Prediction of Strength, Permeability, and Hydraulic Diffusivity of Ordinary Portland Cement Paste

2014 ◽  
Vol 111 (2) ◽  
Author(s):  
B. Kondraivendhan ◽  
B. Bhattacharjee
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Ordinary Portland Cement ◽  
Hydraulic Diffusivity ◽  
Portland Cement Paste

The Effect of Three Different Types of Rice Husk Ash as Ad Mixture for Ordinary Portland Cement

2014 ◽  
Vol 679 ◽  
pp. 228-236 ◽  
Author(s):  
Karya Sinulingga ◽  
Harry Agusnar ◽  
Zakaria Mohd Amin ◽  
Basuki Wirjosentono
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Rice Husk ◽  
Ordinary Portland Cement ◽  
Rice Husk Ash ◽  
Optimum Amount ◽  
Mineralogical Characteristics ◽  
Different Types ◽  
Reactive Silica ◽  
Portland Cement Paste

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

scholarly journals Comparison of Effects of Sodium Bicarbonate and Sodium Carbonate on the Hydration and Properties of Portland Cement Paste

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1033 ◽  
Author(s):  
Yuli Wang ◽  
Fengxia He ◽  
Junjie Wang ◽  
Qianku Hu
Keyword(s):  
Compressive Strength ◽  
Sodium Bicarbonate ◽  
Portland Cement ◽  
Cement Paste ◽  
Sodium Carbonate ◽  
Ordinary Portland Cement ◽  
Setting Time ◽  
Sprayed Concrete ◽  
Final Setting Time ◽  
Portland Cement Paste

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.

Using High Temperature for Improve Compressive Strength of Ordinary Portland Cement Paste (OPC) – A New Approach

2014 ◽  
Vol 894 ◽  
pp. 70-76
Author(s):  
Abdoullah Namdar ◽  
Fadzil Mat Yahaya ◽  
Mashita Mohd Yusoff
Keyword(s):  
Surface Roughness ◽  
Compressive Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Ordinary Portland Cement ◽  
Setting Time ◽  
New Approach ◽  
Force Microscopy ◽  
Atomic Force ◽  
Portland Cement Paste

Cement paste was replaced with kaolin-bentonite. The specimens were exposed to elevated temperature for 3 hours in a ceramic furnace and cooled down to room temperature. After cooling, the effect of kaolin-bentonite (particles sized of < 45μm) on hydration, rehydration, surface roughness and compressive strength of ordinary Portland cement (OPC) paste were investigated. Atomic Force Microscopy (AFM) was used to study surface roughness of OPC paste-additive mixture. The application of fire on OPC paste was analyzed. The results showed imposed heat (500 oC for 3 hours) accelerates the hydration process of OPC, and reduces setting time. Increased heat to 1000 oC, leads to zero compressive strength of specimens, the compressive strength of OPC continuously reduces after specimen has fully cooled down. A method for recovery of compressive strength of OPC after offing fire has been suggested. The method of offing fire has important effects on the compressive strength of concrete. The best results for specimen content are cement-kaolin-bentonite paste, exposure to 500 o C, after 90 days of curing, and cooling down in water. In this case the compressive strength has been increased around 60 % compared to not using additive and not exposing to heat.

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