Compaction performance analysis of alum sludge waste modified soil Syyed Adnan Raheel Shah a,b,⇑ , Zarnish Mahmood a , Aqsa Nisar a , Muhammad Aamir a , Amjad Farid a , Muhammad Waseem c a Department of Civil Engineering, Pakistan Institute of Engineering & Technology, Khanewal Road, Multan 60000, Pakistan b Instituut Voor Mobiliteit, Hasselt University, Wetenschapspark 5 Bus 6, 3590 Diepenbeek, Belgium c Department of Environmental Chemistry, Bayreuth Centre for Ecology and Environmental Research, University of Bayreuth, 95440 Bayreuth, Germany highlights  Sustainable construction is one of the ultimate requirements of the engineering field.  Addition of water treatment waste stabilizer helps in improvement of physical properties of soil.  Soil strength can be improved by addition of stabilizer at optimum level of compaction energy.  Optimum soil compaction effort can help in saving finance during mega projects. article info Article history: Received 5 February 2019 Received in revised form 31 August 2019 Accepted 13 September 2019 Keywords: Sustainable construction Soil strength Alum sludge Soil stabilization Decision making abstract Sustainable construction is one of the ultimate requirements of the engineering field. Addition of waste materials not only contribute to the improvement of the density of soils but also help in the enhancement of its strength properties. In the field, compaction is achieved by compactors and rollers, which consumes a lot of energy for this purpose. In this study, two methods related to compaction energy have been applied to study the relation of compaction energy with the strength of soil before and after addition of alum sludge as a soil stabilizer. An advanced Artificial Neural Networks (ANNs) technique has been applied with reference to the addition of alum sludge percentage, plasticity index, specific gravity, opti- mum moisture content, maximum dry density, AASHTO classification, USCS classification, and group index. It was found that soil strength can be improved even at a low compaction energy level of 600KN-m/m 3 by the addition of optimum percentage of 8% alum sludge as a soil stabilizer. So, roller com- paction effort can also be reduced by addition of this soil stabilizer to save compaction cost i.e. saving of roller fuel consumption and rental cost as well. This study will not only help in environment-friendly con- struction but will also manage finance by utilization of optimum compaction energy in the mega projects. Ó 2019 Elsevier Ltd. All rights reserved. 1. Introduction Compaction is a process in which energy as a load is applied over soil that increases the density or weight of the soil and causes a decrease in the volume of the samples. The Water content and compaction effort are the factors that affect soil compaction and strength [1]. In order to improve the soil properties, compaction is demanded in the field before any structure is constructed on it. The main objectives of compaction are that firstly it helps increase in shear strength of soil that ultimately enhances the bearing capacity of the soil. If a good stabilizer is added prior to compaction soil would demand fewer efforts for the compaction hence energy could be saved. Secondly, it helps increase in the stiffness property of the soil, this reduces the danger of any future settlement after the structure is laid upon. Thirdly it reduces the potential frost heave, as the void ratio and permeability decrease with compaction. Compaction can be affected due to number of reasons those include, type and nature of the soil (i.e. either the soil is clayey or silty or contains sand content, grading, plasticity of soil), the water content of soil at the time of compaction, the envi- ronmental and other conditions at site (i.e. weather, layer thick- ness) and type of machine or plant being used for compaction. Soil compaction is one of the most important terminologies when it comes to civil engineering. The soil is the basic and most impor- tant part as it accumulates the load from the structure and the structure is built upon it. A mechanically strong and stabilized soil https://doi.org/10.1016/j.conbuildmat.2019.116953 0950-0618/Ó 2019 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Department of Civil Engineering, Pakistan Institute of Engineering & Technology, Khanewal Road, Multan 60000, Pakistan. E-mail address: syyed.adnanraheelshah@uhasselt.be (S.A.R. Shah). Construction and Building Materials 230 (2020) 116953 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat