Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:

---

Gypsum is widely used in various industries because of its easy fabrication feature, environmental friendliness and low price. This study was investigated the effect of sodium nitrate as an additive on the physical and mechanical properties of building plaster bodies. Sodium nitrate was added to the amounts of 0.2, 0.4 and 0.8% by weight of gypsum. According to the results, sodium nitrate plays an accelerator role and reducing the setting time of gypsum. Addition of sodium nitrate leads to improvement of the mechanical properties of the gypsum body. The highest flexural strength and compressive strength were obtained for sample containing 0.4 wt% sodium nitrate. By adding 0.4 wt% sodium nitrate, compressive strength and flexural strength increased by 80% and 73%, respectively. The addition of sodium nitrate reduced the porosity and absorption of water of plaster. The X-ray diffraction results indicated that the presence of sodium nitrate created a higher degree of hydration. The higher strength of gypsum bodies could be attributed to lower porosity and needle-like interlocked microstructure. Sodium nitrate can lead to an increase in the precipitation rate of dihydrated calcium sulfate crystals from the saturated solution which can results in a reduction in the setting time and increasing mechanical properties due to the formation of microstructure with more interlocked crystals.
 

Keywords: Gypsum, Sodium nitrate, Setting time, Mechanical properties, Microstructure

Full-Text [PDF 2721 kb]   (904 Downloads)    

Add your comments about this article : Your username or Email:

---