Review Critical overview of two-stage concrete: Properties and applications M.F. Najjar, A.M. Soliman, M.L. Nehdi ⇑ Department of Civil and Environmental Engineering, Western University, London, Ontario N6A 5B9, Canada highlights  Two-stage concrete (TSC) technology and history are presented.  The materials specifications for TSC are outlined.  The engineering properties of TSC and its long-term performance are compiled.  Future research on TSC and need for further development are discussed. article info Article history: Received 19 January 2014 Received in revised form 13 March 2014 Accepted 14 March 2014 Available online 14 April 2014 Keywords: Two stage Concrete Coarse aggregate Grout Flowability Mechanical properties abstract Two-stage concrete (TSC), also known as preplaced aggregate concrete, is a special type of concrete that is produced using a unique procedure which differs from that of conventional concrete. In TSC, coarse aggregate particles are first placed in the formwork and voids between them are subsequently injected with a special cementitious mixture. TSC has been successfully used in many applications, such as under- water construction, casting concrete sections congested with reinforcement and concrete repair. This paper provides a critical overview of TSC, including its development history, material specifications, engi- neering properties and long term-performance. This critical overview of the TSC state-of-the-art should enhance the understanding of its behaviour, thus paving the way for wider implementation of its use in today’s concrete industry. Ó 2014 Elsevier Ltd. All rights reserved. Contents 1. Introduction .......................................................................................................... 48 2. History of two-stage concrete applications ................................................................................. 48 3. Materials specifications ................................................................................................. 49 3.1. Coarse aggregate ................................................................................................. 49 3.2. Grout mixture ................................................................................................... 50 3.2.1. Fine aggregate............................................................................................ 50 3.2.2. Cementitious materials .................................................................................... 50 3.2.3. Admixtures .............................................................................................. 50 3.3. Grout mixture proportions ......................................................................................... 51 3.4. Grout flowability measuring techniques .............................................................................. 51 4. Construction procedure of two-stage concrete............................................................................... 51 5. Properties of two-stage concrete.......................................................................................... 52 5.1. Compressive strength ............................................................................................. 52 5.2. Tensile strength .................................................................................................. 54 5.3. Modulus of elasticity.............................................................................................. 55 5.4. Shrinkage ....................................................................................................... 56 5.5. Creep .......................................................................................................... 56 5.6. Heat of hydration ................................................................................................ 56 http://dx.doi.org/10.1016/j.conbuildmat.2014.03.021 0950-0618/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +1 (519) 661 2111x88308; fax: +1 (519) 661 3779. E-mail address: mnehdi@uwo.ca (M.L. Nehdi). Construction and Building Materials 62 (2014) 47–58 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat