Understanding Stabilized Earth Construction: Testing for Thermal Resistance

Tyler Robertson and Chris Walla

Thermal Issues in Stabilized Earth Blocks
Statement of Intention:
To analyze the thermal issues at work in both a single stabilized earth block and a system of stabilized earth blocks.
Objective:
To analyze the characteristics of stabilized earth blocks and in doing so understand the factors that alter its thermal qualities. For instance, are the thermal qualities affected by changing the mixture of the earth blocks, and if so, in what way? Also, analyze the difference in thermal qualities depending on the technique used for assembling a system of stabilized earth blocks.
Methodology:
Analyze, through both research and testing, what the thermal qualities of different earth blocks are.
Using a variety of earth blocks with multiple proportions of ingredients, measure the ability to hold and dissipate heat by uniformly heating the block and then allowing them to cool. Record the temperature of the block at various intervals of time and then plot these values. Analyze the rate at which heat is lost in these stabilized earth blocks.
Using a variety of earth blocks with multiple proportions of ingredients, measure the ability of these blocks to resist heat flow. By directly heating one end of the earth block, measure and record the temperatures at various locations throughout the block. Note the time that it takes for the heat to travel through the block, and to what extent it heats up.
Analyze the difference in construction techniques for a system of stabilized earth blocks. Experiment with the travel of heat through a system of earth blocks using multiple dimensions, solid earth blocks compared to hollow, multiple arrangements of stacking the blocks, etc. By controlling the heat, measure the rate and amount of heat transfer through the different systems by heating one side and taking measurements at various locations throughout the blocks.
Use the results from both tests (single block and block system) to find the best and most efficient combination for the stabilized earth blocks.
Equipment/Supplies Required:
Various samples of stabilized earth blocks, heat lamp and/or butane torch, thermometer, box to contain the block system and control the heating to specific location of the blocks, and a drill to make holes to the core of the sample.
Expected Results:
That the denser earth blocks will be a better conductor of heat and allow for greater heat transfer. By using different materials to mix in with the soil, the rate at which heat flows will differ greatly among samples, especially materials designed for retaining or restricting heat flow.
By constructing a system where there is a gap or hollow core between the earth blocks, as opposed to being solid, heat will transfer at a much slower rate and therefore have better thermal qualities.
Potential Problems:
The vast majority of possibilities in stabilized earth blocks are far greater than we are able to test or sample. Thus, only a random sample of the possibilities will be accounted for in our experiments. The values that we are searching for may vary only slightly thus bringing human error into account as a major issue. In addition, our instruments are only capable of measuring to a certain degree of accuracy, one that may not be precise enough for this study.
Deliverable Products:
From the experiments, we can collect and plot the data on a chart or graph. By mixing and matching the different characteristics of stabilized earth blocks and their construction systems, we can produce the ideal situation for maximum thermal benefits of stabilized earth blocks.