Water Dynamics in Hardened Ordinary Portland Cement Paste or Concrete:  From Quasielastic Neutron Scattering

2006 ◽  
Vol 110 (36) ◽  
pp. 17966-17976 ◽  
Author(s):  
Heloisa N. Bordallo ◽  
Laurence P. Aldridge ◽  
Arnaud Desmedt
2018 ◽  
Vol 54 (6) ◽  
pp. 4710-4718 ◽  
Author(s):  
Kunal Kupwade-Patil ◽  
Ali Bumajdad ◽  
Craig M. Brown ◽  
Madhusudan Tyagi ◽  
Nicholas P. Butch ◽  
...  

2014 ◽  
Vol 679 ◽  
pp. 228-236 ◽  
Author(s):  
Karya Sinulingga ◽  
Harry Agusnar ◽  
Zakaria Mohd Amin ◽  
Basuki Wirjosentono

The effect of three different types of rice husk ash which distinguish by color, pink, grey and white ashes were used as admixture to ordinary Portland cement paste was studied. Six batches of cement paste was prepared by adding 0-50 wt % RHA. The chemical and mineralogical characteristics of RHA were first analyzed. The characteristic of cement paste was investigated using IR, TGA and XRD. Hydration temperature also recorded. Chemical analysis shows higher amount of silica in RHA which is in range of 95-98wt. %. XRD and IR confirmed the white RHA is amorphous silica. The optimum amount of RHA addition was 10 wt. % which produced comparable properties with cement paste control. Based on Calorimetery Studied, IR, TG and hydration temperature results, white silica was found the most reactive silica but plays limited role as admixture in OPC paste.Keywords: rice husk ash, ordinary Portland cement, cement paste, hydration temperature


Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1033 ◽  
Author(s):  
Yuli Wang ◽  
Fengxia He ◽  
Junjie Wang ◽  
Qianku Hu

Carbonates and bicarbonates are two groups of accelerators which can be used in sprayed concrete. In this study, the effects of the two accelerators sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) (0%, 1%, 2%, 3%, and 4% by weight of ordinary Portland cement OPC) on the properties of OPC paste were compared. The results show that both of them could accelerate the initial and final setting time of OPC paste, but the effect of the two accelerators on the compressive strength were different. After 1 day, sodium bicarbonate at 3% had the highest strength while sodium carbonate at 1% had the highest strength. After 7 days, both of the two accelerators at 1% had the highest compressive strength. After 28 days, the compressive strength decreased with the increase of the two. The improved strength at 1 and 7 days was caused by the accelerated formation of ettringite and the formation of CaCO3 through the reactions between the two with portlandite. The decrease of strength was caused by the Na+ could reduce the adhesion between C-S-H gel by replacing the Ca2+. NaHCO3 was found be a better accelerator than Na2CO3.


2016 ◽  
Vol 119 (9) ◽  
pp. 094308 ◽  
Author(s):  
A. Miskowiec ◽  
M. C. Kirkegaard ◽  
K. W. Herwig ◽  
L. Trowbridge ◽  
E. Mamontov ◽  
...  

2021 ◽  
Vol 154 (15) ◽  
pp. 154903
Author(s):  
Pablo I. Sepulveda-Medina ◽  
Madhusudan Tyagi ◽  
Chao Wang ◽  
Bryan D. Vogt

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