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curing of SAP 3 is wider than the rest, which can
reduce the capillary force of concrete effectively.
Accoring to the datas at the seventh day, it can
be found that SAP 3-0.167% obtains the best
shrinkage property again, immediately followed by
the SAP 1, SAP 2, SAP 3-0.137% and SAP 3-
0.197%. These results can be explained that
inadequately extra water (SAP 3-0.137%) could not
reduce the capillary force and shrinkage strain, and
excessively extra water is unnecessary for the curing
process, which always accompanied with a side
effect.
3.3 Microcosmic Mechanism
SEM measurements were performed to identify the
microcosmic mechanism of the concretes cured by
SAPs. As exhibited in Figure 6, the hydration
products are highly crystalline into the remained
pore of SAP, together with the shrivelled SAP.
Furthermore, the shape of the pore is sphere, which
can also plays a air entraining role and optimizes the
pore strctucture on the cement concrete.
Next, the release of extra water adsord by SAP
can accelerate the hydration process of cement
concrete, enhancing the degree of compactness and
flexural strength.
Figure 6: Microstructure of the concrete cured by SAP.
4 CONCLUSIONS
The mechanical strength and shrinkage strain of
cement concretes with and without SAP were
investigated using flexural strength test and
displacement sensor, respectively. On this basis,
reinforcement mechanisms of SAP were revealed by
using SEM.
Based on the results presented in this paper, the
following concluding remarks can be drawn:
(1) SAP 3 with appropriate amount of extra
water obtained an excellent flexural strength and
shrinkage property in 7 days.
(2) Inadequately extra water would decrease the
curing effect while excessively extra water may
increase the effective w/c, reducing the concrete
strength.
(3) An appropriate water-release speeds of SAP
for at least 7 days was imperative.
(4) A large number of hydration products were
generated and grouped around the remained pores of
SAP, which could enhance the hydration degree and
improve the compactness of cement concretes.
ACKNOWLEDGEMENTS
The authors would like to acknowledge the financial
supports from the Fundamental Research Funds for
Central Universities (No. 310821175014) of
Chang’an University and the Nation Science
Foundation Project (51778061). Special thanks are
expressed to Dr. Xiaolong Sun for his assistance
with the experimental and data analysis works.
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