The effects of silica powder (SP) with different fineness values on the properties of magnesium oxysulfate cement (MOSC) were compared with the effects of fly ash (FA). X-ray diffraction, mercury porosimetry and scanning electron microscopy were used to analyse the effects of the particle morphology and fineness of FA and SP on the mechanical properties, hydration products and microstructure of MOSC

Analytical methods for characterising cement raw meal during heating in different atmospheres were investigated. The effect of replacing limestone with 10 wt% slag on the formation of incipient belite and precursors of the clinker liquid in the temperature range 600–1050°C was quantified using thermogravimetry, X-ray diffraction and equilibrium calculations. The results showed that when calculating

Shrinkage of hardened cement paste is a direct result of its desorption isotherm. The relationship between the desorption isotherm and the relative humidity in a hydrating cement paste is mainly controlled by the pore size distribution (nanopores to micropores). There are several hydration models to describe the microstructure of cement paste, but the desorption isotherm and self-desiccation are not

The production of concrete based on Portland cement consumes huge amounts of water every year, but water conservation is becoming a global concern. To address this issue, a special bonding material activated by carbon dioxide instead of water was prepared. The hardening performance, the composition and microstructure of the reaction products and the hardening mechanism of this bonding material were

Limestone powder has been widely used in concrete structures because of its easy availability and positive effect on reducing the heat of hydration. The addition of limestone powder has a significant influence on the hydration and microstructure of cement paste and therefore affects the strength and durability of concrete. This paper examines the hydration and microstructure of cement paste blended

Red mud (RM) can be used in large quantities in geopolymer technology to reduce the usage of ordinary Portland cement products. The effect of varying the particle size of RM on the potential reactivity of geopolymers and the properties of RM-based geopolymers was investigated in this study. Five different mean particle sizes (MPSs) were blended with blast-furnace slag to prepare RM-based geopolymers

Geopolymer-based materials have attracted increasing interest in construction and infrastructure engineering due to their high mechanical properties but low carbon dioxide emissions. However, it remains unclear whether this type of material can work in a stable way in harsh environments. This study investigated the chemical–physical–mechanical stability of metakaolin-based geopolymer (MKG) mortars

Coal flotation tailings (CFT) was calcined to be used as a supplementary cementing material. CFT and its calcined products were characterised by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. The pozzolanic activity of the calcined products was analysed by the strength activity index. The hydration products of blended cement were characterised

The aim of this research was to investigate the effect of the addition of discrete polypropylene fibres (PPF) and curaua fibres (CF) on the early-age autogenous and drying shrinkage of cement pastes. The fibres used were 12 mm long and the volume fraction varied from 0.3 kg/m3 (0.03%) to 2.7 kg/m3 (0.30%). Autogenous, unrestrained and restrained drying shrinkage tests were performed and it was found

Concretes, depending on their application, may be exposed to elevated temperatures during their lifetime, especially when placed near or in a furnace or during an accidental fire. The thermal stability of alkali-activated mortars and hydrated mortars prepared using ladle slag and two different aggregates was studied. A commercial calcium aluminate cement was used as a comparison for the properties

A calcium sulfoaluminate (CSA) cement has been characterised by X-ray diffraction and energy-dispersive X-ray spectroscopy analysis. Selective extraction methods have been used to improve detection limits for identification and quantitative measurements. Perovskites are present in the cement in the form of brownmillerite and a phase with the following average chemical composition Ca1·95Mg0·05Al0·2

Concrete is extensively used in the construction industry, but the formation and development of cracks undermines the integrity of concrete structures. Improving the mechanical properties of concrete and developing efficient health monitoring of structures are thus essential tasks to be tackled. The research described in this paper was concerned with the effect of nanofibres on the mechanical properties

A novel phosphorus slag-based concrete is illustrated and provided in the paper with the aim of investigating experimentally the water temperature and age effects on its mechanical behaviour. The compressive and splitting tensile experiments of this concrete with different water temperatures (5, 10, 20, 30 and 40°C) and ages (7, 24, 72, 168, 336 and 672 h) are carried out to reveal the corresponding

Under a cyclic wetting–drying chloride attack environment, carbonation is of great significance for chloride transport. In this work the impact of carbonation on the chloride penetration rate was investigated by exposing normal cement paste specimens and pre-carbonated paste specimens with different water/binder ratios and mineral admixtures to the same cyclic wetting–drying conditions. It was found

Calcium sulfoaluminate cement (CSA) has the characteristics of rapid hardening, high early strength, high corrosion resistance and high impermeability, but its ability to continue to show strength increases at middle and late ages is poor. In this study, this drawback was improved by clinker mineral design. Alite (C3S) in Portland cement clinker was used as a seed crystal to induce new C3S in CSA clinker

The chemical compositions of the aqueous phases in alkali-activated slag (AAS) paste and Portland cement (PC) paste were determined up to 28 d with the aim of obtaining a better understanding of the stability of the hydration products in the two binder systems. The saturation levels with respect to the hydration products of PC and AAS were obtained by thermodynamic modelling. The main findings of this

In this work, an eco-friendly lightweight cementless mortar has been prepared primarily from natural resources and industrial solid wastes. Lime–silica fume (lime–SF) paste (1 : 1 wt) was used as a green binder in lieu of cement. The binder was combined with expanded perlite (EP) aggregate with various aggregate volume contents of 25, 50 and 75%. The compressive strength, indirect tensile strength

The influence of sodium chloride (NaCl) on the hydration evolution of calcium aluminate cement (CAC) cured at 5°C, 20°C and 40°C was investigated by calorimetry, X-ray diffraction, differential scanning calorimetry–thermogravimetry, scanning electron microscopy and mercury intrusion porosimetry. The chloride binding capacity and compressive strength of the CAC were also determined. The results showed

Polycarboxylate superplasticiser (PCSs) are commonly used and studies to enhance their compatibility with other concrete raw materials have been undertaken. However, the effect of the side-chain length (SCL) in PCSs on the properties of cement-based materials (CBMs) has not gained enough attention. To fill this research gap, five types of PCSs with different SCLs were synthesised through a redox initiator

The roles of sodium hydroxide, calcium hydroxide and temperature on heat flow evolution and its relation to the reaction stages of alkali-activated coal fly ash were evaluated. The response surface...

The effect of styrene–butadiene copolymer (SB) dispersion on the early hydration of calcium sulfoaluminate (CSA) cement was investigated. Pastes with five different ratios (0, 5, 10, 15 and 20%) of...

Red mud is a byproduct of the aluminium industry and is typically considered hazardous waste owing to its high alkali content and resulting environmental pollution. In this work, Bayer process red ...

An in-depth study of cementitious composites incorporating fly ash cenosphere (FAC) and varying amounts of nano titania (NT) was carried out to explore the potential usefulness of NT in formulating lightweight cementitious binders for structural and functional applications. Cement pastes with fixed weight fraction (50%) of FAC, and varying amounts of NT (1·5–4·5 wt%) were prepared, keeping a fixed

Owing to its exceptional physical properties, silica aerogel is regarded as an attractive candidate material for building insulation applications; however, the widespread adoption of silica aerogel...

Alkali–silica reactivity of granulated ferronickel slag (FNS) aggregate was evaluated by accelerated mortar bar tests. The test results showed noticeable expansions of the samples containing 50% FN...

Fly ash based cements remain the most consumed pozzolanic cement in developing countries like India. However, despite such high demand, only 60% of the fly ash generated in India is consumed. One o...

The aim of this work is to investigate the carbonation resistance of limestone and calcined clay blended cement-based concrete. Two limestone and calcined clay concretes with an average 28 d compressive strength of about 36 MPa were considered. Limestone and calcined clay (with a ratio of 2 : 1) were blended with a general purpose (GP) cement. The GP cement substitution rates considered were 30% and

A new type of small-molecule phosphate superplasticiser (SP) was synthesised in one pot by the phosphorylation reaction of star-polyether with phosphoric acid. By varying the structure of the initiator polyamines, star-shaped small-molecule phosphate SPs with different molecular weights and anionic charge densities were prepared. The synthesised SPs were characterised by means of proton nuclear magnetic

Carbon dioxide (CO2) uptake and the mechanical strength of concrete with and without carbon-dioxide-philic (CDP) amine sorbents were assessed in this study. Cement pastes with three amine-based sorbents (5-amino-1 pentanol, piperazine and 3-amino-1-propanesulfonic acid) were hydrated for 28 d. They were then assessed for carbon dioxide uptake and compressive/bending strength. The carbon dioxide in

The air-entraining capabilities of polycarboxylate superplasticisers (PCEs) with different functional groups were systematically analysed. Using different molecular PCEs, the evolution process from bubbles in fresh cement mortar to pores in hardened cement mortar was investigated, considering their effects on mortar workability and mechanical performance. The results showed that PCEs with various functional

Microcracks can occur in oil well cement, which can lead to regional isolation and casing corrosion or even serious damage to the well. Self-healing cement is therefore of great interest for oil well applications. In this work, a self-healing material (called YW) was prepared by catalytic synthesis of a double-proton acid and characterised by Fourier transform infrared spectroscopy. The self-healing

The outstanding properties of carbon nanotubes (CNTs) mean they can be considered as potential components of high-performance cementitious composites. However, the major challenges of using CNTs in...

Several types of industrial wastes can be used as raw materials to obtain calcium sulfoaluminate (CSA) cement clinker. The first aim of this work was to define the maximum content of zinc that coul...

Different liquid accelerators including sodium aluminate liquid accelerator (SAa), fluoaluminate liquid accelerator (Fa) and aluminium sulfate liquid accelerator (ASa) were selected to investigate ...

This paper investigated the performance of cement mortar with the addition of various percentages of nano-silica (3%, 5% and 10%) at constant water to cement ratio. Early age properties of mortar a...

Growth in the production of cement has led to increasing demands for mineral additions. This study was conducted to develop an alternative addition by calcining dolomite at 800°C to obtain a mixture of periclase (MgO) and calcite (CaCO3). The light-burnt dolomite (LBD) was used to prepare blended cements. The hydration, setting time and microstructure of the cement were assessed and the compressive

Optimisation of the packing density of cementitious materials by the addition of supplementary cementitious materials (SCMs) is a way of obtaining the same service properties with less embodied energy and reduced carbon dioxide emissions. In this paper, ternary cement pastes containing metakaolin (MK) and limestone filler (LF) finer than ordinary Portland cement (OPC) were studied to evaluate the effects

This study examines the mechanism of adsorption–dispersion by superplasticisers with varying side chain density in cement paste. Acrylic acid was used to copolymerise with 2-methylprop-2-ene polyethylene glycol, using chain transfer agent to synthesise polycarboxylate ether superplasticisers (PCEs) with comparable main chain lengths and different side chain densities. Gel permeation chromatography

In this paper, the thermal performance of ground-granulated blast furnace slag (GGBFS) geopolymers is investigated. The geopolymers were prepared with sodium-based alkali activator and exposed to elevated temperature (200 to 1000°C) after 28 d of curing at room temperature. The unexposed geopolymers exhibited excellent compressive strength of 95 MPa. The compressive strength reduced to 8·9 MPa at 800°C

The effect of grinding hydrated tricalcium silicate (C3S) pastes on the bound water content (BWC) measured by thermogravimetric analysis was investigated. The samples were subjected to different curing regimes at 20°C and 40°C at a constant water to cement ratio of 0·5. Hydration reactions were stopped using a freeze drier. To study the effect of grinding, samples were either roughly crushed or finely

Among the several schemes that have been reported to be a satisfactory alternative to Portland cement is Alkali Activated Cement (AAC), which has recently started to gain greater consideration in construction sectors. Conventional two-part alkali activation has many drawbacks, including the activating solution being viscous, problematic and non-user friendly to handle. Thus, this research aims to produce

Because there is a shortage of high-quality fly ash (FA) in Kenya, to successfully build the Mombasa–Nairobi railway, the abundant natural pozzolan resources in the country need to be fully utilise...

During the last decades, alkali-free accelerators have appeared on the market of set accelerator additives for shotcrete. In this work, copolymers poly (AANa-co-DMAA) with variation of their charge...

Novel research on the preparation of grouting materials with a high volume of mineral admixtures is presented. The grouting materials were made from a ternary complex system containing sulfoaluminate cement, aluminate cement and gypsum. The maximum contents of fly ash (FA) and ultrafine slag (UFS) in the grouting materials only containing FA or UFS were 17 wt% and 23 wt%, respectively. It was found

Sulfate and carbonate can cause serious degradation of cement-based materials at low temperature; degradation products generally include ettringite, gypsum and thaumasite. The degradation process is very slow in a natural environment and no useful test method exists to accelerate the degradation process. This study used a voltage of 30 V and an electrical field duration of 20 s to study the acceleration

The results of research on cement composites with expanded graphite for application in temperature monitoring are presented. Two series of cement mortars were prepared with expanded graphite obtained from intercalated graphite by rapid heating at 500°C and 1000°C. The relation between temperature and electrical resistivity and the thermoelectric properties of the mortars with expanded graphite were

The compositions and contents of phases in cement paste soaked in sodium sulfate solution changing with time were investigated in this study. First of all, the porosities in cement paste specimens over time were measured by an in situ X-ray computed tomography (X-ray CT) test. Cement hydration and sulfate erosion occur simultaneously during the soaking process of cement paste specimens in sodium sulfate

This paper presents the influence of mineral additions in blended cement or ‘green’ concrete, on the divalent ions of the cement paste pore solution. Because of the lack of data concerning the dire...

The aim of this paper was to use the surface fractal dimension (Ds) to evaluate the chloride ion penetration of cement mortar in extremely cold regions. Pore structure is a critical factor that inf...

Ti is a common trace element in white Portland cement clinker. Ti4+ generally replaces Si4+ to form a solid solution in silicate mineral, which has an important influence on the mineral crystal for...

Lime mortar with organic additives is one of the most widely used building materials in ancient China and continues to play an important role in historic structure restoration. This study investigated the erosion of ordinary aerial lime and sticky-rice mortars under the cyclic actions of wetting–drying (WD) and dilute sulfate acid (DSA). Comprehensive experimental tests were conducted to study the

Portland pozzolana cement (PPC) and ordinary Portland cement (OPC) OPC-53 grades of cement are commonly used in India. The thermal responses of these types of Portland cement (PC) differed upon analysing the compressive strengths of their hydrated cement block specimens at elevated temperatures. At 800°C, PPC was able to maintain the integrity of the cube, while OPC-53 failed to do so at 500°C. Thermal

According to the C20 Portland cement concrete (PCC) batching standard, magnesium oxychloride cement concrete (MOCC) is made using bischofite from salt lakes and light-burned magnesium oxide as the main raw materials. In this work, the mechanical properties of MOCC (setting time and compressive and flexural strengths) were tested. The rules governing the phase composition and microstructure changes

Seawater from South China Sea was used instead of freshwater to fabricate magnesium oxychloride cement (MOC). To study the basic performance of the seawater-mixed MOC paste, the setting time, hydration exothermic characteristics, compressive strength, thermal stability, seawater resistance, phase composition and microstructure of the paste were analysed in detail. The results showed that the use of

The influence of the capacity of supplementary cementitious materials (SCMs) to consume portlandite on the carbonation resistance of mortar was investigated. Seven different mineral additives (two types of slag, two types of fly ash, two calcined clays and limestone) were used and their reactivity was measured using isothermal calorimetry, strength index measurements, Chapelle's test and thermogravimetric

A soap-free latex (XY-5) was prepared by means of a soap-free emulsion free-radical polymerisation method, using the synthetic polymer P (BA/AANa) as an emulsifier and butyl acrylate (BA), styrene and methyl methacrylate as monomers. The stability, thermal stability and microstructure of the XY-5 emulsion were studied using various methods, including viscosity analysis, zeta potential measurement,

One of the main problems affecting the flow of cement bulk powder is the formation of cohesive arching at the outlet of the hopper, causing blockage of the silo opening and bridge formation. A simple concept is established which outlines these complications. In this context, the interactions of particles lead to a high degree of consolidation of the cement powder and an increase of adhesion force due

In this study, the effect of pH value, a neglected but important factor of magnesium phosphate cement (MPC) pastes, was investigated to generate new ideas in the field of large water-to-solid (w/s) fraction MPC preparation. To avoid the introduction of impurities, the pH value was controlled by adjusting the proportions of diammonium hydrogen phosphate (DAP) and ammonium dihydrogen phosphate (ADP)

Deterioration of the cement asphalt mortar (CAM) cushion in non-ballast slab track can decrease the safety of high-speed railway lines in service. The improvement in the performance of CAM due to the addition of nanosilica was investigated in this study. The workability, mechanical properties and fatigue behaviour of CAM with nanosilica were determined and compared to those of CAM without nanosilica

The instability of magnesium phosphate cement (MPC) in moist environments limits its application. In the work reported in this paper, the residual strength and length evolution of MPCs under variou...