EXPERIMENT STATION BULLETINS. 



367 



DISCUSSION OF THE SAMPLES OF TILE RECEIVED. 



Several drainage systems, where failures with cement drain tile had 

 been reported, were investigated and a number of samples from each 

 drain were sent to the laboratory for further examination. Some sam- 

 ples were also received direct from the manufacturers. In the discus- 

 sion which follows, these samples are referred to by lot number only. 



Ch-emical tests and analyses showed that a portion of the essential 

 constituents of the cement had been dissolved out of the badly dis- 

 integrated tile. This made these tile very porous and brittle — the 

 cementing materials being so weak that the small particles could be 

 rubbed otf with the fingers. Another interesting fact associated with 

 the disintegrated tile was that the disintegration began on the outside, 



Fig. 3 — Exterior and interior views of a badly disintegrated tile showing that the disintegration 

 proceeds from the outside. No signs of disintegration are seen on the inside. 



the interior remaining quite sound until the exterior had practically 

 gone to pieces. In some cases the upper half of the tile showed dis- 

 integration Avhile the lower half was sound, and in other cases the lower 

 half showed disintegration while the upper half was sound — depending 

 entirely on whether water percolated through from above or from be- 

 low. The interior of the tile through which the water flowed showed 

 very little, if an}-, disintegration. 



An examination of a sound, unused tile from lot one showed that 

 there was considerably more variation in the aggregate (graded sand) 

 than is usual in good concrete tile, and that the matrix (very fine 

 sand and cement which bind the larger particles together) was very 

 porous. The report giving a brief history of the tile, and the drains 

 from which they were taken, showed that they were "factory made, 

 hauled from the factory as soon as they could be handled, and laid with- 



