The Use of EDX to Detect Causes of Unachieved Concrete Quality in Batching Plant Models

Abstract

This study investigates the impact of Type D additive, Plastiment 83 AM, on the compressive strength and microstructure of Portland Composite Cement (PCC) concrete with a target compressive strength of 18.7 MPa, utilizing a mixing, stirring, and treatment model that simulates batching plant conditions. The study investigated additive dosages of 0%, 0.15%, 0.25%, 0.35%, and 0.40%, with stirring durations of 15 min, 2, 4, 6, and 6.5 h. Compressive strength tests were conducted at the ages of 7, 14, 28, 56, and 90 days on cylindrical specimens, and at 24 h for setting time tests. Microstructural analysis using Energy Dispersive X-ray Spectroscopy (EDX) was performed at 56 days of age. The results showed that the optimal dosage was 0.15%, combined with the addition of Plastiment 83 AM 0.10% at 2 h of stirring, which achieved the highest compressive strength of 20.5 MPa at 90 days. A reduction in compressive strength of the setting time samples from the initial value to 24 h was observed in mixtures stirred for 6 and 6.5 h. A decrease in compressive strength was also observed in both mixtures between 56 and 90 days. EDX analysis revealed different chemical compositions in each mix. At a stirring duration of 6 and 6.5 h, Plastiment 83 AM dosages of 0.35% and 0.40% showed the presence of Magnesium (Mg) and Aluminium (Al) (at 6 h) and Al and phosphorus (at 6.5 h). The presence of inhibited the hydration process, resulting in a very small increase in compressive strength from 14 to 28 days. Magnesium reduced the compressive strength to 75%, and phosphorus to 63% of the target compressive strength.