Terra Ferma
Sarah Sheppard
Prince of Wales
Floor Location : J 052 V

As rammed earth building is a building idea that is just coming to the world stage, this science fair project is an experiment on the strength of rammed earth walls. In this project the walls that were built used different ratios of dirt:sand:rock to create the perfect ratio for a rammed earth wall. The ratios I used were: 6:4:4, 8:3:3, 10:2:2, 12:1:1, and 14:0:0. These ratios were used because if one used a ratio of less that 6 parts dirt it would surely crumble. However if there was too much dirt, it would simply crack and be just as unstable. rnrnTo begin this experiment, I constructed one form (17 1/2 x 4 x 16) and then from that placed the 5 different mixes of dirt, rock, and sand into it one at a time. Once one of the ratios was put into the form, it was rammed by using a sledge hammer to compact the dirt as much as possible. Once the wall was rammed it was left to dry for 48 hours, then experimented on.rnrnTo conduct the actual experiment, I began with a dried wall. I placed the wall onto the table and waited 10 minutes, to make sure it could hold it's own weight. Then I placed weights on top going by intervals of 5(pounds), until the wall began to show signs of crumbling. I recorded this weight and began with the next ratio of mix. rnrnThe results found the best building method is using a mix of all the materials (dirt, rock, and sand). The best mix used was a ratio of 12:1:1. Although not exactly my hypothesis, it was somewhat close. However, the difference was that it turns out dirt has a strong ability to hold it's particles together and especially when compacted like in this experiment. rnrnIn, conclusion this project was successful. It is now clear to me that rammed earth building is a very sustainable and usable option for house building. Get Digging!