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Computers and Concrete
  Volume 33, Number 4, April 2024 (Special Issue) pages 471-479
DOI: https://doi.org/10.12989/cac.2024.33.4.471
 


Expansion ratio estimation of expandable foam grout using unit weight
WooJin Han, Jong-Sub Lee, Thomas H.-K. Kang and Jongchan Kim

 
Abstract
    In urban areas, appropriate backfilling design is necessary to prevent surface subsidence and subsurface cavities after excavation. Expandable foam grout (EFG), a mixture of cement, water, and an admixture, can be used for cavity filling because of its high flowability and volume expansion. EFG volume expansion induces a porous structure that can be quantified by the entrapped air content. This study observed the unit weight variations in the EFG before and after expansion depending on the various admixture-cement and water-cement ratios. Subsequently, the air content before and after expansion and the gravimetric expansion ratios were estimated from the measured unit weights. The air content before expansion linearly increased with an increase in the admixture-cement ratio, resulting in a decrease in the unit weight. The air content after the expansion and the expansion ratio increased nonlinearly, and the curves stabilized at a relatively high admixture-cement ratio. In particular, a reduced water-cement ratio limits the air content generation and expansion ratio, primarily because of the short setting time, even at a high admixture-cement ratio. Based on the results, the relationship between the maximum expansion ratio of EFG and the mixture ingredients (water-cement and admixture-cement ratios) was introduced.
 
Key Words
    air content; cement grouting; expandable foam grout; expansion ratio; unit weight
 
Address
WooJin Han: 1) Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology,
501 E St. Joseph St., Rapid City, South Dakota, 57701, USA, 2) School of Civil, Environmental and Architectural Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
Jong-Sub Lee: School of Civil, Environmental and Architectural Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, South Korea
Thomas H.-K. Kang: 1) Department of Architecture and Architectural Engineering, Seoul National University, Seoul, 08826, South Korea, 2) Engineering Research Institute, Seoul National University, Seoul, 08826, South Korea
Jongchan Kim: Civil Engineering, Department of Sustainable Engineering, Pukyong National University, Busan, 48513, South Korea
 

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