Surface Characteristics of Portland Cement/Blast Furnace Slag Mixtures

The effect of the degree of hydration and amounts of granulated blast furnace slag on the surface properties of Portland cement pastes were studied. The results obtained showed that the specific surface area S BET (m 2 /g) and pore volume V p (cm 3 /g) decreased on increasing the degree of hydration. The addition of different amounts of granulated slag effected a decrease in S BET and V p to an extent proportional to the amount present. These results were attributed to a replacement of clinker by the amounts of slag added and the formation of hydration products

The Effect of Fly Ash on Some Surface Characteristics and Microstructure of β-CS

The effect of the addition of fly ash (0–15 wt. %) on the surface characteristics of β-C 2 S and its microstructure was investigated using nitrogen adsorption at −196°C together with scanning electron microscope (SEM) techniques. The results obtained revealed that the addition of fly ash up to 5 wt. % increased the specific surface area by 32% followed by a decrease of 34% when the fly ash content was increased up to 15 wt. %. SEM investigation showed that the hydrates produced form an outer shell which coats the fly ash particles

Surface Characteristics of the Pure and LiO-doped MoO/AlO System

Two series of MoO 3 /Al 2 O 3 solids, having the nominal compositions 0.2MoO 3 : Al 2 O 3 and 0.5MoO 3 :A12O 3 , were prepared by impregnating finely powdered Al(OH) 3 samples with calculated amounts of ammonium molybdate solutions. The solids thus obtained were dried at 120°C and then calcined in air at temperatures varying between 400°C and 1000°C. The doped samples were prepared by treating Al(OH) 3 with LiNO 3 solutions prior to impregnation with ammonium molybdate. The dopant concentrations employed were 1.5 and 6.0 mol% Li 2 O, respectively. The surface characteristics, viz. the specific surface area (S BET ), the total pore volume (VP) and the mean pore radius (r) of the various pure and doped solids were measured from nitrogen adsorption isotherms conducted at -196°C. The S BET data measured for different adsorbents calcined at various temperatures enabled the apparent activation energy for sintering (ΔE 3 ) to be determined for all the adsorbents investigated. The results obtained reveal that the S BET value of the pure and doped solids decreased on increasing the calcination temperature in the range 400–1000°C. The decrease was, however, more pronounced when the calcination temperature increased from 500°C to 700°C due to the formation of Al 2 (MoO 4 ) 3 . Lithium oxide doping decreased the S BET value of the solid samples investigated and also decreased the activation energy for sintering to an extent proportional to the amount of dopant present. The sintering process for the pure and doped solids proceeds, mainly, via a particle adhesion mechanism

Physico-chemical and surface characteristics of some granulated slag–fired drinking water sludge composite cement pastes

This investigation aims to study the physico-chemical and surface characteristics of some composite cement pastes. Granulated slag (GBFS) was substituted with fired drinking water sludge (FDWTS) with 5, 10 and 15 wt% to prepare composite cements. The hydration characteristics of composite cement pastes were studied by the determination of portlandite and chemically combined water contents at different curing ages of hydration as well as the phase composition of hydration products. The surface properties were studied using the nitrogen adsorption technique. The results showed that the chemically combined water content increased by using FDWTS instead of GBFS. The free portlandite content increased up to 7 days and then decreased up to 90 days. Compressive strength increases with FDWTS up to 5% and then decreases with its increase up to 15% by weight. The specific surface areas (SBET, m2/g) and pore volumes (VP, ml/g) increased with FDWTS content in composite cement pastes

Preparation of β-dicalcium silicate (β-C2S) and calcium sulfoaluminate (C4A3S¯) phases using non-traditional nano-materials

This paper describes the synthesis of some nano-compounds such as SiO2, Al(OH)3 and Ca(NO3)2 which can be used in the preparation of nano β-C2S as well as nano C4A3S¯. The preparation of β-C2S from nano-SiO2 and Ca (NO3)2 in comparison with traditional materials such as Ca(CH3COO)2, CaCO3 and silica quartz fired at different temperature has been studied. Also, C4A3S¯, can be prepared from nano-materials such as Ca(NO3)2 and Al(OH)3 with pure gypsum in comparison with Ca(CH3COO)2, CaCO3 and calcined Al2O3. The rate of formation of β-C2S and C4A3S¯, can be also studied after firing with chemical and XRD methods. These phases were obtained by crystallization processing at different temperatures. The formation of these phases was monitored by measuring the free lime and insoluble residue contents. The results showed that the extent of formation was found to be much higher with nano-materials as compared to those prepared in a conventional manner. The prepared belite phase from nano-silica and calcium nitrate reduces the temperature synthesis to 1150 °C. Also the preparation of C4A3S¯ from nano Al(OH)3 and Ca(NO3)2 and pure gypsum fired at 1290 °C, was the perfect composition to produced a well formed calcium sulfoaluminate phase in comparison with traditional materials

Surface Area and Pore Structure of Hardened Portland Cement/Silica Fume Pastes Containing a Superplasticizer

Surface characteristics such as specific surface area, total pore volume, hydraulic pore radius and pore size distribution have been evaluated for hardened Portland cement/silica fume pastes containing different amounts of BVF superplasticizer (naphthalene sulphonate addicrete). The derived parameters indicate that the surface properties were greatly affected by the amount of superplasticizer employed. The pozzolanic reaction between silica fume and the free lime released during the hydration of Portland cement, as well as the production of a more dense structure produced by the addition of BVF superplasticizer accompanied by decreasing initial water/solid ratios, resulted in hardened cement pastes with a close-textured structure and the predominance of micropores and/or mesopores with a limited size. Such a structure produced dense pastes with improved mechanical properties