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Effect of carbonic anhydrase enzymes on strength of soil cement
(2026-06-01)
Kingnoi, Namthip
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Ayawanna, Jiratchaya
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Mase, Lindung Zalbuin
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Omar, Rohayu Che
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Chaiyaput, Salisa
This research proposes the originality of using carbonic anhydrase (CA) biocatalyst enzyme with soil cement material for strength development. The soft Bangkok clay with cement up to 30 wt% of dried soil was prepared with the addition of CA at an amount of 100 µl and a concentration of 100 µM. The suitable preparation and curing method of soil cement containing CA was also investigated using different mixing methods (dry mixing and wet mixing) and curing conditions (air curing and plastic wrap curing) for up to 28 days. The improvement of soil cement strength was achieved by increasing cement content and curing time. The compressive strength of soil cement is highly improved with the addition of CA, particularly in the air-curing condition. The formation of CaCO<inf>3</inf> was observed with a tightened microstructure. In addition, the wet mixing method is favorable for improving strength with biocatalyst enzymes due to the dispersion of hydrated cement particles. Mixing small amounts of CA in soil cement not only enhances strength but also contributes to environmental sustainability, making it a viable option for sustainable future construction applications and adaptable ground improvement techniques.
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Partial soil replacement in soil cement using bentonite and polyurethane foam
(2026-06-01)
Rattanapitak, Pornkanok
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Shelina, Aza
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Ayawanna, Jiratchaya
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Kingnoi, Namthip
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Mase, Lindung Zalbuin
This study evaluates the effects of partially replacing soft clay with Ca-bentonite or polyurethane foam in soil-cement mixtures to improve geotechnical performance in soft soils. Cement content was fixed at 20% by total mix weight (% wt), while soft clay was partially replaced with Ca-bentonite or polyurethane foam at 20% wt, 30% wt, and 40% wt. Density, weight, and compressive strength were evaluated at curing ages of 7 and 28 days. The optimal mixture, determined based on compressive strength, was subsequently selected for the permeability test and compared with natural soft clay and a conventional soil-cement mixture. Moreover, scanning electron microscopy was conducted to characterize particle morphology and pore structure, providing microstructural insight into the strength behaviour of mixtures incorporating both Ca-bentonite and polyurethane foam replacements. The results indicate a clear contrast between the two replacement materials. Ca-bentonite increases density and compressive strength through pozzolanic and filling effects. The optimal sample, consisting of 50% soft clay, 20% cement, and 30% Ca-bentonite (S5C2B3) by weight, achieves a 28-day compressive strength of 9.71 MPa with stiff and brittle behaviours. Weight increase is associated with Ca-bentonite swelling, which enhances impermeability. In contrast, polyurethane foam reduces density and strength, producing a lightweight, ductile material due to its porous structure and water loss. Ca-bentonite is suitable for high-strength or low-permeability applications, whereas polyurethane foam is appropriate for lightweight fill where reduced weight is required.
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Utilization of asphalt waste Dust and fly ash for sustainable mortar
(2025-01-23)
Ayawanna, Jiratchaya
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Kingnoi, Namthip
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Sertsoongnern, Pimchanok
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Chaiyaput, Salisa
This study presents a utilization of asphalt waste dust (AD) as a filler material to replace sand in a mortar. Moreover, fly ash (FA) is utilized as an additive of pozzolanic material. The compressive strength and microstructures were investigated to propose the suitable ratio of AD and FA for sustainable mortar. All samples were fixed with a mixing ratio of ordinary Portland cement (CM): sand (Si) at 1: 2.75. The Si was replaced by AD content at 0, 50, 60, 70, 80, 90, and 100% by weight (%wt) of Si, respectively. Furthermore, the FA was added to the suitable mixing conditions of CM, AD, and Si, which is called the suitable mortar containing AD, at 0, 10, 20, 30, and 40 %wt. The results from the compressive strength test were evaluated and compared under the different curing times for 3, 7, and 28 days in saturated limewater. The microstructures of testing samples were analyzed using different characterization techniques including X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (SEM-EDS). From the results, the mortar containing AD showed higher compressive strength than those without AD. After the addition of FA and AD, the compressive strength was more increased rather than using AD without FA. Sand can be replaced with AD as filler aggregates to reduce voids in the mortar. Additionally, FA can be used as a pozzolanic additive in mortars. Therefore, those two waste materials (AD and FA) are alternative materials suitable for use in the development of compressive strength in mortar.
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Utilization of asphalt waste dust with fly ash in mixed cement materials for sustainable construction
(2024-10-01)
Sertsoongnern, Pimchanok
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Ayawanna, Jiratchaya
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Kingnoi, Namthip
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Chaiyaput, Salisa
The production of asphalt concrete generates asphalt waste dust particles that harm the environment. In this study, asphalt waste dust and fly ash were combined in different ratios to serve as cement replacement material. With replacement ratios of 20–30 wt% asphalt waste dust with fly ash, the maximum strength of a mixed-cement sample meets the industrial requirement after 7 days of curing. Compared to a cement concrete sample, a higher strength than the industrial requirement was achieved after prolonged curing under plastic wrap. This curing condition allows the retention of Ca<sup>2+</sup> ions and moisture, contributing to the hydration and pozzolanic reactions in the mixed-cement sample. The strengthened microstructure with the C–S–H phase was clearly seen, while Ca(OH)<inf>2</inf> disappeared in the mixed-cement sample. This finding indicates that upcycled asphalt waste dust in a cement-based material is a potential method for utilizing asphalt waste dust in the construction sector.
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Utilization of ladle furnace slag from a steelwork for stabilization of soil cement
(2022-10-25)
Ayawanna, Jiratchaya
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Kingnoi, Namthip
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Sukchaisit, Ochakkraphat
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Chaiyaput, Salisa
Ladle furnace (LF) slag, waste from the steel-making process, was incorporated to improve the compressive strength of soil cement. LF slag was mixed to replace the cement in the soil-cement samples with wt% ratio 20:0, 15:5, and 10:10 of cement and slag, respectively. LF slag in the range of 5, 10, and 20 wt% was also separately added to the 20-wt% cement-treated soil samples. The soil-cement mixed LF slag samples were incubated in a plastic wrapping for 7, 14, and 28 days. The strength of soil cement was highly developed to be higher than the standard acceptable value (0.6 MPa) after incorporating slag into soil cement. The mixing of LF slag resulted in more hydration products for bonding soil particles, and hence improved the strength of soil cement. With the LF slag mixing either a replacement or additive materials in soil cement, the LF slag to cement ratio is considered to be less than 1, while the cement content should be more than 10 wt%. This is to promote a predominant effect of cement hydration by preventing the partially absorbed water on slag particles and keeping sufficient water content for the cement hydration in soil cement.
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Effect of curing conditions on the strength of soil cement
(2022-06-01)
Chaiyaput, Salisa
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Arwaedo, Nakib
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Kingnoi, Namthip
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Nghia-Nguyen, Trong
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Ayawanna, Jiratchaya
An experimental program was directed to the evaluation of the strength of soil (ball clay)-cement, and soil (soft clay)-cement samples with different curing conditions; tap water, lime-saturated water, plastic wrapping, and open ambient air at 28 days. The compression, and the scanning electron microscopy results were used to describe the effect of curing conditions on the compressive strength of soil-cement samples. The compressive strength of soil-cement samples was ~ 50% that of the plain cement sample. The compressive strength of the soft clay-cement samples was slightly higher than the ball clay-cement samples because of the coarse particles of soft clay containing a high amount of quartz, allowing the water to react with cement powder and increased the strength of soil-cement samples. The tendency of compressive strength development in the soil-cement samples was similar to that of the cement sample. The highest compressive strength was obtained for the lime-saturated water cured samples, suggesting a higher rate of hydration process by the protection of CaCO<inf>3</inf> leaching from cement in the lime water. Thus, the compressive strength in soil-cement samples was enhanced by the binding of cement hydration products between the adjacent soil particles.

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