0‘quv materiallari (ma’ruza matni)

evaluation of test results and in establishing relationships
is valuable, and often essential, a statistical
relation alone, without a physical explanation,
is not a sound basis for claiming that a true
relation exists between two or more factors. Likewise,
extrapolation of a valid relationship must
not be assumed to be automatically valid. This is
obvious but sometimes forgotten by an enthusiastic
author who is under the impression that he
or she has discovered a general ‘rule’.
Whereas we must consider available research, there is little value in collecting together a mass of research findings or giving a general review of each topic of research. Rather, this book has striven to integrate the various topics so as to show their interdependence in the making and using of concrete. An understanding of the physical and chemical phenomena involved is an essential
basis for tackling the unfamiliar, in contrast to the ad hoc approach for picking up clues from past experience, which will work only so far, and sometimes may result in a catastrophe. Concrete is a patient material but, even so, avoidable flaws in the selection and proportioning of the mix ingredients should be avoided.
It has to be remembered that the various concrete mixes now used are derivatives and developments of the traditional concrete, so that knowledge of the basic properties of concrete continues to be essential. In consequence, a large part of the book is devoted to these fundamentals. The original work of the pioneers of the knowledge of concrete which explains the underlying behaviour of concrete on a scientific basis and the classical references have been retained: they allow us to have a proper perspective of our knowledge.