The quest for sustainable alternatives to Portland cement has led to the exploration of a range of materials or their combinations, often with the aim of exploiting synergies in reactions or particle packing to maximize performance. Simultaneous optimization of both presents a viable option to increase the efficiency of cementitious materials. The objective of this study was to evaluate the effect of varying the fineness of the constituents in ternary blends of CEM I – granulated ground blast furnace slag (GGBS) - limestone on hydration kinetics and strength development. Eight (8) ternary cement mixes were tested at 0.5 water/binder (w/b) ratio. Hydration was followed by isothermal conduction calorimetry and setting time. In addition, X-ray powder diffraction, thermogravimetric analysis and compressive strength development up to 180 days of curing were assessed. The efficiency associated with changing the fineness of each component was evaluated in terms of the net heat of reaction and compressive strength. The results show that fine CEM I is critical for hydration at early age, and this is reflected in the compressive strength accordingly. The benefits associated with finer GGBS and similarly limestone depend on the fineness of the other constituents in the blend. Optimization of these should consider the inter-dependencies in terms of kinetics and microstructure development.

Concrete exposed to cyclic freezing and thawing may deteriorate by surface scaling, internally developed cracks or both in combination. The rate of deterioration tends to be accelerated in concretes containing higher levels of supplementary cementitious materials including slag and limestone. A fundamental insight into the relationship between cement composition and freeze–thaw resistance is therefore imperative for developing durable composite cement concretes. Concrete samples prepared from CEM I, binary slag cements and ternary limestone slag cement blends at 0·5 w/b ratio without air entrainment were investigated. The freeze–thaw test was based on the CIF method according to PD CEN/TR 15177. Additionally, phase assemblages in the concretes before and after freeze–thaw damage were evaluated. Before freeze–thaw testing, compressive strengths were similar but the composite cements were slightly more susceptible to carbonation. However, the scaling and internal damage resistance decreased in the order of CEM I, binary and limestone ternary blended cements. The composition of the scaled material differed from the bulk, revealing an absence of portlandite and a marked reduction in AFm and ettringite contents. A probable explanation for the reduced freeze–thaw resistance includes the porosity differences and the lower portlandite content compared to CEM I concrete.