Expansion characteristics of lightweight foamed grout with foaming agent contents

Road subsidence related to cavities sometimes occurs in urban areas in Korea, and local governments have been investigating the distribution of cavities which lead to the development subsidence to prevent disasters. To fill the empty spaces, adequate materials are required. This study presents the expansion characteristics of lightweight foamed grout developed with the intention of improving cavity filling. To estimate the theoretical expansion ratio, the unit weights at slurry and expanded states are measured. As the foaming agent contents increase, the unit weights at slurry states decrease slightly, while those at expanded states decrease rapidly and then converge on a certain value. The theoretical expansion ratio estimated from the two different types of unit weights first increases with an increase in the foaming agent content and then stabilizes. Compared to the measured expansion ratio, the error of theoretical expansion ratio is about 10 to 15%. Considering the difference between the theoretical and measured expansion ratios, the cavities may be fully filled with lightweight foamed grout.