Glazed Hollow Bead Insulation Concrete Research Articles

Research on Glazed Hollow Bead Insulation concrete freezing process with different saturation based on nuclear magnetic resonance

This paper uses experimental analysis to understand the freezing law of water to determine the freezing damage mechanism of Glazed Hollow Bead Insulation Concrete (GIC). The critical saturations of GIC with different Glazed Hollow Beads (GHBs) contents were obtained by the relative moving modulus after testing seven saturations of the concrete (70% to 100%, 5% interval). The critical saturation of GIC-0 (i.e., 0% GHBs content) occurred at ∼ 76–78%. GIC-50 occurred at about 86–88%. GIC-100 occurred at about 89–91%. GIC-0, GIC-50, and GIC-100 were then saturated to S60, Scr, and S100 based on their respective critical saturation. Low-field nuclear magnetic resonance (NMR) was used to study the freezing process of different water types in GIC. The results showed that: 1) The water inside GIC was composed of adsorb water, pore water, and free water; 2) The whole freezing process could be roughly divided into four stages: subcooling stage, rapid freezing stage, stable freezing stage, and the end of the freezing phase; 3) During the freezing and thawing process, the change in unfrozen water content of GIC specimens had a hysteresis curve, while the specimens less than the critical saturation had almost no hysteresis curve. Moreover, the saturation significantly influenced the freezing process of different water types, which determined the proportion of them. This study also determined the evolution of the pore size of GIC, which provides a new idea for analyzing the freezing damage mechanism of porous GIC.

Heat transfer mechanism of glazed hollow bead insulation concrete

In this study, an improved random aggregate adding method was used to develop a microscopic model of glazed hollow bead insulation concrete (GHBIC), and the model's effectiveness was verified through a test. In addition, the heat transfer performance of GHBIC was also studied using the model. The effect of shape, volume fraction, and gradation of coarse aggregate as well as the volume fraction and gradation of glazed hollow bead on the effective thermal conductivity of this concrete was studied. The results show that the glazed hollow bead effectively blocked the heat flow channel of GHBIC. The smaller the particle size and the higher the volume, the blocking effect is more obvious. Finally, considering the fineness of glazed hollow bead, a mathematical model for the thermal conductivity of GHBIC was established.

Seismic performance of interior beam-column joints in reinforced glazed hollow bead insulation concrete frames

Reinforced concrete frames frequently suffer severe damage under strong earthquakes, and the damage is often concentrated at beam-column joints. This paper presents the experimental and analytical findings of the seismic performance of reinforced glazed hollow bead insulation concrete (GIC) interior beam-column joints. Six 1/2-scale GIC interior beam-column joint specimens were tested under quasi-static cyclic loading to measure the failure pattern, hysteresis curves, displacement ductility, energy dissipation and stiffness degeneration. Seismic behavior of GIC joints was investigated to elucidate the influence of concrete type, axial compressive ratio and stirrup ratio on the joint panel. A “three-stage” model was proposed to calculate the shear strength of GIC joints by combining the diagonal compression strut mechanism and the truss mechanism. Nonlinear finite-element analysis of joints was performed to examine the validity of the “three-stage” calculation model by comparing the results with the experimental results.

Effects of High Temperature on Creep Behaviour of Glazed Hollow Bead Insulation Concrete.

Glazed hollow bead insulation concrete (GHBC) presents a promising application prospect in terms of its light weight and superior fire resistance. However, only a few studies have focused on the creep behaviour of GHBC exposed to high temperatures. Therefore, in this study, the mechanism of high temperature on GHBC is analysed through a series of tests on uniaxial compression and multistage creep of GHBC, exposed from room temperature up to 800 °C. The results show a decrease in the weight and compressive strength of GHBC as the temperature rises. After 800 °C, the loss of weight and strength reach to 9.67% and 69.84%, respectively. The creep strain and creep rate increase, with a higher target temperature and higher stress level, while the transient deformation modulus, the creep failure threshold stress, and creep duration are reduced significantly. Furthermore, the creep of GHBC exhibits a considerable increase above 600 °C and the creep under the same loading ratio at 600 °C increases by 74.19% compared to the creep at room temperature. Indeed, the higher the temperature, the more sensitive the stress is to the creep. Based on our findings, the Burgers model agrees well with the creep test data at the primary creep and steady-state creep stages, providing a useful reference for the fire resistance design calculation of the GHBC structures.

Carbonation Resistance Performance and Micro-Structure Analysis of Glazed Hollow Bead Insulation Concrete

In this paper, the carbonation depths of glazed hollow bead insulation concrete (GHBC) and normal concrete (NC) at different carbonation ages are tested. The microstructure of GHBC and NC before and after carbonation were observed and compared by mercury intrusion porosimetry (MIP), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). The results showed that NC had better carbonation resistance than GHBC, and GHBC had a carbonation depth of 1.61 times than that of NC at 28 days accelerated carbonation experiment. The microstructural analysis showed that with the decrease of porosity of the samples, the carbon content and CaCO3 content increased after carbonation. The porosity of NC decreased from 14.36% to 13.53%, the carbon content increased from 4.42% to 5.94%, and the CaCO3 content increased from 18.5% to 56.0%. The porosity of GHBC decreased from 22.94% to 20.71%, the carbon content increased from 4.97% to 5.31%, and the CaCO3 content increased from 70.0% to 82.0%. The above results showed that carbon reacts with hydration products 3CaO·SiO2, 2CaO·SiO2, and Ca(OH)2 to produce a large amount of CaCO3 which causes a large amount of pores to be filled and refined hence the porosity and pore size were reduced leading to increase in the compactness of the material. From the results obtained, the carbonation depth prediction formula of glazed hollow bead insulation concrete was developed, and carbonation life was predicted.

Hysteretic Behavior and Restoring Force Model of Reinforced Glazed Hollow Bead Insulation Concrete (GIC) Columns

Based on the research of mix ratio and mechanical properties of glazed hollow bead thermal insulation concrete (GIC), the quasi-static tests of six GIC frame columns and one normal concrete (NC) frame column are carried out. The stress of frame columns under earthquake is simulated by applying a constant vertical load and cyclic horizontal load, and the hysteresis behavior, skeleton curve, ductility coefficient, stiffness degradation, and energy dissipation capacity of frame columns are studied. Contrast variables include axial compression ratio, stirrup reinforcement ratio and concrete material. The results show that the seismic performance of GIC frame columns is similar to that of ordinary concrete frame columns and frame columns. The stiffness degradation rate and ductility of GIC column are higher than that of NC column with the same parameter; higher axial compression ratio can increase the initial stiffness of GIC and reduce ductility; higher reinforcement ratio can increase ductility, but can limit plastic hinge development and reduce energy dissipation capacity of GIC column. The results can provide theoretical basis for elastic-plastic analysis of GIC column under earthquake action.

Shear behavior of reinforced glazed hollow bead insulation concrete beams

The application of glazed hollow bead insulation concrete can improve the seismic performance of the structure, simultaneously ensuring characteristics such as structural durability, fire resistance, thermal insulation, antifreezing, and impermeability. However, with change in material’s physical and mechanical properties, the shear resistance of vitrified microbead thermal insulation concrete members should be paid attention to. The literature search reveals only a few studies on the shear resistance of glazed hollow bead insulation concrete members. In this study, 14 glazed hollow bead insulation concrete beams and four ordinary concrete beams with C35 strength grade were tested. The mechanical failure process, failure form, failure mechanism, and the difference between vitrified microbead insulated concrete beam and ordinary concrete beam were compared. The effects of shear span ratio, hoop ratio and reinforcement ratio on the cracking load, ultimate load and failure mode were investigated. Combined with the “truss-arch” model, the shear bearing capacity of steel bar and concrete is described, and after considering the softening coefficient of glass microbead insulation concrete, based on the “truss-arch” model, a formula for calculating the shear capacity of inclined section of vitrified microbead insulated concrete beam was obtained. The results show that the shear failure test results of glazed hollow bead insulation concrete beams are similar to those of ordinary concrete beams; the shear bearing capacity of vitrified microbeads thermal insulation concrete beams is ∼13% higher than that of ordinary concrete beams under the same conditions, and stiffness degradation is slow in the later stage. After the constitutive relation and softening coefficient are modified, the “truss-arch” calculation model can be used to calculate the shear capacity of vitrified microbead insulated concrete beams, and the results are in good agreement with the experimental results. The study of the shear behavior of glazed hollow bead insulation concrete beams can provide data and technical basis for engineering application and has important theoretical significance and practical value to further understand the characteristics of this type of concrete structure, guiding engineering design, and promoting engineering application.

The Micro-Analysis of Thermal Insulation Glazed Hollow Bead Concrete after High Temperature

Thermal insulation glazed hollow bead concrete is a new building material, which is bearing general physical and mechanical properties of concrete. Experimental study of concrete after high-temperature, it is different from the ordinary concrete, because there is component of glazed hollow bead. In this paper, based on the observations and analysis of thermal insulation glazed hollow bead concrete after high temperature under electron microscope and comparison with ordinary concrete, the failure mechanism of thermal insulation glazed hollow bead concrete after high temperature are obtained.

Carbonation Experimental Study on Thermal Insulation Glazed Hollow Bead Concrete

Based on the compressive strength, the thermal conductivity, the elastic modulus and the steel bond strength of thermal insulation glazed hollow bead concrete, referring to the carbonation mechanism and the influence factors of the ordinary concrete, considering the impact of raw materials and the influence of construction technology, the study on thermal insulation glazed hollow bead concrete anti-carbonation was proposed. From the test results, it can conclude that for the same intensity level, the anti-carbonation capacity of the thermal insulation glazed hollow bead concrete is better than that of the ordinary concrete. For different strength grade of thermal insulation glazed hollow bead concrete, to some extend, the higher the intensity level is, the stronger the ability of thermal insulation glazed hollow bead concrete anti-carbonation is.

Durability Research of Thermal Insulation Glazed Hollow Bead Concrete

The durability of thermal insulation glazed hollow bead concrete, which is a kind of structure self-thermal insulation material produced in the background of building energy efficiency, has been systematically researched in order to make it with a good workability. Theoretical analysis and experimental study have been made from the raw materials and construction mixing proportion in the basis of the analysis to the influencing factors of its durability so as to can improve its durability.

The Application of Thermal Insulation Glazed Hollow Bead Concrete in Tunnel Cooling Structure

With the mining depth increasing, the effect of temperature on coal mine is outstanding with each passing day. In order to enhance the tunnel insulating layer heat insulation effect, thermal insulation glazed hollow bead concrete will be used in tunnel wall thermal insulation layer, the characteristics of thermal insulation glazed hollow bead concrete will be discussed and the appropriate mixture ratio and coefficient of heat conductivity will also be determined, as well as in the basis of reasonable theoretical analysis and derivation, prediction of the thermal insulation material of surrounding rock after exhaust heat will drop significantly, and it is proved that the thermal insulation glazed hollow bead concrete used in deep mine roadway can produce the benefit and have broad prospects.

Uniaxial Compression Tests Research on C25 Glazed Hollow Bead Insulation Concrete

With the growing global energy crisis, development of economic and land-efficient construction structural system became an significant subject in Civil Engineering field. Under this context, material and structural test and theoretical analysis research is meaningful on new energy-saving building material, glazed hollow bead insulation concrete. In this paper, one mix design that meet insulation requirements of the energy-saving project on coefficient of heat conductivity and compressive strength have been chosen. Under the uniaxial status, prism samples of above mix design have been selected to do compression strength and deformation tests; Systemic analysis of the relationship between the strength and deformation for glazed hollow bead insulation concrete has been carried through, and some results have been provided, including the stress-strain constitutive relationship of glazed hollow bead insulation concrete with grade c25, prism compressive strength, strain, initial elastic modulus, residual strength, ductility, etc.

Uniaxial Compression Tests Research on C35 Glazed Hollow Bead Insulation Concrete

With the growing global energy crisis, development of economic and land-efficient construction structural system became an significant subject in Civil Engineering field. Under this context, material and structural test and theoretical analysis research is meaningful on new energy-saving building material, glazed hollow bead insulation concrete. In this paper, one mix design that meet insulation requirements of the energy-saving project on coefficient of heat conductivity and compressive strength have been chosen. Under the uniaxial status, prism samples of above mix design have been selected to do compression strength and deformation tests; Systemic analysis of the relationship between the strength and deformation for glazed hollow bead insulation concrete has been carried through, and some results have been provided, including the stress-strain constitutive relationship of glazed hollow bead insulation concrete with grade c35, prism compressive strength, strain, initial elastic modulus, residual strength, ductility, etc.