Encapsulation of petroleum sludge in building blocks O.A. Johnson ⇑ , N. Madzlan, I. Kamaruddin Department of Civil and Environmental Engineering, Universiti Teknologi PETRONAS, 31750 Seri Iskandar, Tronoh, Malaysia highlights  Examines the encapsulation of petroleum sludge in block production.  Evaluation of the physical and mechanical properties of blocks manufactured with petroleum sludge.  Provides an alternative to petroleum sludge disposal.  Confirm the environmental acceptability of petrovege block. article info Article history: Received 29 May 2014 Received in revised form 27 November 2014 Accepted 31 December 2014 Keywords: Petroleum sludge Vegetable oil Petrovege block Unconfined compressive strength PAH abstract Petroleum sludge is one of the major solid wastes generated in the petroleum industry; cost-effective treatment and proper disposal has become a problem worldwide. The use of it as a raw material in the production of building blocks was investigated in this paper to find an alternative to dumping this envi- ronmentally unfriendly material into land fill. The petroleum sludge and aggregates were characterized in terms of their composition and grain sizes respectively. The block samples were prepared by adding 8%, 9%, 10%, 11%, 12%, and 13% liquid content of the mixture of vegetable oil and petroleum sludge as a binder. The mixtures were compacted in a cylindrical mold of 50 mm  100 mm sizes with 75 blows using Marshall compacting machine, then were cured through oxidation in an oven at 160 °C for 48, 72, 96 and 120 h. The physical and mechanical properties were evaluated and the high compressive strength recorded compare to conventional building blocks has made it more feasible and interesting in the construction industry. Crown Copyright Ó 2015 Published by Elsevier Ltd. All rights reserved. 1. Introduction In the production and exploration of petroleum, wastes are gen- erated which includes drilling fluid, petroleum waste water, petro- leum effluent treatment plant sludge and bottom tank sludge. Up to five percent of all crude oil produced is not viable. Petroleum refinery with a production capacity of 105,000 barrels per day pro- duces about 50 tons of oil sludge per year [1]. Sludge is a general term used to describe the residual deposits found at the bottom of tanks and other storage vessels. Sludge found in crude oil storage tanks is typically made up of hydrocarbons, asphaltenes, paraffin, water, and inorganic solids such as sand, iron sulfides and iron oxides. An analysis of crude oil sludge shows that greater than 90% of the sludge material is composed of the valuable paraffin, asphaltene, and hydrocarbon. Sludge forms when a crude oil’s properties are changed due to changes in external conditions. Cooling below the cloud point, evaporation of light ends, mixing with incompatible materials, and the introduction of water to form emulsions, make up the most common causes for sludge formation [2]. According to Resources Conservation and Recovery Act (RCRA) sludge is one of the hazardous wastes [3]. The elemental composi- tion of petroleum sludge are nitrogen, phosphorous, potassium, iron, calcium, magnesium, manganese copper, cadmium, chro- mium, lead, zinc, phosphate, nitrogen, calcium, magnesium, sodium, potassium, iron, manganese, lead and chromium [4]. Crude oil sludge is a recurrent problem leading to corrosive effect and reduction in oil storing capacity. For this to be removed it required high cost. The economic effect involves the cost of sludge removal and disposal, where the greater expense is the dis- posal fee of the environmentally-unfriendly material. In recent years, a variety of methods of processing and disposing of petroleum sludge are used globally: thermal, mechanical, biolog- ical, and chemical. All these are not economically sustainable. In addition to the cost of removing, transporting, and land filling involved in cleaning up petroleum sludge, it also contains various http://dx.doi.org/10.1016/j.conbuildmat.2014.12.122 0950-0618/Crown Copyright Ó 2015 Published by Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +60 173847589. E-mail addresses: johnsonolufemi02@gmail.com(O.A. Johnson), madzlan_napiah@ petronas.com.my (N. Madzlan), ibrakam@petronas.com.my (I. Kamaruddin). Construction and Building Materials 78 (2015) 281–288 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat