LOAD TRANSFER EFFICIENCY CONCRETE BLOCK PAVEMENTS FOR LOW VOLUME ROADS

Concrete Block Pavements (CBP) are precast concrete blocks of varying shapes and sizes arranged in a specific pattern over a variety of sub bases and interlocked with graded bedding and jointing sand. The wheel loads on concrete blocks are distributed due to the interlocking effects between bedding and jointing sand with concrete blocks. Concrete block size and shape, joint gap and joint filling sand size, laying pattern will affect the Interlocking effects. These interlocking effects are quantitatively expressed by Load Transfer Efficiency (LTE) which is the deflection ratio between loaded block to adjacent unloaded block. In the present study, laying patterns (stretcher and basket weave), concrete mixes with fly ash at 20% by weight of cement, steel fiber of 0.5% per cubic meter of concrete and combination of fly ash and steel fiber were used. The Load Transfer Efficiency was calculated based on the tests conducted in the field considering all the variables mentioned above. The test section consisted of granular sub base over the subgrade, the base layer is of wet mix macadam and surface course is the concrete block of different sizes with 100mm thick over the 20 mm thick bedding sand size of 4.75 mm and varying sizes of joint filling sand in 5 mm joints. It was concluded from the study that the Honey style block shape has more restraint for Horizontal creep than square and rectangular shape block. It was also noticed that the deflection observed in Honey style block is less compared to rectangular and square shape. Also, it was noted that with the change in block thickness from 100mm, 80mm, 60mm in case of all the three shapes there is a significant reduction in the elastic deflection of pavement blocks as the load transfer will be higher for the thicker blocks because of the higher frictional area. The combination of steel fiber and fly ash in concrete blocks showed an increase in the load transfer efficiency.