807 Results Found

Expansive concrete are used to reduce cracking caused by drying shrinkage in concrete structures such as slabs, beams, columns, and pavement constructions. Although CaO and Sulphoaluminate based expansive agents have been used for decades, MgO-based...

Ultra-high performance concrete (UHPC) has a potential cracking risk due to its large autogenous shrinkage. The use of an expansive agent is an effective approach to reduce autogenous shrinkage of UHPC. However, different kinds of expansive agents sh...

In order to explore the intrinsic relationship between the expansion and strength of cementitious materials with CaO-based expansion agent (CEA), the effects of CEA on the expansion rate, strength, microstructure, and hydration products of cement pas...

Based on the underground reinforced concrete wall of subway stations (Hangzhou, China), this paper studied the influence of a MgO expansive agent (MEA) on deformation and mechanical properties of a reinforced concrete wall. The results show that the...

With the premise of ensuring workability on a fresh mixture, the volume stability of hardened self-compacting steel fiber reinforced concrete (SFRC) becomes an issue due to the content of cementitious materials increased with the volume fraction of s...

Using the volume expansion generated by the hydration of the MgO expansive agent to compensate for the shrinkage deformation of concrete is considered to be an effective measure to prevent concrete shrinkage and cracking. Existing studies have mainly...

Failure to fully backfill the goaf may result in increased exposure of roof strata, significantly raising the risk of roof collapses in mining zones and potentially causing surface subsidence, thereby endangering the safety of mining personnel. To ad...

With the increase of cement output, the demand for cement expansion agents increases, and composite expansion agents have become the development trend. The purpose of this study is to study the microscopic change process and expansion effect of calci...

This study employed a rapid freezing method to investigate the impact of individual additions of expansion agent, steel fibers, and High Elasticity Module Polyethylene Fiber (HEMPF), as well as their combinations, on the freeze-thaw resistance of Hig...

This study addresses the use of porcelain polishing waste as a pyro-expansive agent in clay-based formulations for the production of lightweight aggregates, aiming to reduce the consumption of natural resources and mitigate environmental impacts. In...

The impermeability of concrete is very important to its durability and service life, which could be affected by nanomaterial and mineral admixture additions. This paper tends to enhance the impermeability, strength, and microstructure of concrete usi...

In view of the performance requirements of mass ultra-high performance concrete (UHPC) for the Pang Gong bridge steel cable tower in China, the UHPC incorporating of steel slag powder and hybrid expansive agents is optimized and prepared. The effects...

Expansive agents (CaO, MgO, C₄A₃Š) were incorporated into coal gangue-slag-fly ash based geopolymer (CSFG). The influence of expansive agents on the properties and microstructure of CSFG was investigated by macroscopic tests including setting time, c...

The hybrid use of a superabsorbent polymer (SAP) and expansive agent (EA) is beneficial for mitigating the autogenous shrinkage of ultra-high-performance concrete (UHPC) without compromising strength. However, the unclear mechanisms behind the synerg...

This study explores the impact of an expansive agent (EA) on the performance of internally cured ultra-high-performance concrete (UHPC) using pre-wetted biochar to achieve a synergistic effect in mitigating autogenous shrinkage. Here, the biochar pro...

This study investigates the effects of the combined addition of MgO expansive agent (MEA) and rice husk ash (RHA) on the performance of concrete. Results show that MEA absorbs water and competes with superplasticizers for adsorption, reducing early-a...

Currently, mass concrete is increasingly utilized in various engineering projects that demand high physical properties of concrete. The water-cement ratio of mass concrete is comparatively smaller than that of the concrete used in dam engineering. Ho...

Cement-free concrete has a superior physical performance, such as in its strength and durability, compared to OPC concrete; however, it has the disadvantage of large shrinkage. Large shrinkage can cause cracks due to shrinkage stress in the long term...

This paper studies the influence of assembly unit of expansive agents (CaO and calcium sulphoaluminate) on the limited and free compressive strengths, the limited expansion rate, carbonation resistance, chloride ion penetration resistance and corrosi...

The addition of expansive agents could overcome the main disadvantages of raw concrete including high brittleness and low tensile strength. Few studies have investigated the early hydration kinetics of expansive cementitious binders, though the findi...

To prevent cracks caused by shrinkage of the deck of the Xiaoqing River Bridge, MgO concrete (MC) and steel fiber reinforced MgO concrete (SMC) were used. The deformation and strength of the deck were measured in the field, the resistance to chloride...

The shrinkage of core concrete during construction is the key reason for the separation of steel pipes and core concrete. Utilizing expansive agents during cement hydration is one of the main techniques to prevent voids between steel pipes and core c...

From 1990 to 2018, built-up areas in Tallinn, Estonia’s capital city, increased by 25.03%, while its population decreased by −10.19%. Investigating the factors affecting urban expansion and modeling it are critical steps to detect future expansion tr...

Vinylidene chloride copolymer microspheres were synthesized by in situ suspension copolymerization of vinylidene chloride (VDC), methyl methacrylate (MMA), and/or acrylonitrile (AN) in the presence of a paraffin blowing agent. The effects of shell po...

Aiming at the shortcomings of the current rock-breaking technology, a new type of high-energy expansion agent for energetic materials based on combustion-to-detonation was developed. By characterizing the basic physical and chemical properties of the...

To promote the application of MgO-type expansive agents (MEAs), the expansion stresses produced by compacted MEAs with different activities cured in water at 40 °C were measured using a self-designed expansion stress test apparatus. Based on thes...

In this study, comprehensive investigation of the shrinkage compensation mechanisms of calcium-based expansive agents (CEAs), their effects on the properties of (ultra) high-strength concrete (HSC/UHSC), and the existing problems in applying this met...

Based on the “axial-output method”, the time histories of radial and axial expansive pressures during the hydration process of static cracking agent (SCA) in a cylinder with various diameters were obtained by experiments. With the load input taken as...

Aeolian sand is the primary geological material for construction in desert regions, and its stabilization with industrial solid wastes-based geopolymer (ISWG) provides an eco-friendly treatment replacing cement. This study comparatively investigated...

Mineral expansive from FDG—flue-gas desulfurization—blended with calcium aluminate cement CAC was analyzed as mitigation shrinkage of alkali-activated residual mortars AAM. The AAM mortars were composed of red mud (RM) and bottom ash (BA)...

Cracking is the most prevalent deterioration issue in historic masonry, and grouting represents one of the most effective intervention techniques. Superplasticizer-free Natural Hydraulic Lime (NHL) grout is recommended for heritage conservation due t...

In this study, we construct heterogeneous agent general equilibrium models to investigate the relative importance of labor endowment in driving structural transformation. We aim to explore the following question: beyond the demand-side and supply-sid...

The corrosion of rebars in reinforced concrete structures cracks the concrete, which leads to the degradation of the bond strength between the rebar and concrete. Since bond deterioration can menace structural safety, bond strength evaluation is esse...

This paper presents a multi-agent Double Deep Q Network (DDQN) based on deep reinforcement learning for solving the transmission network expansion planning (TNEP) of a high-penetration renewable energy source (RES) system considering uncertainty. Fir...

In marine structural engineering, the impact resistance of concrete holds high significance. The determination of whether the combined use of expansion agent (EA) and glass fiber (GF) has a synergistic effect on the impact resistance of seawater&ndas...

The high adiabatic temperature rise and low heat dissipation rate of mass concrete will promote rapid hydration of the cementitious material and rapid consumption of water from the concrete pores, which may significantly accelerate the development of...

This study introduces an innovative approach to addressing the plastic shrinkage of ultra-high-performance concrete (UHPC) using an azodicarbonamide (ADC) expansive agent. The influence of ADC on the workability, mechanical properties, and plastic sh...

In the realm of bridge structural engineering, it is customary to meticulously contemplate the material’s strength and rigidity attributes during the dimensioning phase. In recent years, there has been a burgeoning interest in employing Ultrahi...

This is an experimental study on the development of a low-carbon, eco-friendly cement containing a calcium sulfoaluminate expansive agent (CSAe), slag, and silica fume (SF). The cement to be developed has a low water/binder ratio (w/b) of 0.5 and is...

In this study, the characteristics of grout mixed with charcoal as an expansive agent were examined to reduce the pre-hardening shrinkage of cementitious materials. This study compared and reviewed the application of CSA, a conventional expansive age...

This review provides the hydration and volume expansion mechanism of expansive materials, with the goal of utilizing them in the development of sustainable mining methods. The main focus of the review will be the newly developed non-destructible rock...

The combined application of steel–FRP composite bars (SFCBs) and seawater sea-sand concrete (SSSC) in marine engineering not only solves the problem of resource scarcity and reduces the construction cost but also avoids the problems of chloride...

In mass concrete, shrinkage resulting from temperature drop and drying leads to cracking, which can seriously affect the strength and durability of cement-based materials. Fortunately, expansion agents can deter or prevent these effects, especially M...

Increasing the diameter of the drillhole can facilitate drillhole breakage using soundless chemical demolition agents, but it is prone to cause drillhole blowout, resulting in crushing failure. This paper conducted a blowhole prevention test on a lar...

Full-section interval casting technology was adopted for the integral immersed tube of the Chebei Immersed Tunnel. Field tests (Chebei Immersed Tunnel) were conducted to establish the time-dependent development of the concrete shrinkage strain of the...

The urban expansion process involves multiple stakeholders whose interactions and decision-making behaviors have a complex impact on urban land conversion. In this study, we established an urban expansion simulation model that couples two sub-models:...

Understanding the hydration kinetics of cement paste is essential for adjusting the early-age performance of concrete. Low-field nuclear magnetic resonance (LF-NMR) has emerged as an innovative technique to evaluate cement hydration progress by analy...

To reduce the mining of high-grade magnesite and solve the environmental pollution caused by magnesite tailings, magnesite tailings were used to produce MgO expansion agent (MEA), and a detailed study of its performance was carried out in this study....

Traditional expansive agents often fail to address early-stage cracking issues of grouting. A plastic expansive agent (PEA) can generate evenly distributed and closely packed microbubbles in the cement-basted grouting materials during the grout&rsquo...

Calcium sulfoaluminate–calcium oxide expansive agents (HCSA) are commonly used in mass concrete to compensate for thermal shrinkage. However, the ettringite (AFt) formed by HCSA hydration decomposes when temperatures exceed 70 °C. This stud...