We claim the ornamental design for an envelope for constructing a mat of spaced blocks, as shown.
FIG. 1 illustrates an upper right perspective view of our new design for an envelope for constructing a mat of spaced blocks;
FIG. 2 illustrates a top plan view thereof, the opposing bottom view being a mirror image;
FIG. 3 illustrates a front elevational view thereof, the back elevational view being a mirror image; and,
FIG. 4 illustrates a right side elevational view thereof, the left side elevational view being a mirror image thereof.
The envelope illustrated in FIG. 1 forms a mat of spaced blocks for surface overlay purposes, including but not limited to use as an erosion control mat for covering and stabilization of ground surfaces subject to water erosion including ground slopes, water flow channels, shorelines, and underwater surfaces, as well as a separation and vertical drainage layer for marine applications under large stone rip rap, a ballast layer to provide weight for sinking another material that would normally float and as a protective layer/vertical drainage over such material. The envelope has a plurality of central portions separated by cruxiform portions, which filled with a curable flowable material forms mat of spaced blocks. The envelope may be formed of a woven fabric material.
Shading has been applied, for illustrative purposes and the shading lines themselves form no part of the claimed invention.