Matrix Optimization of Ultra High Performance Concrete for Improving Strength and Durability.

Julio A Paredes,Marcos G Alberti,Alejandro Enfedaque,Jaime C Gálvez

doi:10.3390/ma14226944

Julio A Paredes, Marcos G Alberti + Show 2 more

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https://doi.org/10.3390/ma14226944

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Abstract

This paper seeks to optimize the mechanical and durability properties of ultra-high performance concrete (UHPC). To meet this objective, concrete specimens were manufactured by using 1100 kg/m3 of binder, water/binder ratio 0.20, silica sand and last generation of superplasticizer. Silica fume, metakaolin and two types of nano silica were used for improving the performances of the concrete. Additional mixtures included 13 mm long OL steel fibers. Compressive strength, electrical resistivity, mercury intrusion porosimetry tests, and differential and thermogravimetric thermal analysis were carried out. The binary combination of nano silica and metakaolin, and the ternary combination of nano silica with metakaolin and silica fume, led to the best performances of the UHPC, both mechanical and durable performances.

Highlights

Research developed in recent decades has led significant advances in concrete technology that has enabled a continuous increase of the performances of concrete, mainly based on the improvement of the microstructure
These graphs were elaborated from the cumulative mercury intrusion curves shown in Figure 7b, where the total porosity equivalent to 100% of the volume of mercury intrusion is shown
A minimum porosity percentage of 5.91% was reached in the case of the 4MK4SF + 2NS1 sample, which represents tion of the pores according to their size, expressed as percentages of the total porosity respectively

Summary

Introduction

Research developed in recent decades has led significant advances in concrete technology that has enabled a continuous increase of the performances of concrete, mainly based on the improvement of the microstructure. The demand for concretes with improved performance changes the traditional approach for improving the mechanical properties of concrete. The terms such as high-strength concrete (HSC) and ultra-high strength concrete (UHSC) [1,2] are less used. De Larrard and Naaman used the term ultra-high performance concrete (UHPC) to describe concrete of similar characteristics to that described by Richard, and including the concept of high packing density [4,5,6]

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