Authors:B. Pacewska, G. Blonkowski, and I. Wilińska
In this work, the pozzolanic and hydraulic properties of ashes originating from various sources were studied in model systems
such as ash and ash-lime pastes. The sources of studied ashes were: fluidized combustion of brown coal, pulverized combustion
of brown coal and pulverized combustion of hard coal. This article is a continuation of our previously published studies on
cement pastes with mentioned ashes.
The following experimental techniques were applied: calorimetry, thermal analysis (TG, DTG) and infrared absorption (IR).
Previously drawn conclusions relating to the reactivity of ashes in an environment containing Ca2+ ions were confirmed. According to these conclusions, an ash originating from fluidized combustion of coal exhibited higher
reactivity compared to other ashes from pulverized combustion. Pozzolanic and hydraulic properties of this ash were also confirmed.
Differences in the behaviour of ashes originating from pulverized combustion of various types of coal in the presence of water
and Ca2+ rich environment were demonstrated.
Fly ash is the ash precipitated from the exhaust fumes of coal-fired power stations. It consists mainly of active silica and
alumina, with large amounts of glass. The aim of this work was to study the pozzolanic activity of fly ash with lime by means
of DTA as a function of the lime content and the curing time. The curves revealed that the rate of hydration, as indicated
by the residual lime and hydrated compounds, increases with increasing lime content and curing time. It is concluded that
fly ash can be used as a blending material in pozzolanic cement.
The chemical corrosion and the mechanical strength were studied in cement mortars containing an additive of FBCC under conditions
of long-term action of sodium sulphate solution or saturated brine. The observations have shown that saturated brine is a
more aggressive agent, since it leaches Ca(OH)2 and contributes to the decomposition of the C-S-H phase thus worsening the compressive strength as compared with that of
mortars kept in water. The addition of 20% FBCC inhibits the leaching process and counteracts the decrease of compressive
strength in mortars kept in brine. On the other hand, sodium sulphate solution changes favourably the mortar microstructure,
increases of the content of small pores and improves both the compressive and the flexural strengths, as compared with those
of a mortar kept in water.
The properties of hydraulic mortars were studied by means of simultaneous thermal analysis (STA), according to a procedure
proposed in the literature. Hydraulic limes, cement and/or slaked lime were mixed using different proportions of both inert
and reactive aggregates, in order to test the effectiveness of such procedure in distinguishing the different degree of hydraulicity
of such samples. The use of the normalized coordinates suggested in the literature results in overlapping of the clusters
of different kinds of mortars. Modified coordinates are proposed, which give promising results in view of outlining a ‘master
curve’ of hydraulicity.
Authors:Barbara Pacewska, I. Wilińska, M. Bukowska, G. Blonkowski, and Wiesława Nocuń-Wczelik
The so-called pozzolanic activity of waste catalysts from fluidised cracking was investigated. For this purpose a series of
cement mixtures with this waste material were prepared and subsequently the pastes and mortars were produced. Waste aluminosilicate
catalyst was used both in raw form and after grinding in a ball mill for 60 min. The hydrating mixtures were subjected to
the calorimetric measurements in a non-isothermal/non-adiabatic calorimeter. After an appointed time of curing the hydrating
materials were studied by thermal analysis methods (TG, DTG, DTA). The pozzolanic activity factors were determined, basing
on the compressive strength data. The increased activity of cement — ground pozzolana systems has been thus proved. An accelerated
Ca(OH)2 consumption as well as higher strength were found for materials containing ground waste catalyst, as compared to those, mixed
with the raw one. Thus grinding was also proved to result in mechanical activation in the case of the waste catalyst from
The physicochemical properties of spent fluidized bed cracking catalyst and its influence on hydration process of cement slurry
were studied. The samples were cement slurries prepared with water/solid=0.5 and additions of used catalyst amounted to 0,
5, 10, 15, 20 and 25%with resp. to the solid. After definite time they were subjected to thermogravimetric analysis (TG, DTG,
DTA) and, in order to determine the progress of reaction with water, the heat of hydration was measured by means of isotherm
calorimetry. The studies disclosed that the spent cracking catalyst is not merely an inactive filler in cement slurries, but
it modifies the course of the hydration process. The spent catalyst is a pozzolana additive and its presence leads to a decrease
of calcium hydroxide contents in the system. The spent catalyst affect on the heat of cement hydration. Small amounts additive
accelerate the process of binding.
The influence of spent catalyst from catalytic cracking in fluidized bed on the hydration process of cement and the properties
of cement mortars were studied. The spent catalyst was used as an additive to cement in the mortars (10 and 20% of cement).
The samples of mortars kept in water for28 days, then they were placed in sulfate and chloride media for 2 months (the control
samples were kept in water for 3 months). After this time they were subjected to bending strength and compressive strength
determinations. Thermogravimetric and infrared absorption studies were performed and capillary elevation, capability of binding
heavy metals, and changes in mass and apparent density were determined too. The studies disclosed the pozzolana nature of
spent catalyst and its influence on cement mortars being in contact with corrosive media.
Authors:M. S. Amin, S. A. Abo-El-Enein, A. Abdel Rahman, and Khaled A. Alfalous
The object of producing pozzolanic cements has been of considerable scientific and technological interest because such addition of pozzolana increases the chemical resistance to sulfate attack, interpermeability
several industrial areas, including building construction [ 3 ].
Metakaolin, a pozzolana with high reactivity and efficiency, can be used as a modifier additive for the mechanical and chemical performance of concretes and other cementitious
of the Byzantine mortars which were mainly based on hydraulic lime or hydrated lime and pozzolanic materials as brick dust and pozzolana were well chosen by the size dimension of the aggregates according to the dimension of the joint, so that in the