Sole of Concrete—Mix Proportion - The Issues and Discussion of Modern Concrete Science - page 19

The above are some suggestions and opinions about how to establish mix
proportion principle and theory that is adapted to modern concrete. All in all, since
mix proportion guiding principle and theory of old concrete generated inadapta-
bility in modern concrete environment, mix proportion work has trapped in a status
that it solely relies on individual experience rather than theory and recognized
theory. A vivid analogy can be made to explain it. Supposing we are about to
construct a plain concrete pier with a height of 1.3 m, if requirement and in uence

of such factors as construction technology were not taken into consideration, many
people would be confused about whether adopting stiff concrete or high-

owing

concrete is bene cial to project quality and durability, which was the most

important technical problem we needed to settle down in those years. The author
insists mix proportion is a core question of concrete science. If our mix proportion
work loses the guidance of theoretical principle, concrete science may be degen-
erated at the mode of turning from the past semi-experience and semi-theory to
absolutely relying on experience. Therefore, it is a great task for contemporary
concrete scienti c and technical workers to solve this problem.

A.1 Others

A.1.1 Different Opinions

1. Professor Qian Xiao-qian

One-dimensional attribute of the W/C law refers to that W/C decides paste
strength after hydration when cement property is constant. After cement has been
changed into a cementitious material, their mutual relationship sets up the same if
cementitious material is recognized as cement from macroconception. Two-
dimensional attribute of the W/C law is correlation of hardened paste strength and
concrete strength which is built by and it is a kind of sec-

ondary relationship. In the past, property orientation of cement was relatively simple
and aggregates were relatively single. Therefore, adaptability of empirical coef

“ empirical coef cient, ”

cient
was strong. However, nowadays, current cement, especially cementitious property,
becomes various and aggregates are no longer the aggregates in the paste. Adapt-
ability of empirical coef cient is originally facing with challenge, yet it is very

dif As a result, in a

sense, the W/C law has become a conception although no water reducer is employed.
After adding water reducer, if water reducer supplys pure physical attribute, the
above idea still holds. However, all water reducers, not to mention compound water
reducer like retarding, air-entraining, early-strength type, have their chemical
attribute. Even physical phenomenon of air entraining, adsorption, etc., not only
changes setting and hardening process but also changes

cult to establish a relatively universal “ empirical coef cient. ”

fines performance of paste