Modelagem hidro-mecÃnica de estruturas de concreto afetada pela reaÃÃo Ãlcali-agregado

AUTOR(ES)

Luciano de Oliveira Nobrega

DATA DE PUBLICAÇÃO

2008

RESUMO

Some structures of concrete in direct contact with the humidity, that have been executed with the use of potentially reactive aggregate and alkali text cement high, are affected to the alkali-aggregate development of reactions (RAA). The development of these reactions leads to the formation of a gel that in the water presence expands exerting pressure in the solid matrix of the concrete, causing fissurations and displacements undesirable. The present work shows the results of the implementation in a program of finite elements of a based constituent model in experimental comments that the expansion of concrete subject to RAA catches. In this model the parameters that determine speed of formation of the amorphous gel and the amount of water absorbed for the gel are dependents of the degree of wet of the concrete, considered here as a not saturated porous way. Thus, the equations of the mechanical problem (balance of tensions) must simultaneously be decided with the equations of water flow in the concrete, becoming necessary the solution of the connected problem hydro-mechanical (HM). Specific constituent equations for the concrete had been implemented (arched of relative saturation and permeabilities to the water and air). Initially triaxials assays with the objective had been shaped to illustrate the functioning of the model and if to make familiar to its parameters. In these examples the concrete is saturated with similar mechanical characteristics to the used ones in existing structures. Later a case of wall of support in conditions of changeable humidity with induction of distinguishing expanses in the concrete mass is presented. A parametric variation showed a sensitivity of the model to the porosity, to the times of development of the reactions, time of water absorption and relation of concentration of the gel of form to calibrate in gotten easy and efficient way a modeling on the basis of given in laboratory

ASSUNTO(S)

engenharia civil alkali-aggregate reaction modeling reaÃÃo Ãlcali-agregado concreto concrete modelagem

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