Fitting Function for Flexural Strength of Cement Paste

Tomáš Ficker

doi:10.1088/1757-899x/245/3/032008

Abstract

There are many analytical expressions for compressive strength as functions of porosity of cement-based materials but only a few such expressions exist for flexural strength of these materials. In the present paper a new functional candidate for fitting the data of flexural strength of hydrated Portland cement paste has been tested. The functional candidate has been initially derived for porous polymeric materials on the basis of the percolation theory. The parameters of this function have been optimized for the cement paste by using the Levenberg-Marquardt iterative fitting procedure. The optimized function has been capable of accurate reproducing all the measured flexural data. This fact has been confirmed by a high value of the correlation coefficient and rather low values of statistical uncertainties. It has been shown that this modified fitting function is well applicable to the pastes of ordinary Portland cements and probably to other cementitious materials, too.

Highlights

A detailed study of compressive strength as a function of the irregularities of fracture surfaces of hydrated ordinary Portland cement pastes has been published [1]
The graph drawn by the solid line represents the result of the fitting procedure and illustrates a clear dependence of flexural strength on porosity
All the aforementioned facts lead us to the conclusion that the tested function (1) seems to be a good candidate for fitting flexural data of hydrated cement pastes

Summary

Introduction

A detailed study of compressive strength as a function of the irregularities of fracture surfaces of hydrated ordinary Portland cement pastes has been published [1]. When the flexural (bending) strength as a function of porosity is required, one may find only a very limited number of such expressions [2,3,4,5]. One of those few expressions was derived [2] on the basis of percolation theory for polymeric materials but it might be formally adjusted for cement pastes as well:.

Objectives

Results

Conclusion