Evaluating the effectiveness of foam mortar as a lightweight fill for reducing foundation settlement on soft soils: a case study of Indonesian toll road projects

Putu Sari; Mohamad Ansori; Noor Endah Mochtar; Laode Vizenthe; Amanda Annida; Anggoro Atmojo

doi:10.22630/srees.10905

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Evaluating the effectiveness of foam mortar as a lightweight fill for reducing foundation settlement on soft soils: a case study of Indonesian toll road projects

Scientific Review Engineering and Environmental Sciences

Volume 35 (2026): Issue 1 (March 2026)

By: Putu Sari , Mohamad Ansori , Noor Endah Mochtar , Laode Vizenthe, Amanda Annida and Anggoro Atmojo

Open Access

|Mar 2026

Abstract

Evaluating the effectiveness of foam mortar as a lightweight fill for reducing foundation settlement on soft soils: a case study of an Indonesian toll road. The construction of toll roads on soft soil in Indonesia is associated with significant geotechnical challenges, primarily excessive and long-lasting settlement. Therefore, this study aims to evaluate the effectiveness of foam mortar as a lightweight fill to mitigate issues across three distinct toll road projects: Probolinggo–Banyuwangi, Kediri–Kertosono, and Semarang–Demak. The method used was comprehensive numerical analysis, focusing on assessing the magnitude and rate of subsoil compression and slope stability under different scenarios of varying embankment heights, soft soil depths, and soil improvement strategies, including prefabricated vertical drains and replacement. The results consistently showed that incorporating foam mortar significantly reduced settlement. An increase in foam mortar percentage in the embankment also led to a substantial decrease in compression magnitude. Optimal performance was observed with a mix of 75% foam mortar and 25% soil for high embankments. Furthermore, this study provided customized, efficient design solutions for each site. The trend indicates that foam mortar is a viable, cost-effective alternative to conventional methods. This is because the application enhances slope stability and ensures compliance with stringent settlement-rate criteria, offering a practical solution for infrastructure development on compressible soils.

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Articles in this issue

DOI: https://doi.org/10.22630/srees.10905 | Journal eISSN: 2543-7496 | Journal ISSN: 1732-9353

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Language: English

Page range: 40 - 56

Submitted on: Oct 29, 2025

Accepted on: Jan 28, 2026

Published on: Mar 31, 2026

Published by: Warsaw University of Life Sciences - SGGW Press

In partnership with: Paradigm Publishing Services

Keywords:

foam mortar,

lightweight fill,

settlement reduction,

slope stability,

soft soil,

ground improvement

Related subjects:

Architecture and design,

Architecture,

Architects, buildings,

Geosciences,

Geosciences, other,

Engineering,

Mechanical engineering,

Fundamentals of mechanical engineering,

Geosciences,

Geology and mineralogy

© 2026 Putu Sari, Mohamad Ansori, Noor Endah Mochtar, Laode Vizenthe, Amanda Annida, Anggoro Atmojo, published by Warsaw University of Life Sciences - SGGW Press
This work is licensed under the Creative Commons Attribution-NonCommercial 4.0 License.

Volume 35 (2026): Issue 1 (March 2026)