请翻译以下内容 INTRODUCTION The routine production of durable concrete pavements has always been a challenging task. Severe environmental conditions, coupled with the routine use of deicing chemicals and increasing traffic volume, tend to place extreme demands on portland cement concrete (PCC) pavements. In most instances, engineers have been able to specify and build PCC pavements that met these challenges. However, there have also been reports of premature deterioration that could not be specifically attributed to a single cause. Such deterioration often appeared to be the result of problems that arose because of plastic concrete problems (mixture incompatibilities) and/or construction practices (construction-related distress or CRD). Modern concrete mixtures have evolved to become very complex chemical systems. The complexity can be attributed to both the number of ingredients used in any given mixture and the various types and sources of the ingredients supplied to any given project. Local environmental conditions can also influence the outcome of paving projects. Hence, research is needed on characterizing basic concrete materials (i.e., uniformity before and after mixing), identifying potential incompatibility problems, and optimizing mixture proportion because these are key issues to increasing the durability of concrete pavements.