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The article presents the possibilities of using lightweight concrete - foam concrete in road construction. Principles of sustainable development create the need to develop new building materials. Foam concrete is a type of lightweight concrete that has many advantages compared to conventional building materials, for example low density and thermal insulation characteristics. With current development level, any negatively influencing material features are constantly eliminated as well. This paper deals with the substitution of hydraulically bound mixtures by cement foam concrete Poroflow 17-5. The executed assessment is according to the methodology of assessing the existing asphalt pavements in Slovak Republic. The special calculation was used to estimate the modulus of foamed concrete Poroflow 17-5 based on the results of static load tests conducted using the experimental in-situ stand.
Content may be subject to copyright.
Procedia Engineering 161 ( 2016 ) 428 433
1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the organizing committee of WMCAUS 2016
doi: 10.1016/j.proeng.2016.08.585
ScienceDirect
Available online at www.sciencedirect.com
World Multidisciplinary Civil Engineering-Architecture-Urban Planning Symposium 2016,
WMCAUS 2016
Foam Concrete as New Material in Road Constructions
Martin Deckýa,*, Marian Drusaa, Katarína Zgútováa, Matej Blaškoa, Matej Hájeka,
Walter Scherfelb
aFaculty of Civil Engineering, University of Žilina, Univerzitná 8215/1, 010 26 Žilina.
b Iwtech LTd. Trenþín, Slovakia
Abstract
The article presents the possibilities of using lightweight concrete - foam concrete in road construction. Principles of sustainable
development create the need to develop new building materials. Foam concrete is a type of lightweight concrete that has many
advantages compared to conventional building materials, for example low density and thermal insulation characteristics. With
current development level, any negatively influencing material features are constantly eliminated as well. This paper deals with the
substitution of hydraulically bound mixtures by cement foam concrete Poroflow 17-5. The executed assessment is according to the
methodology of assessing the existing asphalt pavements in Slovak Republic. The special calculation was used to estimate the
modulus of foamed concrete Poroflow 17-5 based on the results of static load tests conducted using the experimental in-situ stand.
© 2016 The Authors. Published by Elsevier Ltd.
Peer-review under responsibility of the organizing committee of WMCAUS 2016.
Keywords: Poroflow; subbase layer; bearing capacity; foam concrete;
1. The main advantages and examples of use of foam concrete
In this present day, lightweight concrete (foam concrete) represents a mixture of binder (usually cement), water,
admixtures, additives and technical foam what makes concrete a building material with good mechanical strength, low
thermal conductivity and with simple, yet highly technologically demanding processing.
The function of a filler in the mixture is to fulfil the air bubbles, making it appropriate to produce foam concrete
directly on the construction site using special technological equipment intended for such production. If the foam
* Corresponding author. Tel.: +421 41 513 5709.
E-mail address: decky@fstav.uniza.sk
© 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the organizing committee of WMCAUS 2016
429
Martin Decký et al. / Procedia Engineering 161 ( 2016 ) 428 – 433
concrete was mixed outside the site and transported there by mobile concrete mixers, it would cause a significant
decrease of its volume followed by increased costs. The main advantages of foam concrete structures include:
xSimple and quick pouring - with such pouring it is possible to produce and implement the installation of 400 -
600 cubic meters per day and to significantly reduce construction time and costs.
xComplete filling of cavities and pores without compaction - the advantage of foam concrete is that all cavities get
filled, which means that it is also partly self-levelling.
xGood absorption properties - foam concrete has a fine cell structure, which allows it to absorb kinetic energy
during compression or settlement of the upper construction, [1].
xLow failure rate - in contrast to some of the synthetically lightened materials, the foam concrete is not susceptible
to failure due to the presence of hydrocarbons, bacteria or funguses.
xEnvironmentally friendly - the usage and manufacturing of the foam concrete directly on the construction site
with a dosing device means less traffic disturbing and less manipulation on site. Recycling is also very easy and
energy efficient.
xWide ranges of density, [2, 3] - usually bulk density varies from 300 to 1600 kg.m-3.
Foam concrete [4], has been used in highway construction in the United Kingdom (UK) since 1970, yet it took
about 10 years for foam concrete to become competitive as well as a recognized building material. The greatest
construction suppliers using foam concrete technology in the UK are the Foam Concrete Ltd and The Pump
Engineering Ltd. These companies are behind construction of the following constructions works.
Foam concrete was used as a base material for roads in newly built Hertfordshire (UK) industrial zone. The
original subbase consisted of peat that caused numerous floods in the area in combination with high phreatic
surface. It was necessary to implement drainage before and during construction. It was not possible to use a
common structure of the road because repeating wetting and drying of individual construction layers would
subsequently damage already finished road structure [3].
Fig. 1. Views of preparation of the underlay, a poured layer of foam concrete, the pyramidal formwork
and application of the last layer of foam concrete, [5].
Another example is from Northwest Highway (Route 14) construction, were utilized over 13,000 cubic meters of
density 590 and 410 kg/m3 foam concrete. There were thickness up to 1. 20 m, were they installed to supplement
pre-existing foam concrete to across soft soils in six areas along Route 14. Filled areas varied from 1 meter to 12
meters wide for both eastbound and westbound lanes, including areas to support new storm water drains. Several
low areas were dewatered and carefully constructed to prevent floatation due to rain and groundwater. Upon
completion of foam concrete in these low bearable areas, the hardened foam concrete was quickly covered with
the designed layer of aggregate subgrade of thickness 300 mm. This layer was then covered with concrete
pavement to finishing roadway, [5].
The Central road, Schaumburg, Illinois overpass in length of 3 km, was reconstructed at full depth of a four-lane
road with drainage improvements and installation of curb and gutters. At the east end of the project, the road was
constructed over a marsh area with soft organic underlying soils (peat) located at depth of 3 m to 5 m under the
surface. This project is typical for the construction of lightweight foam concrete road fills. Soft organic underlying
soils with a low bearing capacity, can caused consolidation settlement when there is additional loading or stress
change. The general contractor proposed a combination of a 900 mm thick layer of 400 kg/m3 and 600 mm layer
430 Martin Decký et al. / Procedia Engineering 161 ( 2016 ) 428 – 433
of 500 kg/m3 foam concrete in lieu of the EPS to construct the lightweight fill. The major benefits of the general
contractor decision were in lower unit cost, less installation time, and higher quality of the material, [3].
Fig. 2. Views of a typical “Two-stage” road fill project where steel sheeting is installed down the centreline of the roadway to support live traffic
while excavation, placement of foam concrete, and pavement construction can be performed in the first stage, [6].
At Chicago's O'Hare International Airport, a water retention reservoir project at the north airfield involved
constructing a soil berm over an existing water supply with materials from the reservoir excavation. Due to the
designed burial loading and present depth of the water level, only a minimal amount of additional loading could
be excepted. PROVOTON foam concrete was used to construct a 28' wide, 10' thick spread footing and to provide
the required load reduction over a 2900' long stretch of the water main to support a minimal amount of soil cover
placed on top of the spread footing, [8].
Richards Bay, a deep-water port was opened in 1976 primarily to export coal and by the early 1990s it was
handling almost one-half of all cargo passing through South African ports. Since South Africa has no
commercially navigable rivers, ocean shipping has long been a major feature of its transportation network. The
port's five terminals handle approximately 1650 commercial ocean going vessels annually [7].
Fig. 3. South Africa’s busiest port, foam concrete being placed in 600 mm deep fills, [7].
2. The testing in-situ stand
The testing experimental stand has been built by Faculty of Civil Engineering at University of Žilina (FCE UNIZA),
in order to provide selected research in topics of highway and railways constructions. Testing stand FCE Uniza was
built in 2012-2015 (Fig.4).
2.1. Geological conditions at place of stand
The area of experimental testing stand is a typical for major construction sites, it is composed by layer of
antropogenous soil from past excavation works of class of soil CI – clay of intermediate plasticity. At layer of subbase
soil has been provided all kinds of geotechnical testing – like static plate load test, light falling weight deflectometer
(LFWD) test, CBR in-situ tests by CLEGG device [9], CPT (cone penetration test). In situ testing was accompanied
by laboratory testing for classifications, and technological parameters obtaining - like maximum bulk density of dry
soil ȡd,max =1632 kg.m-3 and wopt = 15.8 %.
431
Martin Decký et al. / Procedia Engineering 161 ( 2016 ) 428 – 433
Fig. 4. Testing experimental stand FCE UNIZA progress.
2.2. Parameters of used foam concrete
Thanks to research activities of iwtech LTd. it has been producing in certain volume homogenous and stiff foam
concrete at desirable bulk density and desirable compressive strength. Code numbers after name Poroflow 17-5 means
1.7 MPa of compressive strength and bulk density 500 kg.m-3.
2.3. In situ verification of equivalent elasticity modulus of layers with Poroflow
Laboratory testing of materials are useful for obtained material properties. In order to know interaction of new
material in real structure behaviour, real physical model at scale 1:1 is the best solution. Inappropriate scale can have
caused also inappropriate results; especially shear resistance of material is influenced by scale effect, [3, 12].
Therefore, in-situ experimental stand was used. Interesting verification was based on the results of the static plate load
test’s (PLT) measurements provided on the surface of foam concrete layer, at three places of different layer’s
composition of pavement structure and on foundation soil too, see Fig. 5.
Fig. 5. Executions of series of measurements at in experimental stand FCE Uniza.
432 Martin Decký et al. / Procedia Engineering 161 ( 2016 ) 428 – 433
For the theoretical calculations in road construction design, the modulus of elasticity of each construction layer is
necessary to be known. Based on known parameters of multi-layered system there is possibility to recalculate the
equivalent modulus of elasticity Ee of the multi-layered composition with foam concrete - Poroflow 17-5. This
recalculation was executed by using an analytical theory Sojuzdornii [11]. The calculation model was designed based
on the equal deformation of the road’s homogeneous materials (attributes are same as those of the subbase) and strain
two-layer’s system of modulus E1 (of top layer thickness of h1) and Esub (elastic modulus of surface layer of subsoil).
Two-layer system’s is loaded by the circular shape plate of diameter d. Equivalent modulus of the two-layer’s system
Ee is calculated as below,
»
¼
º
«
¬
ª¸
¹
·
¨
©
§
¸
¹
·
¨
©
§
n
d
h
arctg
n
n
E
E
e1
5.3
5.2
1
1
1
2
1
S
(1)
where in addition to the already explained symbols is:
5.2 1sub
EEn
(2)
According to the fact, that it was not possible to use the results of PLT on surface of the drainage layer (crushed
stones f- 8/16 was not stable due to small height of layer and poorly graded granulometry), interesting deformation
modulus was ascertained by the empirical relations from the measurements of light falling weight deflectometer
(LFWD) device type LDD 100. Because deformation modulus was determined from the first loading cycle of PLT E1
is practically identical to the modulus from second loading cycle of PLT E2, according to [13] a difference 1.4 % was
not significant. Based on the above, this yields the equation for determination of the deformation modulus from Edef,2
values from LDD 100 equipment (Evd), can be at this case used for determination of the elastic modulus referred as E,
[1]:
663,1
164.0 vd
EE (3)
It has been done also laboratory tests to ensure deformation characteristics of layer of Poroflow 17-5 material. On
the Fig. 6 there is the dependence of elasticity modulus E on bulk density of Poroflow, [2, 14, 15]. It is expected, that
the increasing bulk density of Poroflow is followed by an increase of the elasticity modulus. This characteristic is
mostly required at design of road pavements. It can be used for continuing numerical verifications of structures with
this new material and is numerically similar to equivalent modulus of certain multi-layered structures on standard
subsoil bearing capacity.
Fig. 6. Correlation dependence of elastic modulus on bulk density of Poroflow 17-5, [13].
433
Martin Decký et al. / Procedia Engineering 161 ( 2016 ) 428 – 433
At the final, values of equivalent modulus of elasticity of three Poroflow layers composition in certain geological
conditions is presented in Tab.1. Comparing the results of modulus can be seen influence of PVC separation foil in
composition II and tensile stiffness of geotextile at layer’s composition III, where highest modulus was derived.
Tab 1. Values of equivalent modulus of elasticity of Poroflow layers detected by reversal calculation for measured modulus of subbase Esub.
Layer’s composition I. Ee [MPa]
(Esub) Layer’s composition II. Ee [MPa]
(Esub) Layer’s composition III. Ee [MPa]
(Esub)
Poroflow 17-5 15 cm 1 770
(22.7)
Poroflow 17-5 15 cm 1 450
(21.3)
Poroflow 17-5 15 cm 1 950
(23.6)
Geotextile 250 g/m2 Separation foil Geotextile 500 g/m2
Crushed stones f-8/16 20 cm Crushed stones f-8/16 20 cm Crushed stones f-8/16 20 cm
Geotextile 250 g/m2 Geotextile 250 g/m2 Geotextile 250 g/m2
4. Conclusions
The article describes the latest research activities carried out in experimental in-situ stand of FCE UNIZA in
cooperation with iwtech LTd. It has been presented simple solution how to determined equivalent modulus of subgrade
layers’ composition with foamed concrete. Different testing method and different correlations was used in order to
receive quit realistic values of the most important design characteristic. For objectification of methodology, series of
3D FEM numerical models was created. Currently, the research activities continuing at optimization of the structure
composition, including the selection of the optimal type of geotextile and combined geosynthetics with drainage
function, in order to achieve the highest values of deformations parameters and reliability of structure during lifetime.
Acknowledgements
The research is supported by European regional development fund and Slovak state budget by the project “Research
centre of University of Žilina”, ITMS 26220220183.
This work was supported by the Scientific Grant Agency of the Ministry of Education of the Slovak Republic. Grant
VEGA No. Grant No. 1/0926/16.
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Adding an insulation layer above the frost-susceptible layer in regular pavement structures was proved to be an efficient way to mitigate the influence of climates, such as frost heave and thaw weakening, on pavements in cold regions. However, there is limited research in the area of insulated pavement performance evaluation and design procedures. To bridge the gap and design the structure of insulated pavements, we developed an approach that integrated the selection of the failure criteria, the generation of a trial structure, the evaluation of the thermal and mechanical responses based on a finite-element (FE) model, and the prediction of the pavement rutting and cracking performance. To calibrate the heat transfer process and the thermal field of the FE model, four large-scale pavement boxes were constructed, with one as the control box (no insulation layer) and three others insulated by extruded polystyrene (XPS) boards, tire chips, and foamed concrete, respectively. The spatiotemporal variations of temperature distributions in each box using thermocouples were monitored, and the thermal properties of the insulation materials were back-calculated by a simulated annealing method. Based on the mechanical and thermal responses of various insulated pavements, we calculated the maximum axle load repetitions and developed a sample design table for insulated pavements. The design table indicates that the pavements insulated by XPS boards and foamed concrete can bear more load repetitions than uninsulated pavements, while the tire chips insulated pavement can bear more traffic repetitions only when the overlay thickness is greater than 35 cm. The temperature of the subgrade layer in the insulated pavements is more stable than that in the uninsulated pavements, and a thicker insulation layer results in less temperature variation in the subgrade layer. This study provides new insights into the behavior of insulation layers under cold temperature conditions and helps guide the design of insulated pavements in cold regions.
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The article considers the influence of the water-cement ratio on the formation of the structure of thermally insulating foam concrete, having the D300 average density grade. The basis for the analysis is the contradiction between the experimentally obtained direct dependence of the strength of foam concrete on the water-cement ratio and the practice of improving the structure of the material due to water reduction. The computation of the optimal amount of water in the foam concrete mixture based on the method of absolute volumes is presented. The calculation includes a formula for determining the volume of the interpore space depending on the thickness of the interpore partition, the cell diameter and the type of packing. The actual indicators collected during the experiment confirm the results of the calculations. The influence of the amount of water in the foam concrete mixture on the quality of the foam concrete is evaluated by the compressive strength and the macrostructure character of the material. The strength is determined by the destructive method. The structure is studied using an optical microscope in combination with image processing software. The greatest strength is possessed by a material with a partition thickness exceeding the maximum size of the cement grain, provided that the volume of the interpore space and the sum of the absolute volumes of the components of the foam concrete mixture are equal. A structure with closed pores and dense interpore partitions is observed in foam concrete on a protein foam former with a water-cement ratio, taking into account water in the foam, equal to 0.7.
Article
In this study, influences of waste marble powder (WMP) and rice husk ash (RHA) partially replaced instead of fine aggregate and cement into foam concrete (FC) on compressive and flexural strength, porosity, and thermal conductivity coefficient were investigated using Response Surface Methodology (RSM) and Artificial Neural Networks (ANN) methods. The foam parameter was determined as two levels in the experimental design, and the WMP and RHA parameters were determined as three levels. With the RSM analysis, the most influential parameters for compressive and flexural strength were determined as Foam WMP and RHA, respectively. Likewise, the order of effective parameters for porosity and thermal conductivity coefficient was found as foam WMP and RHA. With the RSM method, R2 values were obtained as 0.9492 for compressive strength, 0.9312 for flexural strength, 0.9609 for porosity, and 0.9778 for thermal conductivity coefficient. Correlation coefficients with the ANN method were found as 0.98393, 0.96748, 0.9933, and 0.96946 for compressive and flexural strength, porosity, and thermal conductivity coefficient, respectively. The ANN method was found to be suitable for estimating the responses. The RSM method was found to be suitable both for estimating the responses and for determining the effective parameters. In addition, the optimum parameters were determined by the RSM method. It was observed that the error rate of the results obtained in the validation tests applied according to the optimum determined parameters was relatively low.
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Principles of sustainable development create the need to develop new building materials. Foam concrete is a type of lightweight concrete that has many advantages compared to conventional building materials, for example low density and thermal insulation characteristics. With current development level, any negatively influencing material features are constantly eliminated as well. This paper is dealing with substitution of hydraulically bound mixtures by cement foam concrete Poroflow 17-5. The executed assessment is according to the methodology of assessing the existing asphalt pavements in Slovak Republic. The ex post calculation was used to estimate modulus range for Poroflow 17-5 based on the results of static load tests conducted using the Testing Experiment Equipment.
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Article
The paper presents results of numerical investigation of fracture behaviour of initially notched beams made of foamed concrete. Extended Finite Element Method (XFEM) was used to simulate the damage and fracture process of the beams subjected to three-point bending. Subsequently, the numerical models were validated by a series of static loading tests. Numerical models simulate correctly the fracture behaviour of beams observed during testing. XFEM method and computer simulation technologies allow for reliable approximation of load–bearing capacity and damage mechanisms of beams made of foamed concrete, which provides some foundations for realistic structural applications.
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Nowadays many problems concerning industrial floors or floors in shopping centres occurred when local geological characterization is not adequately considered by structural designers, material selection is not evaluated properly and in time for future stability, or consolidation of soft organic subsoil laid in active zone is not taken into account during design evaluation. Similar problems occur when flooding effects on subbase layers cause a new settlement of the upper floor structure. Generally speaking, majority of these symptoms of floor damage have their origin in underestimation of the geotechnical risk. At some locations, the selection of support structure and material type is not adequate due to lack of experience and in order to offer the lowest price as a contractor.
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Conference Paper
The high degree of thermal insulation makes foamed concrete a perfect material for use in a passive houses design. Application of foamed concrete as a replacement of compacted soil in a base layer for a foundation has a series of advantages. The material has the strength properties at least as good as well-compacted soil. It can be easily placed (poured) and does not settle, so no compaction is required. Its light weight, ensuring limitation of loads imposed to the subsoil along with providing uniform distribution of reactions from the supported structure, makes the solution excellent for weak soils. Paper shows the concept of a dwelling-house sandwich foundation slab with a foamed concrete base layer and a reinforced concrete structural layer.
Designing and Quality Control of Earth Structures On Transport Constructions
  • M Drusa
  • M Decky
Drusa, M., Decky, M. et al.: Designing and Quality Control of Earth Structures On Transport Constructions (In Slovak). Edis Uniza, 2013, pp. 522 ISBN 978-80-554-0823-1
Application of geotechnical models in the description of composite foamed concrete used in contact layer with the subsoil
  • M Drusa
  • L Fedorowicz
  • M Kadela
  • W Scherfel
Drusa M., Fedorowicz L., Kadela M., Scherfel W.: Application of geotechnical models in the description of composite foamed concrete used in contact layer with the subsoil. Proceedings of the 10th Slovak Geotechnical Conference "Geotechnical problems of engineering constructions"-conference proceedings, 30-31 maj 2011.
Clegg Impact Soil Tester Technical Note. Calculation of Penetration and Elastic Modulus from CIV
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Clegg, B.: Clegg Impact Soil Tester Technical Note. Calculation of Penetration and Elastic Modulus from CIV. Jolimont, 1994.
Evaluation of dynamic methods for earthwork assessment
  • J Vl Ek
  • D Ureková
  • K Zgútová
Vl ek, J., ureková D. Zgútová K.: Evaluation of dynamic methods for earthwork assessment. In: Civil and environmental engineering journal. ISSN 1336-5835. -Vol. 11, no. 1 (2015), s. 38-44.
Foamed concrete used a subbase for some systems structure-subsoil
  • L Fedorowicz
  • M Kadela
Fedorowicz L., Kadela M.: Foamed concrete used a subbase for some systems structure-subsoil. Proceedings on CD of the 7th congress Engineering Geology 2012 on June 14 -15, 2012 in Nový Smokovec, Vysoké Tatry, Slovakia
Earth Structures of Transport Constructions
  • M Decký
  • M Drusa
  • , Pepucha
  • K Zgútová
Decký, M., Drusa, M., Pepucha,., Zgútová, K.: Earth Structures of Transport Constructions. Harlow: Pearson, 2013, p. 180, ISBN 978-1-78399-925-5.