Engineering Journal of Research and Development

APPLICATION OF STANDARD TIME FOR WATER TANK FOUNDATION INSTALLATION USING DIRECT TIME STUDY

Tue, 30 Jun 2026 00:00:00 +0700

Effective time management is a critical factor for the success of construction projects. The construction of water tank foundation installation is a repetitive, high-volume activity, and establishing a time standard is essential for effective project planning and control. This study provides the standard time of water tank foundation installation, which was conducted through a direct time study of 25 water tank bases at Rajamangala University of Technology Lanna, Doi Saket, Chiang Mai Province. The results indicate that the construction process comprises nine sub-activities, with an average standard time of 401.15 minutes, or approximately 6 hours and 41 minutes at 25 bases. The three most time-consuming activities were site preparation and layout at 68.00 minutes, or approximately 1 hour and 8 minutes, ready-mixed concrete pouring at 62.29 minutes, or approximately 1 hour and 2 minutes, and cutting of DB16 SD40 steel reinforcement at 60.43 minutes, or approximately 1 hour, respectively. Although these specific tasks required considerable time due to their inherent complexity, the measured standard time accurately reflects normal productivity levels. This accuracy is attributed to the highly skilled workforce and favorable weather conditions during the study. Ultimately, the standard time derived from this study can be effectively applied to construction planning, cost estimation, productivity assessment, and process improvement.

PERFORMANCE OF SOIL EROSION CONTROL USING GEOCELL COMBINED WITH RUZI GRASS

Ratchanon Thiju, Pitthaya Jamsawang — Tue, 30 Jun 2026 00:00:00 +0700

Soil erosion on slopes induced by rainfall is a critical problem, as rainfall intensity is a major factor that reduces slope stability and may lead to slope failure. This study aims to investigate the erosion control performance of geocells installed in different configurations and the integrated application of geocells with Ruzi grass under varying slope gradients and rainfall intensities. Laboratory experiments were conducted using soil collected from the Lamtakhong Dam area, Nakhon Ratchasima Province. The tests were performed in a flume simulating three slope gradients of 30°, 45°, and 60°, under simulated rainfall intensities of 100, 130, and 170 mm/h. Geocells were installed in ten different configurations to evaluate their effects on surface runoff, soil loss, and sediment concentration. In addition, the combined use of geocells and Ruzi grass was examined by considering Ruzi grass growth periods of 2, 4, 6, and 8 weeks. The results indicate that geocell installation significantly reduces surface runoff and soil loss, with maximum reductions of approximately 65.8% in surface runoff and 89.2% in soil loss compared with the flume without geocells. The erosion control efficiency increases with the proportion of geocell coverage and decreases as slope gradient and rainfall intensity increase. The combined application of geocells and Ruzi grass further enhances erosion control performance, particularly when Ruzi grass reaches full growth. It can be concluded that the integrated use of geocells and Ruzi grass is an effective and suitable approach for designing slope erosion control systems under high-intensity rainfall conditions.

PERFORMANCE EVALUATION OF WIND BARRIERS WITH VARYING POROSITY ON BRIDGE DECK USING COMPUTATIONAL FLUID DYNAMICS

Jirawat Junruang, Virote Boonyapinyo — Tue, 30 Jun 2026 00:00:00 +0700

This study evaluates the performance of wind barriers in reducing wind speeds across a bridge cross-section using Computational Fluid Dynamics (CFD) simulations. The investigation compares the aerodynamic effects of wind barriers with porosity levels of 23% and 54%, respectively. The findings indicate that the bare bridge section, without wind barriers, poses the greatest risk because the airflow directly strikes the traffic surface. Installing 23%-porosity wind barriers on both sides provides the most effective wind shielding, creating a low-velocity zone that covers the entire width of the traffic area. When porosity increases to 54%, wind speed over the bridge deck rises in proportion to the open area, significantly reducing the shielding efficiency. Furthermore, the analysis of installation positioning shows that placing a barrier on the windward side alone can achieve wind speed reductions comparable to those of a double-sided installation. Conversely, installing a barrier solely on the leeward side fails to decelerate the airflow over the traffic surface. In conclusion, wind barriers with 23% porosity reduced wind speed by 65–92% at a height of 2.53 m above the road surface. Therefore, considering the prevailing wind direction is a critical factor in designing efficient wind protection systems for bridge structures.

FLEXURAL PERFORMANCE UNDER WET-DRY CYCLES OF CEMENT-EUCALYPTUS ASH CRUSHED ROCK REINFORCED WITH POLYPROPYLENE FIBERS

Nutt Sabkum, Pitthaya Jamsawang — Tue, 30 Jun 2026 00:00:00 +0700

Cement-treated base incorporating eucalyptus ash (CTB-EA) is a promising pavement material due to its high strength and potential sustainability benefits. However, CTB-EA generally exhibits brittle behavior under flexural loading, resulting in limited post-cracking load-carrying capacity and energy absorption. Therefore, this study investigated the effect of polypropylene fiber reinforcement on the flexural performance of CTB-EA. Flexural tests were conducted in accordance with ASTM C1609 using fiber contents ranging from 0 to 1.25% by volume. In addition, the durability of the material was evaluated under 0, 1, 3, 6, 9, and 12 wetting–drying cycles. The results showed that the incorporation of polypropylene fibers significantly improved the residual flexural strength and toughness of CTB-EA. When the fiber content exceeded 0.50% by volume, the material behavior changed from deflection-softening to deflection-hardening, indicating a transition from brittle to ductile behavior with enhanced post-cracking performance. Among the investigated mixtures, a fiber content of 0.75% provided a favorable balance between flexural strength, residual strength, and toughness. Wetting–drying cycles progressively deteriorated the flexural performance of all mixtures due to the development of microcracks and degradation of internal bonding. Nevertheless, fiber-reinforced specimens maintained considerably higher toughness and post-cracking load-carrying capacity than the unreinforced mixture, even after 12 wetting–drying cycles. The findings demonstrate that polypropylene fibers effectively enhance the flexural performance, toughness, and durability of CTB-EA under wetting–drying conditions, thereby improving its suitability for pavement base applications.

SWELLING BEHAVIOR OF EXPANSIVE SOIL IMPROVED WITH EUCALYPTUS ASH THROUGH SHALLOW MIXING

Songkran Sukcharoen, Pitthaya Jamsawang — Tue, 30 Jun 2026 00:00:00 +0700

Expansive clay is a geological material commonly classified as a problematic soil due to its high free swelling potential upon water absorption, which often leads to damage to buildings and engineering structures. Stabilizing agents such as cement and lime have been widely used to control the swelling behavior of this type of soil. However, eucalyptus ash, a byproduct of biomass combustion, contains major chemical constituents such as calcium oxide (CaO) and calcium carbonate (CaCO₃), enabling it to function as a promising alternative stabilizing agent in terms of effectiveness, cost efficiency, and waste utilization. This study aims to investigate the free swelling potential behavior (maximum swelling: Smax) of expansive clay partially replaced with eucalyptus ash using the shallow mixing technique to produce a composite material with reduced swelling characteristics. Smax tests were conducted on both untreated soils and soils stabilized with eucalyptus ash. Two types of expansive clay were considered: (1) synthetic clay composed of kaolinite and bentonite, and (2) natural expansive clay obtained from the Mae Moh area. The synthetic clay was proportioned to achieve an Smax value comparable to that of the natural clay, serving as a reference baseline for evaluating the effectiveness of eucalyptus ash in reducing swelling under different soil textures and mineralogical compositions. In addition, the effects of varying replacement ratios of eucalyptus ash were examined to determine the optimum ash content, along with an assessment of the influence of the stabilized thickness ratio (STR) on Smax.