关键词: 静态屈服应力;黏弹性;恒定剪切速率;应力松弛;蠕变

Abstract: The static shear rate, stress relaxation and creep tests were carried out by using rotational viscometer to investigate the static yield stress and viscoelasticity of cement paste.The results show that the fresh cement paste is a viscoelastic fluid with yield stress, and its static yield stress is the shear stress corresponding to the transformation of elasticity to viscosity;Yield stress and viscoelasticity of paste can be measured by the constant shear rate, stress relaxation and creep.In the constant shear rate test, the yield stress test of the fresh cement paste depends on the choice of the shear rate during the test, the cement slurry does not exhibit static yield stress when the shear rate is too low, and the static yield stress is small when the shear rate is too high;in the stress relaxation and creep tests, the measured static yield stress of the cement paste is more accurate than the constant shear rate test.For fresh cement paste with its static yield stress unknown, it''s better to select the shear rate and the shear stress range roughly through a constant shear rate test and then accurately test the static yield stress by stress relaxation or creep test.

Key words: static yield stress;viscoelasticity;constant shear stress;stress relaxation;creep