Elastic modulus and stress-strain curve analysis of a tungsten mine waste alkali-activated concrete

Pedro Silva Humbert,João Paulo De Castro Gomes,Clemente Martins Pinto,Natalia Paszek,Luis Filipe Almeida Bernardo,J Castro-Gomes,M Górski,X Zhou,S Yang,J Durán-Suárez,C Sangiorgi

doi:10.1051/matecconf/201927402003

Abstract

In the paper the compressive strength, the elastic modulus and the stress-strain curve of an alkaliactivated concrete were studied. A tungsten mine waste mud (TMWM), aggregate (also from the tungsten mine), glass waste and metakaolin were used as raw materials. Sodium silicate and sodium hydroxide were used as activators. First, TMWM chemical composition was determined by scanning electron microscopyenergy dispersive spectroscopy (SEM-EDS). The maximum particle size was 18mm. Two cubes with side dimension of 15cm were prepared from the mixture. Samples were cured at 60°C for 24 hours. A concrete mixer, vibration table and an oven were used in the process. After the curing process, cubes were cut into seven prisms and one cube with the dimensions 15x7.4x7.4cm and 7.4cm respectively. After 28 days, the laboratory tests were performed. During the compressive strength tests, the displacements were also recorded which allowed drawing the stress-strain curve of the samples. The compressive strength ranged from 17.27 to 28.84MPa. The elastic modulus was calculated by four different standards: ASTM, LNEC and European standard. The elastic modulus ranged from 2.48 to 7.49GPa what showed that the material is more elastic than ordinary Portland cement concrete.

Highlights

Global warming has exceeded its limits in 2015, it is compulsory to find efficient methods for reducing greenhouse gases (GHG)
Tungsten mine waste mud (TMWM) and tungsten mine waste aggregates (TMWA) were collected at the Panasqueira Mines located in the central region of Portugal
The stress-strain curve was drawn through a system which consisted of a compressive strength machine Seidner D7940 Riedlingen, two compressometers, a load cell and a data logger which recorded all the data simultaneously at each second

Summary

Introduction

Global warming has exceeded its limits in 2015, it is compulsory to find efficient methods for reducing greenhouse gases (GHG). Other mechanical properties are related to the compressive strength It is influenced by some factors such as: the characteristics and properties of the precursors; manufacturing procedures, curing conditions and the raw materials ratios [14]. AABs generally can obtain high compressive strength the results can differ depending on the chemical composition of the used materials. It can be calculated for an existing structure using theoretical relationships between the values obtained from nondestructive testing methods and elastic modulus. These methods can be, for instance, the ultrasonic pulse velocity, wave reflection and impact echo [17,18]. Above-mentioned factors can increase or decrease the elastic modulus depending on the concrete mixture [18]

Experimental work

Materials

Samples preparation

Test methods

Results and discussion