Modelling of freezing and thawing effect on the deflections of RC beams made of recycling aggregate concrete

Abstract

Concrete resistance to cyclic freezing and thawing is typically controlled on the samples in an unloading state. Very few experimental tests have been only conducted on the concrete samples subjected to combined static load and frost effects. An experimental program was undertaken by the research team of Bialystok University of Technology to study the behaviour of structural members made of recycling aggregate concrete (RAC) subjected to long term static load and freezing and thawing cycles. In the paper the authors describe an innovative testing procedure for RC model beams made of RAC under constant bending moment and cyclic freezing and thawing. The aim of such studies was to clarify the effects of interaction of climatic and mechanical load on the deformability and cracking state of RC beams made of recycling aggregate concrete. The beams located in the climatic chamber have achieved over doubled defl ection values in comparison with analogical beams loaded in room temperature. The tests made on an innovative beams made of recycled aggregate concrete with an insert of high strength concrete showed signifi cantly increased RC beam’s stiffness, reducing their defl ections by over 30%. The results of current, as well as further planned research will let us develop the guidelines for using recyclable materials in concrete structural elements. Both adopted technical solutions and research procedure, as entirely innovative designs, were enclosed in submission to the patent register.