The Effect of Repeated Temperature Variations and Freeze Thaw Phenomenon on Some Durability Aspects of Concrete (original) (raw)

DURABILITY- KEY FACTOR OF NEW GENERATION CONCRETE PREPARATIONS

Most concretes are excellent at 28 days otherwise a simple repair or replacement may be done. However, concrete is meant to last for decades or centuries. After the first 28 days concrete will continue to mature and age, depending on the original material composition and properties and the environmental actions during service. Sulfates, Chlorides, Acids and Soft water are causing disintegration or expansion. Durability failure may also occur because of internal expansion from concrete constituents that are swelling; usually because of a reaction product absorbing water. This paper focuses different causes and issues related with durability of structural concrete. Hydraulic concrete is one of the most-used construction materials around the world. Portland cement is its principal component, but during its production a lot of energy is needed, and big volumes of greenhouse Gases like CO2 are released.

Experimental investigation of the variability of concrete durability properties

Cement and Concrete Research, 2013

One of the main objectives of the APPLET project was to quantify the variability of concrete properties to 26 allow for a probabilistic performance-based approach regarding the service lifetime prediction of 27 concrete structures. The characterization of concrete variability was the subject of an experimental 28 program which included a significant number of tests allowing the characterization of durability 29 indicators or performance tests. Two construction sites were selected from which concrete specimens 30

Methods of assessing the durability and service life of concrete structures

2017

Characterisation of cover concrete is often the most viable means for assessing the durability and has become increasingly evident over the past 20 years. A variety of field methods and laboratory techniques exist, which provide a number of properties, such as air permeability index, water absorption rate, water permeability index, chloride diffusivity, electrical resistivity, moisture content and porosity gradient. Most techniques are economical and appropriate for assessing the durability of structures subjected to a single mechanism of deterioration. In reality, structures may face multiple deterioration mechanisms, stress/strains due to both environmental and structural loading and related acceleration of deterioration. Developing an understanding of such multimode deterioration may help in addressing the performance gap between laboratory and field. In this paper, a brief review of some of the ways by which a performance testing strategy could be developed is given so that serv...

Contribution to the Experimental Study of the Concrete Behavior in Its Climatic Environment

Energy Procedia, 2013

Several studies have demonstrated the aggressive effect of very high temperatures, exceeding 100 ° C, on the behavior of concrete. However, the effect of local service temperatures remains significant, even very important, if we consider the safety margins provided during the sizing of pieces in the warm regions and their severe climatic conditions of the setting and hardening. In this context, the data on the behavior of the concretes at service temperatures are necessary to predict the safety of the buildings and constructions in various regions. The main objective of this paper is to determine the sensibility of the concrete to its climatic environment, during the period of service in the Saharan regions. It has been shown, by using three different compositions of concrete based on local materials, that the performance of concrete fall considerably with the increase of the temperature until 60 ° C. A thermal enclosure was conceived; the evolutions of the strength are presented and compared with those obtained for the reference results at 20°C temperature. The consequences on the durability and the reliability of structures in these regions are important, which appeals to the necessity in a consideration the risks caused by geo-climatic conditions during the design of structures.

An Experimental Study on the Concrete Durability

IABSE Symposium Report, 2007

The paper provides a tentative for a practical model of assessing the corrosion of reinforcing steel in concrete structures. A theoretical model as well as a formula for both the carbonation depth and chloride ion penetration is presented. Experimental programme presents the influence of carbon dioxide on depth of carbonation.

STUDIES ON DURABILTIY AND SHRINKAGE OF CONCRETE BY USING DIFFERENT METHODS (STATE OF ART REVIEW)IJCIET/issues.asp?JType=IJCIET&VType=8&IType=1 Studies on Durabiltiy and Shrinkage of Concrete By Using Different Methods (State of Art Review

During the ancient period, it was observed that the Romans had created very stunning and hard durable structures by incorporating lime and volcanic red hot stays which was discovered at Italy (Pozzuoli). To strengthen the structures many Researchers had done a study by using the several materials such as latex spheres, fly ash, and glass spheres and so on to improve the durability of the structure. It was identified that the strength of the building will mainly depend on the ITZ characteristic which is one of the factors. By considering Neyveli fly ash, the compressive as well as tensile strength of the concrete was determined by adopting 10%, 20%, 30% and 40%. The comparison was made by using SEM analysis and it was finally compared with the conventional concrete. From the results, researchers had found that 20% of Neyveli fly ash gave the better results with the help of SEM analysis by comparing it with the conventional concrete. It was observed that the cement – based materials was changed from micro level to the macro level. The various properties such as mechanical and chemical changes of the concrete were determined with the help of SEM as well as X – ray diffraction. In this paper, the works carried out by the various researchers on several materials were reviewed with the Portland cement. The pozzolanic reaction was found to be more due to the presence of 25% of fly ash and 75% of cement which reflects to the high iron content. With this review, the suggestion can be made for improving the durability and also to strengthen the structure by incorporating partially with these various materials such as fly ash, glass beads, and glass spheres and so on in the concrete.

Concrete performance subject to coupled deterioration in cold environments

Nuclear Engineering and Design, 2016

The design of concrete durability is normally based on the assessment of its performance when subject to a single deterioration mechanism. In reality, concrete structures are subject to varying environmental exposure conditions which often results in multi-deterioration mechanisms occurring. The Nordic climate, with cold harsh winters, poses a severe challenge to the long-term durability of concrete. The most common deterioration mechanisms are freeze-thaw damage, carbonation and chloride induced corrosion. Research is now more focused on the assessment of coupled deterioration mechanisms. For instance, evaluating how cracks resulting from freeze-thaw influence chloride ingress, or how carbonation changes the surface properties and thereby influencing freeze-thaw scaling and chloride penetration. This paper presents the results of research projects at VTT focusing on coupling deterioration mechanisms. These research projects have built on several decades of concrete durability research at VTT, including 15 years of field station studies. The durability of the concretes has been assessed using both accelerated laboratory testing and also from in situ exposure results from field stations. This research has contributed to the development of concrete performance models and service life tools, supporting a holistic approach for deterioration assessment.