The microstructure and interfacial transition zone characteristics of Portland cement mortars prepared with a polynaphthalene sulfate (PNS) superplasticizer at relatively high dosages (0.8%, 1.5% by mass of cement) and varying sand-to-cement ratios (0.5, 1.0, 1.5) were investigated, using AC impedance spectroscopy, mercury intrusion porosimetry, helium pycnometry and two electrical conductance ...

In this research the effects of adding silica and alumina nanoparticles on flow ability and compressive strength of cementitious composites based on Portland cement were investigated. In the first stage, the rheological behavior of different samples containing nanosilica, nanoalumina and polypropylene, polyvinyl alcohol and polyethylene fibers were evaluated. With increasing of nanoparticles in...

The present study investigates £-radiation effect on structure and selected properties of a tetracalcium phosphate (TTCP)/dicalcium phosphate anhydrous (DCPA)/calcium sulfate hemihydrate (CSH) cement immersed in Hanks’ solution. The results indicate that, at a dosage of 25 kGy, the working and setting times of the cement paste derived from £-ray-sterilized TTCP/DCPA/CSH powder did not change si...

PURPOSE The purpose of this study was to examine the abutment screw stability of screw- and cement-retained implant-supported dental prosthesis (SCP) after simulated cement washout as well as the stability of SCP cements after complete loosening of abutment screws. MATERIALS AND METHODS Thirty-six titanium CAD/CAM-made implant prostheses were fabricated on two implants placed in the resin mod...

In this paper, micro-mechanical properties of styrene–butadiene rubber (SBR) latexmodified cement pastes identified by means of the nanoindentation (NI) technique are related to macro-mechanical properties of SBR latex-modified mortars obtained from standard test methods, considering an SBR latex/cement ratio varying from 0% to 20%. For this purpose, the average value of the hardness and the so...

Concrete is frequently utilized infra-structural construction material all over the world. Cement main part of concrete, during its manufacturing emission gases such as carbon dioxide (CO2) from cement factories create greenhouse effect. In these days various natural pozzolanic materials are used partial replacement to enhance strength and durability reduction in consumption consequently emissi...

A new electrochemical model has been carefully established to explain the carbonation behavior of cement mortar, and the model has been validated by the experimental results. In fact, it is shown by this study that the electrochemical impedance behavior of mortars varies in the process of carbonation. With the cement/sand ratio reduced, the carbonation rate reveals more remarkable. The carbonat...

The prime aim of this study was to investigate the thermal conductivity of concrete using crushed recycled glass as a fine aggregate. Influencing factors on thermal conductivity of concrete are investigated using The Unitherm Model 6000 Guarded Hot Plate Thermal Conductivity Instrument. A total of 36 concrete mixes were produced with different water cement ratios (0.4 and 0.5). Recycled glass w...

Modification of sodium lignosulfonate (SLS) via combined oxidationsulfomethylation was employed to prepare concrete superplasticizer. It was found that the oxidation of SLS by peroxyacetic acid facilitated the subsequent sulfomethylation. After modification, both the molecular weight and sulfo group content were significantly increased, and thus the performance of SLS as water reducer was impro...

The impact of nano-SiO₂ on the early hydration properties of alite-sulphoaluminate (AC$A) cement was investigated with a fixed water to solid ratio (w/s) of one. Nano-SiO₂ was used in partial substitution of AC$A cement at zero, one and three wt %. Calorimetry, X-ray diffraction (XRD), thermogravimetric/derivative thermogravimetric (TG/DTG), mercury intrusion porosimetry (MIP) and scanning elec...