Experimental and numerical creep assessment of fine sand concrete

Abstract

The aim of the present work is to assess the creep of fine sand concrete (FSC) on the bases of sustained bending loads applied on fine sand concrete beams. For comparison purposes, a numerical assessment of creep is also carried out using ANSYS© software. For the experimental creep investigation, four different fine sand concretes were formulated and used to manufacture four reinforced concrete beams respectively, which were then subjected to uniformly distributed bending loads for thirteen months. The experimental analysis focused on the development of creep through the monitoring of long-term deformations and long-term deflections under the sustained bending loads. Factors influencing creep, such as the water/cement ratio, the concrete strength and the fine filler additives, were considered as variables in the testing programme. For the numerical analysis, a non-linear finite element analysis (NLFEA) was carried out to predict the long-term deformations and compare them with the experimental values. The experimental results showed that creep is more pronounced in concrete mixes having higher amount of mixing water, but is reduced in mixes containing plasticizing admixtures such as superplasticizers. The use of fine mineral additives in the form of limestone fillers seemed to result in a denser internal structure of concrete and a reduced pore spaces and hence helped to reduce the creep of concrete. In this sense, an increased strength of concrete also leads to a reduced pore spaces and a denser internal structure of concrete and hence results in a reduced creep. Creep coefficients were worked out for the present fine sand concretes and were found somehow in line with those recommended by some design codes considered in this work. Creep coefficients often lead to realistic long-term deflections of RC members. A comparison between the experimental results and those from the numerical analysis, shows that it is possible to predict fairly accurately the long-term creep deformations using the time-hardening model and the implicit creep method given in the NLFE method of ANSYS© software.