This work concerns with the study of coatings to inhibit the ingress of water and also the use of lithium nitrate to modify the swelling properties of the ASR reaction products. In order to accomplish these objectives concrete samples extracted from a Portuguese structure affected by internal expansive reactions were treated with six different coatings and subjected to natural and accelerated environments. In order to study the modifications produced by lithium nitrate in the expansive properties of ASR products, different test conditions were used namely the application of lithium by immersion and electrical migration. In this work we present the results of the application of these treatments namely by the evaluation of the mechanical, physical, microstructural and electrical properties.