asphaltic bitumen 60/70 covered -with a 1, 5 cm layer 

 of broken stones of 1-2 cm which was treated in turn 

 with a surface treatment of 3 kg/m^ asphaltic bitumen 

 60/70 and finally protected by a 1.5 cm compacted cover 

 of broken stones of 1-2 cm. This protection has served 

 well although attacked heavily during southwest gales. 



Test lb. Penetration of macadam with asphalt mastic. The 

 area has approximately the same cover as described under 

 1. It reaches from N.A.P. to 3.50 m * N.A.P.. The 

 lower part is subject to wave action daily. Bulges 

 have formed in this lower part, the cause of which is 

 unknown. Possibly sand was deposited between the rubble 

 stones during the construction. Water may have accumu- 

 lated in this sand creating ^pressure behind the 

 impermeable cover. Since the voids in the rubble stone 

 are rather small anyway, it is imperative that care be 

 taken to prevent sand and fine material filling the 

 voids . 



It seems undesirable to use the procedures des- 

 cribed under 1 and 2 under less favorable conditions 

 although they did prove satisfactory under the circum- 

 stances of the tests. 



Test 2d. Grouting of set stone with pouring asphalt. 

 Three areas were covered, reaching from N.A.P. to 

 +0.90 and 4-2.00 m N.A.P. respectively. The stones were 

 set in the usual way, after which the spaces were filled 

 with rubble stone, gravel and sand to 8 cm from the 

 surface. Then the sides of the stones- were treated 

 with a cold bituminous priming coat, after which the 

 spaces were filled with pouring asphalt to 2 cm from 

 the surface. The pouring asphalt consisted of 4-3, 3% 

 DX 10, L,.l% asbestos fiber 2-4- mm and 52$ sand 0-2 mm. 

 Twenty-two kg per square meter of pouring asphalt 

 were used, containing 9.5 kg of asphaltic bitumen. 

 The lower parts of the spaces were kept open to let 

 the water pass freely and thus prevent the building up 

 of pressure under the layer. 



This construction appears to be very solid, has 

 served well, and seems sound and economical at ex- 

 posed slopes. 



Protection of the Dune Foot of the "Green Beach" at Terschelling 

 1937 (Figure 1) ' ' " 



In 1937 the beach near the dune foot at one end of the 

 "Green Beach" at Terschelling was repaired and protected after it 

 had been damaged by the sea during high tides. The beach was 



30 



