Searched for: faculty:"Civil%5C%2BEngineering%5C%2Band%5C%2BGeosciences"
(1 - 20 of 52)

Pages

document
Susanto, A. (author), Koleva, D.A. (author), Van Breugel, K. (author)
This work reports on the influence of stray current flow on temperature rise in hardening cement-based materials and consequently altered cement hydration. To simulate stray current, different levels of electrical current were applied to cement paste and mortar specimens immediately after casting. Isothermal calorimetry tests were carried out to...
conference paper 2015
document
Susanto, A. (author), Koleva, D.A. (author), Van Breugel, K. (author)
This paper reports on the influence of stray current flow on microstructural prop-erties, i.e. pore connectivity and permeability of mortar specimens, and link these to the observed alterations in mechanical properties and cement hydration. Mortar specimens were partly submerged in water and calcium hydroxide (Ca(OH)2) as an external environment...
conference paper 2014
document
Blagojevic, A. (author), Koleva, D.A. (author), Walraven, J.C. (author)
This work reports on the investigation of steel corrosion behavior in 1000 mm in length reinforced concrete beams under sustained load, aiming to define a feasible experimental protocol for corrosion monitoring. The beams were subjected to wetting (5% NaCl for corroding cases and tap water for control ones) and drying cycles. Generally applied...
conference paper 2014
document
Susanto, A. (author), Koleva, D.A. (author), Van Breugel, K. (author)
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,...
conference paper 2014
document
Pargar, F. (author), Koleva, D.A. (author), Koenders, E.A.B. (author), Van Breugel, K. (author)
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...
conference paper 2014
document
Susanto, A. (author), Koleva, D.A. (author), Van Breugel, K. (author), Koenders, E.A.B. (author)
Stray current is essentially an electrical current “leakage” from metal conductors and electrical installations. When it flows through cement-based systems, electrical energy is converted to thermal energy that causes increasing temperature due to Joule heating phenomena. The aim of this paper is to shed light on the influence of electrical...
conference paper 2014
document
Pargar, F. (author), Koleva, D.A. (author), Copuroglu, O. (author), Koenders, E.A.B. (author), van Breugel, K. (author)
The level of free chloride concentration in reinforced concrete structures essentially determines the onset of steel corrosion initiation and further propagation. One of the well-known methods for monitoring free chloride concentration is using silver/silver chloride electrodes (Ag/AgCl). These electrodes are sensitive mainly to chloride ions...
conference paper 2014
document
Blagojevic, A. (author), Koleva, D.A. (author), Walraven, J.C. (author)
Chloride-induced corrosion of steel reinforcement is one of the major threats to durability of reinforced concrete structures in aggressive environmental conditions. When the steel reinforcement starts to corrode, structures gradually lose integrity and service life is shortened. Cracks are inevitable in practice and they facilitate ingress of...
conference paper 2014
document
Aquino, R.J. (author), Koleva, D.A. (author), Koenders, E.A.B. (author), van Breugel, K. (author)
conference paper 2013
document
Koleva, D.A. (author), Jonkers, H.M. (author), van Breugel, K. (author)
The improvement of material properties of cement-based materials e.g. reduced permeability, porosity, uniform distribution of hydration products, etc. is of a significant importance and related to durability and sustainability of concrete and reinforced concrete structures. With this respect, a recent and novel approach is to "create" self...
journal article 2013
document
Hu, J. (author), Koleva, D.A. (author), Ma, Y. (author), Schlangen, E. (author), Van Breugel, K. (author)
journal article 2013
document
Susanto, A. (author), Koleva, D.A. (author), Van Beek, C. (author), Van Breugel, K. (author)
Well known is that stray electrical current i.e. current with a spatial distribution in any conductive environment, can affect civil structures, e.g. initiate or enhance steel corrosion or affect microstructural and mechanical properties of the cement-based bulk matrix. While the former is related to polarization effects in conditions of current...
conference paper 2013
document
Varini, M. (author), Koleva, D.A. (author), Denkova, A.G. (author), Mol, J.M.C. (author), Terryn, H. (author), Van Breugel, K. (author)
Polymeric nano-materials utilization in reinforced concrete, aiming to deal with steel corrosion was developed in previous works. Promising results were obtained with PEO–b–PS nano-formations, both in terms of enhanced bulk matrix properties and improved steel corrosion resistance. Recent research has been focusing on a cheaper and commercially...
conference paper 2013
document
Leon Fuenmayor, E.J. (author), Koleva, D.A. (author), Jonkers, H.M. (author), Mol, J.M.C. (author), Terryn, H. (author), Van Breugel, K. (author)
Impressed current cathodic protection (CP) based on pulse technology has been proven to be a more efficient and effective alternative of traditional CP for reinforced concrete applications. Essentially, the superiority of pulse CP is in achieving the required steel polarization with otherwise reduced side effects (e.g. influence on bond strength...
conference paper 2013
document
Susanto, A. (author), Koleva, D.A. (author), Copuroglu, O. (author), Van Beek, C. (author), Van Breugel, K. (author)
This investigation presents a comparative study on mechanical properties, electrical resistivity and microstructure of mortar under DC current, compared to mortar in rest (no current) conditions. Monitoring was performed from 24h after casting until 84 days of cement hydration. A current density level of 10 mA/m2 was chosen as a simulation...
journal article 2013
document
Susanto, A. (author), Koleva, D.A. (author), Copuroglu, O. (author), Van Beek, C. (author), Van Breugel, K. (author)
Corrosion in reinforced concrete structures is not only induced by the penetration of aggressive substances (e.g. chlorides and/or CO2) but also influenced by stray currents. Further, the degradation mechanisms in reinforced cement-based systems due to the combined effect of stray current and chloride penetration have been a serious problem in...
conference paper 2012
document
Koleva, D.A. (author), Van Breugel, K. (author)
This work reports on the corrosion resistance of steel in alkaline model solutions and in cement-based materials (mortar). The model solutions and the mortar specimens were Ordinary Portland Cement (OPC) based. Further, hereby discussed is the implementation of an eco-friendly approach of waste utilization for corrosion control and/or achieving...
conference paper 2012
document
Koleva, D.A. (author), Denkova, A.G. (author), Hu, J. (author), van Breugel, K. (author)
The influence of Pluronic P123 (PEO20-PPO20-PEO70) micelles (of 10 nm size) on the corrosion behaviour of low carbon steel in cement extract (CE) was studied using electrochemical impedance spectroscopy (EIS) and potentio-dynamic polarisation (PDP). Additionally, mercury intrusion porosimetry (MIP) was emplo ed to derive the impact of admixed...
conference paper 2012
document
Hu, J. (author), Koleva, D.A. (author), Van Breugel, K. (author)
This study presents the results from a preliminary investigation on the corrosion behavior of carbon steel in cement extract (CE) in the presence of very low concentration (0.0024 wt. %) polymeric nano-aggregates (PEO113-b-PS780 vesicles). Two types of vesicles were studied: vesicles with a CaO-containing core and vesicles with an “empty” core....
journal article 2012
document
Koleva, D.A. (author), van Breugel, K. (author), Hu, J. (author)
conference paper 2012
Searched for: faculty:"Civil%5C%2BEngineering%5C%2Band%5C%2BGeosciences"
(1 - 20 of 52)

Pages