Page 46 - MSAM-1-3

Materials Science in Additive Manufacturing Optimization of chemical admixtures for 3DCP

viscosity, and thixotropy cannot be further improved by it has a negative influence on the static yield stress. The
adopting other curve fitting methods. interaction of accelerator and superplasticizer (BC) has a
To exclude the run order effects from various statistical positive influence on the yield stress, whereas it possesses
rheological models, the relation between the residual and a negative influence on the plastic viscosity and thixotropy.
run order should be confirmed . Figure 8 shows that the The derived models for static/dynamic yield stress,
[27]
points scatter randomly (no grouping) with the run order, plastic viscosity, and thixotropy with respect to the three
which indicates that run order has no significant impact main factors and their second-order effects can be written
on the responses. as follows:

4.2. Prediction models Static yield stress 829 17189. . A 8027. B
The coefficients of prediction models are presented in 125 5. C 8719. AB 48.889AC 17 24BC. (VIII)
Table 6. A positive value indicates a positive effect on the Dynamic yield stress 166 81856. . A 8 640. B
response, while a negative value implies a negative effect
on the response. The magnitude of the absolute value 10 35. C 11 83. AB 1.4400AC 3 560BC. (IX)
represents how significant the factor is and can be used Plastic viscosity 20 91. 1 650. A 1 010. B
to rank the importance of each factor. Results in Table 6 (X)
suggest that with an increase in the dosage of retarder 0 3685. C 0 0360. AB 17. 000AC 2 230BC.
and superplasticizer, all these rheological parameters Thixotropy 17369 2550A 1357B 725 9C.

decrease while accelerator possesses the opposite influence 262 1AB. 1219AC 244 5BC. (XI)
on the rheological properties. The interaction of retarder
and accelerator (AB) has a negative influence on all the The statistical analysis, as shown in Table 6, was
rheological properties. The interaction of retarder and also conducted to estimate the statistical accuracy of
superplasticizer (AC) possesses a positive influence on the established models. High R-squared value (larger than

dynamic yield stress, plastic viscosity, and thixotropy, while 0.8) and high adequate precision (larger than 4) indicate
A B

C D

Figure 7. Normal probability plots of residuals for different responses: (A) Static yield stress; (B) dynamic yield stress; (C) plastic viscosity; and (D)
thixotropy.

Volume 1 Issue 3 (2022) 7 https://doi.org/10.18063/msam.v1i3.16