Page 406 - Handbook of Thermal Analysis of Construction Materials

384 Chapter 9 - Non-Portland Cement Binders and Concrete

with a more clearly defined crystalline morphology were present when the
water content exceeded 8%. The result was a greater amount of unreacted
water that produced on evaporation a finer pore structure and a significant
degradation of the mechanical properties. These characteristics (at higher
water content) were also found by Abdelrazig, et al., who observed that at
lower water contents struvite morphology was needle-like while schertelite
had a platey morphology. [67] The morphology at low water contents was
considered a contributing factor for maximizing strength.

Figure 10. Young’s modulus as a function of water content, measured at various aging
times. [63]

(a) (b)
Figure 11. Flexural and compressive strength as a function of water content measured after
7 days aging. [63]