KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/kmitl/1

Browse

Settings

Access type: UnknownSubject: search.filters.subject.Flexural strength

Search Results

Now showing 1 - 2 of 2
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Effects of milling followed by different gradation sizes of lawrencepur sand on the properties of cementitious mortar
    (2025-12-01)
    Aslam, Hafiz Muhammad Shahzad
    ;
    Aslam, Hafiz Muhammad Usman
    ;
    Onyelowe, Kennedy C.
    ;
    Noshin, Sadaf
    ;
    Yasin, Mazhar
    The swift rise of urbanization and industrialization has severely depleted natural sand resources and escalated industrial waste accumulation. Environmental damage from over-dredging and limited disposal space has driven researchers to seek alternative solutions. In Lahore, Punjab, Pakistan, coarse pit sand is predominantly used, and overly fine sands from the Ravi and Chenab rivers, which do not meet ASTM grading standards. In this research, Lawrencepur Sand was milled, and its effects on the sand's physical properties and the mortar's mechanical performance were evaluated. For this, comprehensive experimental investigations were conducted, and the mechanical properties of the mortar were assessed at 3, 7, and 28 days. From the experiment, it is clear that milling refines the physical properties of sand by decreasing size, fineness modulus (FM), and absorption, while increasing density and specific gravity, which enhances mortar performance. Milled sand improved mortar density (3.1–11.5 %), compressive strength (10.6–71.4 %), and flexural strength (13.5–48 %), while reducing water absorption by 9–34 %. Excessive milling reduced strength and increased water absorption. SPSS analysis confirmed that milled sand significantly improved mortar performance, with strong statistical validation (p < 0.001). Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analysis also confirmed microstructural densification of mortar by milling, and over-milling led to a decline in performance due to poor packing.
      1
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    High-entropy gallium-based garnet microwave dielectric ceramics with low loss for C-band dielectric resonator antenna application
    (2025-11-01)
    Wen, Xinyang
    ;
    Xiang, Huaicheng
    ;
    Gu, Xiaolong
    ;
    Pulphol, Phieraya
    ;
    Vittayakorn, Naratip
    In this work, (Y<inf>0.5</inf> Nd<inf>0.5</inf> Sm<inf>0.5</inf> Eu<inf>0.5</inf> Ho<inf>0.5</inf> Yb<inf>0.5</inf> )Ga<inf>5</inf> O<inf>12</inf> high-entropy ceramic with a cubic garnet structure was designed and synthesized via a solid-state reaction method. Through the high-entropy regulation of the oxygen dodecahedron, the bond strength increases, the cation's bond valence approaches the ideal value, and the structural stability improves, thereby promoting the Q × f value. Low dielectric loss (Q × f = 130,100 GHz) was obtained in the high-entropy ceramic (Y<inf>0.5</inf> Nd<inf>0.5</inf> Sm<inf>0.5</inf> Eu<inf>0.5</inf> Ho<inf>0.5</inf> Yb<inf>0.5</inf> )Ga<inf>5</inf> O<inf>12</inf> , which exhibited a low relative permittivity (ε<inf>r</inf> ) of 12.36, a negative temperature coefficient of resonant frequency (τ<inf>f</inf> ) of −66.37 ppm/°C, and a high flexural strength of 229.68 MPa. Furthermore, a cylindrical dielectric resonator antenna (CDRA) was designed featuring high radiation efficiency (>90 %) and stable gain (5.91–5.97 dBi) within a 255 MHz bandwidth, showing promising application prospects in the C-band. This work indicates that the high-entropy strategy is feasible for the design of high-performance microwave dielectric ceramics.