The purpose of the study is to know the influence of addition variation of bentonite
content mixture in the amount of 0 gr, 30 gr, 50 gr and 70 gr of wet mold sand can produce
difference of gas flow potential (permeability) and compressive strength with sand mixture
materials (80% river sand and 20% silica sand). The study is also to know variation of the
addition bentonite content from each the study sample that are produce optimum permeability
and compressive strength. The samples in this study use SNI 15-0312-1989 which have a
diameter of 50 mm and height 50 mm. Data is obtained by measuring rate of permeability by
using Permeability Tester, meanwhile value of compressive strength is measured by using
Universal Strength Machine. Other factors that are likely affecting results of measurement are
controlled. The study use experiment method. The results of the study indicated that there
was difference between variety of bentonite addition of wet mold sand toward gas flow
potential (permeability) and compressive strength. Optimum mixture the addition of
bentonite of wet mold sand from each sample of the experiment was: 50 gr the addition of
bentonite produces permeability 104,67 cm
3
/menit and compressive strength 61,87 KN/m
2
.
Keyword: bentonite mixture, permeability, and compressive strengt
