178 MASS. EXPERIMENT STATION BULLETIN 170. 



Fig. 46. — Cement-filled cavity 

 favorably Bliaped for healing 

 over. 



surface with metal, the use of elastic material and special grooves, laying 

 the cement in sections, and many others, have not proved of any material 



value in solving the problem. 



(g) The tissues back of a cavity are 

 rendered more susceptible to decay by 

 the cement filling. This is especially 

 true if proper antiseptic treatment is not 

 given, or if the cavity is not thoroughly 

 cleaned. 



From the various objections given it 

 follows that it is often better to leave 

 the cavity open, or merely to cover the 

 same, than to fill with cement. 



Several methods have been employed 

 for the use of cement, and a detailed 

 description of all of them is hardly 

 worth while. It has been extensively 

 employed as a filling, and also as a 

 covering for the cavity opening, in 

 which case the main cavity itself would 

 be left unfilled. In most of the older work in filling cavities with cement 

 the opening of the cavity was boarded up and grouting of a more or 

 less soft consistency, consisting of 1 part cement to 5 or 8 of sand, 

 gravel or other material, was poured in. 

 When this was partially set the boards 

 were removed and the surface of the 

 grouting was coated with about 1 part 

 cement to 2 parts sand, this extending to 

 the outer edges of the wood and conform- 

 ing to the general contour of the tree. In 

 other cases cement in the proportion of 1 

 part to 2 or 3 parts of sand has been used 

 in a relatively dry form, applied in small 

 quantities, and thoroughly tamped. This 

 method does not require the use of boards 

 at the cavity opening, as the cement, 

 which is uniform throughout, is gradually 

 built up until the filling process is com- 

 pleted. The outer surface conforms to 

 the general contour of the tree. The use 

 of relatively dry cement has proved more 

 desirable for cavity work than grouting, 



followed by a surface covering of a different consistency, and has done 

 away with considerable of the cracking and dislodgment of cement which 

 followed surface covering over grouting. In cavity work of all kinds 

 where cement is used, nails, spikes, wires, iron rods and bolts, wire mesh, 



Fig. 47. — Cement-filled cavity 

 with bolt. 



