Admixtures: All Medicines Have Their Own Side Effects - The Issues and Discussion of Modern Concrete Science - page 122

10.2 Serious Quality Accident Cause by Improper
Chemical Admixture Dosage

The above are negative effect of admixture on concrete in condition of proper
dosage at the same time, which we should pay attention to when employing it. We
should try to let admixture play positive effect and keep negative effect in con-
trollable range as much as possible. Therefore, the biggest using principle of
admixture is a proper dosage. If improper, especially excessive, the negative effect
may outweigh positive effect, which may cause quality problem even result in scrap
of the whole project. Several examples will be listed by the author to explain it in
the following.

10.2.1 Water Reducer

Over dosage of water reducer will increase cracking, resulting in serious quality
problem and also direct scrap of individual project.
Figure 10.1 is photograph of an airport parking apron. Owning to massive
shrinkage crack caused by an over dosage of water reducer, the project was

scrapped finally.

Fig. 10.1 Crack phenomenon of an airport parking apron