Using bio-based polymers for curing cement-based materials

Curing is the process of controlling the rate and extent of moisture loss from the surface of cement based materials. It is the final stage in the production of cement-based materials and it is the essential part for achieving continuous hydration of cement, while avoiding cracking due to drying shrinkage. Continuous cement hydration also...

DC current-induced curing and ageing phenomena in cement-based materials

This paper investigates DC current-induced “curing” and ageing phenomena in cement-based materials. Two current densities were used in a DC current regime i.e. mortar cubes were subjected to DC current flow of 1 A/m2 and 100 mA/m2; tap water and calcium hydroxide were external environment. Conditioning (“curing”) was performed for 112 days,...

Chloride ingress in cracked concrete studied using laser induced breakdown spectroscopy

Cracks are always present in reinforced concrete structures. It is a goal of the current research to study the influence of mechanical cracks on chloride ingress. A compact reinforced concrete specimen was designed, mimicking the cracking behaviour of beam elements. Cracks of different widths were induced by means of mechanical loading. These...

The importance of chloride sensors stability in monitoring ageing phenomena in concrete structures: Ag/AgCl electrodes performance in simulated pore-water environment

One of the reported problems associated with the performance of Ag/AgCl electrodes in alkaline environment, as concrete pore water, has been their poor stability. Open circuit potentials are typically observed to be stable for a time period of a few minutes to some days depending on the thickness and microstructure of the sparingly soluble AgCl...

Study on effective modifiers for damaging salts in mortar

The use of crystallization modifiers for the prevention or mitigation of salt crystallization damage has recently received a lot of research interest in the field of building conservation. However, the use of crystallization modifiers mixed in a lime-based mortar, is still a very new field of research. This paper summarizes the literature study...

Modeling aging of cementitious pore structure

Coupled reactive-transport processes in cementitious materials play a crucial role in the aging process pf building materials. Up to now, the effect of aging on microstructure and evolution of it’s properties, in three dimensions, was studied only by dissolution of certain phases at random locations. In this paper we present a new 3D reactive...

Viscoelastic stress modeling in cementitious materials using constant viscoelastic hydration modulus

Viscoelastic stress modeling in ageing cementitious materials is of major importance in high performance concrete of low water cement ratio (e.g. w/c ~0.35) where crack resistance due to deformation restraint needs to be determined. Total stress analysis is complicated by the occurrence of internal stresses due to shrinkage, which requires...

Modeling and analyzing autogenous shrinkage of hardening cement paste

In this paper, a conceptual model for analyzing the plastic part of autogenous deformation of cement paste based on the Arrhenius rate theory will be presented. The autogenous deformation will be calculated from the elastic deformations with inclusion of creep. Different kinds of cement paste with a water cement ratio 0.3 are tested and studied,...

Protection of aged concrete structures: Application of bio-based impregnation system

This paper focuses particularly on the ageing of concrete due to micro-crack formation or freeze/thaw which results in an increased permeability of the concrete. The bacteria-based repair system presented in this paper aims at recovering the concrete permeability thanks to bacteria-induced calcium carbonate precipitation inside cracks/porosity....

Residual fatigue life evaluation of rail at squats seeds using 3D explicit finite element analysis

A modeling procedure to predict the residual fatigue life of rail at squats seeds is developed in this article. Two models are involved: a 3D explicit Finite Element (FE) model to compute the stress and strain at squats in rail, and the J-S fatigue damage model to determine the residual fatigue life on the basis of the computed stress and strain...

The Noble Patina of Age

This paper discusses the aesthetical aspects of ageing and focusses on the use of the terms ‘patina’ and ‘damage’ to decide on the cleaning of historical facades and the application of artificial ageing. Conservation campaigns can be characterized by the wish to preserve an object, building or building complex as a coherent piece of Cultural...

Changing model properties with time due to corrosion of a dynamically loaded reinforced concrete beam

Structural Health Monitoring (SHM) systems are frequently used in civil infrastructures. One important durability property in reinforced concrete (RC) structures is the level of steel bar corrosion. In a dynamic four-point-bending test, two beams are loaded simultaneously, in which corrosion is accelerated in one of them. Since geophones are...

Ageing of portland cement concrete cured under moist conditions

Deterioration of microstructure in cement concrete will cause changes in the transport properties of the concrete. Transport properties at different ages of the concrete provide information about the microstructural changes of the material. A way to measure the transport properties, i.e. the chloride diffusion coefficient, in the laboratory is...

Pore structure of blended cement paste by means of pressurization¿depressurization cycling mercury intrusion porosimetry

Concrete containing supplementary cementitious materials (SCMs) has different durability properties from that containing pure Portland cement. The durability of concrete is always associated with the properties of microstructure, especially pore structure. Pressurization–Depressurization Cycling Mercury Intrusion Porosimetry (PDC-MIP) was...