ASTM C 1260 (accelerated mortar bar test (AMBT)) is the most popular and time-effective method to evaluate the alkali–silica reactivity of an aggregate. In this study, the test specimens (mortar bars) of AMBT were prepared with six aggregate groups having six different rock mineralogies (limestone, dolomite, andesite, dacite, basalt and dolomitic limestone) and three dosages of cement alkalis (0·42

When concrete is placed in harsh conditions where aggressive chemicals are present, high-performance concrete that provides the highest levels of durability and technical performance is required. At the same time, locally available construction materials must be used so that the cost of concrete production is minimised. Deserts, which generally receive less than 250 mm of precipitation each year, take

This paper aims to provide guidelines for selecting the correct type of carbon nanotube (CNT) to improve the mechanical properties of cementitious materials. Previous researchers have discussed the effect of CNT characteristics on their dispersion quality. However, the effect of these characteristics on the mechanical properties of CNT-reinforced cementitious materials is not fully understood. To clarify

In this study, hydrogen fluoride (HF) was used to generate perforated holes in cenospheres. The cavities of the cenospheres were then filled with coagulants (calcium chloride (CaCl2)) and encapsulated in polyvinyl alcohol to obtain cenosphere microcapsules. The release curve of the cenosphere microcapsules in deionised water was tested using ethylenediaminetetraacetic acid titrimetry, and the corresponding

This study examines the effect of different arrangements of transverse reinforcement in the jacket section on the axial performance of full-scale reinforced-concrete columns strengthened with a seismic section enlargement approach. For the jacket section with seismic details, overlapped channel-shape bars and prefabricated bar units were designed as the closed peripheral hoops, and V-ties or segmented

Although high-strength concrete (HSC) has higher compressive strength than normal-strength concrete (NSC), its application in column construction is often limited by its brittleness and limited post-peak ductility. In this preliminary study, hybrid fibre engineered cementitious composite (ECC) is proposed as a potential encasement material to confine the HSC core and to increase the column's ductility

The restrained volume expansion of expansive agents during hydration is often used to offset strains caused by the shrinkage of cement-based materials (CBMs). The hydration and expansion process of a laboratory-prepared calcium-oxide (CaO)-type expansive agent (CEA) in CBMs and modelling of the same are discussed in this paper. Based on isothermal calorimetry and thermogravimetry/differential thermal

The chloride diffusion coefficient is directly related to the property of concrete to resist the ingress of chloride ions and it is a decisive factor for the durability of reinforced concrete subjected to the chloride environment. The conventional chloride diffusion test requires considerable time to attain a steady-state chloride flow across the specimen. Therefore, the rapid chloride migration test

To address issues related to fast setting time of high-calcium-based alkali-activated binders and low-calcium-based alkali-activated binders' need for curing at elevated temperatures, this study aimed to develop hybrid low-calcium- and high-calcium-based binders with satisfactory fresh and hardened properties. This study was divided into two main phases: (i) production of alkali-activated natural pozzolan/slag

The influences of temperature, relative humidity (RH) and carbon dioxide (CO2) concentration on concrete carbonation in a simulated environment were investigated. The carbonation depth, compressive strength and surface strain of concrete under different simulated environments were tested. The results showed that the effects of temperature, RH and carbon dioxide concentration on carbonation depth and

As the depth of mines increases, the in situ stress increases gradually, resulting in increasingly demanding requirements for the support strength of coal-mine roadways and making it more difficult to provide this support. For this reason, more effective forms of support are needed. Concrete is a typical support form, but ordinary concrete has low support strength, cracks easily and is prone to brittle

In this study the reinforcement correction factor of concrete core testing was investigated in more detail to prepare appropriate outlines for the interpretation of results in order to minimise the uncertainties involved. For this purpose, an extensive experimental programme was undertaken, considering different concrete strength levels, moisture conditions, core size, length-to-diameter ratios of

The behaviour of concrete under sudden impact loads is complex. Moreover, very little is known about the impact behaviour of high-performance fibre-reinforced concretes (HPFRCs). To account for this, nanomodified deflection-hardening HPFRC mixtures incorporating coarse aggregates were produced with three ratios of fly ash to Portland cement (0·0, 0·2 and 0·4), three nanomaterials (nanosilica, nano-alumina

In order to study the size effect in concrete fracture, three-point bending tests are performed on five groups of geometrically similar concrete beams. The electronic speckle pattern interferometry (ESPI) technique is used to measure the full-field deformation of concrete beams. Crack opening displacement data, which is crucial for understanding crack initiation and the evolution mechanism, but which

In this paper, the performance degradation of reinforced-concrete (RC) columns with corroded longitudinal steel bars was experimentally investigated. Ten large-scale RC column specimens were constructed, and the longitudinal steel bars were corroded, to simulate the real severe environmental condition that concrete structures may encounter during their long-term service life, using a hybrid method

Concrete is a highly complex and heterogeneous three-phase composite composed of aggregates, matrix and the interfacial transition zone (ITZ) between them. As the weakest structure of concrete, the ITZ is often ignored due to difficulty in its modelling using the finite-element method. In this paper, concrete models with high-volume fractions of aggregates are established, in which the ITZ structure

Ultra-high-performance fibre-reinforced concrete (UHPFRC) is a relatively newly developed construction material that not only has high compressive strength (greater than 150 MPa), but also high tensile strength (10–20 MPa). The use of UHPFRC enables the design of slender structural members; hence, instability could become a major governing failure mode. However, the estimation of buckling strength

The process of determining crack extension resistance curves (KR curves) associated with the cohesive stress distribution for the complete fracture process of a three-point bending concrete beam at low temperatures from 20°C to −40°C is presented in this paper. A total of 32 concrete beams were divided into two groups, based on different ages, 28 d and 120 d. The KR curves were calculated from curves

By having the potential to remove nitrogen oxide (NOx) air pollutants generated by vehicles and other anthropogenic combustion processes, particularly in urban areas, photocatalytic concrete has attracted significant commercial interests all over the world. In contrast to typical photocatalyst applications in concrete, in which titanium dioxide (TiO2) – the most utilised photocatalyst – is dispersed

This paper reports an investigation into the effect of a severe chloride environment on the flexural behaviour and microstructure of concrete composites combining normal- or high-strength concrete and ultra-high-performance fibre-reinforced concrete (UHPFRC). The normal- or high-strength concrete layers were used in the compression area while the UHPFRC, with three different fibre contents (1, 1·5

Pull-out tests combined with an in situ radiographic movie are presented in order to investigate bond properties between steel rebar and concrete during tests on concrete reinforcement samples. Rebar relative displacement and other theoretically anticipated properties during the loading process, such as regions inside the concrete with maximum compression and longitudinal cracks, could be visualised

Four circular fly-ash concrete columns reinforced by steel rebars with different bond levels were tested to investigate the influence of bond strength of longitudinal steel rebar on the seismic behaviours of reinforced-concrete (RC) members. Furthermore, a fibre-element method considering steel bond slip was used to investigate the influence of bond properties of steel rebar on seismic responses of

The bond between prestressing strands and concrete in the transfer zone of pretensioned concrete members is a complicated mechanism. Concrete creep and shrinkage are dominant time-dependent factors that affect the strand bond. In this study, a semi-analytical bond stress–slip model was developed, based on test results of the standard test for strand bond for 15·2 mm strands. Effects of concrete creep

Beam–column joints are generally recognised as critical regions in the analysis and design of moment-resisting reinforced-concrete (RC) frames subjected to both lateral and vertical loads. Such joints should be designed and detailed to ensure that they have adequate overstrength and allow adjacent beams to reach their full ductile capacities. To develop an improved method for predicting the deformation

Bond behaviour plays an important role in the design and performance of reinforced-concrete structures. In this study, finite-element modelling is used to perform a parametric study. The bond between the glass fibre-reinforced polymer (GFRP) bar and alkali-activated cement concrete is modelled by surface-based cohesive behaviour. The accuracy of the model is validated by comparing model predictions

Twenty-four mortar mixes were tested to assess the effects of mix design factors on complex electrical resistivity. Of these mixes, six were conventional and 18 were conductive mixes, containing varying quantities of either graphite or carbon fibre powder additions, which have been shown in previous studies to reduce the resistivity of cementitous materials. Complex resistance measurements from 20 Hz

Mechanical and durability properties of concrete made with magnesium–silicate–hydrate (M–S–H) binder systems were tested in comparison with Portland cement. The M–S–H binary binder system included 60% magnesium oxide (MgO) and 40% silicon oxide (SiO2), while the ternary system replaced 10% of the M–S–H binder with 10% crushed quartz filler. It was found that the compressive strength of M–S–H concrete