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Penggunaan fly ash sebagai bahan tambahan untuk menggantikan sebagian semen merupakan salah satu hal untuk mendorong penggunaan material alternatif. Penelitian ini mengkaji pengaruh persentase substitusi fly ash sebesar 10%, 30%, dan 50% dengan penambahan zat aditif superplasticizer sikament-NN (Tipe F) dengan dosis 1,2% terhadap kemudahan pengerjaan (workability) dan kekuatan tekan beton. Kinerja beton dianalisis berdasarkan kekuatan tekannya pada hari ke-28 dab kelancaran kerjanya berdasarkan slump. Hasil penelitian ini menunjukan bahwa kombinasi penggunaan fly ash dan superplasticizer sikament-NN (Tipe F) dapat meningkatkan kemudahan adukan, dengan nilai slump maksimum mencapai 14,3 cm pada presentase fly ash 50%. Namun, peningkatan kelacakan ini berbanding terbalik dengan kekuatan tekan yang konsisten menurun seiring dengan peningkatan penambahan fly ash. Nilai kuat tekan maksimum dicapai oleh campuran beton yang hanya menggunakan superplasticizer tanpa fly ash sebesar 320,50 kg/cm2, sementara nilai yang optimal ditemukan pada variasi persentase 10% dengan penambahan superplasticizer 1,2% menghasilkan kuat tekan sebesar 307,65 kg/cm2, sehingga penggunaan kombinasi ini diharapkan dapat memberikan kontribusi efisiensi bagi rekayasa sipil.

Modern infrastructure development often involves the use of mass concrete in large structural elements such as pile caps and foundations. However, massive concrete volumes trigger a significant temperature increase due to the heat of hydration that is difficult to dissipate, posing a risk of thermal stress and structural cracking. This study aims to analyze the temperature rise behavior of mass concrete and evaluate the effectiveness of combining chilled water and fly ash substitution in minimizing these thermal cracking risks.The research method employs a quantitative approach through laboratory testing at PT Adhimix RMC Plant Kaligawe. Specimen blocks measuring 40 x 40 x 100 cm were divided into three variations: normal concrete (BN), concrete with chilled water and 15% fly ash (BAF), and concrete with 25% fly ash (BF). Temperature was monitored using thermocouples at the core and surface for 14 days, then validated using the Portland Cement Association (PCA) formula. The results indicate that the integration of chilled water with 15% fly ash and the use of 25% fly ash significantly controlled extreme temperature surges at the 5th hour. The combination of chilled water and 15% fly ash produced the lowest core temperature of 37.3°C, far below the control concrete which reached 62.4°C. This proves that the combination of precooling methods and fly ash substitution is effective in reducing the heat of hydration during the early hardening period, although the use of 25% fly ash was found to be more stable in maintaining mass concrete temperature.

Self-Compacting Concrete (SCC) requires a high cement content, which contributes to increased carbon emissions; therefore, this study evaluates the effect of partial cement substitution with fly ash (5%, 10%, and 15%) and the addition of Polyethylene Terephthalate (PET) waste (0.5% and 0.7%) on the mechanical properties of SCC with a target strength of f’c 30 MPa. The research employed laboratory experimental methods, including fresh concrete tests (slump flow, L-box, and V-funnel) and hardened concrete tests (compressive, tensile, and flexural strength) at 7 and 28 days. The results indicate that fly ash substitution enhances compressive strength, with the highest value of 49.59 MPa achieved at 5% fly ash at 28 days, exceeding normal concrete (34.73 MPa). The addition of PET tends to reduce compressive strength due to increased porosity; however, it significantly improves flexural strength, as the combination of 5% fly ash and 0.5% PET achieved 4.7 MPa compared to 2.9 MPa for normal concrete. Overall, the combination of fly ash and PET waste shows potential for application in structural elements requiring high flexural performance.

Human activities, from household to industrial operations, generate liquid waste that poses a threat to the environment. Before discharge, liquid waste should be treated to ensure it is safe for release into the environment. This study aims to evaluate the effectiveness of a hybrid ozonation-adsorption method with varying contact times. This study collected leachate samples from the Rajabasa Landfill and used fly ash from the Tarahan Coal-Fired Power Plant as the adsorbent. First, the study used contact times of 20, 40, 60, and 80 minutes for ozonation. Subsequently, the 80-minute sample proceeded to the adsorption stage and was ultimately tested against six parameters. The measured parameters included COD, TSS, TDS, turbidity, UV254, and DO. The results showed that the 80-minute ozonation process significantly reduced TSS, TDS, and DO levels. However, the ozonation process still left intermediate compounds, which were subsequently removed by adsorption. Ultimately, the combination of the two processes yields good results, particularly for COD and UV254. This aligns with the theory that ozonation breaks down complex compounds while the adsorbent absorbs residual pollutants. This hybrid process achieves a 45.47% reduction in COD and an 87.83% reduction in UV254.

The increasing demand for housing in tropical regions requires building materials that are fast to apply, environmentally friendly, and resilient to extreme climate conditions as well as disaster risks. Conventional interlocking bricks are often chosen for their ease of construction, yet they still face challenges such as moisture and early cracking. This study proposes the innovation of the Hybrid Living Green Brick, a combination of lightweight bricks made from rice husk ash and fly ash waste (FRCB) with a biological layer of cyanobacteria. FRCB improves compressive strength by approximately 30% with the addition of 5% rice husk ash, achieving 65 kg/cm², thereby meeting Class 50 requirements (≥50 kg/cm²) according to SNI-15-2094-2000. The incorporation of 3% cyanobacteria provides an additional though not significant strength improvement, while still within the Class 50 category. It also reduces brick weight by 4.3%, with further optimization potential through cyanobacteria integration, and lowers carbon emissions from the firing process. Cyanobacteria induce the formation of CaCO₃ layers that seal pores, reduce water absorption by an average of 10%, and provide self-healing properties for microcracks. Preliminary observations indicate that FRCB offers stable mechanical performance, while biological activity was observed on the 7th day with the formation of pale-white mineral layers continuing until the 28th day. This hybrid innovation shows potential to support sustainable and disaster-resilient tropical construction by combining the mechanical strength of waste-based materials with the biological durability of cyanobacteria against extreme climates. Despite challenges related to moisture control and production standardization, the Hybrid Living Green Brick concept opens new pathways for developing environmentally friendly construction materials that are more adaptive to disaster-prone tropical conditions.

In general, infrastructure development requires materials from nature and one of them is natural coarse aggregate of crushed stone. The rapid development of infrastructure in Indonesia has resulted in the depletion of the natural coarse aggregate. Therefore, other efforts are needed in terms of using coarse aggregate as a construction material. So in this study the aim is to make artificial coarse aggregate made from fly ash. The results showed that this artificial coarse aggregate met the requirements of the General Specifications of Bina Marga 2010 rev 3 as a construction material, namely for an abrasion value of 40% and water absorption of 3%. In this study, 5 types of comparisons were carried out, namely, 70:30%, 60:40%, 50:50%, 40:60%, 30:70 and for the type of composition comparison 70:30% (70% fly ash:30% cement). ) the abrasion value is still below 40%, and the amount of water absorption is below 3% so that this artificial coarse aggregate still meets the standard specifications of General Highways 2010 rev 3. Based on the price comparison that has been made between artificial coarse aggregate and natural coarse aggregate of crushed stone , shows a price disparity of Rp. 35,779 - Rp. 58,779. Thus, this artificial coarse aggregate is one solution that can be developed to reduce the environmental impact due to the presence of fly ash which is quite abundant in Indonesia.

Fly ash and bottom ash (FABA) are combustion residues from coal-fired power plants. Following the issuance of Government Regulation No. 22 of 2021, FABA is no longer classified as hazardous and toxic waste (B3). However, FABA must still be managed properly due to its potential to cause pollution through leachate generated if leaks occur in the FABA disposal area. This study evaluates the lining and drainage systems in the FABA disposal area at PT. PLN Nusantara Power UP Paiton to ensure that leachate does not contaminate surrounding groundwater. The research employs descriptive qualitative and quantitative methods, collecting secondary data to assess the structure and pollution control systems in the FABA disposal area at PT. PLN Nusantara Power UP Paiton. The data includes the disposal area structure and water quality from monitoring wells. Analysis results indicate that the FABA disposal area lining system operates effectively and in compliance with regulations, successfully containing leachate movement and preventing seepage. This is supported by pH, Fe, Hg, and turbidity levels in groundwater from monitoring wells remaining within safe limits. Additionally, the presence of a runoff pond helps contain surface runoff during heavy rain, keeping overflow water under control. Overall, the disposal area structure and leachate management system at PT. PLN Nusantara Power UP Paiton function well, but routine monitoring must continue to ensure no seepage occurs, preventing leachate from contaminating the surrounding environment as an early preventive measure to maintain environmental quality and regulatory compliance.