Preparation of Multifunctional β-hemihydrate Gypsum using Oyster Shell Powder as the Partial Replacement of Ag/TiO2 Particle

2020 ◽  
Vol 35 (6) ◽  
pp. 1073-1080
Author(s):  
Lu Wan
2020 ◽  
Vol 39 (2) ◽  
pp. 363-368
Author(s):  
O.A. Ubachukwu ◽  
F.O. Okafor

The menacing effects of global warming, rising cost of cement, high energy requirements for the production of cement, and the mitigation of environmental pollution have led researchers towards using locally available materials to partially replace cement in concrete or mortar. The concrete produced from such locally available material is called Green Concrete. Few researches have been reported on the usage of Oyster Shell Powder (OSP) to partially replace the Ordinary Portland Cement (OPC). However, none of those reports has reflected the response of such Green Concrete made with Oyster Shell Powder to Splitting Tensile load. In this research, OPC is partially replaced with OSP at the rate of 0%, 5%, 10%, 15%, 20% and 25% in concrete. A total of 72 number of cylindrical metal moulds of 150mm diameter and 300mm height are used to cast the concrete, demoded after 24 hours and cured for 3, 7, 14 and 28 days with three replicates for each curing age and each replacement percentage. The  properties of fresh and hardened concrete were quantified. The results show that the increase of OSP from 0% up to 25% delays the initial and final setting times of cement paste by 25mins and 40mins respectively. It also improves workability by an additional slump of 19mm. In addition, the Splitting Tensile Strength decreased from 1.706N/mm2 for 0% replacement to 1.011N/mm2 for 25% replacement after a three-day curing period, as well as from 2.076.N/mm2 for 0% to 1.388N/mm2 for 25% replacement, after a 28-day curing period. In as much as the Splitting Tensile Strength of concrete is known to be very low relative to its compressive strength; this study has reflected the extent of vulnerability of OSP-Cement concrete to tensile cracking and stress due to loads. Hence, this will result in safer design and loading of such concrete. Keywords: Concrete, Cement, Oyster Shell Powder, Splitting Tensile Strength, Partial Replacement.


2007 ◽  
Vol 103 (1) ◽  
pp. 155-160 ◽  
Author(s):  
Young Soon Kim ◽  
Yang Mun Choi ◽  
Dong Ouk Noh ◽  
Seung Yong Cho ◽  
Hyung Joo Suh

Polymer ◽  
2019 ◽  
Vol 160 ◽  
pp. 265-271 ◽  
Author(s):  
Chi-Hui Tsou ◽  
Chin-San Wu ◽  
Wei-Song Hung ◽  
Manuel Reyes De Guzman ◽  
Chen Gao ◽  
...  

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1322 ◽  
Author(s):  
Joon Ho Seo ◽  
Sol Moi Park ◽  
Beom Joo Yang ◽  
Jeong Gook Jang

The present study prepared calcined oyster shell powder having chemical composition and crystal structure of calcium oxide and lime, respectively, and investigated the fresh and hardened properties of cement mortar incorporating calcined oyster shell powder as an additive. The test results indicated that the hydration of calcined oyster shell powder promoted the additional formation of Ca(OH)2 at the initial reaction stage, thereby increasing the heat of hydration. In particular, the volumetric increase of calcined oyster shell powder during hydration compensated the autogenous shrinkage of mortar at early ages, ultimately leading to a clear difference in the shrinkage values at final readings. However, an excessive incorporation of calcined oyster shell powder affected the rate of C–S–H formation in the acceleratory period of hydration, resulting in a decrease in the compressive strength development. Meanwhile, the degree of flow loss was inconsequential and rapid flow loss was not observed in the specimens with calcined oyster shell powder. Therefore, considering the fresh and hardened properties of cement mortar, the incorporation of calcined oyster shell powder of approximately 3% by weight of cement is recommended to enhance the properties of cement mortar in terms of compressive strength and autogenous shrinkage.


2005 ◽  
Vol 99 (4) ◽  
pp. 1583-1589 ◽  
Author(s):  
Mi Hwa Chong ◽  
Byoung Chul Chun ◽  
Yong-Chan Chung ◽  
Bong Gyoo Cho

2018 ◽  
Vol 5 (4) ◽  
pp. 045403 ◽  
Author(s):  
Wenfeng Luo ◽  
Shuangying Zhang ◽  
Yuewei Lan ◽  
Chen Huang ◽  
Chao Wang ◽  
...  

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