Experimental Study on PPC and Citric Acid Influence on Compressive Strength of Reinforced Concrete
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Date
2025-06
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Addis Ababa University
Abstract
The aim of this experimental study is to investigate the combined effect of partially replacing ordinary Portland cement (OPC) with Portland Pozzolana Cement (PPC) and incorporating citric acid by weight of PPC as chemical admixture on the compressive strength performance of reinforced concrete. PPC, known for its environmental benefits and long-term strength development, is evaluated alongside citric acid, which acts as a set retarder and potential performance enhancer. The experimental work includes tests on setting time, workability, and compressive strength for concrete mixes incorporating varying dosages of citric acid with PPC. The experimental research involved creating concrete samples specifically for C-30 concrete grades, a common choice for reinforced concrete projects, having water cement ratio of 0.50. Concrete samples are created using OPC, PPC and also PPC mixed with citric acid & slump in the range of 50 – 100mm. Citric acids was added to retard the setting time, to enhance the workability & ultimate compressive strength of concrete. Setting time, Slump & compressive strength tests for 0.1%, 0.2%, 0.3% & 0.4 % additions of citric acid by weight of Portland Pozzolanic Cement were performed. Cost comparison was also done between concrete mixes made with OPC and PPC with Citric acid. The laboratory results assure that the optimum dosage of citric acid is 0.3% by weight of PPC cement. This dosage causes a delay in initial and final setting time of 1hr 50 min & 3hr 10 min, respectively; 15% water reduction; a comparable compressive strength result with OPC mix and meets the requirements listed in ACI 301; and an increase in slump length of 55% relative to reference concrete. The laboratory test result shows that as compared with the reference mix, satisfactory setting time, slump & compressive strength result was obtained from concrete mix made with PPC in combination with Citric acid. Moreover, the combination of PPC and citric acid demonstrates promising potential for sustainable and performance-optimized reinforced concrete. This study contributes valuable insights for engineers and researchers seeking to enhance the performance and sustainability of concrete construction materials.
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OPC = Ordinary Portland cement, PPC = Portland Pozzolana Cement, Concrete, CA = Citric acid, Setting time, Workability, Compressive Strength