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This review presents the scope of current efforts to utilize recycled construction and demolition waste in mortars for masonry. More than 100 articles are divided into groups pertaining to the type of mortar, different binder systems, the type of construction and demolition waste (CDW), and its utilization specifics. Cement-based mortars dominate this research domain, whereas recycled concrete is the main material employed to replace virgin aggregates, followed by recycled masonry and recycled mixed waste aggregates. Such application in cement-based mortars could increase water demand by 20–34% and reduce strength by 11–50%, with recycled concrete aggregates being the most favorable. Natural aggregate substitution is disadvantageous in strong mortars, whereas weaker ones, such as lime-based mortars, could benefit from this incorporation. The extent of this topic also suggests possibilities for different recycled material use cases in mortars for masonry, although the available literature is largely insufficient to infer meaningful trends. Nonetheless, the most relevant knowledge synthesized in this review offers promising and environment-conscious utilization pathways for recycled concrete and other construction and demolition waste, which brings opportunities for further research on their use in mortars for masonry and industrial-scale applications. [ABSTRACT FROM AUTHOR]

The chemical reaction between CO2 and a blended Portland cement concrete, referred to as carbonation, can lead to reduced performance, particularly when concrete is exposed to elevated levels of CO2 (i.e., accelerated carbonation conditions). When slight changes in concrete mix designs or testing conditions are adopted, conflicting carbonation results are often reported. The RILEM TC 281-CCC 'Carbonation of Concrete with Supplementary Cementitious Materials' has conducted a critical analysis of the standardised testing methodologies that are currently applied to determine carbonation resistance of concrete in different regions. There are at least 17 different standards or recommendations being actively used for this purpose, with significant differences in sample curing, pre-conditioning, carbonation exposure conditions, and methods used for determination of carbonation depth after exposure. These differences strongly influence the carbonation depths recorded and the carbonation coefficient values calculated. Considering the importance of accurately determining carbonation potential of concrete, not just for predicting their durability performance, but also for determining the amount of CO2 that concrete can re-absorb during or after its service life, it is imperative to recognise the applicability and limitations of the results obtained from different tests. This will enable researchers and practitioners to adopt the most appropriate testing methodologies to evaluate carbonation resistance, depending on the purpose of the conclusions derived from such testing (e. g. materials selection, service life prediction, CO2 capture potential). [ABSTRACT FROM AUTHOR]

Featured Application: Application of superabsorbent polymers in large-scale wall elements, to be used in tunnel systems or ground-retaining structures. The pursuit of durable and sustainable construction has driven interest in innovative materials, with superabsorbent polymers (SAPs) emerging as a promising solution, especially for the concrete industry. SAPs offer significant benefits to the durability of concrete structures, including mitigation of autogenous shrinkage, enhanced freeze–thaw resistance, crack sealing, and stimulation of autogenous healing. This study focuses on the impact of internal curing with SAPs on crack formation and corrosion initiation in large-scale reinforced concrete walls (14 m × 2.75 m × 0.8 m). Both commercial SAPs based on acrylic acid chemistry and in-house-developed SAPs based on alginates were evaluated. Key findings reveal that the reference wall exhibited visible cracking just five days after casting, while the SAP-treated wall remained crack-free throughout a 24-month monitoring period. Moreover, the reference wall showed corrosion initiation at two locations near the cracks within six months, whereas the SAP-treated wall exhibited no signs of corrosion potential. Laboratory tests further demonstrated a slight reduction in chloride penetration and carbonation in SAP-treated specimens compared to the reference. These results highlight the efficacy of SAPs in enhancing the durability and longevity of reinforced concrete structures. [ABSTRACT FROM AUTHOR]

A comprehensive decarbonization approach is reported, involving Direct Separation Reactors (DSRs) and eco-efficient energy sources in the production of hydrated lime. Environmental and economic impacts are calculated through an in-depth life-cycle cradle-to-grave assessment. Integrating a DSR kiln with carbon capture technologies (CCTs) attained a remarkable 65% reduction of CO2 emissions during hydrated lime production, with a minimum environmental impact from the CCT itself. Fully electrified DSR kilns, powered by renewable energy sources, achieve an astonishing 94% decrease in CO2 emissions when compared to conventional reference scenarios, all without adverse environmental effects. In limebased plasters, combining DSR kilns, natural carbonation, and eco-efficient energy sources, particularly with the inclusion of natural gas, leads to carbon negativity. This efficiently offsets all production emissions and even cuts back an additional 30%. In the case of fully electrified DSR kilns, the results are a remarkable 149% CO2 emission reduction throughout the entire cradle-to-grave lifecycle. Carbon capture technologies reduce carbon tax costs by up to 26%, thereby enhancing the economic sustainability of these endeavours. To realize a swift and effective decarbonization of the lime industry, a harmonized effort is imperative and involves balancing the interests of the private sector, environmental protection, and promoting societal well-being, all within a supportive regulatory framework. [ABSTRACT FROM AUTHOR]

Superabsorbent polymers (SAPs) can serve as effective internal curing agents in alkali-activated slag (AAS) systems, mitigating the risk of cracking. However, the influence of SAPs on the properties and microstructure of AAS systems is not yet fully understood. In this study, the effects of SAPs on the properties, reaction products, and internal moisture migration of AAS pastes were investigated. The water released by SAPs during curing supplemented the water consumption in the hydration process, maintained internal relative humidity, and reduced autogenous shrinkage by more than 80%. However, the addition of SAPs not only created voids in the hardened paste, as indicated by the mercury intrusion porosimetry (MIP) results, but also increased the microscopic pore volume of the paste. SAPs did not change the phase composition of AAS hydration products, but increased the differential thermogravimetry (DTG) peak corresponding to the main hydration product C(-A)-S-H gel at 28 days. The increase in chemically bound water in AAS pastes containing SAPs, along with the changes in the transverse relaxation time (T2) peak area corresponding to SAPs in the H1 low-field NMR results, likely are due to the gradual release of water during internal curing by SAPs. [ABSTRACT FROM AUTHOR]

The development of innovative cementitious materials such as Ultra High Performance Concrete (UHPC) requires tailored approaches to assess both the environmental and economic impact of structural applications employing them. For this purpose, in this paper, Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) methodologies are integrated into a Durability Assessment‐Based Design (DAD) workflow which combines structural design algorithms for UHPC with the assessment of the durability performance, with the aim of predicting the evolution of the structural performance all along the service life (SL) in the intended scenarios. As a case study a water tank made of UHPC has been herein selected and compared to a reference made of ordinary reinforced concrete (ORC). While the ORC solution was designed with cantilever cast in situ walls, two different design concepts were assessed for the UHPC basin: one with cast in situ walls and one with precast slabs supported by ORC columns. Moreover, two different mix designs (mainly differing on the alternative presence of silica fume or slag) have been investigated for the UHPC basin and a SL equal to 50 years has been taken into account for each structure. The optimized design, together with the reduced frequency of the maintenance activities for the UHPC structure, allowed by the UHPC superior material and structural durability, resulted into consistent reductions of environmental impacts, up to 76% as for Human Toxicity and Fresh Water Aquatic Ecotoxicity in comparison to the ORC solution. In addition to this, an assessment of the overall construction and maintenance costs that occur during the lifetime of the structures showed a cost reduction higher than 40% for both UHPC solutions, mainly due to a reduction of up to 6% during the construction phase and 91% for the maintenance activities. This also highlights the importance of the correct metrics in evaluating the sustainability of UHPC structural applications, which has to move forward from the units volume or mass of material and its individual constituents to functional units, representative of the benefits of using advanced cement based materials in structurally and environmentally challenging service scenarios. [ABSTRACT FROM AUTHOR]

The combination of environmental actions and mechanical load, which most structural concretes are subjected to, has a synergetic effect on the durability of concrete. The comparative test conducted by RILEM TC 281-CCC WG4 demonstrated and quantified the effect of an applied mechanical load on carbonation performance of concrete with supplementary cementitious materials. Although the effect of loading on the chemical durability of concrete should be taken into consideration for the development of realistic service life predictions, they have been widely overlooked so far. This recommendation proposed by RILEM TC 281-CCC WG4 proposes a testing method for determining the effect of applied load on the carbonation rate of concrete. It specifies a detailed experimental procedure to determine the carbonation development of concretes subjected to compressive and tensile loads. Therefore this recommendation will support the consideration of such combined effects in design codes. [ABSTRACT FROM AUTHOR]

Concrete is currently the most used man-made construction material. Unfortunately it is prone to defects, such as cracks. Crack repair is possible by incorporation of superabsorbent polymers (SAPs) which can fill a crack by swelling and promote formation of healing products. However, SAPs are usually acrylate-based and not biodegradable. Present work focuses on development of SAPs based on poly(aspartic acid) (PASP), which is a biobased and biodegradable alternative of acrylate-based polymers. The developed SAP was incorporated in mortar and the effect on the mortar properties was studied. When adding 1 m% SAP, a decrease in strength was observed, similar to commercially available acrylate-based SAPs. The SAPs showed an efficient and immediate sealing effect in cracked mortar, reflected by a reduction in water permeability over 50%. Hence, the developed biobased SAP shows good sealing properties and could be used as a sustainable alternative for acrylic SAPs in concrete repair. [ABSTRACT FROM AUTHOR]

Although the circular economy principles date back to the late 1960s, only with the recent stimulus from the European Commission and the Ellen McArthur Foundation has this concept gained attention worldwide. The City Hall of Santiago de Cali (Colombia) is implementing a circular economy model through a sustainable construction handbook and its certification. Among others, these stimulate the use of eco-concrete using fly ash and blast furnace slag coming from local industries (industrial symbiosis). Although concretes with these supplementary cementitious materials have been widely investigated regarding mechanical and durability properties, the economic and environmental impacts have been scarcely and independently evaluated, making the material selection a complex process. Therefore, this article presents the environmental and economic assessment of eco-concretes using fly ash and blast furnace slag for the design of a house located in Santiago de Cali (Colombia). The environmental and economic impacts are estimated by means of the environmental life cycle assessment (LCA) and life cycle costing (LCC), which are methodologies based on the ISO and ASTM standards implemented in the online software Building for Environmental and Economic Sustainability (BEES), which was selected for this case study. The results indicate that 40% fly ash concrete or 50% blast furnace slag would be recommended for reducing acidification or global warming potential, respectively. However, considering the existing public policies, the best option for the case study is 50% slag concrete. These results are of significant importance as they allow providing data-based recommendations for designers during the selection of the different eco-concretes. Additionally, these results might help establish a national roadmap to reduce carbon dioxide emissions from the construction sector, which are projected to continue increasing until 2050. [ABSTRACT FROM AUTHOR]

Durability of concrete with supplementary cementitious materials (SCMs) is crucial to the longevity of our built environment. Current research on the carbonation performance of concrete focuses on determining changes in microstructure induced by the chemical and physical interactions of CO2 with the cement phase in samples that do not undergo loading. Although this approach has enabled us to understand the chemical carbonation durability of concrete, the deterioration process is certainly not realistic considering the in-service conditions of structural concrete. Therefore, five different laboratories from RILEM TC 281-CCC WG4 conducted comparative testing of Portland cement concrete with/without SCMs under the combined action of carbonation and mechanical loading. The results indicated that the carbonation depth of concrete undergoing mechanical loading is lower in the case of a limited compressive load, and higher in the case of a high compressive load or tensile load, compared with unloaded specimens. The relative carbonation depth was decreased by 9–16% at 30% of the failure load in compression, independent of CO2 concentration and the presence of SCMs, while it was increased up to 13% at a 60% load level at most. Tension made the carbonation depth gradually increase, and up to 70% higher carbonation depth was reached at 60% of the tensile failure load. The combined effect of carbonation in concrete with SCMs and mechanical loading should therefore not be neglected in the service life prediction of concrete structures. [ABSTRACT FROM AUTHOR]

Fine recycled concrete aggregate (FRCA) possesses substantial limitations for its use due to its significant porosity. Extensive research on the effect of carbonation on the accessible porosity of coarse recycled concrete aggregate is available in the literature, but FRCA information is scarce. The present paper presents results of the effect of carbonation on different fractions of FRCA from <0.125 mm to 4 mm previously sprayed with wastewater from mortar production as an additional source of portlandite. The results of water absorption via the electrical conductivity method, TGA, XRD+Rietveld+PONKCS analysis, EDS mapping, and Life Cycle Assessment (LCA) demonstrate that the efficiency of the treatment depends on the particle size range of the FRCA. It was most effective for the extreme size fractions <0.25 mm and >1 mm of FRCA as a result of the relationship between the amount of precipitated calcium carbonate and the initially accessible porosity in each fraction. As a consequence, mortar produced with 30% replacement of natural sand with carbonated FRCA showed no impact on compressive strength. [ABSTRACT FROM AUTHOR]

Novel hybrid binder concrete mixes with alkali-activated non-ferrous slag (NFS), either alone or in combination with blast furnace slag (BFS), as partial replacement of Portland cement, and containing 50% recycled aggregates, were successfully manufactured. The compressive strength, carbonation resistance, chloride resistance, frost scaling, sorptivity coefficient, and water penetration resistance were thoroughly assessed. The presence of recycled aggregates had an adverse effect on early-age strength, but after 91 days there was no difference between concrete with and without recycled aggregates. The chloride-binding capacity was enhanced in the BFS/NFS system with recycled aggregates (reduction in chloride ingress coefficients of ~28–35% compared to recycled concrete with NFS only). This is most likely caused by the binding of Cl ions in calcium alumina silicate hydrates (C-A-S-H) and ettringite phases. However, when compared to the system with virgin aggregates, BFS/NFS concrete with recycled aggregates showed increased carbonation rate (+30%) and frost scaling (+15%). Durability properties, such as sorptivity and water penetration resistance, were positively affected by the curing time for the BFS/NFS system (~35–45% further improvement from 28 to 90 days with respect to the NFS system). Specimens that were wet cured for 91 days showed improved results compared to the 28-day cured samples due to the slow pozzolanic reaction of the NFS. [ABSTRACT FROM AUTHOR]

This work reports on the self-healing capabilities of mortar specimens with polyurethane encapsulated in two types of cementitious macro-capsules, by comparison with the performance of mortar specimens using the same healing agent encapsulated in glass capsules, as tested in an inter-laboratory testing campaign following a pre-standard procedure. This comparison was performed with a twofold objective of checking the robustness of such pre-standard procedure for varying types of capsules and testing the effectiveness of a new type of cementitious capsule that has never been used before in durability tests. The testing procedure was developed in the framework of the EU COST Action SARCOS. First, the specimens were pre-cracked via three-point bending followed by an active crack width control technique. Then, the self-healing effect was characterised in terms of water permeability reduction. The cementitious capsules offered equivalent or better performance compared to the glass capsules used in the inter-laboratory testing. The average sealing efficiency for the specimens containing cementitious capsules ranged from 54 to 74%, while for glass macro-capsules it was equal to 56%. It was also observed that when applying the pre-standard procedure to test specimens containing capsules with comparable size and geometric arrangement, the same results were obtained in different repetitions of the test. The results obtained confirmed the possibility to use the cementitious capsules as a valid macro-encapsulation system, offering additional advantages compared to glass capsules. The repeatability of the results corroborated the robustness of the adopted testing procedure, highlighting its potential for further standardisation. [ABSTRACT FROM AUTHOR]

A novel linear reservoir-vascular tubes network is presented in this work and the design efficacy is explored by testing concrete beams loaded on bending and by assessing their damage healing and mechanical recovery. The healing system is composed of additively manufactured polymer components that appear equally effective compared to conventional ceramic tubes since the 3D printed polymer-tubes instantly break upon cracking. It is shown that bulk reservoirs embedded into concrete can deviate cracks and detrimentally affect the concrete's resistance to failure. The crack formation and re-opening is monitored by acoustic emission (AE) and digital image correlation (DIC) concluding that initial brittle cracking is shifted after healing to a pseudo-ductile crack re-opening with extended post-softening. The sealed cracks show significant strength and toughness recovery (i.e., above 80% of the original value) escorted also by an ultrasound pulse velocity (UPV) increase (up to 126% relative to the damage state) after a healing intervention. The work critically reports on obstructions of the current design: (i) the network tubes are clogged although the agent was flushed out of the network after healing and as a result re-healing is unattainable; and (ii) vacuum spaces are formed during casting underneath the network tubes, due to limited vibration aiming on the tubes' tightness, but also due to inefficient aggregates settlement, leading to a strength decrease. This work calls attention to the impact of vascular networks design and performance on a complex cracks network and fracture zone development. [ABSTRACT FROM AUTHOR]

Economic and environmental factors call for increased resource productivity. Partial or full replacement of Portland cement by wastes and by-products, and natural aggregates by construction and demolition wastes, are two prominent routes of achieving circular economy in construction and related industries. Municipal solid waste incineration (MSWI) bottom ashes have been found to be suitable to be used as a supplementary cementitious material (SCM) after various treatments. This paper reports a brief literature review on optimum use of recycled aggregates in concrete and an experimental study using replacement of natural aggregate by demolished concrete having MSWI bottom ash as partial replacement of Portland cement, and compares its properties to that of completely natural aggregate concrete. Additional water was added as a compensation for the water absorption by the recycled aggregate during the first 30 min of water contact during concrete mixing. Also the fine fraction of crushed concrete (<250 µm) was removed to reduce the ill-effects of using recycled aggregate. The replacement of aggregates was limited to 23% by weight of natural aggregate. The results prove environmentally safe and comparable performance of concrete including recycled aggregate with bottom ash to that of natural aggregate concrete. [ABSTRACT FROM AUTHOR]

Many (inter)national standards exist to evaluate the resistance of mortar and concrete to carbonation. When a carbonation coefficient is used for performance comparison of mixtures or service life prediction, the applied boundary conditions during curing, preconditioning and carbonation play a crucial role, specifically when using latent hydraulic or pozzolanic supplementary cementitious materials (SCMs). An extensive interlaboratory test (ILT) with twenty two participating laboratories was set up in the framework of RILEM TC 281-CCC 'Carbonation of Concrete with SCMs'. The carbonation depths and coefficients determined by following several (inter)national standards for three cement types (CEM I, CEM II/B-V, CEM III/B) both on mortar and concrete scale were statistically compared. The outcomes of this study showed that the carbonation rate based on the carbonation depths after 91 days exposure, compared to 56 days or less exposure duration, best approximates the slope of the linear regression and those 91 days carbonation depths can therefore be considered as a good estimate of the potential resistance to carbonation. All standards evaluated in this study ranked the three cement types in the same order of carbonation resistance. Unfortunately, large variations within and between laboratories complicate to draw clear conclusions regarding the effect of sample pre-conditioning and carbonation exposure conditions on the carbonation performance of the specimens tested. Nevertheless, it was identified that fresh and hardened state properties alone cannot be used to infer carbonation resistance of the mortars or concretes tested. It was also found that sealed curing results in larger carbonation depths compared to water curing. However, when water curing was reduced from 28 to 3 or 7 days, higher carbonation depths compared to sealed curing were observed. This increase is more pronounced for CEM I compared to CEM III mixes. The variation between laboratories is larger than the potential effect of raising the CO2 concentration from 1 to 4%. Finally, concrete, for which the aggregate-to-cement factor was increased by 1.79 in comparison with mortar, had a carbonation coefficient 1.18 times the one of mortar. [ABSTRACT FROM AUTHOR]

RILEM TC 267-TRM is studying tests for the reactivity supplementary cementitious materials (SCMs). In the first phase, the lime reactivity (LR) test, which is standardised in Indian standard (IS)-1727, gave promising correlations with 90-days cement mortar strength. In Phase 2, working group 1 has looked at further optimisation and robustness study of the LR test. A parameter screening approach for improving the mix design to use fixed mass proportions targeting enhanced reproducibility and robustness was focused. The parameters studied include mixture properties such as the effects of lime (hydrated lime/calcium hydroxide-CH) to SCM ratio, water to binder (binder = CH + SCM) ratio (w/b), activators, curing temperature, and testing age as well as the impact of factors from different national standards (IS and European Committee for Standardisation-EN) such as mould size, shape & type of sand. The modified mixture recommended by the TC uses a fixed CH to SCM mass ratio of 1:1 and the addition of activators. Also, a higher curing temperature of 50 °C in comparison to the 27 °C specified in IS 1727, for the first 2 days is proposed to accelerate the early hydration especially for slowly reacting SCMs. It is also recommended that, the minimum purity and fineness of the CH need to be specified to obtain reproducible results. [ABSTRACT FROM AUTHOR]

Eco-friendly concrete mixtures make efficient use of constituents with reduced environmental impact to secure durable structures. Ternary mixes containing Portland cement, ground granulated blast-furnace slag (GGBFS) and limestone powder (LP) have demonstrated a good balance between environmental impact, economic cost and technical performance. The pore structure of cement-based materials determines the transport of species; hence its description is a valuable tool for predicting their durability performance. In this paper, textural analysis of the pore structure of Portland cement concrete and GGBFS and limestone powder blended concrete is assessed by multicycle mercury intrusion porosimetry (MIP). Results from three intrusion-extrusion cycles were used for determining pore volume, size distribution and surface multifractal dimension. The hysteresis during the experiments is mainly explained by the combined effects of ink-bottle pores and different contact angles for the intrusion and retraction. The analysis of the surface multifractal dimension of the pore structure showed no significant effects of GGBFS and limestone powder on the pore wall texture of concrete samples. The outcome depicts the advantages of using multiple intrusion-extrusion cycles during MIP experiments, as well as the effect of 35 wt.% GGBFS, 25 wt.% GGBFS + 10 wt.% LP, and 25 wt.% of LP, on concrete pore structure. [ABSTRACT FROM AUTHOR]

Increasing awareness for sustainability has led to the development of smart self-healing materials, which can extend the service life and improve safety without human intervention. Vascular networks are observed in biological systems, such as leaf venation and blood vascular systems, and provide inspiration for self-healing mechanisms in engineered systems. Embedding a vascular network in a host material has the advantage of addressing varying magnitudes of damage and allowing for an indefinite replenishment of the healing agent, which are current limitations of intrinsic and capsule-based self-healing systems. These networks are demonstrated in polymer and composite materials, with fabrication methods including removal of sacrificial elements, electrospinning, and an array of additive manufacturing (AM) techniques. Advances in AM allow more complex network configurations to be realized that optimize fluid distribution and healing potential. This review intends to provide a comprehensive overview of the current progress and limitations of the design approaches, fabrication methods, healing mechanisms, and relevant applications of embedded vascular networks. Additionally, significant research gaps and future research directions for vascular self-healing materials are described. [ABSTRACT FROM AUTHOR]

Superabsorbent polymers (SAP) are a new, promising class of chemical admixtures which offer new possibilities in respect of influencing the properties of cement-based materials in the fresh, hardening, and hardened states. Much research work has been done in the last two decades to set the stage for introducing this truly multipurpose agent into the practice of construction. In particular, three RILEM Technical Committees: 196-ICC, 225-SAP and 260-RSC contributed considerably to the related progress by coordinating and combining the efforts of international experts in the field. The major product of the RILEM TC 225-SAP work was the State-of-the-Art Report published in 2012. This comprehensive document covered all topics relevant to the application of SAP as a concrete admixture. Since then further important progress has been made in understanding the working mechanisms of SAP in concrete and the effects of SAP-addition on various concrete properties. The article at hand presents an update on the state-of-the-art and is the concluding document delivered by the RILEM TC 260-RSC. [ABSTRACT FROM AUTHOR]

Carbonation of cementitious binders implies gradual capture of CO2 and significant compensation for the abundant cement-related CO2 emissions. Therefore, one should always look at the CO2-sequestration-to-emission ratio (CO2SP/EM). Here, this was done for High-Volume Fly Ash (HVFA) mortar (versus two commercial cement mortars). Regarding their CO2 sequestration potential, effects of accelerated testing (at 1–10% CO2) on as such estimated natural carbonation degrees and rates were studied. Production related CO2 emissions were evaluated using life cycle assessment with no/economic allocation for fly ash. Natural carbonation rates estimated from accelerated tests significantly underestimate actual natural carbonation rates (with 29–59% for HVFA mortar) while corresponding carbonation degrees are significantly overestimated (67–74% as opposed to the actual 58% for HVFA mortar). It is advised to stick with the more time-consuming natural tests. Even then, CO2SP/EM values can vary considerably depending on whether economic allocation coefficients (Ce) were considered. This approach imposes significant portions of the CO2 emissions of coal-fired electricity production onto fly ash originating from Germany, China, UK, US and Canada. Ce values of ≥0.50% lower the potential CO2SP/EM values up to a point that it seems no longer environmentally worthwhile to aim at high-volume replacement of Portland cement/clinker by fly ash. [ABSTRACT FROM AUTHOR]

Featured Application: Novel cementitious binder. Traditional methods to track the reactivity of supplementary cementitious materials (SCMs) and their contribution to the hydration mechanism mostly use Portland Cement (PC) as an activator. Alternatively, a novel method to assess the reactivity of SCMs called R3 was recently presented. This novel method uses lab grade chemicals such as portlandite (CH), K2SO4, KOH, and CaCO3 to activate the SCM by resembling the pH of the alkaline pore solution created by PC. By using this method, the reactivity of the SCM can be easily quantified from measured heat release, bound water content, and CH consumption. The primary objective of the current study is to apply the novel methodology to analyze the reactivity of Modified Ferro Silicate (MFS) Cu slag benchmarked against siliceous fly ash (FA), ground granulated blast-furnace slag (GGBFS), and inert quartz filler. GGBFS showed the highest cumulative heat release and bound water content due to its latent hydraulic behavior. Determination with XRD analysis of the major phase of the R3 model MFS slag paste showed the participation of Fe in the hydration mechanism by forming Fe-AFm. R3 paste with GGBFS showed the presence of hydrotalcite/Al-AFm, whereas FA showed the presence of ettringite (AFt) as their crystalline reaction products. The experiments also indicate that the MFS slag acts as a reactive pozzolanic material with an acceptable performance in heat release, bound water content, and CH consumption, and can be used as SCM to make concrete. With the possibility of using MFS slag as SCM to replace part of PC, sustainability and circular economy can be fairly well achieved. [ABSTRACT FROM AUTHOR]

Development and commercialization of self-healing concrete is hampered due to a lack of standardized test methods. Six inter-laboratory testing programs are being executed by the EU COST action SARCOS, each focusing on test methods for a specific self-healing technique. This paper reports on the comparison of tests for mortar and concrete specimens with polyurethane encapsulated in glass macrocapsules. First, the pre-cracking method was analysed: mortar specimens were cracked in a three-point bending test followed by an active crack width control technique to restrain the crack width up to a predefined value, while the concrete specimens were cracked in a three-point bending setup with a displacement-controlled loading system. Microscopic measurements showed that with the application of the active control technique almost all crack widths were within a narrow predefined range. Conversely, for the concrete specimens the variation on the crack width was higher. After pre-cracking, the self-healing effect was characterized via durability tests: the mortar specimens were tested in a water permeability test and the spread of the healing agent on the crack surfaces was determined, while the concrete specimens were subjected to two capillary water absorption tests, executed with a different type of waterproofing applied on the zone around the crack. The quality of the waterproofing was found to be important, as different results were obtained in each absorption test. For the permeability test, 4 out of 6 labs obtained a comparable flow rate for the reference specimens, yet all 6 labs obtained comparable sealing efficiencies, highlighting the potential for further standardization. [ABSTRACT FROM AUTHOR]

The exploration of biodeposition treatment for the surface consolidation of natural stones is limited by thus-far used study-specific treatment conditions. This study explores the surface consolidation performance of Bacillus sphaericus in varying treatment conditions and compares the results with the application of a tetraethyl orthosilicate (TEOS)-based chemical consolidant to suggest a more standardized treatment procedure. Initially, the biodeposition medium was optimized for maximal ureolytic activity. Then, consolidation procedures with different times and numbers of applications were conducted on sound (no aging) Maastricht limestone. Consolidation performances were evaluated by comparing the changes in the ultrasonic pulse velocity (P -wave) through the specimens and the drilling resistance of the specimens. Upon two or more subsequent biotreatments, the transmitting velocity of the P-wave increased by up to 25% in the first 20 mm of the specimen. The drilling resistance of the specimen increased by 100% up to a depth of 35 mm from the surface. A minimum of two subsequent biotreatments are suggested for a decent consolidation of Maastricht limestone, and a minimum of four subsequent treatments are suggested to replace TEOS. [ABSTRACT FROM AUTHOR]

This article presents the results of an inter-laboratory study performed by six international research groups in the framework of RILEM Technical Committee 260 RSC "Recommendations for use of superabsorbent polymers in concrete construction". Two commercially available superabsorbent polymer (SAP) samples with different chemical compositions were tested in terms of their ability to mitigate plastic shrinkage cracking of concrete. The SAP mixtures showed a clear reduction of plastic shrinkage cracking in conventional concrete. On the contrary, if only additional water is added and no SAP, the area of plastic shrinkage cracks increases. This suggest the ability of SAP to mitigate plastic shrinkage cracking. Upon addition of the predetermined amount of SAP and additional water, the compressive strength decreased on average by 3% for the mixtures with 0.15% SAP (by mass of cement) and by 10% for the mixtures with 0.30% SAP. [ABSTRACT FROM AUTHOR]

Superabsorbent polymers (SAPs) have been investigated for their potential for internal curing, promotion of self‐sealing, and self‐healing of concrete structures. There has been a lack of publications concerning large‐scale testing of structures with SAPs, and bringing this SAP‐modified concretes from laboratory environment to plant‐scale production might demand adaptations in the mixing protocols. In this paper, a reference mixture and a SAP‐containing mixture were produced at a concrete plant scale and the influence of adding the polymers at different moments was investigated. The addition of SAPs directly in the truck, after the mixing procedure, showed no significant impact on the compressive strength of the concrete, but an agglomeration of particles was found in the air void analysis. The specimens with SAPs added directly in the truck presented an inferior performance in terms of shrinkage reduction when compared to the specimens with SAPs added on the materials belt, with the dry materials. [ABSTRACT FROM AUTHOR]

Development and commercialization of self-healing concrete is hampered due to a lack of standardized test methods. Six inter-laboratory testing programs are being executed by the EU COST action SARCOS, each focusing on test methods for a specific self-healing technique. This paper reports on the comparison of tests for mortar and concrete specimens with polyurethane encapsulated in glass macrocapsules. First, the pre-cracking method was analysed: mortar specimens were cracked in a three-point bending test followed by an active crack width control technique to restrain the crack width up to a predefined value, while the concrete specimens were cracked in a three-point bending setup with a displacement-controlled loading system. Microscopic measurements showed that with the application of the active control technique almost all crack widths were within a narrow predefined range. Conversely, for the concrete specimens the variation on the crack width was higher. After pre-cracking, the self-healing effect was characterized via durability tests: the mortar specimens were tested in a water permeability test and the spread of the healing agent on the crack surfaces was determined, while the concrete specimens were subjected to two capillary water absorption tests, executed with a different type of waterproofing applied on the zone around the crack. The quality of the waterproofing was found to be important, as different results were obtained in each absorption test. For the permeability test, 4 out of 6 labs obtained a comparable flow rate for the reference specimens, yet all 6 labs obtained comparable sealing efficiencies, highlighting the potential for further standardization. [ABSTRACT FROM AUTHOR]