Bleeding of Concrete Bleeding is one form of segregation, where water comes out to the surface of the concrete, being lowest specific gravity among all the ingredients of concrete. Bleeding can be easily identified in the field by the appearance of a thin layer of water in the top surface of freshly mixed concrete. Effects … Read more
The danger caused by segregation is difficult to repair and very costly. Therefore necessary precautions should be taken to avoid segregation. Precautions to Take The concrete mix should be properly designed with optimum quantity of water to make a cohesive mix. Such concrete will not exhibit any tendency for segregation. Field quality control must be … Read more
Following are the effects on concrete due to segregation. Effects on Concrete A segregated concrete is very weak in strength Due to segregation after placing, the concrete in the lower part of a pour of any significant depth can be stronger than that in the upper part. Segregated concrete does not give a homogeneous mass … Read more
Segregation usually implies separation of: (a) coarse aggregate from fine aggregate, (b) paste from coarse aggregate, or water from the mix and the ingredients of the fresh concrete no longer remain uniformly distributed. The points given below are the primary causes of segregation of concrete in field. Causes of Segregation on Site Poorly graded aggregate … Read more
What is Segregation? Wordweb dictionary defines the term “segregation” as – Separation or isolation of one thing from another and place in a group apart from others. In concrete technology, segregation can be of two types. Firstly the coarse aggregate may separate from the main mass of concrete in its plastic state. Secondly, the grout … Read more
Factors Affecting Workability of Concrete A concrete is said to be workable if it is easily transported, placed, compacted and finished without any segregation. Workability is a property of freshly mixed concrete, and a concrete is a mixture of cement, aggregate, water & admixture. Due to this all the properties of concrete, whether in fresh … Read more
Before knowing the term workability let us look at some of the definitions given by scientists and researchers. Definitions of Workability of Concrete According to Granville “it is that property of the concrete which determines the amount of useful internal work necessary to produce full compaction.” Powers defined it as “that property of plastic concrete … Read more
Mix design is a process of selecting suitable ingredients and determining their relative proportions with the objective of producing concrete of having certain minimum workability, strength and durability as economically as possible. Concrete A mix design can be designed in two ways as explained below Nominal Mix Design Nominal Mix It is used for relatively … Read more
Aim To determine the field density of soil at a given location by sand replacement method Reference IS-2720-Part-28-Determination of dry density of soils in place, by the sand replacement method Apparatus Sand pouring cylinder Calibrating can Metal tray with a central hole Dry sand (passing through 600 micron sieve) Balance Moisture content bins Glass plate … Read more
What is Gap Graded Aggregate? Generally we use well graded aggregate or continuous graded aggregate, which means representation of all the standard particle sizes in certain proportion. Assumption made in well gradation is that voids created by the higher size of aggregate will be filled-up by immediate next lower size of aggregate and again some … Read more