Effect of boron-containing aggregates on setting and hardening of Portland cement mortars

Aneta Antolik,Michał A Glinicki,Marek Gawlicki,I Hager,T Tracz

doi:10.1051/matecconf/201816304003

Abstract

Multicomponent cement-based composites are known as versatile structural materials for enhanced radiation shielding. The use of selected elements, like boron, cadmium, or rare earth elements, provides an increased neutron shielding capacity. Because of profusion, reasonable costs and large cross-section for neutron capture, boron containing minerals are suggested as aggregates for radiation shielding concrete. Despite many advantages, boron additives may act as cement setting retarders. Uncontrolled setting and hardening is not acceptable in radiation shielding concrete technology. In this work we present results from isothermal calorimetry measurements on cement mortars with boron-containing aggregates. Four types of boron aggregates were used in the studies: colemanite, ulexite, borax and boron carbide. Based on calorimetric curves, the beginning of setting time was determined. Additionally early mortar strength was investigated and linear relationship between the heat generated in the isothermal calorimeter and the early compressive strength has been observed. The use of isothermal calorimetry allowed us to estimate the limits for the content of boron compounds to be used cement mortar.

Highlights

Due to the continuous development of nuclear power and the use of neutron radiation, new solutions for shielding are needed
Reasonable costs and large cross-section for neutron capture, boron containing minerals are suggested [6] as beneficial aggregates for radiation shielding concrete
Boron has a lot of advantages in radiological protection, e.g. high thermal neutron absorption cross section, does not emit highly penetrating gamma radiation

Summary

Introduction

Due to the continuous development of nuclear power and the use of neutron radiation, new solutions for shielding are needed. Particular elements, like hydrogen, boron, cadmium, or gadolinium, are known to exhibit outstanding neutron shielding capacity [1,2,3]. Such elements, preferably in a form of abundant minerals, could be used as fillers or aggregates in radiation shielding concrete [4, 5]. Reasonable costs and large cross-section for neutron capture, boron containing minerals are suggested [6] as beneficial aggregates for radiation shielding concrete. Boron has a lot of advantages in radiological protection, e.g. high thermal neutron absorption cross section, does not emit highly penetrating gamma radiation. The objective of this investigation is to study the effects of various boron-bearing compounds on cement setting and hardening in order to evaluate the limits for possible use in radiation shielding cement mortars

Materials

Testing methods

Results and discussion

Conclusions