 What is cement? |
Cement is a hydraulic binding mortar. That is, it is a finely divided inorganic material (powder) which, when mixed with water, forms a paste which coagulates and hardens through hydration reactions and processes, and after hardening regains its strength and stability even in water.διεργασιών ενυδάτωσης και μετά την σκλήρυνση επανακτά την αντοχή και την σταθερότητα ακόμα και μέσα στο νερό.
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| What is concrete? |
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Concrete is widely used nowadays for the construction of building frames and more. It is a mixture of cement, gravel and water. Depending on the category, the appropriate ratios of superfluidizers - retarders are added to achieve the appropriate workability without the addition of water.
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| What concrete should I use to build my house? |
The engineer-designer is responsible for choosing the right concrete for the construction of your house, who will the specifications of the concrete in the plans.
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| What does concrete strength class C20/25 mean? |
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Concrete according to the Concrete Technology Regulation (KTS) is characterized by the strength class (C16/20, C20/25 etc.) and the workability class (S1, S2 etc., i.e. how soft it is before it sets) .
It means that we can safely assume that it will be able to receive pressures of the order of 20 Mpa (megapascals) without being damaged, 28 days after its concreting. To certify its real strength, special samples are taken during each concreting, which are kept in a place with suitable conditions and broken with a special press 28 days after concreting. The strength of the cubic samples (with an edge of 15 cm) should be of the order of 25Mpa. The whole process is described in detail in the Concrete Technology Regulation. According to the law, taking the tests is one of the owner's obligations.
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| What does concrete strength class C20/25 mean? |
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a) The minimum required amount of cement per cubic meter must be observed. Cement, on the one hand, has the role of the glue of the concrete, on the other hand, it prevents the oxidation of the reinforcement (steel).
b) Do not add more water than required. The composition of the concrete must ensure workability without the need to add too much water. Adding water to the barrel may make the concrete easier to work but reduces the strength of the concrete.
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| What does sitting on concrete mean? |
There is a scale (S1 to S5) which measures how "soft" the concrete is when concreting, or otherwise how easy it is to work (concrete workability). In this scale, S1 is the very tight concrete while S5 is the very soft. Without the addition of special fluidizers, workability is highly dependent on water dosage, so since too much water reduces strength, categories S2 or S3 are usually specified. Under no circumstances should additional water be added. If there is a need for greater workability, this should be done exclusively with the use of special chemical additives (fluidizers).
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| What is a test and how much should we take in concreting? |
Tests are samples of the concrete used in construction. In each concreting, 6 or more samples are usually taken. They are taken on the project. Special iron molds (matrices) are used which are filled with the concrete used. These are sent to special laboratories where they are preserved for 28 days and then tested for durability. The process is described in detail in the Concrete Technology Regulation. Taking the essays is the responsibility of the owner.
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| Why should we wet the slab after concreting is finished? |
For concrete to "cure" properly it must be in a moist environment. The slab must be wet for at least the first 7 days after concreting. So it is either covered with wet cloths or gets wet often. Concrete that is properly maintained throughout the curing phase is much more durable than concrete that has been maintained for one day.
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| Delivery of concrete from the customer (company or individual) to the project |
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Special importance should be given by the customer to the following actions during the reception of the concrete: Designate a specific person from the customer, who will receive and check:
A. If the load comes sealed directly from the factory and if it has a lead seal on the barrel lever.
B. All shipping slips, before receiving the product, so that they agree with the order.
Check the cleanliness of the "boat" of the pump, before it is used.
If a change in workability is required, this should only be achieved by adding a superplasticizer, in the appropriate dosage, after ensuring re-mixing inside the transport vehicle, for a minimum time of 1 minute/m3 of concrete, e.g. 9 cubic 9 minutes, 5 cubic 5 minutes, with the maximum number of revolutions (10-14 revolutions per minute).
The addition of any material (and water) is expressly prohibited
Any improvers/additives used should be approved in type and quantity by the manufacturing plant. In any other case, the responsibility for the quality of these and any effects they may have on the strength, on the process of setting - hardening of the concrete, as well as on the percentage of air contained in the concrete, is borne exclusively by the customer.
The time of arrival of the drum and the start and completion times of concrete unloading (from the drum) must be recorded on the Shipment Note.
It is recalled that, based on the Concrete Technology Regulation (K.TS. '97), the maximum time allowed to elapse between the production of the concrete in the factory and its unloading-use, should not exceed one hour in duration and fifty minutes if a retarder has been used in the manufacturing plant or one hour and thirty minutes without a retarder. For no reason should the laying of concrete be accepted that will have completed the above time.
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| When and how to order? |
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To place your order, all you have to do is contact us on the phone: 2297027134.
The order should be placed on time, i.e. at least three days before the desired day of collection, so that we can plan everything correctly and without problems.
The order must specify details such as:
1. The desired concreting date
2. The category (quality) of the concrete
3. The desired (pre-measured) quantity
4. The requirement for the so-called "workability" of the concrete (seat category)
5. If additional superfluidizer or other additive is required
6. The minimum cement content
7. The maximum water/cement ratio
8. The format is specified in the factory (12.2.KTS)
9. The maximum aggregate grain
10. Coated or uncoated concrete
11. Paving a quantity of less than 20 m3 (application of "criterion E")
12. The use of a pump (height, type or special characteristics thereof)
13. Possible special requirements for the product, e.g. concrete resistant to surface wear or chemical attack or exposed to air saturated with sea salts (coastal environment) etc.
14. Element to be concreted (foundation, columns, walls, slabs, etc.)
15. Required project feed rate of concrete (barrels/hour)
In the construction of projects located at a distance of up to one kilometer from the sea (coastal environment) it is mandatory to use concrete with a minimum cement content of 330 kg/m3 and the water/cement ratio not to exceed 0.60
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| How much is the weight of 1 m3 of concrete? |
Fresh concrete usually ranges from 2,350 to 2,400 kg per m3. In areas with river (natural) aggregates it can be 2,320 kg and/or 2,300 kg. This means that a 10 m3 drum has a net deadweight of 23.5 - 24 t, which you find by weighing the drum loaded and after unloading the concrete, without spilling the drum wash water out, before weighing.
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| How much concrete do I need? |
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Calculating how much concrete we will need is found through a simple mathematical operation. We multiply the length by the width by the height of the area we want to cover with concrete. E.g. we have a yard 10 meters long, 5 meters wide and we want the concreting height to be 10 cm. 10X5X0.1=5 cubic meters (m3).
For greater convenience you can use the following website: http://www.calculator.net/concrete-calculator.html
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