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<p>Now a days composite type admixtures (water reducing, increased setting time and viscosity modifying agent all in one) are gaining momentum due increased useage of Self Levlling(Compacting) Concrete. High Density, low voids, high strength and improved properties of concrete such as high workability, low permeability to chlorides, increased durability, increased pozolanic activity, etc all made SLC is a best choice.</p>
It is the fine -Coarse aggregates ratio, thats mean we have to use more fine aggregate to avoid segregation
Your answer is correct for the non self levelling concretes. Meanwhile I have been waiting for answers from other fellow engineers.
In ordinary mix ingredients are proportioned such a way that mix is cohesive and without bleeding. Whereas self levelling concrete will be in liquid (semi-liquid) state and flows. At this state dense particles settles down and slurry and PFA/Micro silica will appear on top surface. To avoid this, we add VMA (VISCOSITY MODIFYING AGENT) in required quantity .
flakiness / elogation is the main property of aggregate to be modified for self leveling concrete.
coursier sand can increase bleeding and segregation in SCC
less finer content in cement can also increase segregation and bleeding in SCC
Cement Can be replaced by GGBS, will give you more workability bcoz of GGBS molicular structure(round shaoe)
medium or high performance Polycarbobilyc admixtures will give you good results in SCC
optimum W/C ratio required for SCC
For this purpose we should use light weight aggregate.
round aggregates are most suitable for SCC and by proper grading for coarse and fine agg. bleeding can be effectively avoided
