The purpose of this study was to investigate how the addition of shrinkage-reducing polycarboxylate superplasticiser (SRPC) affected the shrinkage of cement-based materials (CBMs). SRPCs can signif...

In this paper, the macro–micro interfacial bond behaviour of steel fibres embedded in ultra-high-performance concrete (UHPC) matrix was investigated using a single-fibre pull-out test with the para...

The expansion deterioration that occurs in concrete structures exposed to high temperature fluctuation in wet environments is often attributed to delayed ettringite formation (DEF). Due to the complex mechanism and various factors that influence DEF, it is difficult to establish effective methods for predicting the expansion and suppressing deterioration. With the aim of improving the durability and

The random packing of aggregate particles is an important factor affecting the mechanical properties of concrete at the mesoscopic scale. In the current study, a meso-mechanical pretreatment algorithm is developed to construct the random ellipsoidal aggregate model for the mesoscopic structure of fully graded concrete. The Fuller curve combined with equivalent diameter is adopted to ensure equality

The effect of foam porosity on absorption, chloride ingress and resistance to corrosion of embedded steel under a chloride environment was studied. Performance of mixes with water/cement (w/c) ratio of 0.5 and moderate and high foam contents of 20 and 50% were determined and compared with those of a base mix with the same proportions but without foam incorporation. A structural grade foam concrete

Reinforced concrete (RC) walls subject to in-plane lateral loads are essentially subject to axial compression and tension forces in the respective end regions of the wall. The tension forces initially result in elastic tensile stresses in both the concrete and longitudinal reinforcement. Cracking occurs after the maximum tensile stress of the concrete has been exceeded and results in the reinforcement

In this paper, a parametric study based on the load transfer test specified in ETAG 013 was performed with the aim of investigating the efficiency of the confining reinforcement in the local anchorage zone of post-tensioning tendons, in particular when there are two types of confining reinforcement, spiral and stirrups. The parametric study was conducted using the finite element software ATENA 3D and

The main thrust of the work reported herein is to study the effect of chemical additives to make beneficial use of carbon dioxide in enhancing the compressive strength of dry-cast concrete. The additives used in this investigation were calcium and magnesium oxides and silicates, nickel oxide, sodium hydroxide, sodium bicarbonate and strontium chloride. The experimental results showed that both the

Progressive collapse of reinforced concrete flat plate systems can be significantly influenced by the post-punching performance of their slab–column joints under large deformations. This work presents a series of static collapse tests on four flat slab–column joint specimens with slab in-plane restraint. The effects of different punching directions (upward and downward) and embedded beams on the post-punching

Plastic shrinkage cracking in concrete is mainly a physical process, in which chemical reactions between cement and water do not play a decisive role. It is commonly believed that rapid and excessive moisture loss due to evaporation is the primary cause of the phenomenon. This paper presents a new model to estimate the severity of plastic shrinkage cracking, based on the initial setting time and the

Structural health monitoring (SHM) of civil engineering structures has been widely developed to increase safety and to provide cost-effective maintenance programmes. Although the current approaches...

The focus of this work was the thermal properties (thermal conductivity, thermal diffusivity, specific heat capacity and linear expansion coefficient) of steel-fibre-reinforced reactive powder conc...

Cracking is a common form of damage in reinforced-concrete (RC) beams. Cracks affect the frequency and deflection of RC beams. Although a model for the natural frequencies of RC beams with one or t...

In the present work, textile-reinforced concrete (TRC) specimens were produced using high-performance natural curaua unidirectional fabrics as reinforcement. Portland cement was partially replaced ...

The paper investigates the potential for recovering granulated blast furnace slag after four to five years’ storage in a stockpile (weathered) for use as an addition in concrete. The initial research physically and chemically characterised fresh and weathered granulated slag. Thereafter, studies on ground materials in paste and mortar were carried out. The weathered granulated slag was similar to fresh

Moisture transport has a great impact on concrete durability. In this study, a hard-pulse one-dimensional frequency coding sequence of low-field nuclear magnetic resonance (LF-NMR) imaging was applied to investigate moisture transport in cement-based materials (CBMs) considering the influences of the water/binder (w/b) ratio, sand/cement (s/c) ratio and contents of silica fume (SF) and super-absorbent

A ternary hardening-accelerating admixture for Portland cement, comprising calcium fluoroaluminate (11CaO.7Al2O3.CaF2), calcium thiocyanate (Ca(SCN)2) and triethanolamine (C6H15NO3), was studied. The cement paste was investigated using compressive strength tests, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and porous medium surface area analysis. The results showed that

This investigation aims to study the abrasion and impact resistance of fibre-reinforced concrete before and after exposure to salt scaling. Different types of steel fibre and different mixture compositions were used to improve the strength and resistance of the tested mixtures. The variables were the type of steel fibres, surface condition of steel fibres (coated and uncoated), length of steel fibres

In this work, different cementitious systems were used to investigate the shrinkage of concrete under plastic and drying conditions. Emphasis was placed on Portland limestone cement (type IL) with replacement amounts of 10% of Portland cement. Comparisons were made with a cement type with low Blaine fineness (i.e. coarse ground cement). The results indicated that type IL cement has good shrinkage results

Reinforced concrete in aggressive environments, has higher concrete clear cover provided to protect the reinforcement against corrosion. However, providing such higher cover in severe environments ...

Through upscaling from the hydration products to a macroscopic composite, a multi-scale framework is proposed to predict the effective properties of ultra-high-performance concrete (UHPC) with diff...

This paper presents two different approaches to model corrosion-induced crack propagation in reinforced concrete structures. Both approaches are based on a thick-walled cylinder analogy, in which t...

In a post-tensioned precast concrete beam–column connection, the precast beams are post-tensioned to ensure the integrity of the connection and to provide recentring characteristics when the connection is subjected to seismic loads. In this study, the post-tensioned precast concrete beam–column connections were tested under reverse-cyclic loading with the test variables of grout strength at the beam–column

A vast number of numerical approaches have been used to simulate the non-linear behaviour of concrete and reinforced concrete members at different scales. Most approaches were based on the finite-element method and have a variety of disadvantages when modelling brittle materials. Thanks to increasing computational power, mesoscale lattice models have been developed to achieve more accurate results

The use of supplementary cementitious materials as partial Portland cement substitutes in concrete is one of the best strategies for reducing carbon dioxide (CO2) emissions in the cement industry, and also improves the properties of concrete. When highly reactive calcined pozzolans such as metakaolin are used, the setting time of concrete is reduced, and the use of retardants is necessary. The effect

This paper studies the method of determining the fracture parameters of pre-notched concrete beams with horizontal pre-set cracks and the influence of fracture intersection on fracture characterist...

Nowadays, basalt fibre is gaining popularity in the field of construction materials due to its low production cost and enhanced mechanical properties. However, research is still needed into the use of a single type of fibre with different lengths in composite materials. Therefore, in this paper the hybridisation of basalt fibre of various lengths and contents is studied in order to take full advantage

Cemented paste backfill (CPB), a soft concrete-like material, is extensively used in underground mines worldwide for ground support and/or mine waste disposal. One of the most important ingredients in CPB is cement but it is expensive and can amount to 75% of the cost of the CPB. Therefore, CPB reinforced with fibres has been proposed and introduced in backfill operations to reduce the overall cement

In this paper, based on pull-out test results, the influence of the number of chloride wetting–drying cycles, concrete strength, cover thickness, steel bar diameter and number of textile layers used in the textile-reinforced concrete (TRC) confinement on the bond property between concrete and a steel bar is analysed. Furthermore, a bond strength model is developed and the confinement effect of TRC

This paper seeks, as a part of Algerian policy, to encourage the reconstruction of the ground in order to achieve economic reconstruction and the safety of inhabitants and the environment. The study focuses on the hygrothermal behaviour of compressed and stabilised earth blocks that can be used in different climate zones, like the south of Algeria, where the temperature is up to 50°C in summer, and

The combination of realkalisation and migrating corrosion inhibitor (MCI) was proposed as a protective technique for structures subjected to carbonation-induced corrosion; the effects on passivated steel bars in partly carbonated concrete were investigated. The corrosion behaviours of treated steel bars under three exposure conditions (natural indoor environment, accelerated carbonation and simulated

The shear behaviour of large-scale engineered cementitious composite (ECC) beams reinforced with different types of fibre was evaluated. Four types of fibre were used: 8 and 12 mm long polyvinyl alcohol fibres (PVA8 and PVA12), 19 mm long polypropylene fibres (PP19) and 13 mm long steel fibres (SF13). An additional normal concrete (NC) beam of comparable compressive strength was cast and tested for

This paper presents an experimental study into the fundamental response of reinforced concrete members, which incorporate rubber particles obtained from recycled tyres, subjected to combined axial–bending loading conditions. Tests on confined circular members with and without internal hoops or external fibre-reinforced polymer (FRP) sheets are described. The results show that the rubber particles enhance

Pervious concrete has been widely used in parking lots and other lightweight streets. This paper investigates the mechanical strength, porosity and permeability of pervious concrete modified with fly ash, silica fume and basalt fibre. Based on the orthogonal design method, a mixture proportion of pervious concrete was obtained with a compressive strength greater than 40 MPa. In addition, three types

This paper presents forced and ambient vibration tests on a six-storey precast concrete frame building, a structural system that has not often been the focus of such tests in spite of its widespread use. Precast buildings come with semi-rigid connections so their idealisation requires good knowledge of the construction practice for those connections and their details. Structural system dynamic properties

This study presents an estimate of various strength and toughness properties of steel–polyester hybrid fibre-reinforced concrete obtained using artificial neural network techniques. Input parameters used in the development of single and hybrid fibre-reinforced concrete composites in the experimental programme were given as input variables in artificial neural network models. The constituents of concrete

L-shaped concrete-filled steel hollow-section (CFSHS) columns have the potential to be widely used as corner columns, and have the advantage of creating larger usable areas in buildings. However, few experimental tests of this kind of column under diagonal cyclic loading have been reported. Tests on eight L-shaped CFSHS columns with equal legs were conducted to study their hysteretic behaviour; the

The bond response of deformed bars in structural concrete is a phenomenon governed, to a large extent, by the rib-to-concrete contact and interaction, with contact forces depending on both material properties and the kinematics between the contact surfaces (slip and potential separation between the bar and concrete). This phenomenon, presenting similarities with aggregate interlocking in cracked concrete

In early August 2006, a crumb rubber concrete (CRC) bridge deck was constructed in a suburb of Tianjin, China. Although small, measuring 24 × 8 × 0·12 m, it was the first instance of the application of a CRC bridge deck reported in public literature. More than 10 years have passed since, and the last inspection of the deck carried out in June 2017 showed that few cracks have developed in the deck surface

Owing to their capability of meeting both structural and architectural demands, L-shaped reinforced-concrete (RC) walls are widely employed in low-rise and high-rise buildings. In spite of their po...

In the precast industry very early age strength development is crucial for productivity, and it is for this reason that industry has been reluctant to embrace the use of ground granulated blast-fur...

A numerical model for evaluating the permeability of cement mortar is proposed. The numerical model simulates the permeation process of cement mortar under water pressure considering the cement pas...

A systematic study on the chloride penetration resistance and binding capacity of cementitious materials containing varying proportions of low-calcium fly ash or blast-furnace slag is presented. The results show that a larger water/binder ratio of cementitious materials can enhance its binding capacity but reduce chloride resistance regardless of binder type. At a given water/binder ratio, the chloride-binding

Pervious concrete needs to have many pores to achieve high water permeability, but excessive porosity may cause a serious reduction in strength. Herein, it is postulated that the interconnected porosity and open porosity, which can be separately measured, do not have the same effects on the performance of pervious concrete. To evaluate how the interconnected porosity and open porosity influence permeability

Past earthquakes show that a large number of existing reinforced-concrete (RC) buildings sustain relatively substantial damage especially at the beam­­–column connections where it is mostly caused by either diagonal shear cracks due to the absence of transverse reinforcement or by bar slippage due to the insufficient bond length of the beam bottom bars. Slip of the beam longitudinal reinforcement in

The pore structure is of great concern to the mechanical properties and durability of concrete. This paper investigated the pore structures of slag-blended cement paste under steam curing using two non-destructive testing (NDT) tools: electrochemical impedance spectroscopy and ultrasonic methods. Four different pastes containing 0, 20, 50 and 70% slag were prepared. For the electrochemical impedance

In this paper, the effect of the partial substitution of cements with limestone powders (LSPs) with different replacement levels and fineness on the fracture and flexural properties of non-oil-coated polyvinyl alcohol (PVA) fibre-reinforced sulfoaluminate cement (SAC) was experimentally investigated. The properties of the matrix, including the pore structure and fracture behaviour, were evaluated by

In this paper, a precast post-tensioned (PT) concrete beam–column connection, composed of PT composite beams with partially bonded tendons, precast multi-storey columns and cast-in-place (CIP) core region, was developed as an emulative connection. Four full-scale beam–column connections, including an interior and an exterior precast connection and the corresponding CIP control specimens, were tested

In this paper, the stiffness degradation index previously proposed by the authors is used as a seismic performance index for circular concrete-filled steel tubular (CFT) columns. Four performance levels for CFT columns are defined – that is, virtually intact; minor damage; moderate damage; and severe failure. A total of 144 CFT columns are numerically analysed to obtain the stiffness degradation index

This paper presents an experimental investigation on the synergetic effect of magnesium oxide expansion additive (MEA) and superabsorbent polymer (SAP) on the long-term drying shrinkage, autogenous shrinkage, internal humidity and mechanical strength of concrete. Concrete with varying dosages of MEA (0, 4, 6, 8 and 10%) and SAP dosage (0, 0·2, 0·4 and 0·8%) was studied to assess the synergetic effect

Punching tests on continuous concrete slabs are very expensive and elaborate. As a consequence, the majority of the existing punching tests have been performed on isolated specimens representing only the hogging moment region around the considered slab–column connection. Isolated punching tests are valuable in order to analyse the punching shear behaviour systematically. Nevertheless, beneficial effects

Six half-scale, single-storey, one-bay frame specimens were tested to investigate the seismic behaviour of masonry-infilled reinforced concrete (RC) frames subjected to lateral loading. The variables investigated included the type of masonry infill and the types of openings. The crack patterns, failure modes, load–displacement hysteretic loops, stiffness degradation and energy dissipation capacity

In total, 48 cylinders were tested to measure the uniaxial compressive stress–strain relationships of geopolymer concrete composite (GPCC) with fly ash blended with ground granulated blast-furnace slag (GGBFS). Four replica specimens were fabricated for each of the 12 combinations of three parameters: ratio of GGBFS to binder (0·2, 0·3 and 0·4), concentration of sodium hydroxide (8 and 12 M) and curing

To understand the relationship between water permeability and the pore structure of cementitious materials, this paper reviews the literature on both water permeability and pore structure and the correlation between them. Although the majority of this data is for cement paste, mortar, concrete and cemented soil are also included. Based on this study, it is established that the determination coefficient

In sulfate-laden environments, salt weathering presents a serious threat to structures. Numerous explorations have focused on weathering due to partial immersion in a single-sulfate solution, but there are few studies concerning salt weathering attacks due to combined salt weathering. In this work, mortar specimens were partially immersed in a mixed solution of sodium sulfate (Na2SO4) and sodium chloride

The main purpose of this study was to investigate the fracture property of polypropylene fibre (PPF)-reinforced lightweight concrete (LWC) at high temperatures, and also the basic properties including compressive strength, mass loss and relative elastic modulus at different temperatures were investigated. The results showed that adding PPFs into LWC decreased its compressive strength at high temperatures

This research proposes a procedure to retrofit existing structures using self-centring post-tensioned precast concrete (SC-PC) frames. The procedure utilises the initial stiffness of the un-retrofitted structure and predicts the required initial stiffness of the retrofitted one using the N2 method. A modified precast beam-end shape is proposed to double the re-centring moment capacity of the retrofit

The compressive zone of concrete with a circular cross-section is simplified to an equivalent rectangular stress block with a width, height and thickness of the peak concrete strength considering the confinement ratio. The shape factors of the equivalent stress block at any concrete strain level are modelled through selected equations of the ratios of the axial load and moment sustained by compressive

One-phase models of rebar corrosion have been widely used by practising engineers to predict the volume of rust and the time to cracking of the concrete cover, but the models have only considered the deformation of concrete and not the deformation of steel or the rust layer. Neglecting the deformation of the rust layer may result in inaccurate predictions. This study therefore proposes an adjustment

In many cases today, concrete columns do not meet the requirements of current design codes due to a number of deficiencies, including low concrete strength, inadequate transverse rebar and low construction quality. This paper presents the results from an experimental study of a strapping method for retrofitting the axial performance of concrete columns. In the method explored herein, the high-strength