Mechanism Clarification and Knowledge Formation of Unique Behavior of Chemically Prestressed Concrete for Efficient Use of Expansive Concrete
Mechanism Clarification and Knowledge Formation of Unique Behavior of Chemically Prestressed Concrete for Efficient Use of Expansive Concrete
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化学预应力混凝土独特行为的机理阐明和知识形成，以有效利用膨胀混凝土
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发表时间：
2012
期刊：
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通讯作者：
T. Kishi
中科院分区：
文献类型：
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作者：
Y. Sakai;T. Kishi
本文的目的是通过对膨胀混凝土独特性能机理的探讨，了解膨胀混凝土，并提出合适的使用膨胀剂的方法，使普通工程师能够正确地使用它。首先，讨论了膨胀混凝土的非线性机理。通过对水泥石试件断口的观察，证实了水泥石非线性行为的原因之一是由于膨胀作用引起的应变变化引起的微裂纹，因为微裂纹引起塑性变形和刚度降低。不同类型的砾石及其在体积膨胀过程中的应变的实验表明，非线性行为的另一个原因是砾石表面的脱粘。在掺膨胀剂的钢筋水泥浆试件试验中，也证实了钢筋表面的脱粘现象。然而，由于砾石改变了试件中的应变分布，因此使用砾石可以防止钢筋上的剥离。可以说，在化学预应力混凝土中，用碎石和变形钢筋来约束钢筋表面的剥离。在此基础上，指出了使用膨胀剂时应注意的几个问题。
The objectives of this paper are to understand expansive concrete by discussing the mechanism of unique behaviors and to propose appropriate way to use expansive additive so that average engineers can utilize it properly. First, the mechanism of nonlinear behavior of expansive concrete is discussed. From the observations of fracture surface of cement paste specimen, it’s confirmed that one of the causes of the nonlinear behavior is micro cracking due to strain variation introduced by expansive action since micro cracking causes plastic deformation and stiffness reduction. Experiments using different types of gravel and their strain during volumetric expansion indicate that another cause of the nonlinear behavior is the debonding on the gravel surface. Debonding on the rebar surface is also confirmed in the test using reinforced cement paste specimen with expansive additive. The debonding on rebar, however, is prevented by using gravel since gravel changes strain distribution in the specimen. It can be said that using gravel and deformed bar constrain debonding on the rebar surface in chemically prestressed concrete. Based on the above results, some points which should be kept in mind when using expansive additive are pointed out.