Cost-Effective High-Performance Concrete: Experimental Analysis on Shrinkage.

Barbara Kucharczyková,Petr Daněk,Dalibor Kocáb,Ivailo Terzijski

doi:10.3390/ma12172730

Abstract

This paper focuses on the experimental determination of the shrinkage process in Self-Compacting High-Performance Concrete (SCC HPC) exposed to dry air and autogenous conditions. Special molds with dimensions of 100 mm × 60 mm × 1000 mm and 50 mm × 50 mm × 300 mm equipped with one movable head are used for the measurement. The main aim of this study is to compare the shrinkage curves of SCC HPC, which were obtained by using different measurement devices and for specimens of different sizes. In addition, two different times t0 are considered for the data evaluation to investigate the influence of this factor on the absolute value of shrinkage. In the first case, t0 is the time of the start of measurement, in the second case, t0 is the setting time. The early-shrinkage (48 h) is continuously measured using inductive sensors leant against the movable head and with strain gauges embedded inside the test specimen. To monitor the long term shrinkage, the specimens are equipped with special markers, embedded into the specimens’ upper surface or ends. These markers serve as measurement bases for the measurement using mechanical strain gauges. The test specimens are demolded after 48 h and the long term shrinkage is monitored using the embedded strain gauges (inside the specimens) and mechanical strain gauges that are placed, in regular intervals, onto the markers embedded into the specimens’ surface or ends. The results show that both types of measurement equipment give a similar result in the case of early age measurement, especially for the specimens cured under autogenous conditions. However, the early age and especially long term measurement are influenced by the position of the measurement sensors, particularly in the case of specimens cured under dry air conditions. It was proven that the time t0 have a fundamental influence on the final values of the shrinkage of investigated SCC HPC and have a significant impact on the conclusions on the size effect.

Highlights

The definition of High-Performance Concrete (HPC) and Ultra-High-Performance Concrete (UHPC) is developing along with the development of the properties of these materials
The results show a gradual increase in shrinkage values after demolding of both testing sets
The paper presents the results of the experimental analysis focused on the determination of the shrinkage process using two different types of measurement techniques—sensors embedded in the core and into the upper surface of the specimens

Summary

Introduction

The definition of High-Performance Concrete (HPC) and Ultra-High-Performance Concrete (UHPC) is developing along with the development of the properties of these materials. The subsequent development of the HPC resulting from the rising demands for the strength and durability of the concrete structures led to the establishment of the new term, UHPC, with the aim to distinguish these two materials. There are no unified standards for the design of composition of both HPC and UHPC throughout the world because of various raw materials available in particular countries, which lead to the individual design of HPC and UHPC for the specific application. This fact is one of the factors which affect the costs of the construction.

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Discussion

Conclusion