Mechanical and durability properties of concretes ...wbia. W.F.,-S... · and durability properties
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Original Research Article
Mechanical and durability properties of concretesincorporating natural zeolite
Taras Markiv a, Khrystyna Sobol a, Magorzata Franus b, Wojciech Franus b,*aDepartment of Civil and Environmental Engineering, Lviv Polytechnic National University, Ukraineb Faculty of Civil Engineering and Architecture, Lublin University of Technology, Poland
a r c h i v e s o f c i v i l a n d m e c h a n i c a l e n g i n e e r i n g 1 6 ( 2 0 1 6 ) 5 5 4 5 6 2
a r t i c l e i n f o
Received 31 August 2015
Accepted 25 March 2016
a b s t r a c t
This paper investigates the application of natural zeolite as a substitute of cement in
concrete. It studies the mechanical and durability properties of concretes containing 10%
of natural zeolite and superplasticizer, as well as 10% of natural zeolite, superplasticizer and
an air-entraining agent in comparison to concretes without natural zeolite. The study shows
that fresh concrete mixture containing zeolite due to its high surface area demands a higher
dosage of superplasticizer to achieve the targeted slump flow. While concretes containing
natural zeolite characterize a lower compressive strength until 90 days of hardening, the
compressive strength exceeds the strength of the concretes without zeolite after 180 days.
The results also reveal the considerable effectiveness of using a superplasticizer and an air-
entraining agent in zeolite incorporating concretes on water penetration, drying shrinkage
and freezethaw resistance of concretes.
# 2016 Politechnika Wrocawska. Published by Elsevier Sp. z o.o. All rights reserved.
Available online at www.sciencedirect.com
journal homepage: http://www.elsevier.com/locate/acme
Concrete is a fundamental component of modern infrastruc-ture, which is why its strength and durability play animportant role. The properties of concrete in most casesdepend on Portland cement, which remains the mainhydraulic binder in use today. It is known that a partialsubstitution of cement by pozzolans results in an increase indurability of the concrete and, as a result, the service life ofconcrete structures [1,2].
Among the most common natural pozzolanic materialssuch as fly ash and silica fume is zeolite, which is used in someregions of the world, because of its lower cost and accessibility
* Corresponding author at: Faculty of Civil Engineering and ArchitecturePoland. Tel.: +48 0815384416.
E-mail address: firstname.lastname@example.org (W. Franus).http://dx.doi.org/10.1016/j.acme.2016.03.0131644-9665/# 2016 Politechnika Wrocawska. Published by Elsevier Sp
. Although natural zeolites are crystalline, they showproper pozzolanic activity . According to Uzal and Turanli a lime reactivity of the clinoptilolite zeolite is comparable tosilica fume, higher than fly ash and a non-zeolitic naturalpozzolan. Therefore calcium hydroxide as a cement hydrationproduct combines with natural zeolite consisting of reactiveSiO2 and Al2O3 to form calcium hydrosilicates [7,8]. It wasconfirmed by many researchers [1,68], that the pozzolanicreaction in pastes containing zeolite of clinoptilolite typeconsiderably decreased the calcium hydroxide content. Thereduction of free Ca(OH)2 in the hardened concrete improvesthe durability and concrete becomes more resistant tolime leaching by flowing waters and to expansion due tosulfate attack [8,9]. Chan and Ji  concluded that zeolite is
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more effective than pulverized fuel ash but worse than silicafume in improving the compressive strength. A number ofstudies show that the optimal amount of zeolite replacementlevel is approximately 10% . A higher amount of zeolitereplacing cement in concrete causes reduction of compressivestrength.
Najimi et al.  concluded that concretes incorporatingzeolite are characterized by the reduction of the heat ofhydration and consequently of thermal cracking and im-proved durability properties such as chloride ion penetration,corrosion rate, drying shrinkage and water penetration. Sabetet al.  and Ahmadi and Shekarchi  also reported that theincorporation of natural zeolite as a mineral admixture inconcrete enhanced its durability properties. However, varioustypes, structures and purities of natural zeolites influenceconcrete strength and durability in different ways and can leadin some cases to contradictory results in experimental studies.Moreover, properties of concretes with the addition ofdifferent types of zeolite located in various regions of theworld are already partly researched, but there is very lowresearches in particular mechanical and durability propertiesof concretes relating to the zeolite tuffs from fields located inUkraine.
The aim of this paper is to study the effect of natural zeolitecoming from Sokyrnytsia (Ukraine) on the mechanical anddurability properties of concrete. These properties includewater absorption, water penetration, drying shrinkage, freezeand thaw resistance.
2. Materials and methods
The materials used in this study include a clinoptilolite type ofnatural zeolite and commercially available Portland cementCEM I 42.5R. The chemical composition of the natural zeoliteand Portland cement are presented in Table 1. It wasdetermined by X-ray spectrometer ARL 9800 XP. Zeolite incomparison with Portland cement is characterized by a higheramount of silica, alumina and iron oxides, which areresponsible for the pozzolanic activity of zeolite.
The tests of Portland cement properties were carried outaccording to EN 196 . The specific surface of Portlandcement used in the study is 425 m2/kg. Water demand attains27%, initial and final setting time are 200 and 260 min,respectively. The compressive strength of Portland cementCEM I 42.5R after 2 and 28 days is 30.5 and 55.0 MPa.
Table 1 Chemical and mineralogical phase composition of th
Portland cement (CEM I 42.5R)
Chemistry wt.% Mineralogy wt.%
SiO2 20.17 C3S 59.76 Al2O3 4.41 b-C2S 18.12 Fe2O3 2.39 C3A 6.76 CaO 63.45 C4AF 10.91 MgO 2.41 SO3 3.21 Na2O 0.17 K2O 1.02
The mineral composition of zeolitic tuff was determined bymeans of a powder X-ray diffraction method, using aPANalytical X'pert APD diffractometer (with a PW 3020goniometer), a Cu lamp and a graphite monochromator. Theanalysis was performed at the angle range of 5658 2u. PhilipsX'Pert Highscore software was used to process the diffractiondata. The identification of mineral phases was based on thePDF-2 release 2010 database formalized by the ICDD.
Powder X-ray diffraction patterns of the zeolite showedthat clinoptilolite is the major crystalline phase. Zeolitic tuffalso contains quartz as a minor impurity (Fig. 1a). The maincomponents of the natural zeolite are identified as clinopti-lolite, accompanied by other components.
The morphology of clinoptilolite and chemical compositionin the field of main mineral components of the investigatedmaterials was examined by scanning electron microscope SEMFEI Quanta 250 FEG, equipped with EDS. Clinoptilolite occurs informs of thin plates in the range 1030 mm, sometimes ofdistinct hexagonal shapes (Fig. 1b).
According to the thermal analysis, in the first thermolysisphase of the zeolitic tuff, sample mass loss takes place in thetemperature range of 20200 8C (Fig. 2). It is associated withthe release of physically-absorbed water. The secondthermolysis phase of the sample occurs in the temperaturerange of 200440 8C and corresponds to the emission ofchemically bonded water, which is coordinatively andchemically linked to the crystal lattice of the mineral andforms aqua complexes with metal cations that enter thestructure of the zeolite.
A shallow endothermic effect is observed in the tempera-ture range of 440580 8C, which relates to the dehydroxylationprocess of surface due to splitting off of OH groups, whichcorresponds to a small weight loss in the TG curve.
In the high-temperature range of 5801000 8C, the appear-ance of an endothermic effect in the DTA curve can beexplained by a combination of several processes: a deepersurface dehydroxylation, destruction and a depreciation of thecrystal structure of zeolite under high temperatures.
Mercury intrusion porosimetry (MIP) was used for deter-mining the pore size distribution of natural zeolite. The testswere performed for pressures ranging from 0.1 to 200 MPa orpore radii from 10.0 to 3.8 103 mm. The volume of mercury V[m3/kg] intruded at a given pressure P [Pa] gave the porevolume that can be accessed. The intrusion pressure wastranslated on equivalent pore radius R [m] following theWashburn equation:
e cement and zeolite.
Chemistry wt.% Mineralogy wt.%
SiO2 75.34 Clinoptilolite 60Al2O3 8.77 Quartz 30Fe2O3 1.30 Other phases 10CaO 4.6MgO 0.55SO3 0.05Na2O 1.22K2O 2.41
Fig. 1 (a) XRD analyses of zeolitic tuff (clinoptilolite) (Q: qua