Investigation of coconut shell biochar as an eco-friendly additive to mitigate the alkali-silica reaction in recycled aggregate concrete

Alkali-Silica Reaction (ASR) in Recycled Aggregate Concrete (RAC) is one of the main chal-lenges in using demolished concrete in construction. Several methods are available to mitigatethe impact of ASR, and they have less circular economic potential. This study aims - to investi-gate the possibility of coconut shell biochar (CSB) as an eco-friendly additive to mitigate ASRin RAC. In this investigation, the authors have conducted cement mortar bar test experimentsaccording to the American Society for Testing and Materials (ASTM 1260) standard, ScanningElectron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS). Studies havefound a higher rate of ASR in recycled concrete aggregate (RCA) compared with natural con-crete aggregate (NCA). More importantly, it is found that CSB can adsorb cations (Na+ andK+) that cause ASR in RAC, thereby reducing ASR while not compromising concrete strength.Hence, the authors concluded that CSB can effectively mitigate ASR in RAC while sequestrat-ing carbon into concrete structures

Application of Clegg impact value for the evaluation of the properties of asphalt concrete

The Clegg impact hammer is used to obtain a parameter relating to strength or stiffness of soil or similar type of materials. Tha parameter obtained is called the Clegg impact value(CIV). This study has investigated the relationship between CIV and bitument content in a compacted bituminous concrete and the possible application of CIV for the evaluation of the properties of asphalt concrete. It was found that the CIV of compacted asphalt increases to a maximum value and decreases with an increase in bitument content. This relationship was similar to the stability versus bitumen content relationship detemined in the Marshall method of mix design. Optimum binder contents determined using CIV, air voids and bulk density were comparable with those values determined using the standard Marshall method and the Austroads Pavement Research Group method

The effects of mixing and compaction on volumetric properties of an asphalt concrete containing recycled concrete aggregates

Recycled concrete aggregates are produced by recycling demolished concrete elements. They contain relatively weak cement mortar attached on to aggregate particles which tends to break and separate from aggregate particles during mechanical mixing, vibration or compaction of cement or asphalt concrete. This was studied for an asphalt concrete containing recycling concrete aggregates and it was found that the change in particle size distribution during mixing and compaction was significant compared to that of a fresh aggregate sample. This had a considerable effect on the volumetric properies determined for an asphalt concrete sample

Heavy Ion Collisions

The levels of voltage unbalance that exist in some interconnected sub-transmission networks in Australia has been observed to be above the code requirements (e.g. 1% in Victoria). There is a perception that these high levels arise as a result of asymmetrical loads. However, it is identified that the network asymmetry in relation to transmission lines also play a significant role in the lead up to this situation, employing an interconnected 66kV sub-transmission system as the study case. The individual transmission lines of the study network are analysed in order to observe their possible influence arising as a result of line impedance characteristics and line loading levels. A methodology is developed to quantify the contribution of individual transmission lines to the role played by the network at nodal level. The leading contributors to the problem in the study network are explored employing the proposed approach