abstract self compacting concrete (scc) is a new construction material in the world. the aim of this research is to construct self compacting concrete with high compressive strength using combination of nano silica and micro silica. for this purpose, nano silica, micro silica, portland cement type 2, superplasticizer (sp), and gravel and sand have been used. three different groups of samples wi...

Revision of the opinion on Silica, Hydrated Silica, and Silica Surface Modified with Alkyl Silylates (nano form)

This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a predominantly mesoporous structure abo...

nano-silica supported titanium tetrachloride (ticl4.sio2) was prepared and used as an acid catalyst for the 14-aryl or alkyl-14h-dibenzo[a,,j]xanthenesreaction under solvent-free conditions. compared to the classical 14-aryl or alkyl-14h-dibenzo[a,j]xanthenesreaction conditions, this method consistently has the advantage of excellent yields, mild reaction conditions, ease of workup, survival of...

Two simple protocols for the synthesis of three-component condensation reaction of an aldehyde, β-ketoester and urea or thiourea to obtain the 3, 4-dihydropyrimidin-2(1H)-ones (thiones) using nano silica phosphoric acid are reported. Short reaction times, high yields, reusability of catalyst and easy workup are some advantages of these protocols.

one-pot multicomponent reaction between isatin, barbituric acid, and 6-amino-1,3-dimethyl uracil was investigated in the presence of sulfonic acid functionalized nanoporous silica (sba-pr-so3h) and resulted in the formation of spirooxindole dipyrimidines. spirooxindole unit is found in many natural products and biologically active molecules and 1,4-dihydropyridines are an important class of com...

a convenient, rapid, and one-pot method for the synthesis of azo dyes has been developed. in this protocol, diazotization reagent (arn2+ -cro3–sio2) was prepared via grinding of aromatic amines, nano2, wet sio2 and nano silica chromic acid (nano-sca) without solvent at room temperature. the obtained diazotization reagent was sufficiently stable to be kept at room temperature in the dry state fo...

the effects of adding nano-silica particles on the compressive strength and water permeability of concrete and its comparison with that of micro-silica were investigated in this work. the effect of combination of nano- silica and micro-silica were also studied in this work, which resulted in an increase in compressive strength of concrete in comparison with other concrete specimens tested in th...