Shrinkage is the volume change of concrete without influence of external forces. Drying shrinkage, which occurs after the concrete hardening, is one of the most important causes of the cracking in concrete members. In addition to adverse effects on the appearance of concrete, cracks may reduce the strength and durability by increasing the permeability of concrete and facilitate the entry of aggressive

Cracks undermine the structural health of transportation infrastructure. Machine vision-based surface crack analysis is to process infrastructure inspection data collected by imaging devices for identifying the presence, location, and extent of cracks, classifying the corresponding severity levels, and eventually predicting their growth. Unlike the fragmented qualitative discussions on machine vision-based

Numerical simulations are conducted to study the influence of the heat release rate, the fire source location, and the tunnel slope on the smoke spread characteristics of V-shaped slope tunnels. Theoretical analysis and simulation results show that the smoke movement in the V-shaped slope tunnel is affected by the competition effect on both sides, which leads to the fact that the smoke only overflows

In the Chinese district heating network, unheated users generally exist in multi-family residential buildings, which adversely affects the heating performance of the whole building and its surrounding users. These effects are directly related to the fairness of heat metering and the rationality of system adjustment. Aiming to study this effect, a model of a multi-family residential heating system that

Energy consumption prediction for buildings and architectural complexes has become increasingly important. However, existing methods based on simulation software or statistical algorithms have distinct disadvantages. Consequently, this study introduces a novel prediction method based on models between occupant behavior and energy consumption. A new parameter––the occupant behavior characteristic parameter

Heating, ventilation, and air conditioning systems help maintain the appropriate level of thermal comfort and air quality in buildings. To this end, the energy supply of these systems must be guaranteed. However, continuous efforts are required to improve the energy efficiency of this system and reduce greenhouse gas emissions. In the zero-emission building approach, the use of thermoelectric devices

Network hydraulics play a major role in the design and operation stage of the District Heating (DH) systems, considering further hydraulic complexities expected in the near future. This paper presents a mathematical solution procedure that computes the network hydraulics, tailored as unique to the principal basis behind the branched type of DH networks. The procedure makes use of simple input data

While recent studies have shown that wearable sensing technology has the potential to facilitate the evaluation of physical fatigue, the reliability and validity of such measurements during construction tasks have not been reported. Thus, the primary objective of the current study is to establish absolute and relative reliability of textile-based wearable sensors to monitor physical fatigue during

The United Nations Sustainable Development Goal 7 (UNSDG 7) “Affordable and Clean Energy” strives to increase renewable energy share in energy consumption. Building-integrated photovoltaics generate renewable energy and offset fossil fuels carbon emissions. As roof space availability varies among different buildings, the potential to utilize rooftops as photovoltaic systems is uncertain. This study's

It is well-known that supplementary cementitious materials (SCMs) and low water-to-binder (w/b) ratio increase autogenous shrinkage, but the impact on microcracking and long-term transport properties is less understood. This paper examines the effect of microcracking induced by autogenous shrinkage on transport properties of concretes cured up to ~3.6 years. Variables include SCM type (9% SF, 70% GGBS)

The reactivity and early strength of cement:slag binders is usefully enhanced by the addition of sodium sulfate though the underlying mechanisms of the relationship between the enhanced hydration reactions and the structural aspects of the strength behavior remain unclear. In this study, microstructural development in the presence of Na2SO4 was investigated utilizing mercury intrusion porosimetry (MIP)

A recent survey has showed that predicting the long-term deflection of existing concrete bridges after several decades is a great concern in civil engineering. The crux is to predict the creep deflection of a concrete structure after several decades from laboratory tests carried out over few months. This work aims at combining microindentation tests and as short as possible Uniaxial Compression Creep

Extrusion-based concrete 3D printing is at its infancy and many aspects of this new technology need to be thoroughly investigated to pave the way for its widespread use in construction. Since the inherent drying shrinkage of the hardened cement paste is the source of the drying shrinkage of 3D printed concrete, the shrinkage behavior of cementitious 3D printing materials with very high cement to fine

In this study, the early age hydration kinetics of BOF slag is investigated. Isothermal calorimetry and in-situ X-ray diffraction (XRD) are used to examine the effects of K3-citrate concentration and nanosilica addition on slag reactivity. The results reveal that brownmillerite is the most reactive slag phase during the first 24 h of hydration. The kinetics of brownmillerite hydration is controlled

The early effects of three accelerators on a Ca(OH)2 activated ground granulated blast-furnace slag binder at low curing temperatures are discussed. The compressive strength, hydration kinetics, hydration products, and microstructures were investigated by isothermal calorimetry, X-ray diffraction, mercury intrusion porosimetry, scanning electron microscopy, and nuclear magnetic resonance. Results show

Considering the range of PCO2 of previous laboratory experimental works, in this study the carbonation rate of class G Portland cement was investigated at room temperature, in the PCO2 interval from 1 to 51 bar, to fill the existing gap of knowledge, through three types of laboratory experiments. Cement hydration (accompanied by limited carbonation) was carried out for 28 days at atmospheric conditions

The moisture transport and drying shrinkage properties of a certain type of Strain-Hardening Cement-Based Composite (SHCC) are investigated. This material is characterized by the usage of short high-modulus polymeric fibers as reinforcement of a cementitious mortar matrix with comparatively small grain sizes. The drying-induced mass loss and length change of circular cylindrical specimens with a radius

To reduce the dead load of concrete structures, this study developed a high performance lightweight aggregate concrete (HPLAC) by combining the use of ultra high performance cementitious composite (UHPC) and different types of aluminosilicate lightweight aggregates (LWAs). The physicochemical properties of two types of LWAs (i.e. expanded clay and expanded shale) influencing the HPLAC were elaborated

Corrugated cardboard is widely used in underground logistic transportation and warehousing and it has become an important fire hazard source. According to previous warehouse fire studies, upward flame spread on corrugated cardboard plays an important role during the initial stage of warehouse fires and can decide the occurrence of subsequent increasing fire hazards. However, the wavy structural effect

The heat release rates (HRRs) in fire experiments with gaseous fuels in tunnels were generally determined by the product of supplying fuel rates and their heat of combustion with the assumption that gaseous fuels could combust completely irrespective of ventilation conditions. In this paper, systematic calibration of the HRRs of propane fires at varying ventilation conditions in a tunnel was conducted

The adjustment of TBM operational parameters with regard to different strata significantly affects the safety, time and cost in tunnel construction. To assist TBM operation, this paper develops an integrated parameter prediction framework for hard rock tunneling based on combined pre-construction geological information and TBM operational data. The method involves three steps: extraction of TBM working

In comparison to conventional thermal insulators, superinsulation materials (SIMs), such as silica aerogel or vacuum insulation panels, provide a similar insulation performance at half to a quarter of the material thickness but this superior thermal insulation performance typically comes at a significantly higher material cost. However, under certain conditions, the use of superinsulation materials

The input setting of an air conditioner (AC) usage schedule has a significant influence on the results of the bottom-up simulation model of household AC energy use. To set more accurate inputs when estimating the AC energy consumption based on the bottom-up simulation model, it is essential to establish a prediction model for the AC on/off state. However, due to the limitation of the data collection

Today, about 35% of global energy consumption and related carbon dioxide emissions are caused by the construction sector. This paper evaluates and compares the life cycle energy consumption (LCEC) and carbon dioxide emissions (LCCE) of a heritage building (BT1) constructed in 1875, a new building (BT2) constructed with modern constructional elements with similar plans of the heritage building and the

In this paper, we describe patterns of residential heating based on data from 255 homes in and around Edinburgh, Scotland, UK, spanning August 2016 to June 2018. We describe: (i) the room temperatures achieved, (ii) the diurnal durations of heating use, and (iii) common diurnal patterns of heating behaviour. We investigate how these factors vary between weekdays and weekends, over the course of the

Building retrofits have great potential to reduce CO2 emissions since buildings are responsible for 36% of emissions in the United States. Several existing studies have examined the effect of building retrofit measures on CO2 emission reduction. However, these studies oversimplified emission factors of electricity by adopting constant annual emission factors. This study uses hourly emission factors

Household energy transition is beneficial to the environment and public health. However, the subjective welfare of the participants is not guaranteed to be improved. This paper takes China’s clean heating program as an example of household energy transition and investigates the factors that affect participants’ satisfaction with the program. Based on a large-scale household survey in Beijing, we find

The effect of nudging on the usage of an energy-consuming device associated with human indoor thermal comfort is investigated together with the corresponding effect on occupant subjective thermal comfort. Thirty-six subjects participated in an experiment conducted in an environmental room controlled to maintain a stable warm condition (operative temperature: 29.5 °C; corresponding PMV: 1.44). Each

This paper presents a method to estimate the maximum inter-story drift and relative displacement time history of multi-degree-of-freedom (MDOF) shear structures underground-motion excitation by using only one accelerometer installed on a floor when the structures are damaged during the event and hence modal parameters change and become unavailable. First, the absolute acceleration and relative displacement

The urban living habitat is one of the most important measures of socio-economic well-being in each country. Addressing the urban habitat's lifestyle change and pandemic pressure, the Asian cities, particularly, have found the abrupt changes altering local landscape and lifestyle. Cities filled with desires to modernize undertook actions that strained the local culture, perception, and ways of life

To break through the limitations of timber component processing, a new method of automatic processing of timber components – the robotic processing system, is proposed in this paper. The system makes robot, computer, intelligent control platform and other advanced techniques work together through interactive signals. The system has a high degree of integration and reconfigurability, thus, it can be

Radiative exchange in the indoor environment contributes significantly to the thermal comfort sensation reported by human subjects. The radiative exchange can have a strong directional character, depending on the temperature and size of various surfaces such as glazed areas, radiant panels, etc. Radiative asymmetry is known to cause significant thermal discomfort. The paper proposes a numerical simulation

The durability properties of load-induced damaged concrete incorporating recycled concrete aggregates (RCAs) have previously been reported, but the investigation on water transport in recycled aggregate concrete (RAC) subjected to sustained loading remains to be limited, especially involving both numerical simulation and experimental aspects. This paper presents a comprehensive exploration on capillary

The study of steel corrosion in steel-reinforced cementitious system has attracted much attention because this system is used in key buildings and infrastructure, and, thus, its deterioration represents a significant hazard. In many constructions, the top cement surface is coated with a stucco system. In this study, we present experimental results on the corrosion behavior of a rapid-set stucco composite

Concrete in maritime structure is vulnerable to deterioration owing to external sulphate attack, which can be exacerbated by wetting-drying action (WDA), jeopardizing its resistance to cyclic loads such as wind, wave and earthquake actions. This study aims to investigate the compressive fatigue behavior of concrete exposed to sulphate attack and WDA in marine environment. Cyclic compressive loading

In the specific study of medieval fortifications, an advanced knowledge of the state of conservation is required to achieve an effective diagnosis and a detailed evaluation that will provide the basis for establishing the criteria for prevention and restoration. The characterization of the materials and the knowledge of their degree of deterioration is one of the key points to address a restoration

Energy-conservation potential in the air-condition water system for subway stations is huge due to its conservative design method. Also, for operation strategy of such systems, the operation modes are formulated with the fixed schedule. This paper presents a data-based optimization method to obtain optimal parameters of the system for feedforward control. The data mining models are established by using

Joints are the weakest parts of prefabricated tunnels, and it is important to consider the material nonlinearities, mechanical properties and complex behaviours of joints in structural design. Based on existing joints, this paper proposes the design of three new types of joints for fabricated rectangular tunnels, including self-weight mortise and tenon joints, bolt mortise and tenon joints and steel

When carrying out compressive tests on rock specimens, a stress plateau is typically attained following peak strength within a strain range a few times larger than the strain at peak strength. This stress level is commonly known as residual strength. A large database of these tests on granitic rock specimens has been compiled and analyzed in detail with the aim of improving understanding of the residual

Air entraining admixtures (AEAs) are surfactant-based solutions and powders that are used to stabilize air voids in cement paste that protect concrete against frost damage. After reviewing the chemical and structural features of AEA that govern their performance, we discuss: (i) how they establish a stabilizing shell around air voids, (ii) methods for quantifying the distribution of voids after mixing

In this study, we propose a laboratory-scale methodology, based on X-ray micro-tomography and caesium (Cs) as a contrast agent, to advance the understanding of cracking due to alkali-silica reaction (ASR) in concrete. The methodology allows achieving a completely non-destructive and time-lapse characterization of the spatial-temporal patterns of both the cracks and the ASR products. While Cs addition

In this study, the influence of aluminum nitrate on the hydration process of magnesium potassium phosphate (MKP) cement was investigated experimentally and through thermodynamic modelling using diluted systems with Mg/PO4 molar ratio and water-to-cement ratio of 1 and 100 respectively. Three processes contributed to retard cement hydration: the acidic nature of aluminum nitrate which reduced the initial

This paper investigated the influence of hydration temperature on the nanostructure of the AH3 phase formed in calcium sulfoaluminate cements. Orthorhombic ye'elimite (st-ye'elimite) and cubic ye'elimite (ss-ye'elimite) were hydrated in an ultra-wide temperature range (5–220 °C). Results showed that the AH3 phase formed by ss-ye'elimite was always microcrystalline in nature at various curing temperatures

The fast setting of calcium sulphoaluminate (CSA) cement-based systems is typically controlled using set-retarding admixtures, despite the notable efficiency of tartaric acid (TA) in adjusting CSA-based mixtures setting times, its use has only been marginally investigated, with an almost exclusive focus on the early age properties of TA manufactured mortars. This paper aims at evaluating the effect

The facile synthesis of hierarchically porous spherical geopolymer beads via pipetting and low-temperature foaming is reported here. The potassium silica solution and metakaolin-slag-based slurries were modified by amorphous fumed silica in order to regulate the SiO2–Al2O3 ratio and to form a porous structure through chemical foaming technique under alkaline conditions. The addition of fumed silica

Reactive MgO (rMgO) is considered a promising alternative to Portland cement (PC), because its capacity to mineralize carbon dioxide (CO2) can be used to reduce the life cycle global warming intensity (GWI) of concrete. However, the greenhouse gases (GHG) emitted during the manufacture of rMgO may outshine its environmental benefits of CO2 mineralization. The objective of this study is to compare the

The mechanical and durability properties of recycled aggregate concrete (RAC) are generally inferior to conventional concrete due to the old mortar attached to the surface of original aggregate, which induces more complicated interfacial transition zones (ITZs) in the RAC. The microbial induced carbonate precipitation (MICP) modification is a novel and environmentally-friendly method to improve the

This paper characterises the durability of concrete produced with thermoactivated recycled cement (RC) obtained from waste cement paste or the cementitious fraction of waste concrete. The durability of concrete produced with 5–100% RC and water/binder ratios of 0.35–0.65 was assessed through capillary absorption, oxygen permeability, rapid chloride migration and carbonation resistance tests. Overall

The corrosion behaviors of partially and fully debonded steel fibers embedded in ultra-high-performance concrete (UHPC) and their impact on the pullout behavior were investigated. For this purpose, pre-loaded dog-bone samples were immersed in a 3.5% standard sodium chloride (NaCl) solution for 4, 10, and 20 weeks and then pull-out tested. The degree of corrosion on the fiber surface was determined

All over the world, “Construction” is an important sector that consumes a significant amount of resources and produces a lot of waste. Buildings as a whole share nearly one-fourth of total electricity generation in tropical countries that results in adverse effects on the natural environment and their national economies. Enhancing the building energy efficiencies relies on material and technology selection

In this paper, sensor calibration method using data-driven prediction models are developed to eliminate sensor error in the variable air volume (VAV) system. Indoor sensible loads and indoor carbon dioxide (CO2) concentrations, which are the main factors necessary for sensor operation in a VAV system, were predicted using a data-driven model (artificial neural network). Using this prediction model

Pressure control for cleanrooms in the pharmaceutical industry is a necessary means to avoid the cross-contamination. The pressure control of traditional air conditioning can only handle the working stage. In the non-working stage, the system cannot reduce the air change rate per hour (ACH) in order to alleviate the problem of high energy consumption. This paper proposes an improved air conditioning