Advances in adhesion between polymers and concrete

Abstract

The adhesion between polymers and concrete is complex and needs to be studied with adequate methods. One problem is about the best test to determine adhesion strength. The use of traditional tests like direct tension, flexure or shear, normally does not enable the correct determination of the adhesion strength. If the adhesive is good and the substrate’s surfaces are well prepared, the failure is in the substrate. With this kind of faitures it is possible to say that adhesion strength is higher than the failure stress. It is not possible to give a numerical value of adhesion strength. A test based on fracture mechanics makes the determination of adhesion strength easier. The use of a notched specimen concentrates the stresses in the poliymer/substrate joint and adhesive failures are more frequent. With adhesive failures, it is possibie to determine the numerical value of the adhesion strength. The results’ analysis of adhesion tests needs to be made using appropriate methods. The presentation of the results is made in accordance with a square optimisation method where the adhesion in tension and the failure mode are taken into consideration. The use of this method is exemplified with results of adhesion tests for concrete/epoxies resins. The incorporation of fillers into the epoxies enabies a good adhesion even when Lhe concrete is wet. Tension tests were made to study the influence of the type, the granulometry and the quantity of the filler on the behaviour of the bonds.