purpose of this study is to investigate the best
sand cement ratio of  mortar
#civilengineering@ concretetechnology
The purpose of this study is to
investigate the best sand/cement ratio of mortar by using locally available sand and using the same constituent in various concrete mixes of different local coarse aggregate/cement ratio. On the bases of maximum compressive strength and workability of cement mortar, mixes of different
sand/cement (s/c) and water/cement (w/c) were prepared. For each mortar mix flow table test was
performed to check its consistency and cube samples were prepared for 28-day compressive strength test. Thus it was decided to consider mortar mixes with flow value 90% . Using w/c corresponding 90%flow of the mortar and same mortar constituent (sand/cement) with varying coarse aggregate/cement ratio , 20 concrete mixes were prepared .The aggregate/cement was 2:1 for the richest concrete mix and 9:1 for the poorest mix. On the basis of 28-day compressive strength of mortar of flow 90%, it was found that corresponding rich concrete
mix of agg./c 3:1 &3.5:1 had a reduction in 28-day compressive strength of 26% & 24% respectively
and had bad workability in its fresh state. Similarly for lean concrete mixes agg./c 7:1 to 9:1 the
reduction in compressive strength was 21.8% to 39.6% respectively ,while the reduction for the
other concrete mixes were less than
15% with reasonable workability. The reduction in compressive strength for concrete mixes of
agg./c 4.5:1 to 6:1 corresponding to mortar s/c of 2:1 was almost zero and all mixes had good workability.
Thus the best s/c corresponding to 90% mortar flow was 2:1 which can be used in concrete mixes
of varying coarse agg./c ratio with good workability and minimum losses in compressive
strength.

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