The use of and the construction practices for construction joints for concrete curb and gutter shall be the same as those for construction joints for portland cement concrete pavement as outlined in § 5.21 of this chapter. Two dowel bars shall be used through the header to fasten the abutting sections. These dowels shall be the same material, size and covering and the like as provided in § 5.21 of this chapter except that they shall be place on centers of not less than 12 inches and not more 18 inches.