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A study on microbial self-healing concrete using expanded perlite

Amjad Usama Bin, Siddique Muhammad Shahid, Shahid Taha, Ahmed Iftikhar, Alogla Saleh M., Ahmad Jawad

Bulletin of the Polish Academy of Sciences. Technical Sciences

2023

Vol. 71, nr 5

art. no. e146475

The increasing concern for the safety and sustainability of structures is calling for the development of smart self-healing materials and preventive repair methods. This research is carried out to investigate the extent of self-healing in normal-strength concrete by using Sporosarcina aquimarina – NCCP-2716 immobilized in expanded perlite (EP) as the carrier. The efficacy of crack-healing was also tested using two alternative self-healing techniques, i.e. expanded perlite (EP) concrete and direct introduction of bacteria in concrete. A bacterial solution was embedded in EP and calcium lactate pentahydrate was added as the nutrient. Experiments revealed that specimens containing EP-immobilized bacteria had the most effective crack-healing. After 28 days of healing, the values of completely healed crack widths were up to 0.78 mm, which is higher than the 0.5 mm value for specimens with the direct addition of bacteria. The specimen showed a significant self-healing phenomenon caused by substantial calcite precipitation by bacteria. The induced cracks were observed to be repaired autonomously by the calcite produced by the bacteria without any adverse effect on strength. The results of this research could provide a scientific foundation for the use of expanded perlite as a novel microbe carrier and Sporosarcina aquimarina as a potential microbe in bacteria-based self-healing concrete.

A Dynamic Self-healing Key Management Scheme For Wireless Sensor Networks Based on EBS

Ning J., Yin X.

Przegląd Elektrotechniczny

2013

R. 89, nr 3b

92--94

A self-healing mechanism in key management is an important means for large-scale clustering wireless sensor networks that enable nonrevoked nodes use their private information and the received broadcast messages to recover the lost session keys on their own. In this paper, we propose a dynamic self-healing key management scheme for large-scale clustering wireless sensor networks that is based on Exclusion Basis System (EBS). We use forward and backward key chains to form cluster session key chain for self-healing, take t-degree polynomial keys to replace the original keys used in EBS. The analysis shows that the proposed scheme has the properties of forward and backward secrecy and resisting to a collusion attack, which is suitable for resource-constrained wireless sensor networks.

W artykule zaproponowano schemat samo-naprawialnego dynamicznego zarządzania kluczami w sieci czujników bezprzewodowych o dużej skali klasterów, oparty na metodzie wykluczeń EBS. Dzięki wykorzystaniu łańcuchów klucza w przód i wstecznych uzyskano samonaprawialność, natomiast oryginalne klucze w EBS zastąpiono kluczami wielomianowymi stopnia t. Analiza działania wykazała skuteczność opisanego schematu w obronie przed atakami.