Indian Journal of Engineering & Materials Sciences Vol. 22, February 2015, pp. 93-104 Performance of self-curing concrete at elevated temperatures Alaa A Bashandy* Department of Civil Engineering, Faculty of Engineering, Menoufia University, Egypt Received 3 April 2014; accepted 27 August 2015 Self-curing concrete (SCC) can cure without using any external curing methods. Polyethylene glycol (PEG) is one of the chemical agents which minimizes the loss of water and also attracts moisture from the atmosphere and helps in continuous curing of concrete. In this investigation, the effects of the coupled effect of elevated temperature levels of 200 o C, 400 o C and 600 o C and heating periods of 2 h and 4 h as well as air and water cooling action on the compressive strength and splitting tensile strength of conventional-curing concrete and SCC are studied, respectively. Results show that self-curing concrete can be used at elevated temperatures considering its loss of strength. Air cooling is better for ordinary concrete but that may differ for SCC which may cool using water-cooling up to 400 o C. Increasing elevated temperature and heating time decreases the values of residual strengths. Keywords: Self-curing concrete, Polyethylene glycol, Elevated temperature, Cooling, Storage time The fire effect may be defined in terms of elevated temperature in the case of indirect fire effect. Elevated temperature conditions may affect concrete structures such as concrete foundations for launching rockets carrying spaceships, concrete structures in nuclear power stations or those accidentally exposed to fire 1 . The behaviors of concrete types were different when exposed to high temperature. Self-curing concrete (SCC), as a type of special concretes, is not need external curing 2 . SCC can be self-cured without the need of applying extra water or external curing. The internal curing can be performed using different methods such as lightweight aggregate (LWS natural sand or LWA coarse aggregate), wood powder, chemical additives (super-absorbent polymers (SAP) and shrinkage reducing admixture (SRA)). SRA, based on the use of poly-glycol products, has been suggested to reduce the risk of cracking in concrete caused by drying shrinkage. The mechanism of this admixture is based on a physical change due to reduction of the surface tension of the mixing water rather than on a reduction of water evaporation. The compressive strength will be enhanced with the reduced shrinkage arising from water evaporation, making it ideal for concrete placing without any external curing 3-11 . In comparison with the control mix due to the presence of SRA, there is reduction in the shrinkage. However, the risk of cracking related to drying shrinkage can be mitigated but not completely eliminated 12 . At elevated temperatures, there is a deterioration in concrete properties such as losses in compressive strength, the cracking and spalling of concrete, the destruction of the bonding behavior between the cement paste and the aggregates. Several researchers 13-20 have studied normal strength concrete (NSC) structures subject to fire. Various experimental parameters have been examined such as maximum temperature, heating rate, cooling rate and material, storage time after test, types of aggregates used and various binding materials. As the temperature elevated, the strength of concrete decreased up to failure depending on the temperature and heating time. The first effects of a slow temperature rise in concrete will occur between 100 o C and 200 o C when evaporation of the free moisture, contained in the concrete mass, occurs. Instant exposure can results in spalling because of generation of high internal steam pressures. As the temperature approaches 250 o C dehydration or loss of the hydration non-evaporable water, begins to take place. At 300 o C strength reduction would be in the range of 15-40%. At 550 o C reduction in compressive strength is about 55-70% of its original value 13,14 . The range between 400 o C and 800°C is critical to the strength loss 21 . At a temperature over 600°C, all tested concretes suffered deterioration and only a small part of the initial strength is left, ranging from 7% to —————— *E-mail: eng_alb@yahoo.com