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Thepjunthra, Wiphada
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Civil Engineering, Building, Construction & Architecture

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Unfired Bricks Mixed with Para Rubber Latex for Sustainable Construction Materials Janpetch, Natapong; Trakolkul, Chokchai; Plitsiri, Itthi; Thepjunthra, Wiphada
Civil Engineering Journal Vol 10, No 12 (2024): December
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2024-010-12-05

Abstract

This paper aims to study the development of bricks without burning, mixing para rubber latex, and compressing them with the technology of interlocking block production. The ratio of cement, lateritic soil, and water used in the mix was 1:6:11, while the percentage of para rubber latex (PRL) added was 2.5, 5, 7.5, 10, and 12.5% of the cement weight. The optimal PRL content (2.5%–7.5% by cement weight) enhances compressive strength, reduces water absorption, and improves durability, meeting the Thai industrial standard (TIS 77-2545). The PRL7.5 mixture achieved the highest performance, with a compressive strength of 21.42 MPa and a water absorption rate of 7.55%. These advancements are credited to the polymer film network formed from PRL during the hydration process, which strengthens particle bonds and reduces porosity. However, PRL content exceeding 7.5% leads to performance reductions, attributed to thicker polymer films and particle aggregation, which create larger voids within the material. Furthermore, the modified unfired bricks demonstrated enhanced crack resistance, increased ductility, and superior thermal insulation properties. Thermal tests of masonry walls confirmed that unfired bricks provide better thermal insulation. Temperature measurements revealed that houses constructed with unfired bricks consistently maintained cooler indoor temperatures compared to those made with fired bricks, indicating improved thermal efficiency. Environmentally, unfired bricks eliminate carbon emissions from firing processes and offer simpler, more energy-efficient production methods. These bricks provide sustainable alternatives to fired bricks, promoting both environmental and economic benefits for brick-making communities. Doi: 10.28991/CEJ-2024-010-12-05 Full Text: PDF
Piezometer Time-Lag and Pore Pressure Ratio for Identification of Dam Internal Erosion Thepjunthra, Wiphada; Mairaing, Warakorn; Jinakulwipat, Montri; Chalermpornchai, Thawatchai; Kunsuwan, Bunpoat
Civil Engineering Journal Vol 11, No 3 (2025): March
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2025-011-03-019

Abstract

Earth dams on complex geology without proper foundation treatment often face the risk of seepage problems. Sufficient installation and interpretation of field instruments are essential for monitoring dam behavior. Three indicators are introduced for assessment of seepage behavior: time lag (TL), pore pressure ratio (PR), and trigger water level (HW). The normalized TL reflects the washing out and plugging of rock cracks, as well as the progression of internal erosion. The foundation of the studied dam consisted of foliated rocks that were highly fractured, with the axis of the foliations aligned almost in the upstream-downstream direction, with a possible low-stress zone on the syncline axis. The existing crack easily opened in the concave section of the syncline when the reservoir had risen to a certain elevation, resulting in increased permeability and a higher flow to the downstream area, known as “hydraulic fracturing” (HF). The piezometer TL clearly indicated a shorter response time as the operating period progressed. The study dam showed the possibility of HF in the foundation, as observed during 2003–2024. The progression of HF was also confirmed by the increase in PR levels toward downstream. This revealed that the ongoing progression of HF had occurred at sta.2+700, which agreed well with the location of the slip zone that had occurred in 1993. HWwas activated by the reservoir water level response also decreasing with time from 2003 to 2024, confirming that water infiltration through the rock crack progressed with time. These three indicators could act as good warning indices for seepage problems. This compiled knowledge could be transformed into a flowchart to identify the possible risks of hydraulic fracturing in the dam. If the three indices all showed the same trend, the potential for hydraulic fracturing and internal erosion would be very high. Doi: 10.28991/CEJ-2025-011-03-019 Full Text: PDF
Enhancing Durability in Recycled Concrete: Investigating Chloride Permeability with Recycled Aggregates and Plastic Waste Jantarachot, Krissana; Prayongphan, Somchai; Yodsudjai, Wanchai; Thepjunthra, Wiphada; Trakolkul, Chokchai; Thongchart, Siranya
Civil Engineering Journal Vol. 11 No. 7 (2025): July
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2025-011-07-020

Abstract

This study investigates the effects of substituting fine aggregates with recycled plastic in recycled concrete, focusing on chloride penetration, compressive strength, workability, and porosity. Recycled plastic was incorporated at 10% (A10) and 20% (A20) by volume, and properties were evaluated across six mix designs. The control mix without plastic (Mix A) achieved the highest 28-day compressive strength (400 KSC), while A10 and A20 showed reduced strengths of 320 and 255 KSC, respectively. The addition of plastic increased mix porosity, resulting in reduced strength and workability due to diminished cement bonding and lubrication. Chloride ingress was assessed under cyclic wetting–drying exposure using a 3.5% NaCl solution. Results revealed progressive surface chloride accumulation over time. Notably, Mix A showed a 137.96% increase in chloride content at a 0–2 cm depth after 280 days, with Mix A20 exhibiting even higher surface concentrations. Chloride content consistently decreased beyond a 4 cm depth, indicating limited long-term penetration into inner layers. These findings highlight the importance of porosity control in mitigating chloride transport in recycled concrete. A clear relationship between plastic content, increased porosity, and enhanced chloride diffusion was observed. While 10% plastic substitution demonstrated acceptable performance, higher levels significantly compromised durability. The study recommends limiting plastic waste incorporation to 10% by volume and maintaining a concrete cover of at least 8–10 cm over reinforcement to enhance resistance against chloride-induced corrosion. These findings support the controlled reuse of plastic waste in sustainable concrete development, particularly for non-structural or low-exposure applications. Optimizing mix design and incorporating supplementary cementitious materials are suggested to improve long-term durability.
Co-Authors Chalermpornchai, Thawatchai Janpetch, Natapong Jantarachot, Krissana Jinakulwipat, Montri Kunsuwan, Bunpoat Mairaing, Warakorn Plitsiri, Itthi Prayongphan, Somchai Thongchart, Siranya Trakolkul, Chokchai Yodsudjai, Wanchai