High-Performance Concrete, Really High Performance? - The Issues and Discussion of Modern Concrete Science - page 164

In the above discussion, except for the disputable viewpoint that water-reducing
agent increases volume shrinkage, the author has adopted standpoints that are well
recognized by current academia about the other questions.
It can be concluded form the above discussion that the most notable advantage of
HPC is facilitating construction and reducing labor intensity of workers, while the
disadvantages are poor volume stability and increasing possibility of creating crack
and so on.
A conclusion can also be draw form discussion in Chap. 9 of this topic that
property of resistance to drying shrinkage of HPC is weaker than that of OPC.
Meanwhile, it can also be concluded from Chap. 5 that resistance to frost and per-
meability of HPC is poorer than that of OPC. Beyond that, as high-strength grade
cement and early strength cement are commonly employed in HPC, self-healing
ability of concrete is weakened; as possessing relatively higher 28-day strength,
concrete creep can be decreased (creep is an important factor of reducing crack as for
non-prestress concrete).
The above conclusion may be different or contrary to viewpoint of most scholars.

13.2 Comparison of Application Effect During Practical
Engineering

All in all, volume stability of HPC is poor, and possibility of creating crack basing is
increased on the above analysis [ 4 ]. HPC has been applied in China for nearly 20
years, and crack problem is getting serious and serious, which has become

cancer.

”
This also fully proves that practical engineering is consistent with theoretical
analysis. Figure 11.1 shows a landmark project of a provincial capital which has
won China Luban Prize. The

“

floor slab, which was built by C40 HPC, has leaked
water so seriously from top to bottom under effect of continuous rain for three days
at construction site. The whole

Can
you believe it can still afford load of structure? The author thinks it has no practical
strength already, how can durability be talked about? It can be surely said that such
situation is a common phenomenon all over the country under construction envi-
ronment of HPC.
HPC owns characteristics of high shrinkage, many cracks, good workability,
facilitating construction, decreasing labor intensity drastically, and speeding up
project progress, but with a poor durability. HPC is a kind of concrete with the
poorest durability, which is a distinctive academic viewpoint of the author.
However, the reason why HPC has become the most widely adopted and popular
concrete variety, except for overmuch praises on its advantages by many experts
and scholars, main reason may be the following aspects.
1. Decreasing labor strength, meeting the demand of project progress and mech-
anization and commercialization. In the past, concrete was mainly transported
by tower crane when building a building, the speed of which is slow and labor

floor slab has become small bean curd chunk.

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