Ž . Applied Clay Science 20 2001 129–135 www.elsevier.comrlocaterclay Influence of heat treatment on the behavior of clayey soils Majed M. Abu-Zreig a , Nabil M. Al-Akhras b, ) , Mousa F. Attom b a Department of Agricultural Engineering, Jordan UniÕersity of Science and Technology, P.O. Box 3030, Irbid, Jordan b Department of CiÕil Engineering, Jordan UniÕersity of Science and Technology, P.O. Box 3030, Irbid, Jordan Received 30 June 2000; received in revised form 26 April 2001; accepted 15 May 2001 Abstract This study examines the effect of temperature under laboratory conditions of three clayey soils collected from northern Jordan. Soils were subjected to four temperature levels, i.e. 100, 200, 300 and 400 8C. Various soil properties were studied including Atterberg limits, particle size distribution, optimum water content, maximum dry density, swelling potential, and unconfined compressive strength. Experimental results revealed that heat treatment higher than 100 8C resulted in a decrease in liquid and plastic limits, optimum water content, unconfined compressive strength, and swelling pressure of soils tested. However, maximum dry density increased slightly with an increase in temperature to reach a maximum value of 14.3 kNrm 3 at 400 8C for soil-1 compared to 12.9 kNrm 3 at ambient temperature. Heating the clayey soils at 400 8C decreased the liquid limit, plastic limit, optimum water content, swelling pressure, and unconfined compressive strength by 80%, 100%, 65%, 94%, and 100%, respectively, in average compared to soil specimens at ambient temperature. q 2001 Elsevier Science B.V. All rights reserved. Keywords: Temperature; Clayey soils; Atterberg limits; Swelling; Compressive strength 1. Introduction The increase of fires in bushes around the world causes some attention to the effect of heat on clayey Ž . soils William, 1997 . Some researchers carried out their research to study the treatment of soils contami- Ž . nated with waste using heat treatment. Farag 1993 reported the use of incineration as a method to treat soil contaminated by leakage from waste dumps. Ž . Ž Varlakov et al. 1997 used heat treatment between . 800 and 1000 8C to decontaminate soils from ) Corresponding author. Ž . E-mail address: alakhras@just.edu.jo N.M. Al-Akhras . radioactive and toxic substances. Alcocer and Ž . Chowdhury 1993 used thermal treatment of soils contaminated with crude oil. Other researches such Ž . Ž . as Akinmusuru 1994 , Yang and Farouk 1995 and Ž . Ma and Hueckel 1992 studied the thermal conduc- tivity of thermally treated soil bricks. Joshi et al. Ž . Ž 1994 studied the effect of heat treatment 300 to . 700 8C on clayey bricks. The study showed that the strength of clayey bricks increases gradually with an increase in treatment temperature. Heat treatment of clayey soils up to 700 8C leads to physical and chemical changes in the microstruc- ture of clayey soils. Since ancient ages, thermally treated soil bricks were used for building residential houses. Heat treatment of clayey soils causes reduc- Ž tion in cation exchange and compressibility Joshi et 0169-1317r01r$ - see front matter q 2001 Elsevier Science B.V. All rights reserved. Ž . PII: S0169-1317 01 00066-7