Glazed Hollow Bead Research Articles

Mechanical and thermal properties of glass fibre-reinforced ceramsite-foamed concrete

This study investigated the mechanical and thermal properties of glass fibre-reinforced ceramsite-foamed concrete with a volume of entrained air generated by hydrogen peroxide. The effects of hydrogen peroxide content, glass fibre content, glazed hollow bead content and ceramsite content on the compressive strength, splitting tensile strength and thermal conductivity were investigated. The results indicated that with the addition of hydrogen peroxide and an increase in glazed hollow bead and ceramsite content, there was a significant increase in the brittleness of foamed concrete. Glass fibre can obviously improve the splitting tensile strength and reduce the thermal conductivity of foamed concrete. In addition, an empirical compressive strength formula of glass fibre-reinforced ceramsite-foamed concrete was recommended.

Calculation on effective thermal conductivity of recycled aggregate thermal insulation concrete with added glazed hollow beads

Abstract In this paper, available structural models and equations for predicting the effective thermal conductivity (ke) of recycled aggregate thermal insulation concrete, including series, parallel, Maxwell-Eucken, eEffective medium theory, and Gong's model are discussed and extended to three phases by considering the effect of glazed hollow beads (GHBs). The solid porosity of GHBs is estimated and used in the equations. A unified model for calculating ke values is proposed, where the fractal dimension of GHBs is considered. A simple expression characterizing the fractal dimension of GHBs is derived. Nine batch specimens with different concrete mixtures are tested to determine the ke values which are compared with the predicted values. The predicted values from Unified-2 model are found to be in good agreement with the experimental results.

Study of Effective Thermal Conductivity of Glazed Hollow Bead Concrete

Based on analyzing the mechanism of thermal conductivity of glazed hollow bead concrete, this paper divides the channels of thermal conductivity in concrete, constructs the model of thermal conductivity coefficient based on the Theory of Minimum Thermal Resistance, and confirms the model by using the data of other related literatures and the data of our own experiment. The consequence indicates that this model can calculate the thermal conductivity coefficient under arid state exactly. In order to improve the accuracy of this model, we should take the shape of framework, the interface thermal resistance between concrete and framework into consideration

Preparation and Performance of Inorganic Thermal Insulation Glazed Hollow Bead Material

Glazed hollow bead, a kind of inorganic lightweight aggregate that has been recently developed, has raised high concern in the field of thermal insulation of building wall due to its low thermal conductivity, low water absorption, good fireproof performance and relatively high compression strength. In this paper, the preparation of this thermal insulation glazed hollow bead material was introduced in detail, the influence of the amount of gel material on bulk density, porosity, thermal conductivity, compression strength of the thermal insulation glazed hollow bead material was investigated, the surface morphology and surface components were characterized by means of SEM and EDS. Results showed that the density, thermal conductivity and compression strength increased while the porosity decreased with the amount of gel material increasing. Appropriate temperature enables gel material to work at optimal level under which the compression strength increases, on the other hand, the porosity also increases, therefore, the thermal conductivity decreases.

Experimental Study on Hygrothermal Deformation of External Thermal Insulation Cladding Systems with Glazed Hollow Bead

This research analyzes the thermal and strain behavior of external thermal insulation cladding systems (ETICS) with Glazed Hollow Beads (GHB) thermal insulation mortar under hygrothermal cycles weather test in order to measure its durability under extreme weather (i.e., sunlight and rain). Thermometers and strain gauges are placed into different wall layers to gather thermal and strain data and another instrument measures the crack dimensions after every 4 cycles. The results showed that the finishing coat shrank at early stage (elastic deformation) and then the finishing coat tends to expand and become damaged at later stage (plastic deformation). The deformation of insulation layer is similar to that of the finishing coat but its variation amplitude is smaller. Deformation of substrate expanded with heat and contracted with cold due to the small temperature variation. The length and width of cracks on the finishing coat grew as the experiment progressed but with a decreasing growth rate and the cracks stopped growing around 70 cycles.

Research on Properties of Foamed Concrete Reinforced with Small Sized Glazed Hollow Beads

Foamed concrete (400 kg/m3) was prepared through a physical foaming method using ordinary Portland cement (42.5R), vegetable protein foaming agent, fly ash, and glazed hollow beads (GHB, K46) as raw materials. The performance of cement paste as well as the structure and distribution of air voids was characterized by rheometry, SEM, and XRD analyses with imaging software. The effects of GHBs on the compressive strength and thermal conductivity of the foamed concrete sample were also explored. Results show that the proportion of 50–400 μm air voids, average air-void diameter, 28 d compressive strength, and thermal conductivity of the test sample mixed with 2.4 wt% GHBs are 94.44%, 182.10 μm, 2.39 MPa, and 0.0936 w/(m·k), respectively. Excessive amount of GHBs (>2.4 wt%) increases the amount of air voids with diameter smaller than 50 μm in the hardened foamed concrete as well as the degree of open porosity. Moreover, the proportion of 50–400 μm air voids, average air-void diameter, 28 d compressive strength, and thermal conductivity of the sample mixed with 4.0 wt% GHBs are 88.54%, 140.50 μm, 2.05 MPa, and 0.0907 w/(m·k), respectively.

Bond performance of thermal insulation concrete under freeze–thaw cycles

Thermal insulation concrete (TIC) mixed with a sufficient volume of glazed hollow beads (GHBs) is an innovative material and has been proven to achieve an excellent balance between the mechanical and thermal insulation performances due to its self-insulation property. However, the bond between the reinforcing bars (rebars) and the TIC must be good enough in long-term sense for wide practical applications using the TIC. This paper focuses on the experimental study on the deterioration of the bond property between the TIC and rebars in freeze–thaw environment. A total of 132 pullout specimens and 216 cubic specimens made of TIC were prepared, which cover three concrete strength grades, three rebar diameters, and six anchorage lengths. Parts of the specimens were exposed to various number of rapid freeze–thaw cycles prior to their failure.The combination of pull-out and mechanical performance test was carried out to assess the frost damage on bond performance. The frost damage on bond property was quantified based on the bond strength, slip, splitting tensile strength, and relative dynamic modulus of elasticity. The usage of GHB against the harmful effects of freeze–thaw cycles was also analyzed by comparing the failure characteristics of normal concrete to that of the TIC. Interestingly, the bond performance of the TIC is found to be affected by the rebar diameter and anchorage length, rather than the concrete strength. The rebar diameter results in the apparent decrease of bond strength and the variation of failure modes. Lastly, an analytical expression was developed to relate the bond strength with the splitting strength of damaged TIC, which considers the effects of rebar diameter and anchorage length. The proposed equation correlates well with the experimental results.

Flexural performance of glazed hollow bead reinforced concrete beams

Flexural static tests are conducted on glazed hollow bead reinforced concrete beams (referred to as GBLs) with a range of properties. The test variables included concrete material type and cross section depth as well as longitudinal reinforcement ratio of the flexural beams. The test results were analyzed in terms of damage mechanism, ductility, stiffness, and energy dissipation in the flexural beam. The addition of the glazed hollow bead as the lightweight aggregate was to obtain higher ductility and slower degradation of strength and stiffness. It was shown in the tests that the mechanical properties of the GBLs were better than that of normal concrete beams. A finite element model was developed for the beams and the lateral force–displacement curves obtained from analyses were compared with the experimental data. The results of this study are useful in the design and application of glazed hollow bead insulation concrete bending members.

Mechanical properties of thermal insulation concrete with a high volume of glazed hollow beads

Thermal insulation concrete (TIC) represents a new kind of ‘green' concrete that reduces thermal consumption and improves the energy efficiency of buildings. In this study, the mechanical properties of TIC with a high volume of glazed hollow beads (GHBs) and different strength grades were investigated. The various strengths and thermal conductivity values of the material were measured. Relationships between TIC split tensile strength, flexural strength, elastic modulus and compressive strength were obtained from the experimental results. The analysis also covers the constitutive relationships and failure pattern of TIC. A new skeleton model of GHBs was developed to illustrate the failure behaviour and stress–strain relationship of TIC as compared with normal concrete (NC). The results showed that the behaviours of NC and TIC are very similar under uniaxial loading conditions and that TIC is more ductile than NC for the same strength grade.

An experimental study to evaluate the effects of adding glazed hollow beads on the mechanical properties and thermal conductivity of concrete

This paper discusses the effects of glazed hollow bead particles on the mechanical properties and thermal conductivity of concrete and the micro appearances of the specimens through the scanning electron microscope. In the experiments, glazed hollow bead was added to the concrete to substitute sands. The amount of glazed hollow bead was kept at 5, 10, 15 and 20% by weight. The results show that the higher the glazed hollow bead amount, the higher will be the percentage of broken glazed hollow bead particles during the mixing process of concrete and that the addition of glazed hollow bead particles reduces the density, compressive strength, elasticity modulus and thermal conductivity coefficient of concrete. When the glazed hollow bead amount reaches 20%, the density, thermal conductivity coefficient, 56-day compressive strength and elasticity modulus of concrete decrease by 14, 69·5, 18·7 and 21·4%, respectively, compared with normal concrete.

Microstructure and pore fractal dimensions of recycled thermal insulation concrete

Abstract The compressive strength and thermal conductivity of recycled thermal insulation nano concrete with different contents of recycled aggregates were determined. By comparing the micro morphology, it was concluded that the glazed hollow beads, rather than air pores, reduced the strength loss of concrete. This was due to the tight adherence between the glazed hollow beads and the cement mortar, which is more effective than foaming the pores to strengthen concrete by lowering the thermal conductivity. Finally, the pore fractal dimension was established by mercury injection test data. The correlations between fractal dimensions under various recycled aggregate replacement rates and compressive strength/thermal conductivity were compared, and it was discovered that the macro pore fractal dimensions could be used to characterize the changes of concrete strengths and that the average fractal dimension could be employed to describe the variations of thermal conductivity of concrete.

Seismic behaviour of recycled aggregate thermal insulation concrete (Ratic) shear walls

This study investigated recycled aggregate thermal insulation concrete (Ratic) containing glazed hollow beads. The study of ten shear walls investigated shear-span ratio, axial compression ratio, reinforcement ratio and concrete material type. Quasi-static tests were carried out to obtain the failure modes, load–displacement curves, skeleton curves, stiffness degradation and energy dissipation capacity of Ratic shear walls. Compared with shear walls made from normal concrete, the Ratic shear walls offered a slight improvement in bearing capacity and significant improvements in deformation and energy dissipation capacities. A finite-element model was developed and non-linear simulations of shear walls with the same parameters as in the quasi-static test were carried out using Ansys software. The internal stress and strain distributions of different concrete shear walls are intuitively shown in stress contour plots and the reliability of test results further verified. The paper proposes the calculation method of the fourfold line restoring force model used for the restoring force calculation of Ratic shear wall, which is validated by comparing with the test results.

Influencing Factors on the Interface Microhardness of Lightweight Aggregate Concrete Consisting of Glazed Hollow Bead

Lightweight aggregate concrete consisting of glazed hollow bead (GHB) as lightweight aggregate is studied for the influence of nanosilica (NS) content, prewetting time for GHB, water-cement ratio, and curing humidity, on the interface structure between GHB and cement paste. This research analyzed the influences of various factors on the interface zone structure by measuring microhardness (HV) and hydration degree of cement paste (HD) nearby the interface zone (1 mm) between GHB and cement paste at different periods of aging. Due to the sampling limitation, the interface zone in this test is within 1 mm away from the surface of lightweight aggregate. The HD of cement paste was determined through chemically combined water (CCW) test. The results were expected to reflect the influence of various factors on the interface zone structure. Results showed that the rational control of the four factors studied could fully mobilize the water absorption and desorption properties of GHB to improve the characteristics of the interfacial transition zone.

The Research on Mechanical Properties of Foam Concrete Mixed with Glazed Hollow Beads

Adding glazed hollow beads in ordinary foam concrete, the thermal insulation, dimensional stability, waterproofness and cracking resistance would be improved. Through testing the basic mechanical properties of foam concrete mixed with different mix amount of glazed hollow beads and then comparing and theoretical analyzing results obtained, it is concluded that when the content of glazed hollow beads is 30%, the mechanical properties of foam concrete is better than other schemes.

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.

Rural Residential Wall Construction Technology Vitrified Microsphere Thermal Insulation System of Shanxi Luliang

The experimental studies have suggested that thermal insulation glazed hollow bead mortar is a splendid material with thermal insulation and energy conservation. The practices also prove that this material can produce excellent thermal conservation effect when it is applied to building with the request for thermal insulation and energy conservation. In light of the fact that the thermal insulation gazed hollow bead mortar hasn’t been spread in Luliang rural area, taking the actual environment in this area and the special method of the building’s construction into consideration, the construction technology of the thermal insulation gazed hollow bead mortar regarding the thermal insulation and energy conservation of the residential wall will be expounded.

Mix design for recycled aggregate thermal insulation concrete with mineral admixtures

The objective of this study was to prepare a type of recycled aggregate thermal insulation concrete (RATIC), in which thermal insulation particles (TIPs) were used as solid sealed ‘holes' instead of air holes to allow the thermal conductivity coefficient of the concrete to be reduced. This paper presents the results of a laboratory study on the performance of natural and recycled aggregate concrete, which was prepared by the incorporation of TIPs and different mineral admixtures including ultrafine slag (UFS), nanosilica (NS) and nanocalcium carbonate (NCC). The compressive strength, thermal conductivity coefficient and dry density of the concrete mixtures were determined. The experimental results demonstrate that glazed hollow beads, at the optimal level of 130%, significantly reduced the thermal conductivity property of the recycled aggregate concrete. The properties of the concrete were improved by the addition of UFS and NS, while NCC produced a negative impact. As far as compressive strength was concerned, the replacement of cement by 10% UFS or 1% NS improved the mechanical performance, while the replacement of cement by 1·5% NCC and the addition of TIPs decreased the compressive strength of the recycled aggregate concretes. The effects of the UFS and NS mineral admixtures produced greater performance improvements in the concrete than the recycled coarse aggregate. Finally, the optimal mix proportion was determined. For this mix, the thermal conductivity coefficient and compressive strength of the concrete were 0·305 W/(m.K) and 46·7 MPa respectively.

Finite Element Analysis of Uniaxial Compression of Glazed Hollow Bead of Recycled Concrete Short Columns

For traditional ordinary concrete wall column prone to thermal bridges, posted outside the insulation board short life than the life of the building，in the glazed hollow bead of recycled concrete foundation with good thermal conductivity test and compressive strength of the proposed ,use glazed hollow bead of recycled concrete exterior wall column instead of the traditional ordinary concrete wall column ,and using the finite element software ANSYS simulation analysis the uniaxial compression of glazed hollow bead of recycled concrete short columns and ordinary concrete short columns. Comparative analysis showed the same intensity level glazed hollow bead of recycled concrete ultimate compressive bearing capacity of an analog value the same as ordinary concrete short columns. To validate the ANSYS simulation of concrete short columns under uniaxial compression condition .

Effect of latex powder and glass fibers on the performance of glazed hollow bead thermal insulation materials

AbstractGlazed hollow bead, cement, fly ash, and latex powder were used to prepare a glazed hollow bead thermal insulation material by way of compression molding, and the effects of redispersible latex powder on the mechanical properties and water resistance performance of the material were studied. In addition, the action mechanism of latex powder was analyzed. The surface of alkali-resistant glass fibers was treated by styrene-acrylic emulsion, and the effects of glass fibers on the mechanical properties of glazed hollow bead thermal insulation materials before and after treatment were studied, respectively. Moreover, the fracture morphology of the samples was observed and analyzed to explore the reinforced mechanism of fiber. The results show that when the dosage of latex powder is 4%, compared with blank samples, the sample’s flexural and compressive strengths increase by 48% and 20.83%, respectively, and the 2-h and 24-h water absorption of the samples is reduced by 71.37% and 66.94%, respectively. When the dosage of surface-treated fibers is 1.0%, the flexural strength of the samples increases by 35.71% and the compressive strength of the samples increases by 8.34% compared with samples that were mixed with untreated fibers.

Study on the Performance of Glazed Hollow Bead Aerated Concrete and its Influence Factors

The paper introduced a new-style vitrified micro bubbles aerated concrete block. By adding a certain amount of vitrified micro bubbles to general aerated concrete, the compressive and breaking strength can reach the B05 self-insulation standard. And the thermal conductivity of single new-style aerated concrete wall can realize the target of energy saving. It is proved that vitrified micro bubbles aerated concrete is a new wall material with the functions of containment, energy saving, sound insulation and self-supporting.