Key Engineering Materials Vol. 856

Abstract: The main objective of this study is to investigate the mechanical properties of dredged sediments, which are considered as waste from the process of removing sediments from the bottom of a dam's reservoir. The dredged sediments with stabilization can to be reused as construction and building materials in civil engineering works. The mechanical tests included unconfined compressive strength (UCS) and splitting tensile strength (STS) to understand the behavior of the dredged sediments stabilized with ordinary portland cement (OPC) type I and fly ash (FA). The overall test results indicated that OPC type I and FA were effective in stabilizing the sampled dredged sediments from two dams in northern Thailand. The stabilization with 10% FA content was found to be most effective for improving mechanical properties of the stabilized samples.

Abstract: This research intended to investigate the influence of rice husk ash (RHA), green glass cullet (GGC) and local white clay (LWC) in Thailand on the physical properties of fired clay tiles. Utilization of RHA and GGC were the main objectives. Proportion of RHA varying from 10-60% by weight was conducted. Specimens of mixture formulation were sintered at 950 °C. The results revealed that the formula no. A7 containing 70% GGC and 30% LWC can develop greenish color. In addition, scanning electron microscopy was carried out to characterize microstructure and found the glassy phase in fired specimen. Moreover, nepheline (Na₂Al₂Si₂O₈) and wollastonite (CaSiO₃) were detected by the X-ray diffraction technique. These phases can promote the strength of fired clay tiles. Meanwhile, the specimen of formula no. B13 comprising 60% GGC, 30% LWC and 10% RHA can develop the mullite phase (3Al₂O₃2SiO₂). Effect of utilizing RHA in this formula can develop greyish color of ceramic tiles. Physical properties of formula no. A7 and B13 can achieve 30.15, 24.54 MPa of bending strength and 1.91, 11.72% of water absorption. They all can pass Thai Industrial Standard (TIS 2508-2555). The result of this study can be employed to manufacture environmentally friendly fired clay tiles.

Abstract: This article presents the compressive strength and workability of cement mortar (CM) containing recycled asphalt pavement (RAP) as fine aggregate replacement. The effect of the RAP replacement, water to cement ratio, curing time, and aggregate water absorption on compressive strength and flow workability are reported. The results show that the mixing water and mixing time play a significant role in the compressive strength and unit weight of CM containing RAP. The RAP has a higher water absorption and slower rate of water absorption than those of sand. The flow workability of CM increases with RAP replacement due to the unabsorbed water at the initial mixing stage. The main negative factors that affected the compressive strength of CM containing RAP as a fine aggregate replacement are revealed. The unabsorbed water at the initial state of mixing before hardening causes increased flow workability and decreased compressive strength. The findings from this research will promote the mix design approach of CM containing RAP as a fine aggregate replacement, for moving toward increased applications of recycled materials in a sustainable manner in civil engineering construction.

Abstract: Iloprost increases the expression of angiogenic factors and increases dental pulp flow, suggesting the potential of iloprost as a biomolecule to promote dental pulp regeneration. However, the methods to clinically deliver iloprost into the limited root canal area of a tooth and control its release are limited. The purpose of this study was to prepare a thermo-sensitive injectable hydrogel from pluronic F127 (PF127) for delivering iloprost to induce dental pulp regeneration. The PF127 hydrogels were fabricated using thermal crosslinking. The maximum cumulative release iloprost from the hydrogel at 25°C was 60%. No significant cytotoxicity or morphological changes were observed in human dental pulp cells (HDPCs) at any of the PF127 gel concentrations of the iloprost carrier. Moreover, the effect of the 20%wt PF127 gels containing iloprost on the expression of VEGF in HDPCs increased vascular endothelial growth factor (VEGF) gene expression at 72 h. The thermo-sensitive hydrogel at 20%wt PF127 containing iloprost could be used for prolonged drug release in dental applications.

Abstract: This research is concerned with properties of 0.5BZT-0.5BCT through a water based gel casting process by using Ethylene Glycol Diglycidyl Ether (EGDGE) epoxy resin as a gelling agent. A solution of an ammonium salt of an acrylic polymer in water (NH₄PAA) was used as an additive in order to make the dispersion of the powders easier and provide better stability of the slurry and dispersant. The results were found that viscosities of the 0.5BZT-0.5BCT with EGDGE epoxy resin was minimised by the addition of 1.6 wt% of dispersant based on the dried powder weight. The highest green strengths of around 25 MPa were achieved at 30 wt% EGDGE resin content and 44 vol% solids loading. The gel casting samples were studied at sintering temperatures between 1300-1500 °C. The highest values of piezoelectric and dielectric properties corresponded to 0.5BZT-0.5BCT gel casting samples fabricated with a gel casting slurry incorporating 30 wt% EGDGE resin content, 44 vol% solids loading and sintered at 1500 °C, with d₃₃ and ε_r values of 310 pC/N and 2515, respectively.