This is a modified form of a rib knit fabric, which uses tuck stitches to produce a thicker fabric. Cardigan stitches are either classified as Full Cardigan or Half Cardigan, and the fabric looks like a slightly stretched rib knit fabric.
Full Cardigan: A tucked rib knit stitch, which creates the same series of wales (lengthwise ridges/ribs) on both the face and the back of the fabric.
Half Cardigan: A tucked rib knit stitch, which is a variation of the full cardigan stitch. The spaces between the wales (lengthwise ridges/ribs) on the face of the fabric are closer together than those of the Full Cardigan. The back of the Half Cardigan knitted fabric has the same series of wales as the Full Cardigan.