The development of restraint-induced stress in reinforced concrete members at an early age can be tested using setups applying either passive or active displacement control. To provide results relevant for the practical design of minimum reinforcement to limit the crack width, an actively controlled test setup for large specimens was developed to perform a systematic experimental...
Most supplementary cementitious materials (SCMs) are predominantly poorly-crystalline or amorphous. Their reactivity is routinely evaluated through SEM image analysis (SEM/IA), which is a laborious and resource intensive technique. Quantitative X-ray diffraction (QXRD) provides an alternative, facilitating simultaneous evaluation of reaction kinetics and phase assemblages...
The preliminary findings of cyclic tests conducted on a series of half-scale unstrengthened and strengthened masonry walls are presented. Reinforced walls were strengthened by (i) non-prestressed near surface mounted (NSM) glass fibre reinforced polymer (GFRP) bars and (ii) prestressed NSM GFRP. Walls were strengthened symmetrically by vertical bars passing through both mortar...
The scope of this collective paper produced in the frame of RILEM TC 277-LHS is to provide sound knowledge on the use of additives/admixtures in lime-based mortars, based on literature and practice. The most widely known additives/admixtures are systematically presented. Their main effects and testing of their performance have been properly tabulated. It is well known that a...
This recommendation is devoted to testing the resistance of natural stone and fired-clay brick units against salt crystallization. The procedure was developed by the RILEM TC 271-ASC to evaluate the durability of porous building materials against salt crystallization through a laboratory method that allows for accelerated testing without compromising the reliability of the...
The diffusion potentials can cause significant errors in corrosion-related investigations of reinforced concrete structures (half-cell potential mapping, potentiometric sensors). Therefore, an improved understanding of the diffusion potentials in cement-based materials is needed. This study investigates the permselective behavior and its implication for the arising diffusion...
This study investigates the effect of single and multiple hooked-end steel fibres on the mechanical properties of alkali-activated slag-based concrete (AASC) and compares its performance with a similar strength-grade Portland cement concrete (PCC). Three different fibre geometries, i.e. single (Dramix® 3D), double (Dramix® 4D) and triple hooked-end (Dramix® 5D) steel fibres, and...
Impedance spectroscopy was applied to Portland cement and its carbon nanotubes (CNT) composites to measure and describe the electrical conductance phenomena and their dependency on the moisture. Two series of composites were prepared, one with multi-walled, and the other with single-walled CNTs. The percolation concentration was reached only with the single-walled CNTs between 0...
The resource of shear resistance provided by the dowel mechanism of rebar in reinforced concrete (RC) structures can significantly affected by the simultaneous presence of axial loading. This occurs for example of plastic hinges of seismic resistant structures. In fact, at load reversals in cycles of large deformation demand, rebars are subjected to combined axial and shear...
In this study, the influence of calcium formate (CF) on the hydration of a synthesized calcium sulfate hemihydrate (HH) powder was investigated. Isothermal calorimetry measurements showed that CF retards the hydration reaction of HH. This was confirmed by XRD of stored samples and pore solution analysis. Two retardation mechanisms were identified. The combination of pore solution...
In this study, the fresh state and hydration properties of 0–60% lithium slag blended cement pastes were investigated at water-binder ratio of 0.47. The workability of the fresh pastes was evaluated by measuring the air content, marsh cone flow, mini-slump flow, setting times, and through rheology tests. A 40% lithium slag cement could produce 91% strength activity index at 28...
It is believed that many historic mortars were made using hot-lime mixing techniques. They are back in use today, and their good qualities are often praised, including being more compatible and a better match with historic fabrics. This paper studies the methods of producing hot-lime mortars and putties. It discusses the variables that determine the properties of the resultant...
In the near future, the world of civil and building engineering will be dominated by the advent of bio-materials. Even the road paving sector is involved in the transition towards more sustainable solutions, promoting at the same time environmental benefits and economic savings. Currently, one of the main goals is to ensure that bio-binders offer good performance, at least...
The lower bond strength of FRP bars to concrete compared to steel bars has remained an unsolved barrier to the widespread use of FRP-reinforced concrete under extreme loading. Additionally, the degradation of the bond between FRP reinforcement and concretes in aggressive environments adds to the existing concern. In this study, an innovative anchorage system comprised of...
The brick-to-mortar bond often represents the weakest link leading to cracking and failure of masonry structures. For this reason, the in-situ characterization of masonry’s flexural bond behaviour (here defined as flexural bond strength and flexural bond fracture energy), is essential for the assessment of existing buildings. Among masonry bond properties, the flexural bond...
This paper evaluates the effect of poor compaction on the compressive strength, sorptivity, gas permeability and accelerated carbonation resistance of bulk concrete in structures, framed in the scenario of disputes over the quality of the supplied concrete. For that purpose, several real-scale elements (beams, columns and slabs) were cast with concrete incorporating Portland...
The purpose of this study was to evaluate the possibility of using ground waste-expanded perlite (WP) as a sustainable replacement for ground granulated blast-furnace slag (GGBFS) precursor in alkali-activated systems. The nature and amount of hydration products, microstructure, and compressive strength development were investigated in mixtures where GGBFS was substituted with 10...
The impact of dewatering on lime mortars modified using brick dust was studied, as it is of particular importance in conservation applications. Dewatering takes place when freshly mixed mortars come into contact with a porous substrate, such as brick or stone, during on site construction. Since the dewatering process between the mortar and its substrate can modify the mortar...
A new impact-absorbing material is being developed to protect vulnerable road users in urban areas and has been produced and tested, mechanically and environmentally in the laboratory. The main constituent of this innovative material is the rubber recycled from end-of-life tyres to foster a circular use of resources and exploit rubber’s elastic properties. The study aims to...
The utilization of locally available concrete waste for producing recycled concrete aggregates is recognized as one of the most sustainable ways of satisfying the growing demand for concrete production. However, the quality of concrete waste depends on its origin and it may significantly differ from one concrete structure to another. Knowing the chemical composition of the parent...
Digital fabrication methods with concrete have been rapidly developing, with many problems related to component production and material control being solved in recent years. These processes produce inherently layered cementitious components that are anisotropic, and in many cases, produces a weak interface between layers, which are generally referred to as cold joints. While...
Cement is the strength-forming component of concrete. It has been a major building material for more than a century. However, its production is accountable for a considerable percentage of global CO2 emissions and is very energy-intensive. The Ordinary Portland Cement (OPC) production is a thermal process at around 1450 °C. This study shows that the reactivation of Hydrated...
This paper focuses on the in-plane behaviour of rubble stone masonry with lime mortar strengthened with different solutions. For that, 12 rubble stone masonry wall specimens, with construction features typical of ancient historic buildings of Southern Portugal and Mediterranean countries, were subjected to in-plane quasi-static cyclic tests. The applied retrofit solutions are...