268 BRIDGE ABUTMENTS AND PIERS. CHAP. VI. 



Dowels. (a) Straight bars of iron which enter a hole in the upper side of one stone and also 

 a hole in the lower side of the stone next above. 



Dowel. (b) A two-piece steel instrument used in lifting stone. The dowel engages the 

 stone by means of two holes drilled into the stone at an angle of about 45 degrees pointing toward 

 each other. The dowel is not keyed in place. 



Draft. A line on the surface of a stone cut to the breadth of the chisel. 



Expansion Joint. A vertical joint or space to allow for temperature changes. 



Extrados. The upper or convex surface of an arch. 



Intrados. The inner or narrow concave surface of an arch. 



Face. The exposed surface in elevation. 



Facing. In concrete: (i) A rich mortar placed on the exposed surfaces to make a smooth 

 finish. 



(2) Shovel facing by working the mortar of concrete to the face. 



Final Set. A stage of the process of setting marked by certain hardness. (See Cement 

 Specifications.) 



Flush. (Adj.) Having the surface even or level with an adjacent surface. 



Flush. (Verb.) (i) To fill. (2) To bring to a level. (3) To force water to the surface 

 of mortar or concrete by compacting or ramming. 



Footing. A projecting bottom course. 



Form. A temporary structure for giving concrete a desired shape. 



Foundation. (i) That portion of a structure usually below the surface of the ground, which 

 distributes the pressure upon its support. (2) Also applied to the natural support itself; rock, 

 clay, etc. 



Foundation Bed. The surface on which a structure rests. 



Grout. A mortar of liquid consistency which can easily be poured. 



Header. A stone which has its greatest length at right angles to the face of the wall, and 

 which bonds the face stones to the backing. 



Initial Set. An early stage of the process of setting, marked by certain hardness. (See 

 Cement Specifications.) 



Joint. The narrow space between adjacent stones, bricks or other building blocks, usually 

 filled with mortar. 



Lagging. Strips used to carry and distribute the weight of an arch to the ribs or centering 

 during its construction. 



Lewis. A four-piece steel instrument used in lifting stone. (The lewis engages the stone 

 by means of a triangular-shaped hole into which it is keyed.) 



Lock. Any special device or method of construction used to secure a bond in the work. 



Mortar. A mixture of fine aggregate, cement or lime and water used to bind together the 

 materials ot concrete, stone or brick in masonry or to cover the surface of the same. 



Natural Bed. The surfaces of a stone parallel to its stratification. 



Parapet. A wall or barrier on the edge of an elevated structure for protection or ornament. 



Paving. Regularly placed stone or brick forming a floor. 



Pier. An intermediate support for arches or other spans. 



Pitch. (Verb.) To square a stone. 



Pitched. Having the arris clearly defined by a line beyond which the rock is cut away by 

 the pitching chisel so as to make approximately true edges. 



Pointing. Filling joints or defects in the face of a masonry structure. 



Retaining Wall. A wall for sustaining the pressure of earth or filling deposited behind it. 



Voussoirs. The individual stones forming an arch. They are always of truncated wedge 

 form. 



Ring Stones. The end voussoirs of an arch. 



Riprap. Rough stone of various sizes placed compactly or irregularly to prevent scour by 

 water. 



Rubble. Field stone or rough stone as it comes from the quarry. When it is of a large or 

 massive size it is termed block rubble. 



Rubbed. A fine finish made by rubbing with grit or sand stone. 



Set. (Noun) The change from a plastic to a solid or hard state. 



Slope Wall. A wall to protect the slope of an embankment or cut. 



Soffit. The under side of a projection. 



Spall. (Noun). A chip or small piece of stone broken from a large block. 



Spandrel Wall. The wall at the end of an arch above the springing line and extrados of the 

 arch and below the coping or the string course. 



Stretcher. A stone which has its greatest length parallel to the face of the wall. 



Wing Wall. An extension of an abutment wall to retain the adjacent earth. 



