Layer Stabilising Device

A stabilising device adapted for stabilising an underlayer of a first, relatively soft, material with minimal contamination or disturbance of an overlying second layer of material comprising: (i) at least one mixing element capable of mixing a stabilising composition into the underlayer, (ii) means for lowering the or each mixing element into the underlayer, and (iii) means for introducing the stabilising composition into the underlayer, characterised in that the device additionally comprises means for substantially reducing contamination of the overlying layer with the stabilising composition and/or underlying material and/or for substantially reducing disturbance of the overlaying material in use during mixing of the underlayer with the stabilising composition, and means for lowering the contamination reduction means into the overlying layer.