A mat for stabilizing particulate materials includes a planar quadrilateral grid formed by a plurality of intersecting struts. A reinforcement zone strengthens each of the strut intersections. Upstanding cylindrical tubular members are disposed on the grid in a rectangular array such that the central longitudinal axis of each of the tubular members extends through a strut intersection. Longitudinal ribs are formed on an interior cylindrical sidewall of each of the tubular members and are disposed such that each of the ribs perpendicularly intersects a strut adjacent a bottom end of the tubular member. Sockets are spaced uniformly along two adjacent sides of the mat, with each socket secured between two of the tubular members by a pair of struts. Pins are spaced along the other two adjacent sides of the mat, opposite the sockets, with each pin also secured between two of the tubular members by a pair of struts. The pins are dimensioned for insertion through the sockets, such that a plurality of the mats may be connected in adjacent relation. The free ends of the pins may be deformed after insertion through the sockets to provide permanent securement. The grid, tubular members, pins and sockets are all integrally molded from a semi-rigid thermoplastic material such as high density polyethylene. One or more geotextile layers may be applied to the upper face, the lower face, or both faces of the mat. The mat is intended to stabilize particulate materials such as soil, sand, asphalt, gravel, and may be employed in erosion control and paving applications.