130 The Philippine Journal of Science 1921 
mens were taken out of the molds and stored either in the labo- 
ratory air or in the moist-air closet until the time of rupture. 
With a few exceptions, the test specimens sent to the mate- 
rials testing laboratory of the Bureau of Science were hand- 
mixed. From personal observation of the activities of concrete- 
mixing gangs in various parts of the Archipelago I am in a 
position to account for the exceptionally low and erratic re- 
sults obtained from specimens made on the building site. 
Laboratory tests of many of the aggregates gave high and 
‘uniform results; however, the proportioning of the same ag- 
gregates and cement in the field in the Philippine Islands is, 
in general, a haphazard operation that results in an arbitrary 
mixture which bears little relationship to the concrete prescribed 
by the designer. In some instances both the cement and the 
aggregates are measured loosely, with the result that instead 
of using from 90 to 100 pounds to the cubic foot as packed in the 
barrel, the cement is used in volumes that weigh anywhere from 
50 to 70 pounds to the cubic foot. By using this method one 
barrel of cement is made to go a long way, but the resultant 
concrete is very friable and gives extraordinarily low com- 
pressive strength. In other instances I have seen the sand 
and gravel measured in wheelbarrows—a certain number of 
loads of each to one barrel of cement—with the result that the 
actual ratio of cement to sand to gravel was unknown. 
Irregularities also occur in the operation of mixing that cast 
light on the discordant results secured from a lot of specimens 
made from the same batch of concrete. The usual method em- 
ployed in making concrete by hand in the Philippines is to mix 
the sand and cement dry until it is fairly homogeneous; in 
general this means that a barrel of cement is dumped on the 
sand and the pile shoveled through once to form a cone. Some- 
times the cone thus formed is shoveled through once more. The 
workmen now form a crater in the center of the cone while a 
man plays an ordinary garden hose or pours pails of water 
into the depression thus formed. The amount of water added 
is determined by the mixers, who continue to call for water 
until the mortar has lost all of its stiffness and plasticity, and 
the shovel can be passed through the mass with a minimum 
amount of labor. No attempt is made to measure the water; it 
is used in such superabundance largely for the purpose of re- 
ducing to a minimum the work of mixing and placing. The 
mortar thus drenched with water is soupy, and more than 
once I have seen it flow over the edge of the wooden mixing 
