This paper presents the results of an experimental investigation on the material properties and self-healing ability of a blended cement mortar incorporating blast furnace slag (BFS). The effect of different types and Blaine fineness of BFS on the material properties and self-healing was investigated. Thirteen cement mixtures with BFS of different types and degrees of Blaine fineness are tested to evaluate the mechanical properties, namely compressive strength, bending strength, freeze–thaw, and accelerated carbonation. The pore structure is examined by means of mercury intrusion porosimetry. Seven blended mortar mixtures incorporating BFS for cement are used to evaluate the mechanical properties after applying freeze–thaw cycles until the relative dynamic modulus of elasticity reached 60%. The experimental results reveal that incorporating BFS improves the mechanical properties and self-healing ability. In the investigation of self-healing, smaller particle and high replacement ratios of BFS contribute to increasing the relative dynamic modulus of elasticity and decreasing the carbonation coefficient in the mortar after re-water curing. Moreover, BFS’s larger particles and high replacement ratio are found to provide better self-healing ability. A regression equation is created to predict the relative dynamic modulus of elasticity in mortar considering the Blaine fineness, BFS replacement ratio, and curing conditions.

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The objective of this study was to determine the influence of environmental conditions on the pore structure of mortar. For this purpose, the experimental program was designed with the following two series: Series 1 included both a 10year outdoor exposure test set and a laboratory test set and Series 2 included only a laboratory test set. The pore structure of mortar specimens was evaluated using the Mercury Intrusion Porosimetry method. In general, the pore structure change due to temperature in both the outdoor exposure test and the laboratory test showed the same tendency. The test results confirmed that the pore structure of mortar coarsened and that the volume of pores with a diameter range of 40 to 2000 nm increased due to the increase in temperature and the decrease in relative humidity. Furthermore, this paper reports evidence for the relationship between pore structure change and maturity, and an improved maturity function is proposed. The change in the pore structure is determined by the proposed maturity function, which considers the curing temperature history and the relative humidity. The relative humidity is an additional and novel factor forming the new maturity function for the prediction of pore structure change.