I conducted an earthen candle-holder workshop for parents at the San Pedro Child Development Centre in Muzon, the Philippines, in order to show them how earthen materials should be prepared to prevent cracks, and how diverse shapes of rammed earth can be created according to formwork.

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I prepared some supplies and conducted soil tests and analyses prior to the workshop. The soil for the workshop was extracted from a site near the San Pedro Development Centre, sieved to remove coarse gravel and then dried in the open air for a day. I conducted an optimum micro-filler effect test using local soil and changing the ratio between soil and sand, and discovered that earthen materials have a maximum cohesion when the ratio of soil and sand is one to two or three. I also created several samples of earthen candle holders with this ratio.

 

In the workshop, I showed the parents how to prepare earthen materials using one cup of soil and two cups of sand and how the samples of earthen candle holders made from the mixture were as strong as a rock without any chemical additives such as cement. I also instructed them to add a small amount of soil to a paper cup and press it hard with their fingers or chopsticks, and repeat the process, layer by layer. 

 

The parents who participated really enjoyed making their own earthen candle holders by touching the soil with their hands and they were also interested in how to prepare earthen materials to prevent cracks.