The Use of Lightweight Foamed Concrete as Fill Material for Road Embankment on Soft Ground in Sarawak

Settlements are the main problem on soft ground construction in Sarawak. The research is to study the feasibility of using foamed concrete (FC) as fill material for road embankment on soft soil and peat soil (soft ground) by replacement method. This study focuses mainly on the idea of innovative “floating road embankment” on soft ground by density and bearing capacity comparisons. There are three (3) mains approaches to be solved before applying on construction field, which is FC mixing techniques, appropriate properties of FC and FC road embankment design procedure. A new innovative mixing technique that could produce big volume mixing is developed. The technique is focused on the sequence of mixing, whereby adding water will be the last part of the mixing to avoid segregation. This technique also found that horizontal shaft mixer could produce the FC with no segregation. To perform the replacement, the research focuses on density at between 700-1300 kg/m3, where it is almost similar to the density of the soft soil and peat soil. It is found that workability is “just right” when the FC can perform self-compacting. The range of workability for small scale (less than 100 litres) and big scale production (more than 100 litres) are respectively at 13-16 cm and 16-19 cm. FC compressive strength shall not be less than 1 kN/m2, which is better strength than normal soil and enough for supporting the load and resist the vehicles vibrations. The study also found that water-cement ratio at 0.2-0.3 could produce strength at the range of 1-3 kN/m2. The additional admixture like Polyvinyl alcohol (PVA) and quarry dust could increase the strength highly at 300% and 60% respectively, but PVA is difficult to produce and is costly. The result of FC shrinkages is only 0.156%, which could be neglected in the production of FC. At the final stages of the research, the design procedure is developed and the lightweight embankment is applied on field at allowed settlement range. Finally the “lightweight FC road embankment” is successfully produced with saving time and cost. Keywords: Foam concrete, density, workability, strength, settlemen