Project title: ‘Experimental investigation of creep and shrinkage deformation of new concrete and cement composites’

Postdoctoral researcher/project promoter: Andīna Sprince

Scientific supervisor: Leonīds Pakrastiņš

Project period: 01.05.2020 to 30.04.2023 (36 months)

Project funding: 133,805.88 EUR including ERDF funding 113,734.99 EUR (85%), state budget funding 13,380.58 EUR (10%) and Riga Technical University funding 6,690.31 EUR (5%).

Project Summary: 

The aim of the research project is to experimentally determine the long-term properties of new concrete and cement composites (NCCC) – creep deformation in compression and tension, and shrinkage deformation – using a new method of deformation determination – quantitative image analysis (QIA), which will be a new approach to deformation determination.

In the design of buildings and civil engineering structures, it is necessary to predict the performance of structural elements and the evolution of possible effects throughout their service life. Creep deformations occur in structures under sustained loads and can cause excessive deflection, cracking, instability, buckling, loss of prestress and other anomalies. Since the beginning of the 20th century, researchers and cement engineering composite technologists have been working on the development of new and different types of structural multi-component concrete and cement engineering composites, creating cement composite matrices that are much stronger, more durable and more environmentally friendly. Unfortunately, there is insufficient information on the long-term properties of such new engineered concrete and cement composites, as existing standardised methods for determining creep strains under compressive loading are inadequate for newly developed concrete and cement composites.

To address the scientific problem, the project proposes to apply a digital image analysis (QIA) method for the determination of long-term properties, which has not been used for this purpose so far. The application and use of the QIA method would also solve the problem of recording micro-deformations caused by tensile loading, and it should also be mentioned that this new approach could potentially allow the monitoring of long-term deformations of existing structures. It is proposed to use new testing equipment, to apply a new specimen shape and to experimentally validate the method by determining the long-term tensile and compressive properties of newly developed concrete and cementitious engineering composites using new creep lever jigs in tension and adapted creep lever jigs in compression, as well as by applying new specimen shapes for the determination of creep deformations in tension.

The achievement of the scientific objective will contribute to the development of new, more promising and more environmentally friendly multi-component engineering composites of concrete and cement and to the design of safer, more rational stress-field compliant structures whose long-term performance can be more accurately predicted and evaluated.

Expected output of the research:

• presented at 2 international scientific conferences;
• published in 2 international scientific conference proceedings, which will be indexed in the Scopus database;
• published in 2 peer-reviewed scientific journals with a citation rate higher than the industry average (IF=1.721), which will be indexed in the Scopus database;
• published in 2 popular science articles on the internet and/or in print journals;
• submitted at least 1 patent application;
• developed 1 scientific description and recommendations.

Keywords: new concrete and cement composites, creep and shrinkage deformation, long-term properties.

Results:

• Literature analysis on methods for determination of long-term properties of different concrete and cement composites under different stress states, their operating ranges, as well as on concrete and cement composites to be tested in them.
• In-depth literature review, study of quantitative image analysis (QIA) methods used in research, their operating ranges, applications for scientific research purposes, review and analysis of the technical support used in them.
• As part of the competence development, several remote workshops organised by BrightTALK on the correct use of different photographic equipment, the correct set-up of technical parameters to perform the necessary measurements, and the processing of the resulting images-measurements were attended.
• Knowledge transfer to students through advice on scientific work.
• The first experimental studies were carried out in good time. As a result of the experiments, geopolymer concretes were designed and produced. 20 cylindrical specimens were cast and used for experimental tests.