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Characterization of the reactivity of mineral additions by different microstructural and mechanical approaches

Bouglada M. S., Naceri A., Baheddi M.

Mining Science

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2018

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Vol. 25

129--146

EN

This paper presents an experimental study aimed at evaluating the reactivity of natural and industrial local mineral additions (pozzolan, slag and limestone) by different microstructural and mechanical approaches. Binary, ternary and quaternary cement compositions were prepared with partial replacement of the clinker by additions limited to 20%, according to CEM II / A cement specifications. The reactivity during the hydration process is characterized by the hydraulic power of the additions to react with the water and the hydrates of the cement and the pozzolanic capability of fixing the portlandite to form new mineral phases which contribute to the resistance as much as the hydrated products of cement. An experimental methodology was established for the reactivity illustration of the additions by a microstructural approach based on a study of the physicochemical and microstructural properties realized by X-ray diffraction (XRD), the scanning electron microscopy (SEM) on pastes. Further, thermogravimetric analysis (TGA), mercury microporosity (MIP) on mortars at 28 days of age was performed. A mechanical approach based on compressive strength at 2, 7 and 28 days to determine the activity index according to ASTM C 618 has been undertaken. The results obtained show a good correlation between the microporosity, X-ray diffraction and the resistance activity index, in particular for the slag, as for the thermogravimetric analysis that clearly confirms the pozzolanic activity of the pozzolan addition. As for mechanical performance, a binary mortar with 20% slag showed a better compressive strength at 28 days (49.40 MPa) with a reactivity index (87.90%) compared to the control mortar. Further, the slag developed better resistance (49.53 MPa) in combination with the other additions for quaternary mortars (pozzolan, limestone and slag) with an optimal rate of 5, 5 and 10%, respectively. Nevertheless, the pozzolan showed better compressive strength values compared to the slag for the binary mortars at young age 2 and 7 days of 25.67 and 32.07 MPa, respectively.

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Reologia betonów napowietrzonych a cementy z dodatkami mineralnym

Sikora H., Piasta W.

Budownictwo i Inżynieria Środowiska

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2012

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Vol. 3, no. 3

141-146

PL

W pracy podjęto próbę wyjaśnienia wpływu napowietrzenia oraz cementów zawierających dodatki mineralne na odkształcenia reologiczne betonów. Betony wykonano z następujących cementów: cement portlandzki i dwa cementy portlandzkie z dodatkami zawierającymi żużel wielkopiecowy, krzemionkowy popiół lotny oraz mielony kamień wapienny. W wyniku przeprowadzonych badań stwierdzono, że napowietrzenie betonów powoduje spadek skurczu i pęcznienia betonów zawierających cementy portlandzki i żużlowo-popiołowy, natomiast zwiększa skurcz betonów z cementów zawierających mączkę wapienną. Badania odkształceń prowadzono za pomocą aparatu Amslera, stosując po 6 próbek każdego betonu o wymiarach 10×10×50 cm.

EN

The studies were carried out to find the effect of air entrainment and blended cements on rheological deformations of concretes. The cements used were ordinary Portland cement and two blended Portland cements containing: blast furnace granulated slag-fly ash blend and limestone powder. It was stated that air entrainment results in lowering of shrinkage and swelling of concretes made of OPC and blast furnace granulated slag-fly ash blend cement. The increase in both deformations of air entrained concrete occurs when the limestone cement is used. The linear dimension changes was measured with Amsler’s apparatus, according to the Polish standard PN-B-06714-23:1984, using 6 samples of each concrete with dimensions 10×10×50 cm, equipped with steel pins cemented in the both ends of the beams. The first measurement was made after 24 hours from concrete beams preparation.

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Nowe dodatki mineralne do betonu

Kosior-Kazberuk M.

Budownictwo i Inżynieria Środowiska

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2011

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Vol. 2, no. 1

47-55

PL

Co raz szersze stosowanie paliw alternatywnych w różnych dziedzinach gospodarki oraz procesów termicznego przetwarzania osadów ściekowych powoduje powstawanie dużej ilości nowych materiałów odpadowych. Względy ekologiczne i ekonomiczne są przyczyną wzrostu zainteresowania potencjalnym wykorzystaniem gospodarczym popiołów powstających w tych procesach. W pracy analizowano możliwość stosowania nowych materiałów odpadowych jako aktywnego dodatku do zaprawy i betonu. Porównano wybrane właściwości kompozytów cementowych zawierających popioły, pochodzące ze spalania osadów ściekowych oraz ze wspólnego spalania biomasy roślinnej i węgla, z wynikami uzyskanymi dla materiałów z popiołem ze spalania węgla kamiennego.

EN

The wider and wider usage of alternative fuels as well as the thermal mineralization processes in different industrial sectors generates large amounts of new waste-materials. The ecological and economic reasons result in the increase in the interest in potential utilization of ashes arising in these processes. The possibility of application of new waste-materials as active addition to mortar and concrete is analysed in the paper. The selected properties of cement composites containing ashes, originating from the combustion of sewage sludge as well as from co-combustion of the vegetable biomass and the coal were compared to the characteristics obtained for materials with the coal ash.