Particle breakage is one of the issues that significantly affect the strength characteristics of aggregate. In this paper, the strength of pre-crushed limestone aggregate was evaluated through investigating the friction angle, stress-strain behaviour, and single-particle strength. The particle breakage phenomenon was studied for samples prepared at different conditions, including non-soaked samples, water-soaked samples, and acid-soaked samples. The purpose of preparing the samples at different conditions was to simulate the effect of environmental factors on the breakage behaviour of limestone aggregate. The test program of this paper consists of two phases of triaxial tests: the initial shearing and second shearing. The test results showed remarkable variations among the samples since limestone aggregate tended to experience more particle breakage after being soaked in water and acid solution. Also, the volume change results exhibited an increase in dilation as the breakage index increases. The test results of this study presented the importance of considering the role of environmental factors in evaluating the particle breakage of limestone aggregate.