A permeable surface covering unit comprises a top surface, a bottom surface and at least two pairs of sides. A cavity is formed in the unit from the top surface to the bottom surface, and has side walls. The cavity may be a side cavity between units and/or a core cavity within the unit. An undercut is provided in the cavity. Pervious material plugs fill the cavity and extend into the undercut. Thereby the plug is locked into the cavity like a rivet and resists being dislodged by mechanical or hydraulic forces.

Methods of manufacturing a plurality of mats useful with a plurality of frame style seal members in a load-supporting surface include at least one milling machine, router or pre-formed mold forming at least first and second elongated grooves in first and second offset outer edges of at least a first side of each among at least first and second stepped-configuration, reversible mats. Each groove causes the seal member(s) seated therein to extend into a gap formed between the mats, abut at least one seal member extending from another mat into the same gap and form a liquid-tight seal therewith.

A mat that includes first and second side beams, a core structure located between and connected to the side beams, with the support structure including longitudinal members and having a height that is less than that of the side beams, a plurality of joining rods that attach the side beams to the support structure, with the joining rods passing through the sides of the side beams and the sides of the longitudinal members of the support structure; one or more elongated members attached to the upper portion of the support structure to form with the beams the top surface of the mat, and one or more elongated members attached to the lower portion of the support structure to form with the beams the bottom surface of the mat. If desired, steel plates can be provided between the beams and longitudinal members to increase the strength and ruggedness of the mat.

An industrial mat having a supporting structure; an upper layer provided above the supporting structure for forming an upper surface of the mat, a lower layer provided below the supporting structure for providing a lower surface of the mat; and lifting elements attached to the upper layer, the lower layer or the supporting structure. The lifting elements include D-shaped members, O-shaped members, U-shaped members, eyelets, hooks, circular or polygonal rings, chains, or cables that are configured and dimensioned for attachment to attached to the supporting structure or the upper or lower layer with sufficient strength to provide certified overhead lifting of the mat for installation and reclamation thereof.

An industrial mat having a supporting structure; an upper layer provided above the supporting structure for forming an upper surface of the mat, a lower layer provided below the supporting structure for providing a lower surface of the mat; and lifting elements attached to the upper layer, the lower layer or the supporting structure. The lifting elements include D-shaped members, O-shaped members, U-shaped members, eyelets, hooks, circular or polygonal rings, chains, or cables that are configured and dimensioned for attachment to attached to the supporting structure or the upper or lower layer with sufficient strength to provide certified overhead lifting of the mat for installation and reclamation thereof.

An industrial mat having a supporting structure; an upper layer provided above the supporting structure for forming an upper surface of the mat, a lower layer provided below the supporting structure for providing a lower surface of the mat; and lifting elements attached to the upper layer, the lower layer or the supporting structure. The lifting elements include D-shaped members, O-shaped members, U-shaped members, eyelets, hooks, circular or polygonal rings, chains, or cables that are configured and dimensioned for attachment to attached to the supporting structure or the upper or lower layer with sufficient strength to provide certified overhead lifting of the mat for installation and reclamation thereof.

A mat that includes first and second side beams, a core support structure located between and connected to the side beams, with the core support structure including longitudinal members and having a height that is less than that of the side beams; one or more elongated members attached to the upper portion of the core support structure to form with the beams the top surface of the mat, and one or more elongated members attached to the lower portion of the support structure to form with the beams the bottom surface of the mat. Preferably, a plurality of joining rods attach the side beams to the support structure, with the joining rods passing through the sides of the side beams and the sides of the longitudinal members. Also, steel plates can be provided between the beams and longitudinal members to increase the strength and ruggedness of the mat.

Apparatus for forming a liquid-tight seal across gaps formed between at least first and second adjacent mats in a load-supporting surface includes at least one seal member configured to be coupled to each among first and second outer edges of at least a first side of each among at least first and second adjacent mats and extend laterally outwardly therefrom into one among at least two gaps formed between the adjacent mats and abut at least one other such seal member extending into the same gap from the other adjacent mat that forms the gap.

A paver locking system. The paver locking system may include; a paver assembly, including a paver; and straps attached to a back portion of the paver. The paver locking system may further include a paver spacer; and a securing mechanism for securing paver straps to the paver spacer.

A mat that includes first and second side beams, a core support structure located between and connected to the side beams, with the core support structure including longitudinal members and having a height that is less than that of the side beams; one or more elongated members attached to the upper portion of the core support structure to form with the beams the top surface of the mat, and one or more elongated members attached to the lower portion of the support structure to form with the beams the bottom surface of the mat. Preferably, a plurality of joining rods attach the side beams to the support structure, with the joining rods passing through the sides of the side beams and the sides of the longitudinal members. Also, steel plates can be provided between the beams and longitudinal members to increase the strength and ruggedness of the mat.