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

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

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

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 various curing conditions were investigated to assess the effect of steel slag and fly ash on the stability of MPC. The microstructure of hardened MPC was analysed using X-ray diffraction, scanning electron microscopy

Cracks will affect the service life of concrete, even if they are small ones. A crack healing method based on biomineralisation is presented to repair microcracks in concrete specimens. By analysing the change in permeability, adopting two different ultrasonic detection methods, and conducting unconfined compressive strength tests, scanning electron microscopy and X-ray diffraction tests, this method

The lifetime of a geothermal well is strongly dependent on the long-term performance of the cement used for its construction. The critical zones in well cements are the outermost layers, where the cement encounters either the steel casing or the rock formation. The current paper presents a study of the changes in the interfacial transition zone that forms between geothermal cements and volcanic rocks

LiAl-layered double hydroxide (LiAl-LDH) has been reported as a potential hardening accelerator of calcium sulfoaluminate (CSA) cement. Until now, little has been known about the effect of synthesis conditions and post-synthetic treatments of LiAl-LDH on the performance of CSA cement. The present work shows two methods for the synthesis of LiAl-LDH – a solvothermal method and a separate nucleation