Building Materials, Third Edition

200 Building Materials

The percentage of bulking of the sand due to moisture is calculated from the formula:

Percentage bulking =

h

1100

h

ʈ-¥

Á ̃Ë ̄¢

II Method: The damp sand (consolidated by shaking) is poured in a 250 ml measuring cylinder
up to the 200 ml mark. Then the cylinder is filled with water and the sand is stirred well. The
sand surface will be found to be below its original level. Supposing the surface is at the mark
y ml, the percentage of bulking of the sand due to moisture is calculated as:

Percentage bulking =

200

1100

y

ʈ

Á ̃-¥

Ë ̄

Determination of Surface Moisture in Fine Aggregate (Field Method)

Determination by Weight: The container is filled up to the mark with water and the weight
in grams determined. It is emptied. Enough water is placed in the container to cover the
sample, after which the sample of fine aggregate is introduced into the container and the
entrained air removed. The container is then filled to the original mark and the weight in
grams determined. The amount of water displaced by the sample is calculated as:

Vs = Mc + Ms – M

where Vs = weight in g of water displaced by the sample

Mc = weight in g of container filled up to the mark with water

Ms = weight in g of the sample

M = weight in g of the sample and container filled to the mark with water

Determination by Volume: A volume of water sufficient to cover the sample is measured in
milliliters and placed in the container. The weighed sample of fine aggregate is then admitted
into the container and the contained air removed. The combined volume of the sample and
the water is determined by direct reading when a graduated flask is used. Where a pycnometer
or volumetric flask of known volume is used, the combined volume of the sample and the
water is determined by filling up to the mark with a measured volume of water and
subtracting this volume from that of the container. The amount of water displaced by the sample
is calculated as:

Vs =V 2 – V 1
Where Vs = volume in ml of water displaced by the sample
V 2 = combined volume in ml of the sample and water
V 1 = volume in ml of water required to cover the sample
The percentage of surface moisture in terms of the saturated surface-dry fine aggregate and
in terms of the weight of wet fine aggregate are calculated as:

P 1 =

-

¥

-

sd

sd

VV

100

MV

P 2 =

-

¥

-

sd

sd

VV

100

MV

where P 1 = percentage surface moisture in terms of saturated surface-dry fine aggregate

Vs = weight in g of water displaced