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.