Page 65 - ICJ Jan 2023

TECHNICAL PAPER COLLECTOR’S EDITION

RESULTS AND DISCUSSION compounds. This may possibly explain

Strength tests were carried out on soil-cement the fall in strength as sand fraction is
cubes prepared using two cement contents of increased. It must however be noted that
5 percent and 10 percent by weight. Fig 3 shows inspite of this fall in strength the cubes of
strength results of soil-cement cubes for six ML soil with 80 percent sand are stronger
different soils using 5 percent cement. Here, wet by about 25 percent than the cubes of
compressive strength of soil-cement cubes is other soils with the same sand percentage.
plotted against the sand content of the soil. The
strength values shown in the figure represent the (iii) The increase in wet compressive strength
mean of 3 cubes. The following observations can of soil- cement bears no relation to the
be made from the results shown in the figure. quantum of sand added.

(i) Wet compressive strength increases with Results of the strength tests for different soils
increase in sand content for the soils BG, using 10 percent cement are shown in Fig 4. In the
BC, SBC and MBC. The increase is very case of higher cement contents, the response to
significant for soil-cement blocks using BC variation in the sand content of the soil seems to
and BG soils. There is a three fold increase in be different compared to the lower cement content
strength for BC soil, when the sand content of 5 percent. There is a marginal variation in the
of the soil is changed from 36 percent to wet compressive strength of soil-cement cubes as
78 percent. Similarly, the strength doubles
for BG soil for a change in the sand content the sand content of the soils is doubled for BG, BC,
from 48 percent to 83 percent. In case of MBC, and SBC soils. There is hardly any variation
MBC soil there is a 50 percent increase in in strength for BG and BC soils when the sand
strength for a change in the sand content content is doubled by about 40 percent. There is
from 38 percent to 80 percent. The strength 10 percent variation in strength for MBC and SBC
increase is only marginal for SBC soil as soils. The strength has gone up by 20 percent for
the sand content of the soil is increased. SH soil as the sand content is doubled. In case of
It is to be noted here that BC soil has only ML soil there is 25 percent decrease in strength
montmorillonite clay mineral, and the as the sand content is doubled. However, all the
other soils (BG, SBC and MBC) have both cubes are 2 to 3 times stronger than the 5 percent
montmorillonite and kaolinite. cement stabilised cubes.

(ii) In the case of ML soil there is a 50 percent
fall in wet compressive strength as the The following points are clear from the results of
sand content of the soil goes up from 40 strength studies on soil-cement blocks.
percent to 80 percent. Similarly there is a
marginal fall in strength for soil-cement (i) Soil gradation can be easily modified by
cubes using SH soil. Both these soils have sand addition. Adding more sand to any
predominantly kaolinite clay mineral. soil leads to increase of sand content
The high value of strength for the virgin and a proportionate decrease in the clay
soil indicate the possible presence of fraction of the soil.
reactive compounds in the clay fraction.
The addition of sand also reduces the (ii) Wet compressive strength of soil-cement
clay fractions including the reactive increases with increase of sand content for

66 The Indian Concrete Journal | November 2018