ABSTRACT Research on fly ash has currently shifted towards exploring the characteristics that determine its activity in the cement paste environment. Reactive silica is the principal parameter that determines the pozzolanic potential of a...
moreABSTRACT Research on fly ash has currently shifted towards exploring the characteristics that determine its activity in the cement paste environment. Reactive silica is the principal parameter that determines the pozzolanic potential of a fly ash, its tendency, that is, to react with available calcium hydroxide to form hydration products with binding properties. Once reactive silica is accurately measured, there exists a good opportunity to relate it with the future strength development of a blended cementitious system. In the work presented herein such a correlation was developed. Its validity was tested for the case of several systems containing various kinds of fly ashes (of different lime content, multicomponent containing both types of fly ash and processed one). Results testify that the developed relationship can be applied to obtain a first approximation of the k-value of the respective blended cements, enabling an almost rapid prediction of the quantity and, most importantly, the quality of the ash used in the mix design.
Even though the use of pozzolanic and latent hydraulic materials (such as fly ash, slag and natural pozzolans) in the construction sector is nowadays a common practice, certain deficits associated with these materials have initiated...
moreEven though the use of pozzolanic and latent hydraulic materials (such as fly ash, slag and natural pozzolans) in the construction sector is nowadays a common practice, certain deficits associated with these materials have initiated research that aims to reduce the negative effects that they introduce into cementitious systems. With respect to fly ash, its relatively slow pozzolanic reactivity hinders
ABSTRACT Three different cements (CEM I, CEM II/B-M and CEM IV/B according to EN 197-1) containing 0%, 23.5% and 38% of pozzolan, respectively, were pulverized to obtain three additional gradations from each cement, with nominal maximum...
moreABSTRACT Three different cements (CEM I, CEM II/B-M and CEM IV/B according to EN 197-1) containing 0%, 23.5% and 38% of pozzolan, respectively, were pulverized to obtain three additional gradations from each cement, with nominal maximum grain sizes of 40, 20 and 10 μm. Cements with the two finer gradations are classified as “microfine” cements. Suspension properties, groutability and effectiveness of all cements were evaluated for water-to-cement ratios (W/C) of 1, 2 and 3 by weight. A superplasticizer was used to optimize rheological properties. The properties and performance of all suspensions tested are affected primarily by W/C ratio and cement fineness. All microfine cement suspensions have acceptable apparent viscosity, behave as Bingham fluids, are stable for W/C = 1, have reasonable setting times for field applications, have mostly predictable groutability and provide satisfactory strength to grouted sands. The finer gradations of II/B-M cement exhibited the best overall behavior and are considered as the most promising compared to similar gradations of the other two cements.
ABSTRACT The present investigation focuses on the hydration evolution of ternary blended cements composed by natural pozzolan (NP) and ferronickel slag (FNS), which is produced during the pyrometallurgical treatment of laterites for the...
moreABSTRACT The present investigation focuses on the hydration evolution of ternary blended cements composed by natural pozzolan (NP) and ferronickel slag (FNS), which is produced during the pyrometallurgical treatment of laterites for the production of ferronickel. The slag and pozzolan were grounded to a specific surface area of 4000 cm2/g and twelve different cement mixtures were produced containing up to 20% Portland cement replacement with the above-mentioned cementitious materials. The produced blended cements were tested by determining their initial and final setting times, standard consistency, flow of normal mortar, soundness and compressive strength at 2, 7, 28, 56 and 90 days. X-ray diffraction and TG/DTG analyses were used for the determination of the hydration products, whereas the microstructure of the hardened cement pastes and their morphological characteristics were examined by scanning electron microscopy. According to the results, the ferronickel slag could be readily utilized together with natural pozzolan as substitutes for cement, presenting significant environmental benefits in waste management practice.
A holistic environmentally sound waste management scheme that transforms agricultural plastic waste (APW) streams into labelled guaranteed quality commodities freely traded in open market has been developed by the European research...
moreA holistic environmentally sound waste management scheme that transforms agricultural plastic waste (APW) streams into labelled guaranteed quality commodities freely traded in open market has been developed by the European research project LabelAgriWaste. The APW quality is defined by the APW material requirements, translated to technical specifications, for recycling or energy recovery. The present work investigates the characteristics of the APW quality and the key factors affecting it from the introduction of the virgin product to the market to the APW stream reaching the disposer. Samples of APW from different countries were traced from their application to the field through their storage phase and transportation to the final destination. The test results showed that the majority of APW retained their mechanical properties after their use preserving a "very good quality" for recycling in terms of degradation. The degree of soil contamination concerning the APW recycling and energy recovery potential fluctuates depending on the agricultural plastic category and application. The chlorine and heavy metal content of the tested APW materials was much lower than the maximum acceptable limits for their potential use in cement industries.
Even though the use of pozzolanic and latent hydraulic materials (such as fly ash, slag and natural pozzolans) in the construction sector is nowadays a common practice, certain deficits associated with these materials have initiated...
moreEven though the use of pozzolanic and latent hydraulic materials (such as fly ash, slag and natural pozzolans) in the construction sector is nowadays a common practice, certain deficits associated with these materials have initiated research that aims to reduce the negative effects that they introduce into cementitious systems. With respect to fly ash, its relatively slow pozzolanic reactivity hinders
... TITAN Cement provided supplementary financial support for the experimental work. The assistance of Mr. E. Chaniotakis (TITAN) and the TITAN R&D staff is gratefully acknowledged. References. ... 35243. 3. SN Ghosh...
more... TITAN Cement provided supplementary financial support for the experimental work. The assistance of Mr. E. Chaniotakis (TITAN) and the TITAN R&D staff is gratefully acknowledged. References. ... 35243. 3. SN Ghosh and LS Sarkar, Mineral admixtures in cement and concrete. ...
ABSTRACT Three different cements (CEM I, CEM II/B-M and CEM IV/B according to EN 197-1) containing 0%, 23.5% and 38% of pozzolan, respectively, were pulverized to obtain three additional gradations from each cement, with nominal maximum...
moreABSTRACT Three different cements (CEM I, CEM II/B-M and CEM IV/B according to EN 197-1) containing 0%, 23.5% and 38% of pozzolan, respectively, were pulverized to obtain three additional gradations from each cement, with nominal maximum grain sizes of 40, 20 and 10 μm. Cements with the two finer gradations are classified as “microfine” cements. Suspension properties, groutability and effectiveness of all cements were evaluated for water-to-cement ratios (W/C) of 1, 2 and 3 by weight. A superplasticizer was used to optimize rheological properties. The properties and performance of all suspensions tested are affected primarily by W/C ratio and cement fineness. All microfine cement suspensions have acceptable apparent viscosity, behave as Bingham fluids, are stable for W/C = 1, have reasonable setting times for field applications, have mostly predictable groutability and provide satisfactory strength to grouted sands. The finer gradations of II/B-M cement exhibited the best overall behavior and are considered as the most promising compared to similar gradations of the other two cements.
