توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Diagnosis of AAR in a hydroelectric concrete gravity dam wall and characterisation of the concrete for its rehabilitation
نویسنده(ها):
اطلاعات انتشار: دومین کنفرانس بین المللی بتن و توسعه، سال
تعداد صفحات: ۱۹
Signs of concrete distress in a hydroelectric concrete gravity dam in the Snowy Hydro network was noted in routine surveys on the crest of the dam wall and measurement of vertical movements along the crest over a number of years. The distress was also manifested in the form of cracking in some sections of the dam wall. Concrete elements of the associated power station had also shown some degree of distress in the form of cracking. Alkali–aggregate reaction (AAR) was considered among other mechanisms as alikely cause of cracking. In order to investigate the main causes of cracking of the various elements of the power station and the dam wall, core samples ranging in length from 0.3 m to 10 m were extracted and investigated for the presence of AAR, its extent, likelihood of continuing reaction,residual expansion potential, and effect on the strength of concrete. Results of the investigation showed that mild AAR was present in some sections of the wall of the power station but not in the floor, where drying shrinkage could have caused the observed cracking. Mild AAR was also present in sections of the dam wall with minor visible cracking, but it was stronger and more widespread in the badly cracked area. Based on the measurement of the residual expansion, it was suggested that the walls of power station could be treated by appropriate surface coating to mitigate the progress of AAR, and the badly cracked portion of the dam wall be anchored to stabilise the vertical movement. Other portions of the dam wall did not appear to need treatment.<\div>

۲Performance of glass powder as a pozzolanic material in concrete : a field trial on concrete slabs
نویسنده(ها): ،
اطلاعات انتشار: دومین کنفرانس بین المللی بتن و توسعه، سال
تعداد صفحات: ۲۱
Earlier laboratory work by the authors indicated satisfactory performance of glass powder (GLP) in concrete as a pozzolanic material. In order to investigate the performance of GLP in concrete under field conditions, a field trial was conducted using a 40 MPa concrete mix, incorporating various proportions of GLP (0, 20, and 30%) as cement replacement. Ten mix formulations were used to cast ten concrete slabs (1.5 × 2.5 × 0.25 m). Cylinders and prisms were also manufactured at the time of casting for the measurement of compressive and splitting tensile strength, shrinkage, expansion, ultrasonic pulse velocity, volume of permeable voids, etc. Core samples were drilled from the slabs at various ages for the same tests. Strength results showed that at 28 days the reference mixes and only the mix containing 20% glass powder had met the strength requirement for 40 MPa concrete, whereas at 90 days and later ages the mix containing 30% glass powder had also caught up in strength. This indicated further strength development due to pozzolanic reaction. The strength of some cores drilled from the trial slabs was considerably lower than those of corresponding laboratorycured cylinders, and this has been attributed to inadequate compaction. The flexural strength of concrete largely followed the same trend as the compressive strength. The mixes performed satisfactorily with respect to drying shrinkage and alkali reactivity, and there were indications that GLP reduces the chloride ion penetrability of the concrete, thereby reducing the risk of chloride induced corrosion of the steel reinforcement in concrete. The results have demonstrated that GLP can be incorporated into 40 MPa concrete mixes at 20– 30% to replace cement without harmful effects. The rate of strength gain is slower in GLPbearing concrete compared to the control mixes, but the final strength is well above the 40 MPa target. The use of GLP provides for considerable utilisation of waste glass in concrete and significant reductions in the production of green house gases by the cement industry.<\div>

۳Investigation of Coastal Concrete Bridges To Extend Their Service Life
نویسنده(ها): ،
اطلاعات انتشار: چهارمین کنفرانس بین المللی سواحل و بنادر و سازه های دریایی، سال
تعداد صفحات: ۱۴
A 9 year old bridge located in marine environment has been investigated to determine the time when corrosion activity is likely to become of concern and intervention needed to prevent progress of corrosion damage. Various techniques of characterisation of reinforced concrete have been applied to some elements of the bridge and discussed in relation to service life of the elements.<\div>
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