Sulphate resistance and passivation ability of the mortars made from pozzolan cement of CEM IV/A (P) type according to European
Standard EN 197-1 (zeolite blended cement with 60.82 mass% of PC clinker, 35.09 mass% of zeolite and 4.09 mass% of gypsum
abbreviated as ZBC) and ordinary Portland cement (abbreviated as PC) are introduced. Resistance tests were performed in water
and 5% sodium sulphate solution (both 20°C) for 720 days. The increased sulphate resistance of pozzolan cement relative to
that of PC was found. The key quantitative insight into the hydrate phase behaviour is given by thermal analysis. This is
due to pozzolanic reaction of zeolite with PC resulting in reduction of the formed Ca(OH)2 opposite to the reference PC. Ability of pozzolan cements with 15 to 50 mass% of zeolite to protect steel against corrosion
was verified in 20°C/85% RH-wet air within 180-day cure. Steel was not corroded in the mortars made with pozzolan cement containing
up to 35 mass% of zeolite. Pozzolan cement of CEM IV/A (P) type containing 35 mass% of zeolite is a suitable cementitious
material for concrete structures exposed to sulphate attack. Steel is protected against corrosion by this pozzolan cement
in the same measure as the reference PC.
The present study is based on the influence of the addition of a pozzolanic material as a result of the activation of an industrial
waste coming from the Spanish paper industry on the heating as well as hydration heat of the cement mortars made with 10 or
20% of active addition.
Once the sludge has been calcined at different temperatures (700–800°C) and stays in furnace (2 and 5 h), the calcined products
showed high pozzolanic activity. The maximum activity corresponded to the paper sludge calcined at 700°C for 2 h (S1). Besides,
it can be proved that there was an increase both of the heating and also of the hydration heat in the first 23–25 h for both
additions (10 and 20% of S1) regarding the reference cement mortar. This behaviour would be related to the influence of different
effects: filler and pozzolanic during the first hours of reaction, and by the dilution effect for longer hydration times,
mainly when 20% of S1 was added.
Authors:A. Duran, M. Robador, M. Jimenez de Haro, and Veronica Ramirez-Valle
Mortars taken from the walls of three historical buildings in Seville: Pond of Patio de las Doncellas in Real Alcazar of Seville,
the Monastery of Santa Maria de las Cuevas and the Church of El Salvador were investigated.
The techniques employed were thermogravimetry (TG), differential thermal analysis (DTA), XRD, FTIR, SEM with EDAX, Bernard
calcimeter, granulometry, mercury intrusion porosimetry and mechanical strength tests.
The majority of the studied mortars consist of calcite and silica. Gypsum was detected in samples of four mortars from the
Santa Maria de las Cuevas Monastery and two from the El Salvador Church, whose samples were taken from the upper layers of
the walls, but gypsum was not detected in the internal mortars layers. Only in two of the samples of the Monastery, the presence
of cellulosic material as an organic additive was detected.
All the studied mortars could be regarded hydraulic, so much by results from ratios between mass loss due to CO2 and H2O, hydraulic module and assays of compressive strength. The values obtained by these three techniques are related, providing
good agreements between them.
These results give useful information that aids in understanding the technology of historic mortars, and how to plan the restoration
of these wall paintings.
Authors:R. Lawrence, T. Mays, P. Walker, and D. D’Ayala
A high speed method of thermal
analysis was developed to allow the carbonation profile of lime mortars to
be followed within a convenient time-frame. The loss in mass on heating, up
to 700C, of lime/sand mixtures of different proportions was related to
the known quantity of lime in each mixture. It was shown that a heating rate
of 50C min–1 produced data which had
a very high correlation with known quantities of Ca(OH)2.
Thismethod can be used to measure the extent of carbonation at varying depths
through a limemortar. This can be repeated at intervals to give an insight
into the shape and extent of the carbonation front as it develops over time.
Authors:M. Ismail, M. Ali, A. El-Milligy, and M. Afifi
The effect of impregnation time on the physico-chemical and mechanical properties of polyester-cement mortar composite has
been investigated. The samples were soaked in unsaturated polyester resin containing 40% styrene monomer at impregnation times
ranging from 1–15 hours and then exposed to 50 kGy of γ-irradiation. The effects on polymer loading, compressive strength,
apparent porosity, and water absorption in addition to IR spectra and TGA of the samples were studied. It was found that,
the polymer loading and compressive strength increase with the increased of soaking time up to 4 hours and there is no significant
improvement of the polymer loading and compressive strength increase with the increased of soaking time up to 4 hours and
there is no significant improvement of the polymer loading and strength. Whereas, the apparent porosity and water absorption
behave in an opposite direction. These are attributed to the presence of polymer in the pores of the samples. IR spectra showed
that, new bands appeared as result of the reaction between polyester and set cement. TGA showed that, the polyester cement
composite has higher thermal stability as a compared to irradiated polyester.
Authors:M. Franquelo, M. Robador, V. Ramírez-Valle, A. Durán, M. Jiménez de Haro, and J. Pérez-Rodríguez
Roman ceramics of two hydraulic mortars used to build the pond and water channel of Mithraeum house from Mérida (Spain) have
been studied. The sizes of the ceramic fragments found were different in both of the samples studied, showing different behaviour
in the reactions with the lime. The X-ray diffraction of the ceramic shows the presence of quartz, mica (biotite), anorthite
and hematite accompanied by amorphous phase, being observed scarce vitrification. The presence of mica confirms a firing temperature
for manufacturing the ceramic below 900°C. In one of the ceramics studied, X-ray diffraction did not show calcite. However,
in the FTIR appear bands that could be assigned to carbonates absorptions and likewise, carbonates were identified in the
DTA-TG curves. Ca and small quantities of Si and Al were also identified by SEM-EDX on the surface of the pores that could
be due to an amorphous phase formed in the reaction of lime with the Si and Al of the ceramic. On the other hand, in other
ceramic samples carbonates (about 10%) were detected. The carbonates have been found filling the pores, sometimes accompanied
by a new calcium-aluminium-silicate phase produced by the reaction between the lime and the amorphous phase of the ceramic.
The carbonates and the new phases formed inside the pores are responsible for the decrease of the porosity and for the formation
of new phases during the heating of the ceramics.
Authors:A. Cherem da Cunha, J. Gonçalves, P. Büchler, and J. Dweck
The cement industry is one which most emits polluting gases to the environment, due to the calcium carbonate calcination,
as well as to the burning of fossil fuels during the manufacturing process. Metakaolin (MK), in partial substitution to cement
in its applications, is having a special worldwide growing role, for the technological increment due to its pozzolanic activity
and mainly to the reduction of those emissions. In the present paper, the effect of pozzolanic activity of metakaolin was
analyzed by thermal analysis in pastes and mortars of type II Portland cement in the first three days of the hydration, during
which, relevant initial stages of the hydration process occur.
By non-conventional differential thermal analysis (NCDTA), paste and mortar samples containing 0, 10, 20, 30 and 40% of metakaolin
in cement mass substitution and using a 0.5 water/(total solids) mass ratio, were evaluated. The NCDTA curves, after normalization
on cement mass basis and considering the heat capacity of each reactant, indicate that the pozzolanic activity behavior of
metakaolin is different in pastes and mortars. Through the deconvolution of the normalized NCDTA curve peaks, it can be seen
that ettringuite formation increases as cement substitution degree (CSD) increases, in both cases. Tobermorite formation is
more enhanced in mortars than in pastes by MK, with a maximum formation at 30% of CSD. In the pastes, tobermorite formation
increases as CSD increases but it is practically the same at 30 and 40% of CSD.
, Lubelli B. , Hees van R. , Nijland T.
Evaluation of spreading and effectiveness of injection products against rising damp in mortar/brick combinations , Procedia Chemistry , Vol. 8 , 2013 , pp. 139 ‒ 149 .