a method of forming a liner for a passage such as a sewer includes forming panels composing the liner using a neat resin of a first viscosity and a polymer concrete of a second , high viscosity . the neat resin is inserted into a mold cavity before the polymer concrete and is displaced upwardly by the polymer concrete pour to impregnate a fiber layer disposed along the periphery of the mold cavity . resulting panels preferably have an offset joint to increase the joint strength between upper and lower panels forming the liner .