An E-glass-reinforced epoxy-based nanocomposite containing organomodified nanoclay (15–20 nm) and calcium silicate particles (75–149 $\mu$m) was developed through mechanical shearing mixing and hand layup techniques. Three weight fractions (2, 3 and 4%) of nanoclay were selected to study the effects of nanoclay on mechanical and wear behaviour of nanocomposites. Tensile and flexural properties of nanocomposites were evaluated and compared. The wear properties were evaluated for three speed (3.14, 4.19 and 5.24 m s$^{−1}$) and load (20, 50, and 80 N) conditions based on a design of experiment (L16 matrix) concept. The wear loss results were statistically analysed to study the significance of load, speed and nanoclay content. The morphologies of wear surface and fracture surface were examined with the aid of a scanning electron microscope (SEM) to identify the wear and fracture mechanisms. It was found that the wear loss increases with increasing nanoclay amount due to the particle agglomeration effects. Statistical analysis determines that the load is the most significant parameter affecting the wear resistance of nanocomposites. The mean and S/N ratio analyses rank the parameters significance in affecting wear resistance as follows: load $>$ nanoclay content $>$ speed. The wear mechanisms of nanocomposites are complex due to the observation of multiple features such as fibre thinning, matrix wear and fibre/matrix debonding as against abrasive wear in the pure epoxy. Tensile and flexural test results show that a good dispersion of nanoclay is achieved with 2 wt% amount in epoxy-based nanocomposites. The mechanical properties degrade above 2 wt% due to the excessive reinforcement,uneven distribution and the particle agglomeration effects. Fractography studies of tension-failed samples show that pure epoxy resin fails by multimode gauge explosive mode, whereas nanocomposites fail mainly by the matrix/fibre interface failure and fibre breakages.