XIV. W. E. COOK. 
A. test, somewhat on the same lines as the Melbourne 
experiments, was made in connection with a contract under 
the Water and Sewerage Board, Sydney, comparing the 
tensile strength of briquettes made with— 
(a) 1 part cement to 1 standard sand. 
Ch eae 5» 95, L bluestone dust or toppings. 
(c)al*., >» 95 + Standard sand and + bluestone 
dust or toppings. 
The results up to date are :— 
Bluestone Sand and 
Time. Sand. Dust. Bluestone Dust. 
7 days ne 460 a2 o01 ae 464 
28 4s es 631 on 647 Hef 639 
3 months... 825 ce 801 he 787 
Bie a J. $60 (.. 920 -2 2 eee 
ae F 911 ain 920 aA 869 
toe. a ~=« 8850C~C«‘ ‘NN! OA ee 
Hach test is the average breaking strain of 4 briquettes. 
They were all made on the same day, and were treated 
exactly alike. In this and all other briquette tests the 
briquettes, after being moulded, stay in the moulds 24 
hours in the air; the moulds are then removed, and the 
briquettes are placed in water, and remain immersed until 
tested. 
In this case the contractor was allowed to use $ sand 
and + bluestone dust in place of each part of sand, because 
by careful sieving it was found that the stone, as delivered, 
contained dust to the extent of one quarter of the sand 
specified. 
From the above figures, or from the diagram, it will be 
seen that bluestone dust is strongest throughout, except 
at three months. It should follow that the mixture of 
sand and dust is stronger than sand, but such is not the 
case; though at 7 and 28 days, and also at 6 and 12 
months, there is practically no difference between the two. 
It is intended to continue this experiment up to 5 years. 
cae 
