This study examined the physical properties of a three-component mineral binder that is typically used in deep-cold recycling. Test binders were produced using Portland cement, hydrated lime, and cement bypass dust (CBPD) as a byproduct derived from cement production. The suitability of CBPD for use in road binders was assessed. Effects of the three-component binder composition on the setting time, soundness, consistency, and tensile and compressive strengths of the cement pastes and mortars were determined. The pastes and mortars of the same consistency obtained at different w/b ratios were tested. On this basis, the mixture proportions resulting in road binders satisfying the requirements of PN-EN 13282-2:2015 were determined. By mixing cement, lime, and CBPD during the tests, binder classes N1 to N3 were obtained. The replacement of 40% of cement mass with the CBPD high in free lime produced road binders suitable for recycled base layers. The total content of CBPD and hydrated lime in the road binder should not exceed 50% by mass. The potential risk of mortar strength reduction due to KCl recrystallization was discussed.

Damage to concrete structures may occur as a result of internal effects. Alkali silica reaction (ASR) is a long term reaction between alkalis and reactive

Alkali-silica reactivity of expanded glass granules in structure of lightweight concrete G Bumanis, D Bajare, J Locs et al.-Effect of mineral additives (natural pozzolana and sand of dunes) by substitution of cement on the performance and durability of mortars

The paper reports the results of the tests used to determine hydration kinetics, physical properties and microstructure of hydraulic road binders. Seven hydraulically bound mixes were produced by mixing Portland cement (CEM I 32.5R), hydrated lime, and cement by-pass dust (CBPD) in proportions established as per the experimental plan. Cement by-pass dust was found to have the greatest effect on the increased water demand, hydration heat and soundness of the binder paste. Minerals derived from the hydration of input components were identified in the composition of the binder phases. In CBPD rich binders sylvite and calcium chloro-aluminate hydrate were present. The test results show that when planning the use of normal setting hydraulic road binders containing CBPD in road construction, the water to binder ratio w/b must be taken into account to ensure proper consistency, soundness, and amount of hydration heat release.

Alkali-silica reaction (ASR) is a reaction between amorphous or poorly crystallized siliceous phase, present in aggregates, and sodium and potassium hydroxides in the pore solution of concrete. Chemical admixtures such as lithium compounds are known to have high potential of inhibiting ASR. The aim of this study was to determine the effect of lithium nitrate on ASR in mortars containing high reactive opal aggregate over a long period of time. Mortar bar expansion tests were performed and microstructures of mortar bars were observed by scanning electron microscopy coupled with an energy dispersive X-ray microanalyser. Results from this study showed that effectiveness of lithium nitrate in mitigating ASR was limited over a long period of time. A larger amount of ASR gel which was formed in the presence of lithium nitrate indicated that the deterioration processes intensify within longer periods of time, which so far has not been observed in literature. Microscopic observation confirmed the presence of alkali-silica gel and delayed ettringite in mortars with lithium nitrate.

Alkali–silica reaction (ASR) is a sequence of complex chemical processes, resulting in the formation of alkali silica gels with high swelling ability. ASR leads to the expansion of concrete and the degradation of its microstructure. The susceptibility of aggregates to alkali reaction depends, among other factors, on the type and origin of the aggregate, the presence of reactive forms of silica, the mineral composition, and the geometric properties of the aggregate, such as shape and grain size. This study aimed to investigate the impact of the grain size of polymineral post-glacial gravel aggregate, originating from the northern regions of Poland, on its susceptibility to ASR. The expansion of mortars made from polymineral aggregate and the cracking of grains and cement matrix due to the occurring reactions were analyzed. Based on the conducted research, it was observed that the expansion of mortars depends on the grain size of the aggregate. It was demonstrated that the fraction of reactive aggregate generating the most significant elongation of mortars is in the range of 1.0–2.0 mm. The reaction of silica with alkalis continued until the depletion of reactive components in the aggregate. The relationship between the progress of corrosive processes and the grain size of the aggregate was evident in the form of different linear elongation increments of mortars over time. The expansion of mortars was caused by the swelling ASR gel, inducing stress in the grain and the surrounding cementitious paste.