Investigation of the Effect Fly Ash on the Water pH of the Concrete Mixture in Terms of Compressive Strength and Absorption
Sandra Ajeng Liliani*, Gabriel Jose Posenti Ghewa, Marsela Febriani Jehudu
1Department of Civil Engineering, Gadjah Mada University, Yogyakarta, INDONESIA
2Departemen of Civil Engineering, Soegijapranata Catholic University, Semarang, INDONESIA
*Corresponding author: sandraajengliliani@mail.ugm.ac.id
INTISARI
Indonesia’s construction industry often encounters challenges related to the availability of water with a neutral pH (7), particularly in regions with aggressive environmental conditions such as peatlands and sulfate-rich areas. Acidic water, characterized by a low pH, can negatively affect the properties of concrete, leading to decreased durability and strength. This study investigates the effectiveness of fly ash as an additive to neutralize acidic water (pH 5) and its influence on the compressive strength and water absorption of concrete. The experimental program includes three variations of concrete mixtures: (1) concrete mixed with neutral pH water, (2) concrete mixed with acidic water (pH 5), and (3) concrete mixed with acidic water that has been neutralized using fly ash. The acidic water was simulated by adding 2.5 mL of hydrochloric acid (HCl) to 10 liters of water. Neutralization was achieved by dissolving 200 grams of fly ash per liter of water for 5–15 minutes, resulting in a pH level of 7. Compressive strength and absorption tests were conducted on cylindrical specimens, with dimensions of 15 cm × 30 cm for compressive strength and 10 cm × 5 cm for water absorption, at curing ages of 28 and 56 days. The results show that concrete mixed with acidic water exhibited a decrease in compressive strength compared to concrete mixed with neutral pH water. However, concrete produced with fly ash-treated water demonstrated improved compressive strength, indicating that fly ash
contributes to pH stabilization and enhances hydration.reactions. The absorption tests reveal that concrete mixed with acidic
water has a higher absorption rate due to increased porosity, whereas fly ash-treated concrete shows reduced absorption, indicating improved durability
REFERENSI
ACI Committee 232. Use of fly ash in concrete (ACI 232.2R-03). American Concrete Institute: Farmington Hills,
MI; 2003. p. 41.
Arunakanthi E., Rao H. Sudarsana and Reddy I.V. Ramana (2012) “Effects of Hydrochloric Acid in Mixing And
Curing Water on Strength of High-Performance Metakaolin Concrete” International Journal of Applied Engineering
and Technology Vol. 2 (2) April-June,pp.68-76. ISSN: 2277-212X
ASTM C 642 – 06. Standard test method for density, absorption and voids in hardened concrete. American Society
for Testing and Material.
ASTM C39/C39M – 14. Standard test method for compressive strength of cylindrical concrete specimens. American
Society for Testing and Material.
Carroll, R., Jeffries, T. C., & Reynolds, J. K. (2025). Sulfur Regulation on Microbial Biodiversity in a Montane
Peatland. European Journal of Soil Science, 76(1). https://doi.org/10.1111/ejss.70045
Fatimah, I. N., Budi, A. S., dan Sangadji, S. (2018): Pengaruh kadar fly ash terhadap kuat tekan pada high volume
fly ash-selfcompacting concrete (HVFA-SCC) benda uji D 15 cm x 30 cm usia 28 hari, e-Jurnal MATRIKS TEKNIK
SIPIL, 508-512.
Gobel, A. P., Nursanto, E., dan Ratminah, W. D. (2018): Efektifitas pemanfaatan fly ash batubara sebagai adsorben
dalam menetralisir air asam tambang pada settling pond penambangan banko PT. Bukit Asam (Persero), Tbk. Jurnal
Mineral, Energi Dan Lingkungan, 2 (1), 1.
Hatungimana, D., Taşköprü, C., İçhedef, M., Saç, M. M., dan Yazıcı, Ş. (2019): Compressive strength, water
absorption, water sorptivity and surface radon exhalation rate of silica fume and fly ash based mortar, Journal of
Building Engineering, 23, 369–376.
Indexed, S., Oyebisi, S., Ede, A., Ofuyatan, O., Oluwafemi, J., State, O., Olutoge, F., & State, O. (2018).
MODELING OF HYDROGEN POTENTIAL AND COMPRESSIVE STRENGTH OF GEOPOLYMER
CONCRETE. 9(7), 671–679.
Kucche, K. J., Jamkar, S. S., & Sadgir, P. A. (2015). Quality of Water for Making Concrete : A Review of.
International Journal of Scientific and Research Publications, ISSN:2250-3153, 5(1), 1–10.
M. Tokyay, Cement and Concrete Mineral Admixtures, ixtures, Taylor & Francis Group,New York, 2016, p. 12.
Mahmoud, S., Mawlood, I. A., & Hilal, N. N. (2019). Influence of Mix Water Quality on Compressive Strength of
Making Concrete Influence of Mix Water Quality on Compressive Strength of Making Concrete. November, 1–5.
Moayedi H, Kassim K A, Kazemian S, Raftari M, and Mokhberi M. (2014): Improvement of Peat Using Portland Cement and Electrokinetic Injection Technique Arabian Journal for Science and Engineering 39(10) 6851–6862
Nagrockiene, D., Rutkauskas, A., Pundiene, I., & Girniene, I. (2019). The Effect of Silica Fume Addition on the
Resistance of Concrete to Alkali Silica Reaction. IOP Conference Series: Materials Science and Engineering, 660(1), 599–609. https://doi.org/10.1088/1757-899X/660/1/012031
Nath, P., & Sarker, P. (2011). Effect of fly ash on the durability properties of high strength concrete. Procedia
Engineering, 14, 1149–1156. https://doi.org/10.1016/j.proeng.2011.07.144
Prayuda, H., Setyawan, E. A., dan Saleh, F. (2017): Analisis sifat fisik dan mekanik batu bata merah di Yogyakarta,
Jurnal Riset Rekayasa Sipil, 1 (2), 94.
Regunathan, P. (2015). A review on the compressive strength of concrete improved with various types of pozzolan.
April, 8–9.
Ritung S, Wahyunto N K, Sukarman H and Suparto TC. (2011): Peta Lahan Gambut Indonesia Skala 1: 250.000 BB
Litbang SDLP Bogor
Rommel, E., Wahyudi, Y., dan Dharmawan, R. (2015): Tinjauan permeabilitas dan absorpsi beton dengan
menggunakan bahan fly ash sebagai cementitious, Jurnal Media Teknik Sipil, 13 (2), 141–145.
Taylor, J., Pape, S. dan Murphy, N. (2005): A summary of passive and active treatment technologies for acid and
metalliferous drainage (AMD). In Proceedings of the in Fifth Australian workshop on Acid Mine Drainage, 31–43.
Tizia, H., Olivia, M., dan Saputra, E. (2020): Kuat tekan dan porositas beton menggunakan air gambut dan kapur
tohor untuk konstruksi di lingkungan gambut. Jurnal Teknik, 14 (1), 61–68.
Zhang, S. P., dan Zong, L. (2014): Evaluation of relationship between water absorption and durability of concrete
materials, Advances in Materials Science and Engineering, 4-5.