hi..if you want to know correct value of shear strength parameters, conduct direct shear test and evaluate the parameters c and phi. The unit weight of concrete normally 24 kN/m3 and cohesion depends on the grade of concrete. In your case it is a composite i.e. concrete and strength. so simulate this type composite material in direct shear box test and evaluate the same. ok all the best..

I want idea about the range of shear strength parameters of cement concrete block (400mm cube) when it is used in river bank as protection material.

I am not a civil engineer, but as a hydrologist have been involved with some bioengineering projects and placement of or review of rip rap, gabions, j hooks, barbs, cross vanes, boulders or drop rock for stabilizing stream banks. In most or at least many instances, it is not the construction material of blocks that contribute to failure, but installation procedure that include keying in the base materials properly into the channel and extending and keying into the bankfull or floodplain levels. Knowledge of the bank materials relative to erodibility and stability is also important. Also, besides the shear stress related to stream velocity, abrasion from sediment and bedload, there can be pressure and stress applied from the bank materials as it saturates, and especially if the bank materials are unstable or failure prone. Bioengineering with combination of structural and biological components (such as black willow cuttings or posts driven into the bank) can sometimes be used. By looking at the downstream side of point bars, the largest materials found may approximate the D84 particle size of bedload moving. If your blocks are not substantially larger than the bedload commonly moved by the river, that could be a concern unless the blocks are cemented or glued together and properly keyed into the bank or bed materials with rebar or other supports. We had a successful bank bioengineering stabilization along a major river, but one year had 8-10 bankfull and larger flood events, and that contributed to partial failure issues that had to be repaired, resulting in also placement of river barbs to reduce the bank stress, similar to Rosgen J Hooks. We later estimated that the upriver sand mining operations were resulting in the Clean Water Effect with accelerated erosion as described by Matt Kondolf (spelling ? California professor) in his studies.