  The plateau phase in the radio afterglows has been observed in very few
gamma-ray bursts (GRBs), and 27 radio light curves with plateau phase were
acquired from the published literature in this article. We obtain the related
parameters of the radio plateau, such as temporal indexes during the plateau
phase ($\alpha_1$ and $\alpha_2$), break time ($\Tbz$) and the corresponding
radio flux ($F_{\rm b}$). The two parameter Dainotti relation between the break
time of the plateau and the corresponding break luminosity ($\Lbz$) in radio
band is $\Lbz \propto \Tbz^{-1.20\pm0.24}$. Including the isotropic energy
$\Eiso$ and the peak energy $\Epi$, the three parameter correlations for the
radio plateaus are written as $\Lbz \propto \Tbz^{-1.01 \pm 0.24} \Eiso^{0.18
\pm 0.09}$ and $\Lbz \propto \Tbz^{-1.18 \pm 0.27} \Epi^{0.05 \pm 0.28}$,
respectively. The correlations are less consistent with that of X-ray and
optical plateaus, implying that radio plateaus may have a different physical
mechanism. The typical frequencies crossing the observational band may be a
reasonable hypothesis that causes the breaks of the radio afterglows. We
calibrate GRBs empirical luminosity correlations as standard candle for
constraining cosmological parameters, and find that our samples can constrain
the flat $\Lambda$CDM model well, while are not sensitive to non-flat
${\Lambda}$CDM model. By combining GRBs with other probes, such as SN and CMB,
the constraints on cosmological parameters are $\om = 0.297\pm0.006$ for the
flat ${\Lambda}$CDM model and $\om = 0.283\pm0.008$, $\oL = 0.711\pm0.006$ for
the non-flat ${\Lambda}$CDM model, respectively.
