Since late 90s, there has been a large investment in web archiving. Accessing these huge information sources is getting more and more attention. Web archive users profiles differ from casual web users profiles. Archive users need to analyze, evaluate and compare the information which requires complex queries with temporal dimension. These queries can not be performed by currently proposed access methods: wayback machine, full-text search and navigation. In this paper, we address this requirement by proposing a data model and a temporal query language for web archives which take into account different topics in web pages and the issues related to web archiving. In our approach, a captured web page is visually segmented into semantic blocks. A concrete block notion is introduced to represent these different semantic blocks. A concrete block is a triplet: frame block which keeps properties of a block, the content (textual and:or non-textual) and the importance accorded to a block. Each of them is times-tamped with a period called validity. A web page, identified with an url, is a set of concrete blocks and a web site is a set of pages. Pages and sites are generated dynamically by manipulating concrete blocks when needed. Operators for data manipulation, navigation and ranking are also proposed.