Partially S9t concretes are the concretes left exposed idle till the time of casting. These concretes are neither fully fresh nor fully dead, but are in between these two. Even to day no information about the systematic study on the behaviour of partially set concretes is available in published literature or elsewhere. The experience gained from the extensive pioneering works of the author for over three decades or so in this area on varieties of concretes, led the author to formulate the technical theory, and propose an altogether new concept namely, Selfing and Crossing, which forms the subject matter dealt elaborately and vividly in this present book. The concept of Selfing and Crossing along with several illustrations of practical importance has been explained first, which is followed by categorization and definitions of various types of Selfing and Crossing. The efficiency and usefulness of the proposed Selfing and Crossing formulations have been demonstrated on a large variety of practical field problems providing step by step calculation procedure in details with suitable explanations and remarks. The book ends with Critical Remarks on various phases and items along with hints of probable scope for future extension for which an Appendix on Spring Function has been added. This book will be of great help to the students of UG, PG and research scholars of Civil engineering.