Compaction characteristics of banting soft soil subgrade stabilized using waste paper sludge ash (WPSA)

Abstract

This paper presents the laboratory result on compaction characteristic for soft soil subgrade which was stabilized by using waste paper sludge ash (WPSA). The soft soil sample was collected from Banting Selangor, Malaysia named as Banting soft soil and classified as slightly sandy Clay with intermediate plasticity. Additive of WPSA is a finely waste product produced from the incinerated waste paper. In ASTM C618, this WPSA samples are categorized as Type-C fly ash due to the high free lime (CaO) content (>20%) and possesses some cementitious and pozzolanic, resulting in the self-cementing characteristics. Therefore no entire activators such as lime are required. Objectives of this study are to determine the dry density and moisture content of Banting soft soil stabilized by WPSA through the different energy and method of compaction and to determine the Atterberg limit properties of Banting soft soil stabilized using WPSA. Several percentage of WPSA (4%, 8%, 12% and 16%) was used to stabilize the soft soil. Meanwhile the compactions methods are used in this study are standard proctor test and modified proctor test. The Atterberg limit properties testing involved the liquid limit testing, and plastic limit testing. The result showed the plasticity indexes of soft soil stabilized with series percentage (4%, 8%, 12% and 16%) of WPSA were reduced parallel to the increment of liquid limit and plastic limit result. Meanwhile, the compaction result for stabilized soft soil showed an increment dry density value followed by decrement of moisture content for modified compaction and standard compaction. However, 4% WPSA were giving the best of optimum moisture content and maximum dry density stabilized soft soil from modified compaction. From this experimental study, it shows that WPSA has a significant and effective to improve the geotechnical properties of soft soil.