Alternative Software for Evaluating Preliminary Rock Stability of Tunnel Using Rock Mass Rating (RMR) and Rock Mass Quality (Q) on Android Smartphone

Nowadays, tunneling is applied to a variety of constructions such as subway station, water supply tunnel and underground mine. Tunnel safety is one of the most important factors of construction. Most tunneling is operated in remote area that is difficult to reach. This research aims to develop an alternative software for Android smartphone, which use for estimating preliminary rock mass stability and suggesting support method for the early state tunnel. Suitable rock mass classifications for tunnel are rock mass rating (RMR) and rock mass quality (Q system). They are applied to the application. Android operating system is chosen because it is the most popular operating system in the world. The application is programmed by the official programming software from Google, the Android Studio. PSU-RQ is the name of this application. PSU-RQ is easy to use because it reduced the complexity of the theories by numerical logic. The application results are verified by comparing with Excel standard worksheet. PSU-RQ is reliable and accurate. The application is tested in a tunneling case study as an example. Whenever a smartphone is available, the user can estimate preliminary rock mass stability and support method of tunnel instantly. However, long-term stability investigation is necessary

Long-term curing impact on properties, mineral composition and microstructure of hemp shive-cement composite

Fibre Hemp Shiv (FHS) is one of the most widely used bio-aggregates for the development of eco-friendly building materials. Research on composites with an FHS aggregate has usually been limited to short-term property analyses that depend on the type of binder. Such properties are determined after (7–90) days of curing. Most scientists have focused on researching composites with lime (L) based binders. This work focuses on composites with a cement (CEM) binder and FHS aggregate, and investigates the impact of long-term curing (for 1 year) on the physical properties (density, compressive strength and thermal conductivity) of composites with non-treated and mineralized FHS (mineralization is performed with aluminium sulphate (AS) and hydrated lime (L)). In order to determine the causes of the changes in properties during long-term curing, changes in the mineralogical composition are analysed. X-ray diffraction, differential thermal and thermogravimetric analyses as well as research on the microstructure of the composites are implemented. The lowest change in properties due to inhibition of hydration is determined for composites with a non-treated aggregate. Mineralized aggregates are characterized by lower cement hydration capability over a long-term period. The change of properties after 1 year of curing depends on the AS/CEM ratio. For all 1-year cured composites, there is a reduction in the peak intensities of C2S, C3S and ettringite, whereas there is an increase in the peak intensities of calcite, (except for composition with the highest AS/CEM ratio – AS30L18), Calcium Silicate Hydrate (CSH) and portlandite (except for the non-mineralized composition). Lower ratios for AS/CEM (AS18L36 and AS21L42) and, respectively, higher L/CEM ratios in compositions lead to the formation of vaterite. In addition, the above-mentioned composition has the highest L/CEM ratio, which ensures that more hydrates participate in the carbonation process, thus leading to higher compressive strength, denser composite structure and higher thermal conductivity due to higher heat transfer by conduction