Research and Development in design and application of concrete-polymer composites in Europe

Prof. Dr. Ir. Dionys Van Gemert Department of Civil Engineering

Katholieke Universiteit Leuven, Kasteelpark Arenberg 40, 3001 Heverlee, Belgium e-mail: Dionys.VanGemert@bwk.kuleuven.ac.be

ABSTRACT This paper deals with concrete-polymer composites as prototype advanced construction materials and systems, with emphasis on European developments. Evolutions in the areas of new building materials like mineral polymers and textile reinforced earth, of new systems like fibre reinforced polymer laminates for structural strengthening and porous polymer-cement concrete, of new construction methods for encapsulation of polluted sites, of new repair techniques for timber structures. These materials and techniques proved to be reliable and durable, which encouraged research in applications as well as in theoretical background. This has led to more appropriate design methods and to a better understanding of the physical-chemical interaction between the hardened polymer phase and the crystalline cement microstructure. These new findings bring new interest and new applications for concrete-polymer composites. Special applications in highways and infrastructure, repair materials, applications in renovation and restoration are discussed. Field and laboratory experiences on durability of the polymer-based systems are described. KEYWORDS: Concrete-polymer composites, repair, construction, strengthening 1. INTRODUCTION In the industrialised world the sixties and seventies of last century were characterised by an unlimited belief in new and modern materials and techniques. The use of polymers was considered to be a sign of progress and modern attitude in construction. Glass fibre reinforced polyester panels, polyester resin and polyester mortar were known as inexpensive plastics. Epoxy glues were used as highly performing adhesives in concrete precast applications, epoxy resins were used as binders in chemically resistant coatings and flooring systems. Research aimed at developing new, improved polymers was continuously done. The use of polymers gradually extended to concrete crack injection, repair mortars for concrete and stone, consolidation of masonry, repair of timber structures. At that time building materials science was an underdeveloped field of construction industry and science. So the extended use of pure polymers led to inherent chemical and physical incompatibility problems, mechanical malfunctioning and durability problems. In the early seventies the oil crises learned that mineral oil as a cheap basis for polymer production was not longer available. It was also found that oil reserves were limited. As a consequence all uses of polymers were questioned. First of all the waste of fossil oil for energy production, and secondly the massive use of polymers as alternative for classical, mineral building materials such as concrete, masonry, timber and metals. The use of polymers became part of a search for durable or sustainable construction materials. Polymers were used in these areas were their specific properties were needed. In combination with classical construction materials a synergic effect could be obtained. Combinations of concrete and polymer are called concrete-polymer composites or CPC. This evolution led to new applications of polymer modified repair mortars for concrete, stone and masonry. Pure polymer concrete building components were partly replaced by CPC, as in flag-stones and building panels. Consolidation of masonry by means of epoxy grouts was replaced by two-step injections of mineral binder grouts followed by epoxy resin injection. A better knowledge of materials behaviour, especially in the field of admixtures, and a better understanding of curing processes allowed the development of highly performing mineral or modified mineral concretes, mortars and

grouts. CPC-science is now an invaluable element in the development of sustainable construction materials [1]. 2. DEVELOPMENT OF CPC-SCIENCE Organisation of international congresses is a criterion for the development of knowledge about concrete-polymer composites. A list of the earliest events is given in [2]. A list of the most important congresses and symposia is given in Table 1.

Table 1. Overview of major international events in Polymers in Concrete Year

Venue

Congress or Symposium Name

1967

Paris, F

RILEM Symposium, Synthetic Resins in Building Construction

1975

London, UK

1st International Congress on Polymers in Concrete

1978

Austin, USA

2nd International Congress on Polymers in Concrete

1981

Koriyama, J

3rd International Congress on Polymers in Concrete

1984

Darmstadt, West-Germany

4th International Congress on Polymers in Concrete

1986

Aix-en-Pro-vence, F

RILEM International Symposium, Adhesion Between Polymers and Concrete, ISAP ‘86

1987

Brighton, UK

5th International Congress on Polymers in Concrete

1990

Shanghai, China

6th International Congress on Polymers in Concrete

1992

Moscow, USSR

7th International Congress on Polymers in Concrete

1994

Seoul, K

1st EASPIC Symposium on Polymers in Concrete

1995

Ostend, B

8th International Congress on Polymers in Concrete

1997

Koriyama, J

2nd EASPIC Symposium on Polymers in Concrete

1998

Bologna

9th International Congress on Polymers in Concrete

1999

Dresden, G

RILEM 2nd International Symposium, Adhesion Between Polymers and Concrete, ISAP ‘99

2000

Shanghai, China

3rd Asia Symposium on Polymers in Concrete ASPIC-2000

2001

Honolulu, USA

10th International Congress on Polymers in Concrete

2002 Poitiers, F Orgagec ’02 Organic Materials: a future in the field of civil engineering? Environmental Uncertainties?

2003 Chuncheon, Korea 4th ASPIC Symposium on Polymers in Concrete

2004 Berlin, Gemany 1

1th Congress on Polymers in Concrete - June 2-4

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In between some local workshops and seminars on the use of polymers in concrete were organised, some of which got international resonance. Special applications of polymers, e.g. in industrial floors, were treated in separate colloquia [3]. Not only scientific knowledge improved, but also practical use of polymers in concrete grew steadily. Whereas the first researches mostly were application and performance oriented in civil, mechanical, chemical, electrical and transportation engineering, nowadays research is much more directed towards fundamental aspects of structure and microstructure building in the composite polymer-concrete, towards synergic aspects, towards new polymer types and new polymer states, e.g. polymers in solution instead of polymers in emulsion or as re-dispersible powders. 3. IMPORTANCE OF POLYMERS IN EUROPEAN CONSTRUCTION INDUSTRY During the European Colloquium Orgagec ’02 organised by Laboratoire Central des Ponts et Chaussées in Poitiers, France, in March 2003, M. de Longchamp presented figures of consumption of polymers in the European Union (15 members; 330 million inhabitants) in 2000 [4]. Some data for the largest components in polymer consumption are listed in Table 2.

Table 2. European consumption of polymers in construction Application field Type Consumption Textiles in architecture Polyester/glass

PVC/polyester Carbon/Kevlar

28 000 tons 100 000 tons not significant

Highway noise barriers System concrete-timber Recycled plastic Transparent plastics Concrete Timber Metal Vegetation screens

± 30 % ± 2% ± 5% ± 10% ± 15% ± 10% ± 10% Total 1.970.000 m², 15 % increase/year

Impermeable membranes PVC PE (HD + LD) EP, PU, UP resins SBS, APP bitumen modif.

200 000 tons 250 000 tons 50 000 tons 88 000 tons

Road paintings Liquid, hot melt, strips 280 000 tons Tubing for optical fibres PEHD 200 000 tons (2001)

600 000 tons (exp. 2010) Tubes for sewers, gas, water… PVC, PE, PP, UP 2 761 000 tons Concrete modification 486 000 tons Total polymers in construction 6 850 000 tons/year

This consumption of 6 850 000 tons/year represents about 20 % of the total market of polymers (plastics) of 34 250 000 tons/year in the European Union. On average about 8 % of polymer consumption concerns thermosets, the rest being termoplasts [5]. The relation to other industries is shown in Table 3. However, if the consumption of polymers is compared to the consumption of other construction materials, its relative share is only about 1 %, Table 4.

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Table 3. Relative share of polymers in construction to other industries Industry Relative share of polymer market

% Packaging 35 Construction 20 Transportation 15 Electrical/Electronic 10 Sports and pleasure 5 Furniture 4 Medicine 4 Various 7

Table 4. Relative share of building materials in EU-construction industry (year 2000)

Construction material Consumption (tons) Ratio (%) Concrete and cement based 503 000 000 71 Tiles and bricks 73 000 000 10 Timber 54 000 000 7 Iron and steel 24 000 000 3 Stone, quarry 16 000 000 2 Asphalt and bitumen 16 000 000 2 Polymers 6 850 000 0,97 Flat glass 5 200 000 0,73 Mineral wool 2 000 000 0,3 Copper 1 300 000 0,2 Aluminium 900 000 0,1

The share in weight is only about 1 %, but in financial turnover polymers represent more than 10 % of construction industry. It is expected that in about 10 to 15 years polymers in construction will be the prime part of the polymer market. The amount of polymers, used in concrete-polymer composites, is only a minor part in polymers for modification of concrete, which also include water reducing agents (121500 tons of super-plasticiser in EU in 1998). However, due to the synergic action between polymers and the cementitious matrices, the impact on performance of building materials largely overpasses the weight ratio. The Construction Products Directive 89/106/EEC (CPD) defines the essential requirements for construction products as follows:

1. mechanical resistance and stability 2. safety in case of fire 3. hygiene, health and the environment - dangerous substances

- global environment impact 4. safety in use 5. protection against noise 6. energy economy and heat retention

The European Legislation assumes that a producer is responsible for knowing and complying with all applicable legislation. This is a difficult area, because up to now only national regulations exist, and chemicals and dangerous substances are also dealt with by several DGs (Directorate General), e.g. DG Enterprise, DG Environment, DG Agriculture, DG Health, DG Consumer Protection, etc. The European Commission for Standardisation CEN is now harmonising the regulations and a database on dangerous substances regulations is available [6]. With respect to global environment impact, the European Union is striving at an integrated product policy, to reduce the environmental impact of the whole life cycle of products. The Union will use market forces efficiently to reach environmental policy objectives, in a way that prices should reflect also the environmental costs, demand should be more oriented towards ecological products, and supply should adapt and even promote ecological products.

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All developments in using concrete-polymer composites should take into account this policy of the European Union, which is similar to the policy in the rest of the world. As engineers we tend to stress on most of the 6 essential requirements of the construction products directive, but we have to admit that our interest in the 3rd one for hygiene and health is rather limited, presumably because of lack of knowledge in the field. Producers and construction engineers will have to collaborate with the medical world, to meet also those essential requirements. 4. NEW MATERIALS 4.1 Mineral Polymers Repair mortars for stone and concrete are widely used in construction industry. Well-known are polymer mortars and polymer-cement mortars, each with their own specific properties and proper application domains. A special development in stone restoration mortars are the mineral polymer mortars. The binder in this type of restoration mortar is based on metal oxide and water-soluble metal salts. Both components react with each other to create ‘mineral polymer’ chains. The reaction mechanism is as follows: n (MeO + MeCl2 + H2O) = (–Me–O–Me–O–)n + n HCl (1) ZnO and ZnCl2 are used in the case of stone repair materials. The HCl acid formed during the reaction is eliminated through a reaction with salts of weaker acids present in the filler or the substrate, e.g. calcium carbonate 2HCl + CaCO3 = CaCl2 + H2CO3 = CaCl2 + H2O + CO2 ↑ (2) The carbonate dissociates in water and carbon dioxide. This gas evaporates by which the equilibrium of the reaction spontaneously moves to the right. The molecular chain or polymer is formed, hardens and adheres to the substrate. The polymer molecules are linked by polar bonds, which also assure the bond to the substrate. The reaction mechanics makes it clear that due to the formation of CaCl2 this material is not suited for reinforced concrete repair, and that only calcareous stone can be used as filler. Normally one uses quarry sand from the stone that has to be repaired, and by mixing of pigments and by the use of different aggregate gradings the desired colour and texture can be composed. The mortar is rather porous by the CO2-gas formation. In the pores CaCl2 and other rest salts remain. CaCl2 can hydrolyse to Ca(OH)2 and further carbonise to CaCO3 . The latter can cause some efflorescence on the mortar surface. By rain or brushing this deposit can be removed. However, this phenomenon is similar to the one in fresh natural stone, where the pore water also contains Ca(OH)2. Therefore natural stone and repair mortar will show the same ageing effects, called ‘patina’. The mineral polymer mortar is water and damp permeable, and is applied on a primer, being the pure binder and thus permeable too. On a wet substrate the bond is poor. The hardening reaction is very fast. After half an hour the mortar can only be worked with a knife or a chisel. After one day the mortar can be shaped with all the normal stonecutters’ tools [7]. 4.2 Textile reinforced earth Industrial waste deposit requires a special technology for the construction of the impermeable membranes beneath the deposit as well as on top of it: leakage must be avoided; liquid and gas drainage must be provided. The capacity of a waste deposit depends to a great extent on the slope angle. The slope inclination of the waste hill is limited by the need to cover the hill with a green layer, consisting of 0,3 to 1,0 m of protective soil and garden mould. Because this layer rests on an impermeable PE-foil, its stability may cause severe problems. Therefore the earth is reinforced with textile fibres. One French method is to make a mixture of soil and continuous polyester fibres, thus

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making a material with high internal cohesion. Most of the properties as density, permeability, grain size distribution, ... are the same as the properties of the base material. This base material should be sand; because of the mix procedure the grainsize should be smaller than 10 mm and at least 95 % should be larger than 80 �m. The main improvements of this composite material are the shear properties, especially the cohesion. Due to the improved cohesion, steep slopes up to 70° can be built. The sand and the fibres are mixed on site with a mix proportion of 0,15 to 0,20 % of fibres by weight of sand. This mixture is applied in layers of 0,1 m; each layer is compacted. Due to these layers, the soil gets anisotropic properties. The cohesion, as determined by direct shear tests, can vary between 20 kPa and 300 kPa, depending on the angle between the shear surface and the direction of the layers. In the worst case of a shear surface parallel with the layers, there still is an improvement in shear resistance of 20 to 30 % [7]. Alternative systems were developed, were the fibres are replaced by a honeycomb system, where the cells are filled with soil material. 4.3 Textile fabric composites [8] Textile composites represent a class of materials, which are reinforced by textile pre-forms for primary (structural) and secondary applications. Textile composites are considered as attractive materials because of their excellent drapability, possibilities for near-net-shape pre-forms, higher toughness properties resulting from the fact that some fibres are oriented in the out-of-plane directions. Improvements in the out-of-plane mechanical properties such as fracture toughness, give textile composites a better impact resistance. The drapability and flexibility of fabrics reduce the number of production steps and material waste, both leading to a lower production cost. Figure 1 shows briefly a comparison between textile fabric composites and traditional composites such as short and unidirectional fibre reinforced composites.

Figure 1. Comparison between textile fabric composites and traditional composites.

Following the history of composite development, textile performs were introduced later, after traditional reinforcement architecture like continuous unidirectional or discontinuous random-fibre reinforced polymers. Textile performs can be classified into woven, braided and knitted fabrics. Textile preforms can be directly processed without any treatments like pre-preging. Fibre bundles can be knitted into a particular shape that is close to a desired final product. Knitted fabrics are made by interlocking loops of yarn, Figure 1. Based on the yarn feeding and knitting direction, knitted fabrics can be categorised into two types: warp and weft knitted fabrics. In the weft knitting technique, one single yarn is fed into the knitting machine. The yarn forms loops by the separate and consecutive movement of the needles. In this way the knitted fabric is created row by row. The rows are usually called ‘courses’, the columns ‘wales’.

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What are knitted or woven (textile) fabric composites?

Textile technology offers:1. Flexible preform2. Near-net shape preform3. Seamless preform

+ Lower material waste+ lower production steps

Knitted fabric Woven fabric

Other fabrics:braid, stitch, sandwich etc

Figure 2. Principle of knitted and woven textile fabric composites (courtesy S. Pandita). The possibilities for production of all kinds of building and machine components are very wide, as can be seen in Figure 2. 5. NEW CONSTRUCTION SYSTEMS 5.1 CFRP-external reinforcements for concrete Strengthening of reinforced concrete structures by means of external, epoxy bonded steel plates is a well-known technique. Disadvantages in some cases are the weight of the steel plates and their limited available length, by which difficult overlaps are needed. Carbon fibre reinforced epoxy laminates were developed to overcome these difficulties: high strength fibre composite laminates are relatively thin and can be delivered to the construction site in rolls, in lengths of up to 300 m or more. A wide variety of cross-section dimensions are available on the market: 18 mm x 5 mm to 120 mm x 1,5 mm; fibre content 60 %, laminate strength 1600 - 1800 MPa, average stiffness up to 250.000 MPa. The gluing procedure is nearly identical to the one with steel plates. Care must be taken in preparing the bonding surface of the CFRP-laminate: grit-blasting the surface may damage the fibre bond, and lead to premature fibre peeling. In those cases where increased stiffness is not required, but only increased strength, CFRP-laminates will be more economic than steel plates. Design and practical application are now well developed in Belgium and in Europe [9,10]. 5.2 PU-injection for Punch-out Repair Punch-out damage occurs in highway concrete pavement slabs, depending on the type and composition of the sub base layer, traffic conditions and drainage systems. Water enters the foundation, is pressurized by traffic load repetitions, and pumps fines out of erodible subbases. The concrete slab looses its support, and a strong fatigue bending load occurs by which the concrete as well as the reinforcing steels are broken. It was found that polyurethane grouting presents an effective method for thorough and latent punch out damages. Taking into account the right procedures, a reliable and durable repair of punch-out distresses will be obtained [11]. Several hundreds of punch-out damage zones have been repaired by this method in Belgium alone.

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6. NEW FIELDS OF APPLICATION 6.1 Porous polymer-cement concrete [12] Porous concrete is a material with a large water accessible porosity which has good drainage capacities and noise reducing properties. The use of the material as top layer on roads necessitates a sustainable material from the mechanical point of view as well as for the resistance towards freezing and thawing cycles. To understand the behaviour of porous concrete as top layer on roads, it is not only necessary to look at the macroscopic properties of the material. Explanations rather have to be searched for in the microscopic structure of the material. It is the interaction between the polymer film, the cement hydrates and the aggregates which determines the final properties of the material. It is among others due to the increased adhesion between the aggregate and the binder matrix that sufficient mechanical strength and good durability properties are obtained, even with high water accessible porosity. The structure of porous concrete can be studied at different levels. At the highest level, the macro-level, the structure of the road has to be considered, as there is the layer thickness, the width of the lane, the slope of the lane. The composite samples, made in the laboratory, can be considered at this level. At the meso-level, three phases are distinguished: the aggregates, the polymer-cement co-matrix, in which also the fine aggregates are included and the water-accessible pores. At this level, the interaction of the different phases is important. At the micro-level, the micro-structure of the polymer-cement co-matrix is visible. The interaction between the polymer film and the cement hydrates is focussed on at this level. The macro-level focuses on the real-size application of porous concrete. In this research, porous concrete is used as top layer on highway roads. The thickness is determined by the noise reducing capacities of the pavement, which are depending on the traffic speed. A cross-section of the site pavement is illustrated in Figure 3.

Figure 3. Cross section of the ‘porous concrete’ pavement. The placing of the top-layer in porous concrete can be done according to the wet-in-wet procedure or to the wet-on-dry method. In the wet-in-wet procedure, the continuously reinforced concrete pavement, which is used as base course, is cast with a conventional slip form paver. After two to four hours, depending on the weather conditions, the top layer in porous concrete is cast. This results in a good adhesion between both layers, since the porous concrete and the concrete of the base course mingle into each other and a blended interlayer occurs. In this interlayer, the porosity varies from very small, comparable to the porosity of the continuously reinforced concrete, to a very large porosity comparable to the pure porous concrete. The advantage of this method is a good adhesion between both concrete layers. In the wet-on-dry method, the porous concrete is poured on the hardened base course. To assure a persistent adhesion between both layers, additionally bonding compounds are needed. Often, polymer-cement slurry is used for this purpose. However, this layer forms the weak chain of the

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mechanism. Failure occurs due to decohesion of the top layer in porous concrete and the normal pavement concrete. At the meso-level, between 10-3 and 10-1 m, three different phases can be distinguished: the discontinuous phase containing the aggregates; the continuously distributed phase of the cement-polymer matrix and thirdly the phase formed by the pores. The latter contains the water accessible pores, which are mostly connected with each other throughout the structure. Therefore this phase can be seen as a continuous matrix, twinned with the cement-polymer matrix. The general mixture composition, as well as the density and the volume fraction of the different components of porous concrete are given in Table 5.

Table 5: mixture composition of porous concrete Composition

[kg/m³ concrete] Volume fraction [m³ component/m³ concrete]

Coarse aggregate 4/7 Fine aggregate 0/1 Cement (CEM III/A 42.5 LA) Polymer emulsion (50 % solids) Water

1350 kg/m³ 90 kg/m³

280 kg/m³ 56 kg/m³ 56 kg/m³

49 % 3.3 % 9.1 % 5.4 % 5.6 %

The structure of porous concrete observed at the micro-level is mainly focussing on the structure of the polymer-cement co-matrix. The discussion therefore can be held more general, covering all applications of polymer modified cement mortar or concrete. Important at this level are the interactions between the polymer film (PF) and the aggregates (A), Figure 4. Mechanisms of crystal growth, size of crystals, gel-porosity, reduced porosity of the interface between the binder matrix and the aggregates are visible at this level. Properties measured on a test lane at Herne (B) are listed in Table 6.

Figure 4. Polymer film, connecting two aggregates, 1000 x, etched sample.

Table 6. Properties of the porous concrete taken from the test lane at Herne-Galmaarden

Compressive strength - 28 days, 158 mm cube - 90 days, 158 mm cube Flexural strength - 28 days, 100x100x400 mm prisms Splitting tensile strength Statical modulus of elasticity Dynamic modulus of elasticity Accessible porosity

26.0 N/mm² 29.5 N/mm² 4.4 N/mm² 3.9 N/mm² 24 200 N/mm² 27 200 N/mm² 19 %

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6.2 Repair of timber structures [13] Deteriorated parts of wooden beams are being replaced by epoxy mortar prosthesis. Deterioration often occurs at beam ends, supported in masonry walls, and at connections between horizontal and vertical or inclined elements. The decayed part is removed by sawing or cutting, Figure 5. A casing is than installed which reconstitutes the original shape of the beam, Figure 6.

Figure 5. Deteriorated beam end. Figure 6. Repaired beam end. If the reconstruction has to meet aesthetic requirements, the casing should be made out of the same wood as the original beam, and it will be kept in place to cover the epoxy mortar of the prosthesis. The connection between the original wood and the prosthesis is secured by means of anchoring bars, being stain protected steel rods or fibre reinforced plastic rods. Design of both the polymer mortar prosthesis and the anchoring system is based on research of bond properties between polymer mortar and wood as a function of humidity of the wood and layout of the anchors [14]. A typical deterioration of wood at a node is shown in Figure 7. It concerns the roof structure of a 17th Century barn at Herckenrode (B), which is a part of a monumental Abbey of Cistercian nuns. The polymer-based repair is shown in Figure 8, 9, 10.

Figure 7. Deteriorated timber truss. Figure 8. A chainsaw is used to remove bad parts.

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Figure 9. Steel rods are used to improve Figure 10. Repaired horizontal beam and connection the plastic behaviour of the prosthesis. in truss. The epoxy mortar repair of wooden beams is often called polymeric restoration of timber beams. The technique has been further developed for the strengthening of broken beams, were bending as well as shear forces are present. The technique is often combined with externally bonded steel plates or fibre reinforced plastic laminates, glued on the wooden beams [13]. 7. FUNDAMENTAL RESARCH Fundamental research is executed on building of the microstructure of polymer-cement concrete as a function of the properties of the polymer, its film forming temperature, the cement properties and the curing conditions. An integrated model has been proposed that explains the intermingling of phases during simultaneous polymer hardening and cement hydration of a PCC-mortar or PCC-concrete [15]. The model helps in explaining the behaviour of concrete-polymer composites under chemical attack, e.g. by sulphuric acid, Figure 11 and 12.

Figure 11. PCC, SAE, 50x Figure 12. PCC, SAE, 150x Figure 11 shows the attack by sulphuric acid in a pore of concrete, modified with SAE. At the bottom of the pore, fine CaSO4-crystals are visible. At the edges of the pore, the intermingled cement hydrates and polymer film are still visible. As can be seen in Figure 12, the CaSO4-crystals grow through the composite layer. Possibly, the amount of polymer was too small to form a continuous film to prohibit the growth of the crystals.

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Another new research field concerns nano-composites. [16] The intimate association of inorganic entities with macromolecules is an intrinsic feature of many biological hard materials such as bones, shells, or spines. This may lead to a remarkable improvement of mechanical properties such as strength, toughness or ductility. As far as dense synthetic materials are concerned, two main bio-imitation routes have been developed: hybrids on one hand and nano-composites (NC) on the other hand. Hybrids are usually defined as materials in which the association of organic and inorganic species is at molecular level via ionic-covalent bonds whereas, in nano-composites, nano-scale clusters or particles may still be identified and distinguished from the embedding matrix. In terms of Gibbs concept of phase, an hybrid material is a single phase, whereas a nano-composite could be considered as a mixture of phases, although the properties of nano-phases may significantly differ from those of macro-phases. Covalent coupling of the nano-phase with the matrix may further blurry the picture. In concrete-polymer composites the admixing of polymers in solution instead of emulsion could lead to the desired nano-composite structure. 8. CONCLUSIONS

The use of polymers in construction industry is steadily growing. The synergic action of polymers and cement mortar and concrete offers great opportunities for improvement and a wide range of new and innovative applications. Society and environment require corrective actions to be taken continuously. The use of polymers should be well-considered to guarantee better performance and improved sustainability. Polymers are no longer special construction materials that replace classical mineral or organic building materials. They are now one vital component in the production of composite and sustainable building materials. They will further allow the development of new and durable constructions, as well as new and durable restoration and retrofitting techniques.

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9. REFERENCES 1. Ohama Y., Sustainable Construction Materials in Japan, Proceedings Van Cauterenleerstoel

“Construction Materials and Environment”, 27 November 1996, K.U.Leuven 2. Ohama Y., Handbook of polymer-modified concrete and mortars. Properties and Process

Technology, Noyes Publications 1995 3. Seidler P., Proceedings International Congresses “Industrial floors” 1987, 1991, 1995, 1999,

2003, Ed. P. Seidler, Fraunhofer Verlag, Stuttgart 4. de Longchamps M., Réalités économiques des polymères dans la construction, Proceedings

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14. Van Gemert D., Herroelen B., Schueremans L., Dereymaeker J., Strengthening of wooden structural elements by means of polymer concrete, Proceedings IXth International Congress on Polymers in Concrete ICPIC 98, Bologna, pp. 577-588

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