The effects of alumina nano-fibres are investigated in this paper on the mechanical performance of Ultra High Performance Fibre Reinforced Cementitious Concrete and their efficacy in enhancing the durability of the cementitious composite when exposed to extremely aggressive conditions, with main reference to the stimulated autogenous crack sealing and self-healing capacity. A tailored characterization

One-part blended cements with 65% limestone and 35% Portland cement (PC) were activated by 3–8%wt. of four powdered sodium silicates of different modulus SiO2/Na2O = 1–3.26. Pastes were cured at 20 °C for 180 days in dry and underwater conditions. The use of moduli <3.26 promoted quick setting and low strength of the pastes. The use of modulus = 3.26 showed the best results in terms of workability

Ultra-high performance concrete (UHPC) has been successfully used for thin bonded overlay to rehabilitate concrete bridge decks. The performance of the overlay depends on shrinkage and bond to the substrate that can determine the service life of repair. In this study, pre-saturated lightweight sand (LWS) and CaO-based expansive agent (EA) were used to design low shrinkage non-proprietary UHPC. The

The dynamic compressive behaviour of hybrid basalt-polypropylene fibre-reinforced concrete (HBPRC) under confining pressure was investigated using a Hopkinson compression bar device with active confining pressure. The relationship between the pore structure and the dynamic compressive behaviour of HBPRC was discussed. The results indicate that the dynamic compressive behaviour of HBPRC under confining

Successful implementation of extrusion-based 3D printing (3DP) of concrete requires knowledge of material flow behavior during pumping and extrusion and its influence on shape stability of printed elements. Limited emphasis exists on flow behavior and process-induced variations in material properties (rheology and composition) during printing. This paper delineates the effect of flow behavior and process-induced

The mechanical and structural behavior of infrastructure and buildings under high-temperature environment is one of the major concerns in retrofit technologies. The present study aims to experimentally investigate the effectiveness of dispersed micro-fibers on the tensile behavior of uncoated carbon textile-reinforced mortar (TRM) after exposure to high temperatures. The main experimental parameters

As a low-carbon cementitious material, the supersulfated cement (SSC) is composed of a thimbleful of cement clinkers and massive industry by-products, i. e: gypsum and slag. However, the concrete made from SSC suffers low strength, poor carbonation resistance, inferior frost resistance, etc. In such a scenario, two types of alkali activators (lactates and sodium hydroxyl) were employed to improve the

Calcium aluminate cement (CAC) shows some superior properties compared to Portland cement. However, the conversion of metastable hydrates limits the application of traditional CAC. This study reports a low cost and high strength quarternary phase (Q phase, Ca20Al26Mg3Si3O68)-metakaolin (MK) composite. The mechanical property and microstructure of this composite hydrated at ambient temperature were

Crack spacing is an important property governing the tensile strain capacity of strain-hardening cementitious composites (SHCC). This paper presents a generic model to determine the crack spacing of short and randomly oriented polymeric fiber-reinforced SHCCs, which takes into account of the fiber/matrix interface chemical bond, the fiber/matrix interface slip-hardening behavior, and two-way fiber

This paper investigates the effect of the bauxite sand and coarse aggregate on the quasi-static mechanical properties and resistance against high-velocity projectile impact of cement composites with 28-day compressive strengths from 34.2 to 197.2 MPa, in comparison to that of the siliceous sand and granite coarse aggregate. Mechanical properties investigated include compressive strength, elastic modulus

Fly ash-based geopolymers incorporated with 2% nano-SiO2 (NS)/nano-TiO2 (NT) particles were subjected to microstructural and statistical nanoindentation analysis. With the addition of both types of nanoparticles, the compressive strength of geopolymer and the micromechanical properties of N-A-S-H gel were increased. NS exhibited higher reinforcement effect than NT on macro-strength. However, NT more

While high ductility Engineered Cementitious Composites (ECC) have demonstrated effectiveness for infrastructure repair, the microcracking induced by the high material shrinkage may decrease the structural durability of ECC in aggressive environments. The objective of this research is to develop a self-stressing ECC, the expansion of which against the restraint of the repaired structure automatically

This paper studies the evolution of elastic and thermal properties of cementitious composites containing micro-size lightweight fillers after exposure to elevated temperatures (up to 800 °C). A multiscale investigation is carried out to study the thermal degradation of cementitious composite materials at multiple scale levels: at cement past level, the dehydration kinetics of cement hydrates (i.e.

Expansive characteristics of calcium sulfoaluminate-belite (CSAB) cement can be harnessed for making shrinkage-compensating concrete. The level of expansion is dependent on several factors, such as the amounts of ye'elimite and calcium sulfate available in CSAB cement. Moreover, calcium sulfate from an external source can also influence the expansion characteristics by increasing the supersaturation

Carbonation-load coupling effects can aggravate the inhomogeneity of recycled aggregate concrete (RAC) which contains old attached mortar (OAM) and new added mortar (NAM). In this study, these mortars are first distinguished using an iron oxide. Afterwards, accelerated carbonation coupled with four-point bending effects is applied on the RAC samples, and the carbonation depths in compressive, load-free

Concrete is the most widely used construction material in the world. Surely, it is extensively employed in the construction of rigid pavements. Repetitive loads on the pavement cause cracks which allow the ingress of harmful compounds and thus reduce the durability of concrete. Hence, this research presents an ecofriendly solution to impart self-healing capability to concrete by using bacteria as a

The addition sequence of raw materials during mixing is one factor that affects the fresh and hardened properties of ordinary Portland cement (OPC). Similar to OPC, the properties of alkali-activated materials (AAMs) may be susceptible to the mixing procedure, yet the mixing procedure's effect is still unclear. This research aims to investigate how different mixing procedures affect the fresh and hardened

A microstructure-guided diffusivity model of cement paste is devised to explore the dependence of the relative diffusivity on the microstructure evolutions of cement paste from fresh state via non-spherical cement particles hydration to hardened state. The microstructure-guided diffusivity model contains three main components: (1) the microstructure of fresh cement paste is generated to simulate the

Reynolds dilatancy is one of the main mechanisms responsible for the lubrication layer (LL) formation during pumping of self-consolidating concrete (SCC). In this study, the effect of morphological characteristics of coarse aggregate on Reynolds dilatancy of 30 different SCC mixtures was investigated. The Reynolds dilatancy measurements were carried out using a coaxial-cylinders tribometer. New methodology

The present study investigated the carbonation of calcium sulfoaluminate (CSA) cement blended with blast furnace slag. Paste samples were prepared by substituting CSA cement with slag at dosages of 0, 30, 50, and 70 wt%. The samples were carbonated for 28 days at a CO2 concentration of 3% after a sufficient pre-curing period. The test results indicated that slag incorporation did not affect the phase

This study aims to predict the autogenous shrinkage of alkali-activated concrete (AAC) based on slag and fly ash. A variety of analytical and numerical models are available for the prediction of autogenous shrinkage of ordinary Portland cement (OPC) concrete, but these models are found to show dramatic discrepancies when applied for AAC due to the different behaviours of these two systems. In this

An energy storage microsphere, prepared by encapsulating phase change materials in high-strength hollow microsphere, was proposed in this paper. The research objective was designed to utilise energy storage microspheres (ESM) in the cement mixture to achieve low hydration exothermic, without negatively affecting other properties. In this study, ESM were prepared and the difference between sealed and

This article evaluated the effect of improved autogenous mortar self-healing in the alkali-aggregate reaction (AAR). Prismatic mortar specimens were cast with different contents of polypropylene microfiber and crystalline admixture. The crack-induction method (for subsequent self-healing) was the AAR accelerated mortar bar test itself. After AAR-testing, the specimens were submitted to wetting and

This paper aims to quantitatively examine the effect of sodium chloride (NaCl) on the frost-induced mechanical deterioration of mortar. After the freeze thaw cycles (FTCs), the mechanical properties of sealed specimens (70 × 30 × 5 mm) saturated with NaCl solutions were investigated. As found, the specimens with a lower water-to-cement ratio (W/C) show no clear reductions in their flexural strength

The properties of silicon nanowhiskers suggest that they are ideal candidates for high-performance cementitious composites. In this study, we used SiC nanowhiskers (SiC NWs) without treatment and treated them at 500 °C. The SiC NWs were dispersed in water, and the corresponding effects of dispersion at 0.25, 0.50, and 1.00 wt% of cement were investigated. The rheological properties and fluidity of

This paper presents a numerical approach for predicting spalling in concrete structural members under fire conditions. The proposed approach evaluates spalling by taking into account the stresses generated due to pore pressure, thermal gradients, and structural loading under fire conditions. This approach is incorporated as a spalling sub-model into a macroscopic finite element based model that is

Ohmic heating (OH) curing method has been proved to cure conductive fibers enhanced cementitious composites by electric-heating conversion under ultralow temperature, and this curing effect depends greatly on the heating efficiency. This paper presents a novel idea of utilizing carbon nanofibers (CNFs) to regulate and control the heating efficiency of carbon fibers (CFs) enhanced cementitious composites

It is crucial to investigate the evolution of microstructure to understand the deterioration mechanisms of shotcrete under cyclic freezing and thawing (F-T). In this study, nanoindentation and X-ray micro-CT techniques are integrated to characterize microstructural damage of shotcrete and its evolution due to F-T actions. An integrated statistical method of nanoindentation and micro-CT (NI-MCT) is

This study focused on the development of 3D printed building components incorporating MgO–SiO2 binders. The effects of parameters such as MgO/SiO2 and water/binder ratios and superplasticizer dosage were evaluated to produce 3D printable MgO–SiO2 binders. The assessment of rheological and mechanical properties, which led to an optimum mix that satisfied the printability criteria, was supported by microstructural

Mineral-impregnated, carbon fiber composites (MCF) are a promising alternative to conventional concrete reinforcements. For the efficient industrial production of MCF, sufficient processing time for the impregnation suspension must be ensured. In the present investigation, a metakaolin-made geopolymer (GP) has been developed and tested for this purpose. The impregnation of carbon-fiber yarns was performed

Pore structure is an important factor that affects both vapor adsorption and water absorption performances of the expanded perlite insulation mortar. This study aims to explore the change in the pore structure of the expanded perlite insulation mortar in heat-rain cycles and investigate the effects on capillary water absorption and vapor adsorption performances. The expanded perlite insulation mortar

The service life of concrete structures is often threatened by unfavorable dynamic loads. Optimizing the material damping can improve the vibration damping of the structure. In this study, a polyvinyl alcohol fiber-reinforced high-volume fly ash (PVA-HVFA) cementitious composite was developed with high damping characteristics and moderate mechanical properties. The coupling effects of frequency and

More sustainable and environmentally friendly concretes are essential to reduce the climatic and environmental impact of the growing demand for concrete to fuel urban sprawl. This manuscript reports on an experimental study designed to test the fire resistance of one such concrete, prepared to contain natural zeolite-bearing tuff. The fire resistance of concretes containing natural zeolites has received

Yield strength development of 3D printable concrete by the early age activation reactions plays a vital role in the printability of geopolymer concrete. This study presents a rheo-chemical approach to investigate the early age strength development due to alkali reactions for the formulation of suitable 3D printable one-part geopolymer concrete. The influence of design parameters, including activator

Geopolymer binders, having high mechanical performance and associated low carbon dioxide (CO2) emission, are a promising alternative to Portland cement. However, the brittle fracture of geopolymer matrices may cause catastrophic failure. In this context, seeking to unite the concepts of textile concrete technology and additive manufacturing, this work proposes the development of composites of geopolymer

The confining effect of concrete cover and stirrups reduces the rate of bond deterioration due to corrosion. However, the large dispersion in recorded experimental data makes it difficult to clearly separate the influence of cover depth and stirrup confinement on bond degradation. This study utilises the discrete 3D Rigid Body Spring Model (RBSM) to conduct a meso-scale investigation regarding the

With the development of the sustainable cement industry, the self-healing properties of concrete have received widespread attention. In many studies, both microorganisms and fibers play an important role in promoting the self-healing ability of concrete. In particular, some recent studies have tried to load microorganisms with fibers for improving the self-healing ability of concrete; and these studies

To investigate the dispersion of montmorillonite (MMT) nanosheets in cement, MMT was modified with three organic surfactants of various alkyl chain lengths (C1-OMMT, C10-OMMT and C16-OMMT) and then compounded with cement. Of all nanocomposites, the one containing 0.5 wt% of C10-OMMT exhibited the most significant enhancement in compressive strength by 11.2% and in the hydration degree by 11% with low

Efforts are currently underway to improve the performance of small electric antennas and resonator-based antennas embedded in the civil infrastructure. One of the main limitations of these small antennas is that they have narrow bandwidths which limit their use when embedded in concrete. The present work shows that by changing the amount of iron (III) oxide microparticles in a cementitious matrix,

Durability of concrete is a key design parameter and is strongly related to the penetrability of the cementitious binder matrix. This research evaluated methods to estimate the durability of concrete in service, using different procedures to characterize the penetrability of concrete, mortar, and paste. Mercury intrusion porosimetry (MIP) was compared to several standardized testing methods (surface

Microencapsulated phase change materials (MCPM) have been shown to be a promising material that can be used in cementitious composites for thermal energy storage. This paper evaluates the thermal efficiency of MPCM incorporated in the cementitious composite and quantitatively identifies the influential mechanical and chemical damages that can lead to reductions in thermal efficiency of MPCM with melamine

Geopolymer foam concrete (GFC) has attracted significant research interest in various fields, thanks to their porous structure which brings the inherent merits of lightweight, acoustic and thermal insulation, and fire resistance. This review is focussed on three primary functional properties of GFC, namely mechanical properties (compression and flexural strengths), serviceability (thermal conductivity

This study investigates the long-term (570 days) performance of alkali-activated slag (AAS) mortar materials exposed to combined wet-dry cycles and sodium sulphate solutions (i.e. 5 wt% and 10 wt%). Physical and mechanical characteristics of AAS mortars (i.e. visual appearance, compressive/flexural strength, mass change, capillary porosity, water sorptivity) as well as mineralogical and chemical parameters

This work investigates spent caustic as an alkaline activator for the consolidation of municipal solid waste incineration (MSWI) fly ash through the alkaline activation process. The effects of comparable alkalinity of NaOH solution and spent caustic, and the addition of blast furnace slag (BFS) on consolidation MSWI fly ash were investigated. Compressive strength measurement for alkali-activated MSWI

The Freeze-thaw (FT) performance of cementitious materials is dependent on the degree of saturation (DOS). It has been proposed that FT damage can occur during freezing when the DOS is greater than a critical DOS (DOSCR). In a previous study, a systematic methodology has been developed to determine the DOSCR of cement paste samples using high precision length change measurements during freezing and

The influence of molybdate on the spontaneous passivation of the low-carbon steel and a novel 10% Cr steel in saturated Ca(OH)2 solution was investigated in this study. The results show that molybdate promotes spontaneous passivation of low-carbon steel at the early exposure time and its passivation capability can be further enhanced with increasing concentration of molybdate. Unexpectedly, when adding

Tobermorite is a natural mineral found in the microstructure of special concretes, such as autoclaved concrete and oil well cement, and along with jennite has been extensively studied for their analogy to the layered atomic structure of C –S –H. By employing creep microindentation tests, which allow measuring the logarithmic creep, this work aims at further investigating the viscoelastic behavior of

This work focuses on studying the alkali-activated fiber reinforced composites (AAFRCs) with steel slag (SS) as a precursor material. Apart from finding a sustainable way to reuse the enormous amount of industrial by-product SS, it is also the aim to develop material systems with excellent ductility that may be used in a variety of applications. Using SS as a partial replacement (0%–25%) for fly ash

This paper aims to examine the effect of orientation and alignment of carbon fibers contained in a cement-based sensor under a magnetic field (MF) on the electrical and piezoresistive sensing properties of the resulting cement-based composite. The electrical conductivity and piezoresistive responses in two directions of aligned carbon fiber cement-based composites, i.e., parallel and perpendicular

In this study, the macro properties (residual compressive strength), meso properties (mesoscopic images), and micro properties (reaction products and pore structures) of paste specimens with various limestone and calcined clay contents at elevated temperatures (20, 300, 550, and 900 °C) are experimentally investigated. According to the experimental results, (1) the strengths of all samples increase

We investigated the sulfuric acid resistance of low-calcium alkali-activated materials (i.e., geopolymers) supplemented with an iron mineral admixture (i.e., hematite). Geopolymers without and with 5% hematite were produced at two alkali contents (Na:Al = 0.86 and 1.39). Acid degradation reactions were comprehensibly studied through three replenishes of acid. Results demonstrate that hematite is chemically

Chloride-induced corrosion of steel rebar embedded in concrete is one of the major concerns influencing the durability of reinforced concrete structures. It is widely recognized that the carbonation in concrete affects the chloride diffusivity and accelerates chloride-induced reinforcement corrosion. The service load-related cracks also have a dominant influence on reinforcement corrosion. This study

Sprayable engineered cementitious composites (ECC) has demonstrated in field applications as a promising repair material. However, the large cement dosage that leads to a high carbon footprint and potential restrained shrinkage cracking suggests needed improvements. In this study, a sprayable ECC was developed using calcined clay limestone cement (LC3), calcium sulfoaluminate (CSA) expansive additive

This paper provides a comprehensive review of the material behaviour for extrusion-based concrete 3D printing spanning from the early age to long-term performance. We begin with a discussion on the recent progress on the understanding of early-age behaviour. Following this, the mechanical response in the hardened state, and the different strategies to introduce reinforcement are reviewed. Finally,

Cement composites were realized containing graphene-based materials having different oxygen content (from 0 to 45%). It was found that the polarity of the reinforcement influences both the dispersion in water and the chemical interaction with the hydrated cement matrix, and thus the mechanical performance of the composites. In particular, the reinforcements with the highest oxygen content result aggregated