CHAPTER III
Methodology
Research Design
Experimental method of research was utilized in this study. Each of the samples was
compared to the normal sample. Each of the samples was setup at the same time with only two
variables were manipulated. Each sample used same amount of cement and volume of water
(200mL). The ratio for each sample of sand to Tahong shells as aggregate was change
accordingly to certain ratio while the amount of the cement remains constant as shown in Table
1. The ratio of 1:7 was used as the control that will provide the basis for series of testing in terms
of density, water absorption and heat capacity.
Sample
Ratio
Cement
Sand
Normal
T1
T2
T3
1:7
1:6:1
1:5:2
1:4:3
1.375 kg
1.375 kg
1.375 kg
1.375 kg
9.63 kg
8.25 kg
6.875 kg
5.5 kg
Tahong
shells
1.375 kg
2.275 kg
4.125 kg
Table 1. Ratio and mass of the mixture
The independent variable in this study is the amount of Tahong shells in each sample
while the dependent variable is the density, water absorption and heat capacity of the sample.
Experimental design
Preparation of Tahong Shells
Ratio and Proportioning of
mixture
Production of the mixture and
curing
Testing of sample
Astec Physical Test
Water Absorption
Data Gathering
Statistical Analysis
Heat Capacity
Experimental Procedure
Processing of Tahong shells
The processing of bottles starts with the air drying process of the Tahong shells for 1
week. Dirt and unwanted materials were removed followed by another 1 day drying process. The
shells were grinded using a blender to produce sand like material as shown on Figure 1.
Weighing and Adjusting Proportions
Proportions of the mixtures were adjusted based on the typical ratio of a concrete mixture
of 1:7 (1 part of cement to 7 parts of sand) as the normal (N). The 1:7 ratio of the typical
concrete mixture was used as the control for the whole measurements. This ratio is based on the
sandcrete mix proportion used to make CHB. The measurement for cement remained constant
throughout the sample. The ratio of sand and cement was adjusted on the following ratios.
Mixing and Curing
The measured mixture was sent to a hollow block making site and air dried for 7 days.
Testing
In order to come up with the density of the common concrete and concrete with PET as
an aggregate the formula for density was used. Masses and volume of the standard and
treatments were measured. The samples for the standard and the treatment were trimmed
following the dimension standard concrete hollow block before they are weighed.
In order to test for water absorption, samples of the standard and treatments of equal
volumes were submerged each in 2000 mL beaker of water. Every 6 hours, the level on each of
the beaker was recorded.
The test for heat capacity of the standard and treatment samples were calculated using the
formula Q= mC∆t and Qt= (mC∆t)cement+(mC∆t)sand+(mC∆t)Shell. The specific heat (C) of cement
is 920 J/kg∙K, sand is 800 J/kg∙K and PET 1000 J/kg∙K (Engineering toolbox, 2016). The ∆t of
each sample were derived after exposing each sample to heat for 5 minutes.
The mass of each sample were derived from its mass after it was trimmed with a
dimension of the concrete hollow blocks. The Q of each component per sample was computed
using the formula Q= mC∆t and the summation of each component’s Q is the heat capacity of
each sample.
Statistical Treatment
This study used the t-Test for paired sample to determine the significant difference
between standard concrete mixture to the concrete mixture with PET as aggregate. The
significant level set for all analyses was 0.05 and Microsoft Excel was used as a tool for
computing data for analysis.