Recent Status of Research and Development of Concrete-Polymer Composites

Recent Status of Research and Development of Concrete-Polymer Composites

Reena Sehgal1, Sonu Chhikara2, Nitish Malik3, Heeralal4

1,2,3Department of Civil Engineering, Ganga Institute of Technology and Management, Kablana, Jhajjar, Haryana, India

4Department of Civil Engineering, CBS Group of Institution, Jhajjar, Haryana, India

Abstract- The present paper reviews the recent status of research and development activities of concrete-polymer composites such as polymer-modified concrete (mortar), polymer concrete (mortar) and polymer-impregnated concrete (mortar) in the Japanese construction industry. Polymer-modified concrete (mortar) comprise of repair systems for deteriorated reinforced concrete structures, strengthening (or retrofitting) methods and exfoliation (or delamination) prevention methods for existing reinforced concrete structures, liquid-applied membrane waterproofing systems, advanced polymeric admixtures such as high-grade redispersible polymer powders and hardener-free epoxy resins, intelligent repair materials, application of accelerated curing, semi flexible pavements, and drainage pavements with photo catalyst. Polymer mortar and concrete are related to new liquid resins, setting shrinkage control, thermal properties and temperature dependence, lightweight or porous polymer mortars and concretes, artificial marble products and precast products. The polymer-impregnated mortar and concrete are mainly concerned with field polymer impregnation techniques using silane-based barrier penetrants.

Keywords: Concrete-polymer composites; polymer-modified concrete (mortar); polymer

concrete (mortar); polymer-impregnated concrete (mortar); research and development

1. INTRODUCTION

   For the past five decades, Japan has actively researched polymer-modified concrete (mortar), polymer concrete (mortar) and polymer-impregnated concrete (mortar), and currently used as popular construction materials because of comparative high performance, multifunctionality and sustainability compared to conventional cement mortar and concrete [1-4]. Concrete-polymer composites are environment-conscious or sustainable construction materials, and confirm to concerns of saving of natural resources, the longevity of infrastructures and the environmental protection. This paper reviews recent research and development activities of the concrete- polymer composites in the Japanese construction industry.

2. GENERAL TRENDS IN RESEARCH AND DEVELOPMENT ACTIVITIES IN POLYMER-

   MODIFIED CONCRETE (MORTAR)

   Presently popular polymeric admixtures are polymer dispersions: styrene-butadiene rubber (SBR) latex, poly(ethylene-vinyl acetate) (EVA) and polyacrylic ester (PAE) emulsions, and redispersible polymer powders: poly (vinyl acetate-vinyl versatate-acrylic ester)(VA/VeoVa/AE), poly(ethylenevinyl acetate) (EVA) and poly(vinyl acetate-vinyl versatate) (VA/VeoVa) powders.

   1. Repair systems for deteriorated reinforced concrete structures

      Longevity of infrastructures is crucial in the development of effective repair materials and their execution systems. Repair materials for the deteriorated reinforced concrete structures include impregnants for concrete quality modification and improvement, corrosion-inhibiting coating materials for reinforcing bars, patch materials, surface preparation materials, coating materials for finish and protection, and grouts for concrete cracks.

   2. Strengthening (retrofitting) of existing reinforced concrete structures

      Recently, slabs and beams (or girders) have often been strengthened with overlays to increase their thickness (or depth) by the troweling or shortcreting work of polymer- modified mortars on the bottom surfaces. Existing reinforced concrete columns and shear walls have also recently been retrofitted with the troweling or shortcreting work of polymer-modified mortars for seismic strengthening methods.

   3. Adhesives (bonding) agents for exfoliation (delamination) prevention methods

      New exfoliation (or delamination) prevention methods using polymer-modified mortars and pastes for adhesives or bonding agents with vinylon, aramid, polyethylene and alkali-resistant glass fiber sheets are adopted due to its easy application to wet concrete substrates.

   4. Liquid-applied membrane waterproofing systems

      Generally, polymer-modified mortars or slurries for the polymer-modified cement membrane waterproofing systems are prepared at polymer-cement ratios of 20 to

      300% by using PAE and EVA emulsions, and have tensile strengths of 0.7 to 8.0MPa, elongations of 25 to 400% and adhesions to the concrete substrates of 0.75 to 2.8MPa as waterproofing membranes.

   5. High-grade redispersible polymer powders

   In the manufacture of polymer-modified mortar products, replacement of polymer dispersions by the high-grade redispersible polymer powders, i.e., the change of two- packaged systems to onepackaged systems is promoted in Japan. Commercial high-grade redispersible polymer powders are EVA, PAE, poly(styrene-acrylic ester)(SAE), VA/VeoVa and VA/VeoVa/AE powders.

3. INTELLIGENT REPAIR MATERIALS

   1. Hardener-free epoxy-modified mortars with auto- healing or self-repairing function

      Recent research attests that even without any hardeners the epoxy resin can harden in the presence of the alkalis or hydroxide ions produced by the hydration of cement in the epoxy-modified mortars as expressed by the following formula:

      Such hardener-free epoxy-modified mortars and concretes have an auto-healing or self-repairing function for the micro cracks, and may be intelligent materials as shown in Figure 1.

      Figure 1 Simplified model for autohealing mechanism of microcrackes in epoxy- modified cementitious systems.

   2. Polymer-modified mortars with nitrite-type hydrocalumite

   Nitrite-typehydrocalumite: [3CaOAl2O3Ca(NO2)2H2O (n=11~12)] is a corrosion-inhibiting admixture or anticorrosive admixture which can adsorb the chloride ions (Cl-) causing the corrosion of reinforcing bars and liberate

   the nitrite ions(NO2 -) inhibiting the corrosion as expressed by the following formula:

   3CaOAl2O3Ca(NO2)2 nH2O +

   2Cl 3CaOAl2O3CaCl2 nH2O+2NO2

   It provides excellent corrosion-inhibiting property to the reinforcing bars in reinforced concrete.

   Polymer-modified mortars using polymer dispersions and redispersible polymer powders with the nitrite-type hydrocalumite (calumite) have \ superior corrosion- inhibiting property and durability.

4. APPLICATIONS OF ACCELERATED CURING

   The autoclave curing can be applied to SBR-modified concretes using slag for precast products. The feasibility study to examine hardener-free epoxy resin as a polymeric admixture for the accelerated curing of cement concrete shows that the application of a 120ºC-autoclave curing or 90 ºC steam curing plus 120 ºC heat curing to hardener- free epoxy-modified mortars with polymer-cement ratios of

   10 to 20% develops about twice to three times higher flexural strength and about twice higher compressive strength than unmodified mortar (ordinary cement mortar).

5. PAVEMENT APPLICATIONS

   Semi flexible pavements are executed by grouting the voids of open-graded asphalt concretes with polymer- modified pastes or slurries. The pavements are applied to heavy traffic roads, intersection pavements, bus stops, parking lots and airport runways because of their excellent rutting resistance, load spreadability, abrasion resistance, oil resistance and colorability.

6. RECENT RESEARCH ND DEVELOPMENT ACTIVITIES IN POLYMER CONCRETE (MORTAR)

   Widely used liquid resins include thermosetting resins like unsaturated polyester (UP) resin (i.e., polyester-styrene system), epoxy (EP) resin, vinyl ester (VE) resin and polyurethane (PUR), tarmodified resins and acrylic resins such as polymethyl methacrylate (PMMA) and glycerol

   methacrylate-styrene. Recently, new polymer concrete and mortar using waste expanded polystyrene (EPS) solution- based binders have been developed as an effective recycling method of EPS in Japan. Table 1 shows the Applications of polyester concrete in Japan.

   1. New liquid resins

      Ecologically safe EP and UP resins with low styrene contents of 30% or less for polymer mortars and concretes, and low-odor methacrylate binders for floor coatings and

      linings are developed for environment-conscious materials selection.

   2. Setting shrinkage control

      Low-shrinkage UP resins without any shrinkage-reducing or low-profile agents are developed for UP concretes, and PMMA concretes with low setting shrinkage are made by the combined use of a polymeric surfactant, steel fibers and vinylon fibers.

   3. Thermal properties and temperature dependence

      The thermal properties and temperature dependence of mechanical properties being most important properties for the structural uses of polymer concretes are examined for UP and EP concretes.

   4. Lightweight or porous polymer mortars and concretes

      Ultra lightweight, lightweight or ultra-lightweight porous EP concretes are produced by a prepacked concrete method, and porous acrylic concretes for drainage pavement are developed.

   5. Artificial marble products

   Recently demand for polymeric artificial marble products using polymer pastes with flameretarding fillers such as aluminium hydroxide and magnesium hydroxide has gradually increased. The three largest markets of the artificial marble products are washstand and systematized kitchen

   and baths fields.

7. RECENT RESEARCH AND DEVELOPMENT ACTIVITIES IN POLYMER-IMPREGNATED

   CONCRETE (MORTAR)

   Currently, polymer-impregnated concrete (mortar) are rarely used as construction materials because of high processing cost and cumbersomeness of manufacturing and application process despite of their excellent performance.

8. STANDARDIZATION WORK

   Recently the wide application of polymer-modified mortar and concrete, and polymer mortar and concrete has brought forward the standardization of test methods and their quality requirements.

9. CONCLUSIONS

Recently, environment-conscious concrete-polymer composites are arduously developed for sustainable development in the construction industry. Many national and institutional standards for them have been published in Japan. The concrete-polymer composites with high performance,

multifunctionality and sustainability are expected to become the promising construction materials in Japan in the 21st century.

TABLE 1.

APPLICATIONS OF POLYESTER CONCRETE

REFERENCES

1. Ohama, Y., Recent Research and Development of Trends of Concrete- Polymer Composites in Japan, Proceedings of 12th International Congress on Polymers in Concrete, Volume I, Chuncheon, Korea, Sept. 2007, pp.37-45.

2. Dr. M. Aamer Rafique Bhutta and Dr. Yoshihiko Ohama, Status of the Recent Research and Development of Concrete-Polymer Composites in Japan, Proceedings of the International Workshop on Cement Based Materials & Civil Infrastructure (CBM-CI), NED Engineering University, Karachi, Pakistan, Dec. 2007, pp. 289-294.

3. Ohama, Y., (Recent Trends in Research and Development of Polymer- Modified Mortar and Concrete in Japan.) Proceedings of the 5th Asian Symposium on Polymers in Concrete, Volume I, Structural Engineering Research Centre, CSIR Campus, Chenai, India, 2006, pp.3-11.

4. Ohama, Y., (Recent Trends in Research and Development in Polymer Mortar and Concrete in Japan) in Proceedings of 6th International Symposium on Cement & Concrete, Contributing to Global Sustainability, Volume 3, XIAN, China, (2006), pp.1651-1655.

AUTHOR PROFILE

Reena Sehgal B.Tech., M. Tech. Scholar in Civil Engineering (Structural Design) from Ganga Institute of Technology and Management, Kablana, Jhajjar, Haryana (India) affiliated to Maharshi Dayanand University, Rohtak, Haryana (India).