Effect of Water-Cement Ratio on Flexural Strength of RC Beams Made with Partial Replacement of Coarse Aggregates with Coarse Aggregates from Old Concrete

This research paper presents an experimental evaluation of the effect of water-cement ratio on the flexural strength of reinforced concrete beams made with 50% replacement of coarse aggregates with recycled concrete aggregates (RCA). 72 reinforced concrete beams were cast using 0.54, 0.6, 0.65 and 0.70 water-cement ratio. In each ratio, 12 beams were cast using RCA and 3 beams were cast using all-natural coarse aggregates (NCA). Beams were cured for 7 and 28 days. After curing, all beams were tested with central point load in a universal load testing machine. From the obtained results, it is observed that the maximum reduction in flexural strength of RCA beams is about 28% when compared to the 0.54 w/c ratio beams of the same group and 31.75% in comparison to NCA beams cast with same w/c ratio. The maximum deflection and average strain in beams remained within limits. The observed cracking pattern shows shear failure of all beams

Synthesis of titania-bentonite nanocomposite and its applications in water-based drilling fluids

Titania or TiO2-bentonite nanocomposite was synthesised by environmental friendly and cost effective hydrothermal method. Synthesised nanocomposite was successfully characterised by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). The target of the study was to enhance the rheological behaviour of the water-based drilling fluid (WBDF) by using synthesised nanocomposite. The experimental results revealed that Titania-bentonite nanocomposite exhibited better rheological characteristics than conventional WBDF. Rheological properties in particular yield point (YP) and 10-min gel strength (10-min GS) were improved by 57 % and 40 % compared to basic drilling fluid after addition of 1.0 g of the synthesised nanocomposite at 65.56 °C. API filtrate loss volume and High Pressure High Temperature (HPHT) filtrate loss volume were slightly reduced by 10 %, and 9.2 %. These scientific results can be used to formulate enhanced WBDF at elevated temperatures