DETERMINATION OF MATERIAL PARAMETERS AT PATHRI SUPER-PASSAGE ON UPPER GANGA CANAL

Abstract

A new R.C.C. trough is being constructed on Pathri Super-passage. It will superimpose a load intensity of 45 t/m2 on the haunches (built of lime-brick masonry) between the arches. To ensure the structural safety Of lime-brick masonry and lime-boulder masonry, comprehensive field and laboratory tests have been performed. Field tests includes cyclic plate load tests, block crushing and core-drilling for permeability tests at different locations. Further, various laboratory tests have been performed in order to get physical and engineering. properties of sediment (on the super-passage); lime-surkhi mortar and b'ricks (used in the structure). These include classification of sediment, determination of lime-mortar content in masonry, unit weight and water absorption of lime mortar and bricks, uniaxial compre-ssive strength tests and ultrasonic tests on lime mortar. Chemical analysis of lime mortar has also been done. On the basis of these tests it was found-that the sediment on the super-passage is 2.16 m thick, poorly graded silty sand, with its saturated unit weight equal to 1.97 gm/cm3. For lime-surkhi mortar, the modulus ratio was 64.5, water absorption about 27% and uniaxial- compressive strength about 26 kg/cm2. In lime-brick and lime-boulder masonry, the'percen-tages of lime mortar are about 50 and 32 respectively. Their average compressive strengths are about 52 and 6 kg/cm2 res- (vi) pectively. The modulus ratio for lime-brick masonry and lime-boulder masonry have been found to be equal to 128 and 15 respectively. The in-situ permeability of lime-brick masonry is of the order of 9x10-6 cm/sec. The percentage of lime in the lime-surkhi mortar obtained from lime-brick masonry is quite low i.e. 9.1%. The above test data clearly indicates the excellent quality of the material used in the haunches and it can easily bear the new super-imposed pressure due to proposed construc-tion. Further, no significant weathering has taken place in last 136 years and is unlikely to occur .in the life-time of R.C.C. trough.