208 The Philippine Journal of Science 1921 
obtained from 1 : 2 : 4 mixtures composed of the same kind of 
aggregates. More careful proportioning of cement and aggre- 
gates would undoubtedly have given more uniform results. 
MISAMIS 
Good results were obtained from 1: 2:4 concrete specimens 
coming from Misamis, the average being 1,534 pounds per square 
inch for specimens aged 28 to 34 days; the minimum value of 
922 pounds per square inch in this series is less than half of the 
maximum value, 2,039 pounds. The three 1 : 2.5 : 5 test pieces 
gave low results, which average 698 pounds per square inch. 
The compressive strength values show that care was taken in 
proportioning and that concrete materials of good quality are 
available in this province. One sample of sand from Cagayan 
River must be classed as excellent. It yielded an extraordinarily 
resistant 1:3 mortar, unsurpassed in compressive strength by 
any other mortar recorded in this paper. The average ultimate 
compressive strength, at 28 days, of specimens made with the 
use of this sand is 5,508 pounds per square inch, which is nearly 
twice that of specimens made of Ottawa sand. The high strength 
of this mortar is primarily due to the very coarse and graded 
granulometric composition of the sand combined with hard- 
ness and cleanness of the grains. This sand is composed prin- 
cipally of rounded basaltic pebbles and contains very little 
quartz. 
NUEVA ECIJA 
Values obtained from concrete specimens coming from Nueva 
Ecija are poor, particularly those made of Binutuan River ag- 
gregate, which is soft, dirty, and fine-grained. ‘The 1 : 2 : 4 test 
pieces made of this aggregate gave the extraordinarily low result 
of 288 pounds per square inch, which is very close to the mean 
compressive strength of 246 pounds per square inch given by 
the 1 : 3 : 6 specimens at 28 days, so that it is not improbable 
that the same mixture was used in casting all four of these speci- 
mens. The results were so bad that the district engineer was 
ordered to use a different aggregate. The 1:2:4 specimens 
made of Guimba River sand and Baliuag River gravel gave 
higher compressive strengths; but these values also are unsatis- 
factory, and, moreover, they are markedly variant. The aver- 
age given by these four cubes is 614 pounds per square inch. 
Preliminary laboratory tests of available Nueva Ecija sands 
would certainly have given valuable information, which would 
have resulted in the elimination of the unsuitable materials 
that were unfortunately used in actual construction. 
