrete is composed of three main components, namely cement, water and aggregates. And if needed it will be added auxiliary material (admixture) to change certain properties of the concrete. The properties of concrete in a state that is still fresh and after hardening can show considerable differences. Depending on the type, quality and comparisons of the mixed materials used. Grouping of concrete basically develops from time to time, and adjusts to the needs of each country or agency concerned.

Based on unit weight (SNI 03-2847-2002)

Lightweight concrete : unit weight <1,900 kg / m³

Normal concrete : unit weight 2,200 kg / m³ - 2,500 kg / m³

Concrete weight : unit weight> 2,500 kg / m³

SNI does not classify heavy concrete, but in general concrete with a unit weight above 2,500 kg / m³ is categorized as heavy concrete, although some apply a value of 3,200 kg / m³ as a heavy concrete lower limit Concrete whose unit weight is between the above categories is generally not effective comparison of its own weight and strength, although there is no prohibition to make concrete with a unit weight between 1,900 kg / m³ - 2,200 kg / m³

1. BASED ON CONCRETE QUALITY

(SNI 03-6468-2000, ACI 318, ACI 363R-92) from cylindrical test objects (dia. 15 cm, height 30 cm)

1. Low quality concrete (low strength concrete): fc '<20 MPa
2. Medium quality concrete (medium strength concrete): fc '= 21 MPa - 40 MPa
3. High strength concrete: fc '> 41 MPa

2. BASED ON SERVICE

1. Conventional concrete, is a normal concrete that does not experience Prestressed pre-service stress
2. Pre-stressed concrete is concrete which is given pre-service stress at the time of manufacture, with a pre-stressing system
3. Post-tensioned concrete, is concrete which is given pre-service stress at the time of manufacture, with a post-tensioning system.

Pre-service stress delivery is generally designed to provide opposing forces with service style, so that when the reinforced concrete construction bears the load, it practically reduces the workload. This type or group concrete must be designed, implemented and supervised by experienced consultants and specialist contractors

3. BASED ON THE ENVIRONMENT

Concrete in special environments is generally grouped based on conditions that threaten the resistance of reinforced concrete construction:

1. concrete in a corrosive environment, because of the influence of sulfate, chloride, alkali salts, etc.
2. concrete in a non-corrosive wet environment
3. concrete in the environment exposed to weather
4. concrete in an environment protected from weather

in general, treatment, materials or design and implementation requirements are required specifically for the environment that have the potential to threaten the durability or durability of construction

4. BASED ON MAKING

From the way it is made, concrete is generally grouped:

1. In-site cast concrete, which is casted concrete in place, with mold or reference installed in the location of structural elements in buildings or buildings or infrastructure
2. Pre-cast concrete, which is concrete casted at a special manufacturing location, and then transported and assembled to be installed in the location of structural elements in buildings or buildings or infrastructure.

What is HEBEL and how to make it

What is HEBEL and how to make it

CivilWork       Comment   

Light brick is one of the development of appropriate technology. Whereas the beginning of light brick was made to replace brick with a weight that is certainly lighter and also soundproof. Even though it is called light brick, this brick is actually not too light, one light brick weighs around 8-10 kg depending on dimensions. Only when compared to ordinary / normal concrete of the same size, this lightweight brick is much lighter. So that the suitability of this light brick is given the name of lightweight concrete instead of lightweight brick. Light brick, the name given to this lightweight concrete is so sticky and "ingrained in the community" that we no longer need to change its mention to light concrete. This lightweight brick function is generally used the same as red brick or ordinary brick, namely as a partition and does not accept structural loads. Light brick has several advantages compared to ordinary brick, such as having precise shapes and dimensions so that it will save adhesive and do not need to broadcast much.

Basically, this lightweight brick is lighter than ordinary concrete because due to the lightweight brick, air pores are formed. The cavity is wrapped in concrete so that it causes inside the light brick there is a lot of small empty space. Maybe, at first it will sound weird if a light brick turns floating on the water. How could it be? Light brick that is concrete can float in water? If we discuss it in physics, light brick floats because it has a smaller density than Water. Is it possible that light brick has a density smaller than water? yes, because density is the weight of objects of the same volume. while if we weigh light brick then to get the density must be divided by volume. While the light brick volume consists of many air cavities.

To make it easier and easier to understand, I made a simple analogy. Why do ships made of iron float? yes because of that, the influence of air. you know ... the iron on the ship is not a lot of cavities? Imagine we have a large ball with an iron wrapper with an empty space of air that is not connected to the outside air. then the ball will float, just like light brick, the pore is almost not connected to the outside air.

The fewer cavities that are connected with the air outside and with each other, and the smaller the absorption power / light brick absorption, the longer the lightweight brick floats in the water. so don't be surprised, if there is a light brick floating in just one week, it's gone. This is because absorption which fills the pores / cavities in light brick gradually fills with water and is also affected by the connection between pores.

In the market, there are several types of lightweight bricks, namely lightweight AAC and CLC bricks. Generally light brick that is widely produced in the market is light brick CLC. Then what is AAC light brick? AAC lightweight brick is a lightweight brick Autoclave Aerated Concrete This lightweight brick is made with the help of high pressure steam. Where in the making of the dough is inserted into the Autoclaved tool. In the tool it will be given high pressure and temperature, so that AAC brick material which is a material of lime and silica sand will react to form pores. AAC light brick production requires large investment costs, because it requires a boiler and an aerated chamber as well as maintenance and also needs a team of experts to run the tools and methods. But the light brick produced will generally be lighter than the light brick CLC.

AAC light brick has a dry density between 650 kg / m3 up to 700 kg / m3. while CLC ring bricks range from 800 kg / m3 to 1000 kg / m3.

If AAC brick requires expensive equipment and special environmental manufacturing, it is different from CLC light brick. CLC lightweight bricks can be said to be conventional. Cellular Lightweight Concrete, or what we used to call CLC, is an ordinary concrete mix with Cement and aggregate (fine). For concrete to have a light weight, a lot of pores are needed. To form these pores, admixture is added during stirring. The additive or admixture is a Foam Agent which is useful for making foam / cavities during stirring. CLC light brick density will depend on the specific gravity of the foam produced by the foam agent.

How to install light brick is similar to the installation of ordinary brick or brick. The difference is that the entire installation process must be very thorough, if not, the level of precision will not be achieved so that the couple and the show become wasteful. Jidar aluminum and water pass must absolutely be used. To keep the couple's mixture (both with instant cement and ordinary cement) can have the same thickness, then use a special spoon that has square teeth at the end which is usually called roskam. With this roskam, a pair of 3-5 mm thick will be obtained. Unlike red brick and brick, this pair only uses a mixture of cement and water, without sand.

6 Advantages and Disadvantages of using Precast Concrete

6 Advantages and Disadvantages of using Precast Concrete

CivilWork       Comment   

Precast concrete or in Indonesian, "precast concrete, what's the difference with conventional concrete? Hmm !! This article will review "precast concrete", but it might not be so detailed or there might be something wrong with the contents of this writing. Understandably it's still in the learning stage too, but I try to give what I know. Hehehe. Immediately, what is "precast concrete". Prefabricated concrete is a component or structural element that is not cast / printed in a place where the element is installed, but is printed / cast in another place where the casting and maintenance process is carried out properly according to the existing method. After the element is made, then it is taken to the location to be compiled into a complete structure according to its function. Basically, precast concrete is not made at the project implementation site, but precast factories.

Well..! Now what are the advantages of precast concrete compared to conventional concrete? Precast concrete has many advantages compared to conventional concrete. Here are the advantages of precast concrete (according to my knowledge), among others:

1. Project execution time can be faster. By using precast concrete, for example in a building project, when the structure work is still in the foundation stage, where the implementation can coincide with the production of precast concrete (eg precast floor columns on the elements to be installed first can be produced earlier, at the age of concrete it has been reached and the bottom structure work is finished, the element is ready to be installed, with the overlapping work, the project becomes shorter.
2. Use less begesting.
3. Guaranteed quality, because it is done with good methods and good care in precast concrete manufacturing plants.
4. Reducing construction costs, because the wages of precast manufacturing workers are lower than the wages of workers in the project.
5. Does not affect the weather.
6. More environmentally friendly, because the project location is not much dirt from concrete remnants and begesting.

That's the advantage of precast concrete that I know. There is no ivory that is not cracked. Once the saying goes, so is precast concrete. Prefabricated concrete also has drawbacks / weaknesses. Shortages of precast concrete include:

1. Additional costs for transportation, because it is printed on a precast concrete manufacturing plant.
2. Equipment that has a large capacity for erection (installation) is needed.
3. A large stock area is needed for curing.
4. A large area is needed for the production.
5. Technical problems and additional costs that will arise when implementing the installation of precast concrete elements, especially on the connections.
6. That is the weakness of precast concrete. To minimize the need for proper planning and methods.

After knowing what are the advantages and disadvantages of the precast concrete, the components of the structure whose implementation uses precast concrete. Prefabricated concrete methods can be carried out construction: Buildings (precast piles, precast beams and columns, precast walls and precast floors). Bridges (girder, deckslab, diaphragm, voided slab). Sheet pile. And many more.