The pozzolanic reactivity of monodispersed nanosilica hydrosols and their influence on the hydration characteristics of Portland cement

2012 ◽  
Vol 42 (12) ◽  
pp. 1563-1570 ◽  
Author(s):  
Hesam Madani ◽  
Alireza Bagheri ◽  
Tayebeh Parhizkar
Author(s):  
Kasper E. Rasmussen ◽  
Mette Moesgaard ◽  
Lea L. Køhler ◽  
Thuan T. Tran ◽  
Jørgen Skibsted

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
A. K. Parande ◽  
Karthick Stalin ◽  
Ravi Kumar Thangarajan ◽  
M. S. Karthikeyan

Indigenous resources for natural and artificial mineral admixtures with high pozzolanic reactivity have been employed in many countries around the world. Extensive studies have been conducted for this purpose. With the use of agricultural waste residue, apart from improving properties of concrete, main benefits come from saving natural resources and energy, as well as protecting the environment by using these mineral admixtures (agroagricultural waste). The effective level of blending Portland cement (PC) in mortar or concrete with such mineral admixtures depends on many factors, such as the type of admixture and the cement replacement level. In the present paper two types of agroagricultural waste residue, namely, rice husk ash, bagasse ash and byproduct from thermal waste and fly ash were used. The above mentioned admixtures were thermally treated at a temperature of 650∘C. Characterizations of mineral admixtures were carried out by FTIR and XRD, and Microstructural properties were evaluated in concrete and mortar with partially replacement levels varying from 5% to 30%. Various tests such as water absorption, bulk volume of the specimen, dry weight of the specimen saturated mass, and coefficient of water absorption were concluded. The results showed that as the percentage of replacement level increases in the entire three admixtures studied, water absorption also increased.


2010 ◽  
Vol 45 (11) ◽  
pp. 1173-1180 ◽  
Author(s):  
Alireza Naji Givi ◽  
Suraya Abdul Rashid ◽  
Farah Nora A. Aziz ◽  
Mohamad Amran Mohd Salleh

In this study, nano-SiO2 has been used as a high reactive pozzolan to develop the microstructure of the interfacial transition zone between the cement paste and the aggregate. Mechanical tests of blended cement-based concretes exposed that in addition of the pozzolanic reactivity of nano-SiO2 (chemical aspect), its particle grading (physical aspect) also revealed considerable influences on the blending effectiveness. It was concluded that the relative permeability reduction (relative to the control concrete made with plain cement) is higher for coarser nano-SiO2 after 90 days of moisture curing. However, finer nano-SiO2 particles showed better effects in early ages. These phenomena can be due to the free spacing between mixture particles that was associated with the global permeability of the blended cement-based concretes. This article presents the results of the effects of particle size ranges involved in nano-SiO2 blended Portland cement on the water permeability of concrete. It is revealed that the favorable results for coarser nano-SiO2 reflect enhanced particle packing formation accompanied by a reduction in porosity and particularly in particle spacing after 90 days.


HBRC Journal ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 118-124 ◽  
Author(s):  
E.E. Hekal ◽  
S.A. Abo-El-Enein ◽  
S.A. El-Korashy ◽  
G.M. Megahed ◽  
T.M. El-Sayed

2014 ◽  
Vol 1064 ◽  
pp. 42-48 ◽  
Author(s):  
M. Hamadache ◽  
M. Mouli ◽  
F. Dif ◽  
N. Bouhamou ◽  
A.S. Benosman

Our work aims to studying the addition of the natural pozzolan located in Beni Saf (Algeria) at non-destructive testing for the evaluation of pozzolan mortar reinforced to corrosion. We chose to study this natural addition because of its low cost and its pozzolanic reactivity. To do this, we have carried out tests on mortars made to Portland cement CEM I 42,5 N and substituted by weight based percentages of different natural pozzolan (10%, 20% and 30%). We have measured the corrosion potential and the corrosion speed of different deadlines. The results indicated that is it possible to highlight the beneficial effect of this addition. The analysis of achievements shows that the addition of the pozzolan in optimal quantities has the following advantages: protection of reinforcement against corrosion and increase the resistance against the sulfate attack (5% Na2SO4).


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