Autogenous Dilatancy
Model of MgO Concrete Based on the Degree of Hydration
Xiangli HE1, Yuefeng
MA2
1College of Water
Conservancy & Civil Engineering, China Agriculture Univ., Beijing, 100083, China,
E-mail: hxl0806@cau.edu.cn
2 Investment Assessment
Center of Treasury Department,
Abstract: Volume expansion would generate
when MgO hydrates, and the crack of concrete could be prevented when MgO is
mixed properly in concrete. With certain amount and mix method of MgO in
concrete, the autogenous dilatancy of MgO concrete is related with concrete
age, as well as temperature and temperature history of concrete. Essentially, similar
with the hydration of cement in concrete, the autogenous dilatancy of MgO
concrete develops synchronously with the hydration of MgO in concrete. The more
the hydration of MgO develops, the larger the autogenous dilatancy of MgO
concrete gets. So the autogenous dilatancy of MgO concrete is essentially related
with the degree of hydration of MgO in concrete, and the influence of
temperature and temperature history to autogenous dilatancy is just the externalization
of the influence of temperature and temperature history to hydration of MgO. Some
of the previous models cannot satisfy the general rule of autogenous dilatancy
characteristic of MgO concrete, others merely explain the influence of
temperature and temperature history to autogenous dilatancy and cannot describe
the essence[4-6]. With the presentation of the autogeneous
dilatiancy characteristic of MgO concrete, this article borrows ideas from the concept
of equivalent age and degree of hydration[7], and establishes the
new autogenous dilatancy model of MgO concrete which bases on the degree of
hydration of MgO in concrete. In this model, the antogenous dilatancy of MgO
concrete is treated as the function of degree of hydration and equivalent age,
and the influence of degree of hydration to the autogenous dilatancy of MgO
concrete is considered properly. So the physical chemistry background of this
model is definite. This model describes the autogenous dilatancy characteristic
of MgO concrete of different temperature and different temperature history with
one simple formula, and it is easy to treat in mathematics and digital program.
In this article, the test data and calculation case are used to certificate the
new model, result (Fig.1 and Fig.2) shows that, this model can not only satisfy
the general rule of the autogenous dilatancy characteristic of MgO concrete but
also have much higher compatibility to the test data. Compared with other
models, this model has much superiority, and it is quite valuable for theory
research and digital simulation of autogeneous dilatancy of MgO concrete.
Keywords: MgO; autogeneous dilatancy; equivalent age;
degree of hydration
Fig.1 Fitted
result of model to test data
Fig.2 Calculation
case of temperature and deformation of different points in dam