Showing papers in "Cement and Concrete Research in 2018"

TL;DR: The main conclusions of an analysis of low-CO2, eco-efficient cement-based materials, carried out by a multi-stakeholder working group initiated by the United Nations Environment Program Sustainable Building and Climate Initiative (UNEP-SBCI) are presented, based on the white papers published in this special issue as discussed by the authors.

TL;DR: In this article, the relationship between fresh and hardened paste, mortar, and concrete material properties and how they influence the geometry of the created object is explored and classified by construction application to identify the spectrum of future research exploration in this emerging field.

TL;DR: A review of one-part AAMs in terms of raw materials, activators, additives, mechanical and physical properties, curing mechanisms, hydration products, and environmental impacts can be found in this paper.

TL;DR: In this article, the authors studied the rheological requirements for printable concrete in terms of yield stress, viscosity, elastic modulus, critical strain, and structuration rate.

TL;DR: A vision is presented on 3D printing with concrete, considering technical, economic and environmental aspects, and it is expected that for structures with the same functionality, DFC will environmentally perform better over the entire service life in comparison with conventionally produced concrete structures.

TL;DR: In this article, a numerical model was developed to analyse the mechanical behavior of fresh, 3D printed concrete, in the range of 0 to 90 min after material deposition, based on a time-dependent Mohr-Coulomb failure criterion and linear stress-strain behaviour up to failure.

TL;DR: In this article, the main required concrete states for extrusion and deposition processes are analyzed with respect to required performances and potential admixtures, and possible side effects and incompatibilities are discussed, as well as how they could be unconventionally used for printable concrete purposes.

TL;DR: In this paper, the influence of the calcined kaolinite content of calcined clays on the hydration of Limestone Calcined Clay Cements containing 50% of clinker (LC3-50) was investigated.

TL;DR: An overview of recently proposed building processes, defining the type and range of yield stress evolution that they require for successful building and an overview of admixtures, focusing on “set on demand” solutions, concluding that activators should be added as closely to the delivery point as possible.

TL;DR: In this paper, the authors provide an overview of different particle-bed 3D printing techniques for the production of concrete elements, i.e., selective binder activation, selective paste intrusion and binder jetting.

TL;DR: This paper provides a systematic overview of a number of digital fabrication techniques using reinforced concrete that have been developed so far, proposing a possible organization by structural principle, or place in the manufacturing process.

TL;DR: In this paper, the influence of carbonation on the microstructure of cement paste cast with Ordinary Portland Cement, fly ash based Portland Pozzolana Cement (PPC) and Limestone Calcined Clay Cements (LC3) using X-ray diffraction (XRD), thermal analysis (TGA), scanning electron microscope (SEM) and mercury intrusion porosimeter (MIP).

TL;DR: In this paper, the potential of Limestone Calcined Clay Cement (LC3) for use in structural concrete in comparison with Ordinary Portland Cement and fly ash based blended cement (FA30) was described.

TL;DR: In this paper, the authors evaluated the effects of two types of graphite nanoplatelet (GNP-C and GNP-M) and one type of carbon nanofiber (CNF) on rheological properties, hydration kinetics, autogenous shrinkage, and pore structure of ultra-highperformance concrete (UHPC).

TL;DR: In this article, a fly ash microsphere (FAM) is used to reduce the internal friction between fly ash and slag grains and mitigate the agglomeration of flocs and fragmentation to release the locked water.

TL;DR: It is suggested that, in parallel to the introduction of robotic fabrication methods, digital technologies may be key for the introduction several innovations like rebar-free reinforcement using non-convex granular media and truly digital concrete through the coupling of massive data collection and deep learning.

TL;DR: In this article, isothermal calorimeter and in-situ XRD were adopted to study the heat and mineral evolution of NaOH activated fly ash, metakaolin and ground granulated blast furnace slag.

TL;DR: In this paper, the potential of fiber hybridization was evaluated using micromechanical modeling, and the ultimate tensile strain of hybrid-fiber SHCCs was estimated using a semi-empirical method.

TL;DR: This review examines the types of models employed to approximate properties of concrete, which include a variety of linear combination, statistical, machine learning, and physics-based models that are required to optimize the proportions of a mixture.

TL;DR: In this article, the effect of increasing slag content and activator dosage on the sulfuric acid resistance of fly ash geopolymer (GP) binders has been investigated and compared with Portland cement (PC) mix using various physical and microstructural techniques.

TL;DR: In this article, a literature review summarizes the state-of-the-art, reporting corrosion rate data for a broad range of cement types, w/b ratios and environmental conditions.

TL;DR: In this article, a review of the published research regarding carbonation and chloride-induced corrosion of steel reinforced concrete (SFRC) is presented, and a deterioration theory for cracked SFRC exposed to chlorides and carbonation, based on the damage at the fiber-matrix interface.

TL;DR: In this article, the effects of calcium silicate hydrate are reviewed in detail, with a focus on synthesis, and their influence on the hydration mechanism and the development of mechanical properties, such as early and long-term compressive strength and porosity.

TL;DR: In this paper, the authors present various mechanisms that can explain the cause of excessive autogenous shrinkage exhibited by alkali activated slag mortars compared to Portland cement mortars (OPC).

TL;DR: In this article, an ultra-stable foam used for foamed concrete was fabricated by modifying the gas-liquid interface by coupling the effects of an organic surfactant and nanoparticles.

TL;DR: In this article, the consequences of accelerated carbonation at 3% CO2 were compared with those of natural carbonation (0.04%) in Cement Pastes (CEM I and CEM V/A) and three major constitutive phases (C-S-H of different C/S ratios, portlandite and ettringite).

TL;DR: In this paper, carbonation of AAS mortars activated by NaOH and waterglass with different alkali dosages and silicate moduli has been investigated after exposure to 3.2% (v/v) CO2 at 20.5% RH for 56 days.

TL;DR: In this paper, a review of applications of both two-dimensional neutron radiography and three-dimensional Neutron tomography to investigate specific aspects of durability and deterioration of cement-based materials is presented.

TL;DR: In this paper, the influence of fly ash and metakaolin added as substitutions of magnesium potassium phosphate cement (MKPC) on the microstructures and compressive strengths of the MKPC pastes were investigated.

TL;DR: In this article, the effect of nanoclay in presence of water reducing agent, such as PCE, on rheology, and the compatibility between nanoclayer and PCE have not been well studied.