This paper studies activity cycle diagrams (ACD) for modeling construction processes using activities as the basic elements. An ACD is obtained by combining the activity cycles of all involving resources. Two basic symbols are introduced to graphically represent the activity cycle of a resource with incorporating resource requirements into individual activities. Then the activity cycle based modeling (ACBM) method is studied to translate the ACD statements of a process into an equivalent executable SLAM II simulation model. The translation can be automated by implementing the generalized rules into a computer system. This approach simplifies the modeling task for a construction process into defining an activity cycle diagram, which is much easier than directly constructing a simulation model. A concreting process example is used to illustrate the method.