Cement Fineness and Workability
Dear All In many papers i have read that increaing cement fineness water consistency increases while water demand in concrete mix decreases kindly give reason for this contravercy statement regards Dilip Yadav
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Re: Cement Fineness and Workability
I received the paper you emailed me and have sent you a reply. But for the benefit of others reading this thread I have copied my reply to you here;-
I think what this paper is saying is that although finer cement causes an increase in both the measured consistency and water demand of cement paste. There is another factor to take into account when considering workability of concrete. This factor is the fineness of the cement particles themselves and their positive effect on concrete workability. eg
"As per our findings, with an increase in the fineness of cement, both consistency of cement and workability of concrete increase. Increase in consistency means increase in water demand to get cement paste of standard consistency while increase in workability means increase in flowability at the same water/cement ratio. In other words decrease in water demand to get the same workable concrete. Apparently it looks to give a controversial situation. But it can be more easily understood by considering that workability of concrete determines the amount of work done to achieve a certain value of compaction. When the water is added, it wets the surface of particles and reduces the interparticle frictional resistance. When fineness of cement increases beyond a certain particle size, the particles of cement itself starts acting as lubricants in the concrete. Therefore, the particles flow and less effort/work is required for compaction of concrete i.e. the water demand decreases to obtain the same degree of workability."
So, it is not really a contradiction. It is just that a factor other than water content is coming into play with respect to workability of concrete... the lubricating properties of the fine particles of cement themselves.