Ali Reza Chamsaz - Department of civil engineering, Islamic Azad University Shahroud branch, Shahroud, Iran,
Ahmad Ganjali - Department of civil engineering, Islamic Azad University Shahroud branch, Shahroud, Iran,
Afsaneh M. Jafari - Department of chemistry, Islamic Azad University Mashhad branch, Mashhad, Iran,
Amir Hossein Sharifi - Department of mechanical engineering, Islamic Azad University Mashhad branch, Mashhad, Iran,
Amir Mohammad Mozhdehi - Department of civil engineering, Islamic Azad University Shahroud branch, Shahroud, Iran,

In this study zinc borat nano oxide supported with preyssler was added to fresh concrete mixture with the aim of investigating if it is able to improve the compressive strength of concrete or not. To follow this goal the produced zinc borat nano oxide supported with preyssler, and the nanocompsite added to C25 grade concrete by the weight of cement. The adding levels by the nanocomposite are selected as 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% and 5% for constant water-cementitious material ratio of 0.45. The compressive strength was examined at 7 and 28 days for 150 X 150 X150 mm size cube samples. The results illustrated a significant drop in compressive strength and also the setting time substantially increased and an entirely honey combing concrete was made, and the compressive strength after 2% adding nanomaterials reached to 0 MPa. After examination and research into the discovery of the reason for this event in compressive strength and the sharp rise in concrete setting time, it was found that the presence of borate and its adjacent to the water led to the formation of boric acid and this phenomenon is the reason for this result.

Zinc borat; compressive strength; heteropolyacid; Preyssler; concrete