In the framework of the LAA project, prototypes for a new type of calorimeter, intended for the detection of both electromagnetic (e.m.) and hadronic showers, muons and missing energy (e.g. neutrinos) at high-luminosity multi-TeV pp colliders, were tested. The detector consists of scintillating plastic fibres embedded in a lead matrix at a volume ratio 1:4, such as to achieve compensation. The optimization of the construction of the detector modules is described, as well as the performance concerning e.m. shower and muon detection and e/π separation. We used electron, pion and muon beams in the energy range 10-150 GeV for this purpose. For the energy resolution of electrons we found 13%/trE, with a constant term of 1%. The signal uniformity was better than 3% over the total surface of projective modules. The signal linearity for e.m. shower detection was better than 1%, and the e/π separation was better than 5 × 10-4 for isolated particles. Channeling effects are negligible, provided that the angle between the incoming particles and the fibre axis is larger than 2°.