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The best known and effective methods for the reduction of the negative effects of an alkali–silica reaction in concrete include the application of mineral additives with an increased aluminium content and reduced share of calcium, as well as chemical admixtures in the form of lithium compounds. Because both aluminium and lithium ions increase the stability of reactive silica in the system with alkalis, it is possible to presume that the application of both corrosion inhibitors together will provide a synergistic effect in the ASR limitation. The paper presents the results of studies on the influence of combined application of metakaolin and lithium nitrate on the course of corrosion caused by the reaction of opal aggregate with alkalis. The potential synergistic effect was studied for the recommended amount of lithium nitrate, i.e., the Li/(Na + K) = 0.74 molar ratio and 5%, 10%, 15%, and 20% of cement mass replacements with metakaolin. The effectiveness of the applied solution was studied by measurements of mortars expansion in an accelerated test, by microstructure observations, and by determination of the ASR gels composition by means of SEM-EDS. The influence of metakaolin and the chemical admixture on the compressive and flexural strengths of mortars after 28 and 90 days of hardening were also analysed. The results of the studies revealed a synergistic effect for mixtures containing metakaolin at 15% and 20% cement replacement and lithium nitrate admixture in alkali–silica reaction expansion tests. It was found that corrosion processes in mortars with 5 and 10% levels of metakaolin became more severe after adding a lithium admixture to mortars with metakaolin only. The obtained results were confirmed by observations of the mortars’ microstructures. There was no synergistic impact of lithium nitrate and metakaolin on compressive strength characteristics. The compressive strength of mortars containing a combination of metakaolin and lithium nitrate decreased both after 28 and after 90 days, compared to mortars with metakaolin alone.

Heritage building structures in many situations contribute unique value to national cultural heritage. In engineering practice, monitoring of historic structures includes visual assessment. This article assesses the condition of the concrete in one of the most recognizable buildings in Łódź, the former German Reformed Gymnasium, located at Tadeusza Kościuszki Avenue. The paper reports a visual assessment of the structure and the degree of technical wear affecting selected structural components of the building. A historical analysis of the building’s state of preservation, characterization of the structural system, and an assessment of the condition of the floor-slab concrete were carried out. The state of preservation of the eastern and southern facades of the building was found to be satisfactory, while on the western side (with the courtyard) the facade is in a poor state of preservation. Tests were also conducted out on concrete samples taken from individual ceilings. The concrete cores were tested for compressive strength, water absorption, density, porosity, and carbonation depth. Corrosion processes including the degree of carbonization and the phase composition of the concrete were identified by X-ray diffraction. The results are indicative of the high quality of the concrete produced more than 100 years ago.

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.

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.

Multidimensional analysis was carried out to check the impact of bitumen foaming on its properties. Unmodified bitumen 50/70, bitumen 50/70 modified with 2.5% synthetic wax and control bitumen 70/100 were used in the experiment. The main research goal was to establish whether it is possible to predict the Ageing Index (IS) using a data set consisting of three main subsets containing i) foaming parameters (ERm, HL), ii) selected rheological properties of bitumen (for example ZSV, δ) before and after foaming, and (iii) bitumen chemical changes after foaming determined using FTIR spectroscopy. All bitumen types were foamed at various temperatures (110 °C to 180 °C), air pressures (100 kPa to 700 kPa) and water contents (1% to 5%). Due to large multicollinearity between input variables, the input data set was transformed into a new data set that was reduced using Factor Analysis (FA). The use of the FA method together with the data from the FTIR analysis allowed building a highly effective regression model for predicting the Ageing Index. The Ageing Index model had a matching error of 0.1 and the coefficient of determination > 95%. Analysis results were validated against the bitumen 70/100 results. It should be noted that the input data set presented here can be a good starting point for predicting other rheological characteristics of foamed bitumen.

Cement kiln dusts (CKD) generated during the production of Portland cement clinker differ markedly in composition and, hence, in properties. These dusts are commonly used as an addition to cement. In this article the way in which the selected dusts obtained from the cement kiln bypass system (CBPD) react with water and the phenomena accompanying this process at early stage are discussed. For this purpose, the kinetics of hydration was investigated using the calorimetric method and volume change observations. Phase and microstructural changes were investigated by X-ray diffraction (XRD), thermogravimetry (TG) and scanning electron microscopy (SEM). It was found that the CBPD hydration process is primarily associated with the presence of free lime. It is characterized by a significant initial heat emission, which is accompanied by swelling the paste as a result of calcium hydroxide and calcium chloride salts formation.

The effectiveness of lithium nitrate as a chemical additive which reduces the negative effects of alkali aggregate reaction was subject to research by scientists in many centres around the world. The literature data on the impact of lithium nitrate on the physical and mechanical properties of cements are rare. Without a precise definition of the impact of lithium nitrate on the cement properties, it is extremely hard to determine its real advantages in practical usage. In this paper, studies were undertaken to assess the impact of LiNO3 on the properties of pastes and mortars with Portland cement. The rate of hydration of the cement with lithium additive was examined by isothermal calorimetry, measurements of setting time and phase composition of cement pastes in the initial stages of hydration. The influence of the admixture on the compressive strength development of mortars after 2, 7 and 28 days of hardening was also researched. Results indicate that lithium nitrate accelerates the early hydration of Portland cement, affecting the precipitation of hydration products. The compressive strength of mortars with lithium admixture decrease after 28 days, although 2 an 7-day strength were greater than the control mortars.

The objective of the research presented in the paper was to analyze the ash formed in the process of incineration in the thermal sewage sludge treatment facility being a part of Sitkówka-Nowiny wastewater treatment plant, located in the vicinity of Kielce. The research involved the investigation of heavy metal and total phosphorus content, leachability of certain ions and X-ray phase analysis. The comparison of the obtained results with those available in literature revealed similarities in the crystallographic structure of ashes from different treatment plants. Then, the differences observed in the content of heavy metals in particular ashes are related to the composition of sewage flowing into treatment plants. Attention was also paid to a significant sulphate content revealed in the leachability analysis, found both in the ash from Sitkówka-Nowiny treatment plant and in the ash analyses results available in the literature sources. High sulphate concentration can limit the use of ash for construction purposes.

Damage and defects observed in concrete elements, such as a network of microcracks, popouts and eflorrescence can be caused by a variety of deleterious processes. The causes can include mechanical (overloading), physical (freeze-thaw cycle) or chemical exposure (sulphate corrosion, alkali-aggregate reaction). This paper analyses distress due to alkali-silica reaction, detected in selected concrete structures. The analysed concrete elements exhibited cracking, exudations and surface popouts. Identification of the presence of hydrated sodium-potassiumcalcium silicate gel can be considered the primary symptom suggestive of an alkali-silica reaction attack. Other damage-causing mechanisms can occur simultaneously.

Alkali-aggregate reactivity (AAR) is one of the major causes of damage in concrete. Potential susceptibility of aggregates to this reaction can be determined using several methods. This study compares gravel alkali reactivity results obtained from different tests conducted on coarse aggregates with complex petrography. The potential for the reactivity in the aggregates was revealed in the chemical test using treatment with sodium hydroxide. Optical microscopy, scanning electron microscopy and X-ray diffraction were used to identify the reactive constituents. The expansion measured in the mortar bars test confirmed that the aggregate was potentially capable of alkali silica reactivity with consequent deleterious effect on concrete.

The study analyzed the possibility of using the acoustic emission method to analyse the reaction of alkali with aggregate in the presence of lithium nitrate. Lithium nitrate is a chemical admixture used to reduce adverse effects of corrosion. The tests were carried out using mortars with reactive opal aggregate, stored under the conditions defined by ASTM C227. The acoustic activity of mortars with a corrosion inhibitor was referred to linear changes and microstructure of specimens in the initial reaction stages. The study found a low acoustic activity of mortars with lithium nitrate. Analysis of characteristic parameters of acoustic emission signals, combined with the observation of changes in the microstructure, made it possible to describe the corrosion processes. As the reaction progressed, signals with different characteristics were recorded, indicating aggregate cracking at the initial stage of the reaction, followed by cracking of the cement paste. The results, which were referred to the acoustic activity of reference mortars, confirmed that the reaction of opal aggregate with alkali was mitigated in mortars with lithium nitrate, and the applied acoustic emission method enabled the detection and monitoring of ASR progress.

Alkali reaction with reactive aggregates is an example of concrete internal corrosion. Cracks and damage to elements of a concrete structure are the result of the formation of an expansive alkali-silica gel. One of the ways to minimise the effects of this damaging reaction is to use lithium compounds as an admixture to concrete mixes. Lithium ions are believed to reduce the reaction between the alkalis and aggregate or minimise damaging expansivity by modifying chemical composition of the reaction products. This paper presents the results from the tests carried out on mortars from reactive polymineral gravel with lithium nitrate according to the modified ASTM C1260 standard and ASTM C227 . The findings show that lithium ions decrease mortar expansion until it reaches the levels markedly lower than those set out in the standards. A considerable reduction in the number of microcracks may indicate either lower swelling capacity of the gels or reduced reactivity of the aggregate, leading to the reduction in the quantity of damaging expansive products.