Performance of Residual Properties for High Strength Concrete Incorporating Nanosilica against Temperatures

Durability, high-temperature resistance, impact and blast resilience, radiation-shielding properties, irradiation endurance and - of course - good mechanical properties are required of the cementitious composites to be used in a variety of high-performance structures. Among these, tall buildings, road and railway tunnels, off-shore platforms, gasification plants, wind and solar mills for the production of "clean" energy should be mentioned, as well as nuclear power plants, and radioactive- and hazardous-waste repositories. Hence, understanding, measuring and modelling concrete behavior under extreme environmental conditions is instrumental in making concrete structures safer and more efficient. To this end, the hot and residual properties associated with the exposure to high temperature, fire and thermal shock are treated in this paper. Reference is made to ordinary vibrated concrete (Normal-Strength Concrete - NSC), as well as to a number of innovative cementitious composites, such as Fiber-Reinforced Concrete - FRC, High-Performance/High-Strength Concrete - HPC/HSC, Ultra High-Performance/Very High-Strength Concrete - UHPC /VHSC, Self-Compacting/Consolidating Concrete - SCC, Light-Weight Concrete - LWC, shotcrete and high-strength mortars. It is shown that these materials can be "tailored" according to a variety of requirements and functions, even if several aspects of their behavior (like spalling in fire and long-term mechanical properties under sustained high temperature) are still open to investigation.

Download Full-text

Residual Compressive Strength of High-Strength Concrete Exposed to Elevated Temperatures

Advances in Materials Science and Engineering ◽

10.1155/2019/6039571 ◽

2019 ◽

Vol 2019 ◽

pp. 1-22 ◽

Cited By ~ 3

Author(s):

Hussein M. Elsanadedy

Keyword(s):

Compressive Strength ◽

High Temperature ◽

High Strength Concrete ◽

Elevated Temperatures ◽

High Strength ◽

Strength Concrete ◽

Residual Properties ◽

Binder Ratio ◽

Strength In Compression ◽

Normal Strength

High-strength concrete (HSC) has several well-known technical, aesthetic, and economic advantages over normal-strength concrete (NSC), which explains the increasing popularity of the former material in the construction domain. As in the case of NSC, however, high temperature adversely affects HSC mechanical properties even more than in NSC, as indicated by the many studies performed so far on HSC at high temperature (hot properties) or past a thermal cycle at high temperature (residual properties). Since many code provisions concerning concrete properties versus high temperature were developed for ordinary concrete and the available models (in terms of stress-strain relationship) come mostly from the tests on NSC—as the tests on HSC are less numerous—developing predictive relationships for HSC exposed to high temperature is still an open issue, especially with reference to many parameters affecting concrete compressive strength, like temperature as such, heating rate, water-to-binder ratio, and strength in compression, to cite the most relevant parameters. To this purpose, a large database (more than 600 tests) is examined in this paper, which is focused on HSC residual properties and on the variables affecting its residual strength. Available design models from various guidelines, standards, codes, and technical reports are tested against the database, and new regression-based models and design formulae are proposed for HSC strength in compression, after the exposure to high temperature.

Download Full-text

Ultrasonic Pulse Velocity and Morphology of High Strength Concrete with PVC Waste Aggregate

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.e6483.018520 ◽

2020 ◽

Vol 8 (5) ◽

pp. 3783-3788 ◽

Cited By ~ 2

Keyword(s):

Silica Fume ◽

High Strength Concrete ◽

High Strength ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

High Ratio ◽

Hardened Cement ◽

Strength Concrete ◽

Residual Properties

In this paper, morphology and ultrasonic pulse velocity (UPV) of high strength concrete with a relatively high ratio of condensed silica fume and PVC waste aggregate as sand replacement have been examined. The plastic aggregate was obtained from shredding PVC waste sheets used for secondary roofing and covering walls. Variables tested were PVC plastic grading and ratio of sand replacement with such plastic, in addition to curing time of concrete. Results of scanning electron microscopy showed that there is a good bond between PVC aggregate particles and hardened cement paste. There was a relatively small reduction of UPV value of concrete, increased with increasing PVC aggregate content, reached 14.3% at 40% PVC content. The UPV lost is slightly increased with increasing concrete age from 7 days to 56 days. Results also showed that the effect of PVC aggregate grading on the residual UPV is not important. Based on the measured residual properties of high strength with silica fume and PVC granules, there is a high degree of silica fume hydration and the existence of PVC particles has no effect on such hydration.

Download Full-text