Combined Effect of Heat Stimulation and Delayed Addition of Superplasticizer with Slag on Fresh and Hardened Property of Mortar
To obtain the high quality and essential workability of mortar, different types of superplasticizers are used. The superplasticizers are the chemical admixture used in the mix to improve the fluidity of mortar. Many factors influenced the superplasticizer to disperse the cement particle in the mortar. Nature and amount of replaced cement by slag, mixing procedure, delayed addition time, and heat stimulation technique of superplasticizer cause the varied effect on the fluidity of the cementitious material. In this experiment, the superplasticizers were heated for 1 hour under 60 °C in a thermostatic chamber. Furthermore, the effect of delayed addition time of heat stimulated superplasticizers (SP) was also analyzed. This method was applied to two types of polycarboxylic acid based ether SP (precast type superplasticizer (SP2) and ready-mix type superplasticizer (SP1)) in combination with a partial replacement of normal Portland cement with blast furnace slag (BFS) with 30% w/c ratio. On the other hands, the fluidity, air content, fresh density, and compressive strength for 7 and 28 days were studied. The results indicate that the addition time and heat stimulation technique improved the flow and air content, decreased the density, and slightly decreased the compressive strength of mortar. Moreover, the slag improved the flow of mortar by increasing the amount of slag, and the effect of external temperature of SP on the flow of mortar was decreased. In comparison, the flow of mortar was improved on 5-minute delay for both kinds of SP, but SP1 has improved the flow in all conditions. Most importantly, the transition points in both types of SP appear to be the same, at about 5±1 min. In addition, the optimum addition time of SP to mortar should be in this period.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1132777Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF
 P. K. Mehta and P. J. M. Monteiro, "Concrete: Microstructure, properties, and materials," 3rd Edition, 2013 pp. 281-288.
 F. Winnefeld, S. Becker, J. Pakusch, and T. Gotz, “Effects of the molecular architecture of comb-shaped superplasticizers on their performance in cementitious systems, 2007, pp. 251-262
 M. Kinoshita, Recent development of new chemical admixtures, Kagakukogyo, (1998), pp. 383–391.
 M. S. Salehi, Z. Tahery, S. Sasaki, and S. Date, “Effect of Thermal Stimulation of Admixture to Workability of the Mortar,” International Journal of Engineering and Technology, (2017), pp. 183-188.
 Z. Tahery, F. Rahmanzai, S. Date, Effect of Delaying Addition of Heat Stimulated Superplasticizer on Fresh Properties of Mortar, Materials Science and Engineering Technology, (2017), pp. 396-400.
 Hewlett PC. Experiences in the use of superplasticizers in England. In: Malhotra VM, editor. Superplasticizers in concrete, SP 62-6. Detroit: American Concrete Institute, (1979), pp. 101±22.
 M. Uysal, K. Yilma, Effect of mineral admixtures on properties of self-compaction concrete, Cement & Concrete Composites, (2011), pp. 771–776.
 M. Uysal et al, the effect of mineral admixtures on mechanical properties, chloride ion permeability and impermeability of self-compacting concrete, Construction and Building Materials, (2012), pp. 263–270.
 K.-C. Hsu et al, Effect of addition time of a superplasticizer on cement adsorption and on concrete workability, Cement & Concrete Composites, (1999), pp. 425±430.
 H. El-Didamony, M. Heikal, I. Aiad, S. Al-Masry, Behavior of delayed addition time of SNF superplasticizer on microsilica-sulphate resisting cement, Ceramics – Silikáty, (2013), pp. 232-242.
 M. Heikal, I. Aiad, influence of delaying addition time of superplasticizer on chemical process and properties of cement pasts, Ceramics – Silikáty, (2008), pp. 8-15.