Mehdi Khodadad Saryazdi | Yazd University (original) (raw)

Mehdi Khodadad Saryazdi

Assistant Professor at Yazd University
Phone: 98-913-151-9441
Address: Safaeeyah, Pejoohesh streat, Civil Engineering Department, Yazd University, Yazd, Iran

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Papers by Mehdi Khodadad Saryazdi

International Journal of Civil Engineering, Sep 15, 2012

Self-desiccation is the major source of autogenous shrinkage and crack formation in low water-bin... more Self-desiccation is the major source of autogenous shrinkage and crack formation in low water-binder ratio (w/b) concretes which can be reduced by internal curing. In this paper performance of high strength self consolidating concrete (HS-SCC) with w/b of 0.28 and 0.33 including autogenous shrinkage, drying shrinkage, compressive strength, and resistance to freezing-thawing was investigated. Then, for the purpose of internal curing, 25% of normal weight coarse aggregate volume was replaced with saturated lightweight aggregate (LWA) of the same size; and its effects on the material properties was studied. Two modes of external curing, moist and sealed, were applied to test specimens after demoulding. Autogenous shrinkage from 30 minutes to 24 hours after mixing was monitored continuously by a laser system. The initial and final setting time were manifested as a change of the slope of the obtained deformation curves. Shrinkage after initial setting was 860 and 685 microstrain (µε) for 0.28 and 0.33 w/b mixtures, respectively. The saturated LWA reduced these values to 80 and 295 µε, respectively. By LWA Substitution the 28day compressive strength of 0.28 w/b mixture was reduced from 108 to 89 and 98 to 87 MPa for moist and sealed cured specimen, respectively. The corresponding values for 0.33 w/b mixture was 84 to 80 and 82 to 70 MPa. Shrinkage of 0.28 w/b mixture without LWA after moist and sealed cured specimen dried for 3 weeks was about 400 µε. Shrinkage of moist and sealed cured specimen containing LWA was reduced 9% and 25%, respectively. On the contrary for 0.33 w/b mixture an increase was noticed. Freezing-thawing resistance was improved by sealed curing, decreasing w/b and substituting LWA.

Engineering review, 2017

Studies show that mortar and concrete are used as the main materials in more than 80% of technolo... more Studies show that mortar and concrete are used as the main materials in more than 80% of technologies. Therefore, pay attention how to increase workability and improve performance required of mortar and concrete. Mortar can be made in numerous ways, but studies have shown that the ready mixed mortar has many advantages compared to others, but without quality control and production monitoring, the customer confidence would be missed. The aim of this study is to investigate the possibility of using specialized sand in the factory for making mosaic mortar mix and controlling mortar properties. In this study, mortar specimens were created by specialized sand for making mosaic, and ordinary sand in different ratio of cement to sand. Also, specimens were produced by the ready mix mortar. The results of the compressive strength and water retention of mortar, the comparisons of fracture specimens and scanning electron microscope (SEM) images showed the possibility of using specialized sand ...