CHALLENGE JOURNAL OF CONCRETE RESEARCH LETTERS 10 (1) (2019) 1–6 * Corresponding author. Tel.: +20-10-0145-9515 ; Fax: +20-47-327-8731 ; E-mail address: noha@kfs-hiet.edu.eg (N. Y. Elwakkad) ISSN: 2548-0928 / DOI: https://doi.org/10.20528/cjcrl.2019.01.001 Research Article Mechanical properties of self-curing concrete (SCUC) Noha Yehia Elwakkad a, * , Khaled Mohamed Heiza b a Department of Civil Engineering, Higher Institute of Engineering and Technology, Kafr El-Sheik, Egypt b Department of Civil Engineering, Minoufia University, Minoufia, Egypt A B S T R A C T According to lack of water, labor self curing concrete (SCUC) is necessary in construc- tion projects. In this study, it is focuses on concrete application with new admixture to achieve SCUC. The present study involves the use of shrinkage reducing admixture polyethylene glycol (PEG 400) in concrete which helps in self curing and helps in bet- ter hydration and hence strength. The effect of admixture (PEG 400) on water reten- tion, compressive strength, split tensile strength and modulus of rupture by varying the percentage of PEG by weight of cement from 0% to 1% were studied for M1 and M2 mixes. It was found that using PEG400 with dosage 0.3%, 0.5% gives an early strength to the concrete. It was also found that 0.5% of PEG 400 by weight of cement was the optimum for both M1 and M2 mixes. A R T I C L E I N F O Article history: Received 22 October 2018 Accepted 2 March 2019 Keywords: Self-curing concrete Water retention Relative humidity Hydration Absorption Water permeability 1. Introduction Curing is the maintaining of a satisfactory moisture content and temperature in concrete during its early age so that desired properties (of concrete) may develop. Curing is essential in the production of concrete that will have the desired properties. The strength and durability of concrete will be fully developed only if it is cured. No action to this end is required, however, when ambient conditions of moisture, humidity, and temperature are sufficiently favorable to curing. Otherwise, specified cur- ing measures shall be discussed (Mather, 2001). New developments in curing of concrete are on the horizon as well. In the next century, mechanization of the placement, maintenance, and removal of curing mats and covers will advance as performance-based specifica- tions quantify curing for acceptance and payment. In ad- dition, effective sealants and compounds that prevent the loss of water and promote moist curing conditions will be in high demand. Self-curing concrete should be- come available in the future (Tikalsky et al., 2006). 1.1. Advantages of self-curing concrete  Reduces autogenously cracking.  Self-curing  Reduce the permeability.  Increases mortar strength and early age strength suf- ficient to withstand strain.  Greater utilization of cement.  Lower Maintenances. 1.2. Literature review and research objective Junaid et al. (2015) made a comparison between the conventional cured concrete and self-curing concrete by adding admixture polyethylene glycol (PEG-4000, 1% weight of cement) in concrete which helps in self-curing and in better hydration and hence strength. The results show that the Concrete cured internally using 1% PEG- 4000 attained more compressive strength than conven- tional cured concrete. Indirajith et al. (2016) carried out comparative experi- mental tests between self-curing concrete (both external self-curing and internal self-curing) by using PEG and con- ventional concrete for M20, M25 and M40 grade. Self-curing concrete resulted in better hydration with time under dry- ing condition compared to conventional concrete. Slump value increases with increase in the quantity of PEG. It was studied that the strength increases at different proportions of PEG i.e., 1% is optimum for M20 and M25 grade 0.5% for M40 grade and 0.3% for high strength self curing concrete.