ILLUSTRATIONS. 



Plate I. Crushed cube of concrete froni Carcar Bridge, showing disintegration 

 of gravel. 

 II. Crushed cube of concrete from Pantal Bridge, Pangasinan, showing 



disintegration of mortar. 

 III. Cone from crushed cube of concrete from Abatan River, Cortes, Bohol, 

 showing effect of using- gravel covered with green algae. 



IV. Crushed cube of concrete made from first-class aggregate. 



141 



