Segregation of concrete refers to the separation of coarse and fine aggregates from the cement paste during the handling and placement of concrete. This can result in an uneven distribution of materials and affect the quality and strength of the concrete. To prevent segregation, it’s essential to:
1. Use well-graded aggregates: Ensure that the aggregates are of the right size and distribution to minimize the risk of separation.
2. Proper mixing: Mix the concrete thoroughly to achieve a uniform consistency and avoid over mixing, which can lead to excessive air entrainment.
3. Control water content: Maintain the correct water-cement ratio to prevent excess bleeding and segregation.
4. Use additives: Employ additives or plasticizers to improve the workability of the concrete and reduce the risk of segregation.
5. Proper placement: Handle and place the concrete carefully, using appropriate techniques and equipment to minimize dropping heights and avoid excessive vibrations.
Segregation of concrete
I will discussed about the segregation of concrete, today that is play a harmful role in loss of homogeneity in concrete, causes of bleeding in concrete in it’s plastic state and also during the transition of plastic to stiffen state, causes of segregation of concrete and types of segregation and control ability of segregation.
Segregation of concrete is defined as the phenomenon of the separation of constituents such as coarse aggregate, paste and water of a homogeneous mixture of concrete is in plastic state, also during the transition of plastic to stiffen state as a result bleeding of concrete, segregation of concrete is play a important role to occurrence of bleeding in concrete.
Segregation of concrete occurs in a phenomenon of plastic state of concrete that means phase of concrete when it is freshly mixed, fresh concrete during the Compaction and placing,after this a transition state occured which is this state of concrete is seriously affect the behavioural properties of concrete.
Coarse aggregate are evenly coated with sand and cement paste from a homogeneous mass of a good quality of concrete in construction of structures, during handling, transporting and placing, due to compaction and vibration the paste of cement and sand gets separated from coarse aggregate, then concrete segregates during the state of transit conditions that is segregation of concrete.
What is segregation of concrete?
Regarding this, “what is segregation of concrete?”, it is the phenomenon of the separation of concrete constituents in which heavy aggregates particles settles down and water rises up to the surface and upward movement associated with fine particles of cement, it is the cause of bleeding in concrete.
Segregation of concrete is highly affect the construction of structures in concrete technology which is separation of constituents materials in concrete, segregation is associated with separation of coarse aggregate or setting down from the rest of metrix from the concrete mixture, separation of cement paste from the concrete in stage of freshly mixed concrete compacted and transported, separation of water from the concrete mix as a form of plastic state of concrete that is cause of bleeding in concrete and play a important role in affecting the behavioral properties of concrete during the construction of structures in freshly mixed concrete.
When the freshly mixed concrete in the plastic state of concrete handling, transporting and placing cause of vibration,jerk and compaction the sand and paste of cement get separated from coarse aggregate, result segregates of concrete during the transit state of concrete in construction of structures.
Segregation of concrete meaning
Segregation of concrete means the partition of course material such as cement paste,sand, water from coarse aggregate that is occurs in increasing the water quantity in the concrete mix, the coarse aggregates are detached thus results in segregation of concrete which is described the particulate solids tend to separate in transit state of concrete application by virtue of differences in the size, density, shape and mechanical, transport behaviour of concrete has been focus of both modeling as well as experimental investigation.
Segregation also occurs due to over vibration or compaction of concrete, in which cement paste comes to the top and coarse aggregates settles at the bottom due to settling down which is available in the two form in too dry mixes that is described the coarse aggregate is segregated from the rest of the matrix and secondly in too wet mixes that is described the cement paste is detached away from the coarse aggregate.
Types of segregation
Types of segregation depend on the constituents seperation of freshly mixed concrete in construction of structures which is separated as follows-:
1. Coarse aggregate separation or setting down from the rest of the matrix.
2. The cement paste or the matrix separating out from the aggregate.
3. Separating out of water from the rest of the material having lowest specific gravity.
Segregation of concrete causes
Concrete is a mixtures of cement, coarse aggregate,fine aggregates , water and admixtures which is consist the different size and their specific gravities are different from each other like as aggregates specific gravities fall in the range between 2.6 to 2.7 and also cement consists the range between 3.1 to 3.2 , so having behavioral of show a tendency to separate from each other in their constituents is play a important role in causes of segregation. Some important factor of segregation of concrete causes are follows-:
1. Difference in size and weights of concrete constituents.
2. Difference in specific gravities of concrete constituents such as aggregates and cement
3. Water cement ratio is poor, play a important role in cause of segregation.
4. Bad quality products and poor engineering behavioral practices.
5. Practised excessive vibrations to the freshly concrete in construction of structures such as being excessive vibrations to the plastic state of concrete.
6. Improper grading of concrete and mix proportions of constituents of concrete.
7. Practices Insufficient mixing and compaction of concrete.
8. Carelessness while working on complex reinforced elements and during working on heights.
9. Transportation of concrete over long distance or over long period of time also cause of segregation.
How to prevent segregation of concrete
Generally we discussed about the segregation of concrete today that is play a harmful role in loss of homogeneity in concrete, causes of bleeding which is affect the gaining strength of concrete and it’s behavioral properties in construction of structures and complete the project of structures under the time period, so the goal is not to necessarily eliminate segregate ,but rather to manage it to ensure the concrete’s quality to increase the strength of concrete, it’s resistance ability and a long life of concrete construction of structures.
Regarding this, “how to prevent segregation of concrete?”, the proper selection of constituents of concrete such as cement,coarse aggregate, fine aggregates, water and admixtures, their proper proportioning to grade of concrete and attentiveness action while working is a play a important role in preventing of segregation of concrete. Some important factors that is prevent the segregation of concrete ara as follows-:
1. Proper selection of materials of concrete, proper proportioning of concrete materials and attentiveness while working.
2. As per requirement addition of admixtures like AEA and Pozzolanic materials.
3. Use of chutes working in depth greater than 1.5 m, always attentiveness in limiting height from which concrete is dropped.
4. Proper checking and testing of quality of concrete on construction of substructures.
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How to control the segregation of concrete
1. Can be controlled by maintaining proper proportioning the mix
2. Adding air entraining agents admixtures is very effective in control of segregation.
3. For transportation shortest route should be selected that is very effective.
4. Consider the Limiting height 1 metres from which concrete is dropped.
5. Avoiding excess vibration in freshly mixed concrete in construction of structures over long time period.
6. Specially proper handling, placing, transporting, compacting and finishing of concrete in construction on substructures.
7. Fine aggregates could be used to overcome the ensure the concrete’s quality.
8. Specially attentiveness in design mix of concrete in construction of structures
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1)what is concrete and its types and properties