Development of Soda Residue Concrete Expansion Agent

A new type of concrete expansion agent has been successfully developed for the first time in the world by utilizing an industrial waste residue soda residue and an industrial wasteliquor.Adding 3%-6% of the agent into Portland cement enables a shrinkage compensating concrete to be prepared.Mortar and concrete containing this expansion agent have better shrinkage compensating and mechanical properties.The raw materials component,production process,technical properties,micro analysis of mortar made with this expansion agent,mechanism of expansion and research results are described in this article.The experimental results show that the new type of concrete expansion agent accords with the standard and its main mineral component is xCaO ySO 3 zAl 2O 3.

NUMERICAL METHOD AND RANDOM ANALYSIS OF CEMENT CONCRETE EXPANSION

The numerical method and random anal- ysis of cement concreteexpansion are given. A mathematical procedure is presented whichincludes the nonlinear charac- teristis of the concrete. Anexpression is presented to pre- dict the linear restrained expansionof expansive concrete bar restrained by a steel rod. The resultsindicate a rapid change in strains and stresses within initial days,after which the change gradually decreases.

Relationship Between Autogenous Deformation and Internal Relative Humidity of High-strength Expansive Concrete

The relationship between autogenous deformation and internal relative humidity（IRH） of high-strength concrete and high-strength expansive concrete were investigated.The experimental results indicate that,there exists a good linear relationship between autogenous shrinkage and IRH of high-strength concrete but a nonlinear relationship between autogenous deformation and IRH of high-strength expansive concrete with expansive agent.The new autogenous deformation curve can be obtained by transforming the autogenous deformation data of high-strength expansive concrete,and there exists linear relationship between the autogenous deformation and IRH.The concept of ＂critical internal relative humidity＂ was proposed,which is defined as the value of IRH when autogenous deformation is zero,to effectively reflect the autogenous deformation characteristic of expansive concrete.

Bearing Behavior of Cast-in-Place Expansive Concrete Pile in Coral Sand Under Vertical Loading

The low side friction of piles in coral sand results in the low bearing capacity of foundations.In this paper,expansive concrete pile is utilized to improve the bearing capacity of pile foundations in coral sand.Both model tests and numerical simulation are performed to reveal the bearing mechanism of expansive concrete pile in coral sand.Results showed that the lateral earth pressure near pile increases obviously and the side friction of piles is improved,after adding expansion agent to the concrete.The horizontal linear expansion is 1.11%and the bearing capacity increased 41%for the pile,when 25%expansion agent is added.Results in finite element numerical simulation also show that ultimate bearing capacity increases with the increase of the linear expansion ratio.Besides,the area for obvious increase in side friction is below the surface of soil about three times the pile diameter,and the expansion leads to a high side friction sharing of the pile.Therefore,the cast-in-place expansive concrete pile is effective in improving the bearing capacity of piles in coral sand.

Expansive Behaviors of Self-stressing Concrete under Different Restraining Conditions

The expansive behaviors of the expensive concrete under different restraining conditions were systemically studied. The experimental results indicate that expansive deformation obviously increases before 10 days and tends to be constant after 25 days regardless of the restraining conditions. The mixture ratio of expansive cement and restraining conditions are the main factors affecting expansive deformation. Self-stress can be obtained when the expansive deformation is restrained. The higher self-stress could be obtained when the expensive concrete is restrained by steel tube. For specimens under steel tube restraining, the wall thickness and the length of the steel tube have important influence on self-stress. Both the radial self-stress and axial self-stress in concrete core increase when wall thickness or length of the steel tube increases.

Study of the Application of Expansive Cement in Building Construction

A China’s construction industry continues to develop,the amount of building construction has increased significantly,and construction technology has been continuously advancing.In particular,the application of expansive cement in building construction is becoming more popular.The correct use of construction technologies can not only speed up the progress of the construction project,but also reduce the project cost significantly.In this paper,the application of expansive cement building construction is discussed in detail,and the solutions of related problems are proposed.