INORGANIC POLYMER COMPOSITES IN CONCRETE CONSTRUCTION: PROPERTIES, OPPORTUNITIES AND CHALLENGES

Use of high-strength composites in concrete construction is gaining worldwide acceptance. The major application areas are repair and retrofit to improve the performance or correct deficiencies. These composites have very high specific strength and do not corrode. The major disadvantages are the weakness of the resin under high temperature and UV radiation. Recent advances led to the development of high temperature matrices. The results reported in this paper deal with composites made with inorganic polymer that is not only high temperature resistant but also environmental friendly. The water-based system is completely nontoxic. The performance of this adhesive is compared to an organic adhesive for strengthening plain and reinforced concrete beams using carbon fibre sheets. The comparison is made using the experimental results of plain and reinforced concrete beams strengthened with bonded carbon fibre sheets and tested to failure under flexural loading. Strength, failure pattern, and cracking of beams strengthened with the two systems are compared. The results indicate that the inorganic adhesive is as effective in increasing the strength and stiffness of reinforced concrete beams as the organic adhesive. For plain concrete, the behaviours of the two systems are comparable for equivalent fibre volume fraction. The inorganic matrix has a tensile strain capacity of only 0.07%, whereas the organic matrix has a strain capacity of about 4.8%. The brittleness of the inorganic matrix results in crack formation in the composite and a minimum build-up of strain along the interface of the composite and concrete. This phenomenon leads to failure of the composite by rupture of the carbon sheets instead of delamination, which occurs in most of the organic matrix repaired beams. Based on the results available so far, the inorganic matrix composite can be used in standard repairs of reinforced and prestressed concrete structures. The challenge is to create field workable system that can compete with the inorganic systems.

• ABSTRACT

• INTRODUCTION

• PROPERTIES OF THE INORGANIC MATRIX – FIBRE COMPOSITES

• REVIEW OF REINFORCED CONCRETE BEAMS STRENGTHENED WITH CARBON SHEETS AND ORGANIC POLYMERS

• REVIEW OF PLAIN CONCRETE STRENGTHENED WITH ORGANIC POLYMERS

• RESEARCH PROGRAMME

• EXPERIMENTAL INVESTIGATION: STRENGTH TESTS

• STRENGTHENING PROCEDURE

• RESULTS AND DISCUSSION: REINFORCED CONCRETE

• LOAD-DEFLECTION BEHAVIOUR

• COMPARISON OF STRENGTH INCREASE

• COMPARISON OF STRESSES AND STRAINS

• TEST RESULTS AND DISCUSSION: PLAIN CONCRETE

• FAILURE PATTERN

• LOAD-DEFLECTION BEHAVIOUR

• INCREASE IN FAILURE LOADS

• EXPERIMENTAL PROGRAM: DURABILITY TESTS

• TEST RESULTS AND DISCUSSION: WET-DRY EXPOSURE

• TEST RESULTS AND DISCUSSION: SCALING EXPOSURE

• OPPORTUNITIES AND CHALLENGES

• CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES