• Resources Recycling
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• v.29 no.1
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• pp.43-52
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• 2020

The objectives of this study were to identify the optimal mix of foam concrete with the low-strength and high-flow for the repairing ground subsidence situation emergently by utilizing a large amount of industrial by-products and evaluate the possibility by applying it to the site. The factors of the experiment were the mixing ratio of mixing water and a foaming agent and the mixing ratio of foam over paste volume. The optimal mix identified by the experiment was applied to the field and basic properties were evaluated. The results of the experiment showed that the optimal mixing ratio of mixing water and the foaming agent was 10%. Moreover, when the mixing ratio of pre-foam over paste volume was 170%, it satisfied the target. However, to ensure stable quality when applying to the field, the foam mixing ratio was set 140% for the field application. The field application test of foam concrete with the low-strength and high-flow using an eco-friendly binder satisfied all target performances. Therefore, the possibility of using it as a mixture and construction method for a ground repair system is confirmed. However, there was a quality deviation between the upper part and the lower part due to the separation between foam and paste. Consequently, further studies are needed to improve it.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.168-169
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• 2019

This study examined the effect of foam volume ratio and curing temperature the air dry density and compressive strength of lightweight concrete using bottom ash. Test results showed that the lightweight concrete possessed the compressive strength of 3.4~22.7 MPa at the air dry density of 1,041~1,583 kg/m3.

• Journal of the Korea Institute of Building Construction
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• v.16 no.1
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• pp.35-43
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• 2016

Concrete is a representative heterogeneous material and mechanical properties of concrete are influenced by various factors. Due to the fact that pores in concrete affect determining compressive strength of concrete, studies which deal with distribution and magnitudes of pores are very important. That way, studies using picture imaging have been emerged. Studies on mechanical performance evaluation of structural lightweight foamed concrete and FEM analysis based on picture image are inadequate because lightweight foamed concrete has been researched for only non-structural. Therefore, in this study, cement paste with foaming agent to evaluate mechanical performance is made, FEM analysis with picture image is conducted and young's modulus of experiment and analysis are compared. In this study, dosage of foaming agent is determined 7 level to check pore distribution and water-binder ratio is determined 20% to progress research about structural light weight foamed concrete. Weight of unit volume is minimum at 0.8% of foaming agent dosage. However, weight of unit volume is increased over 0.8% of foaming agent dosage because of interconnection with independent pores. For FEM analysis, cement paste is photographed to use image analyzer(HF-MA C01). Consequently, the fact that Young's Modulus of experiment and FEM analysis are same is drawn by using OOF(Object Oriented Finite elements).

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.743-748
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• 2006

This paper presents results of an experimental study conducted to investigate the effect of volume fraction of fibers on the mechanical properties of a fiber-reinforced, lightweight aggregate concrete(FRLAC) that was produced without an autoclave process. The FRLAC enhanced the strength of lightweight, cellular concrete by adding polypropylene fibers and lightweight aggregates. To investigate the effect of volume fraction of fibers on the mechanical behavior of FRLAC and to determine the optimal volume fraction of fibers, a series of compression and flexural strength tests on FRLAC specimens with various fiber volume fractions(0%, 0.10%, 0.25%, 0.50%) were conducted. It was observed from the tests that a 0.25% volume fraction of fibers maximized the increase in the strength of FRLAC and the fibers controlled cracking in FRLAC.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.356-362
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• 2016

Light-weight concrete uses forming agents for reducing weight and high heat insulation property. However, the forming agents make problems of decreased volume and compressive strength of the concrete. This research aims to having weight-reduction and securing heat insulation property using recycled wasted form polyurethane without any forming agents. A small quantity of admixture used for constructability and avoiding material segregation. We picked admixtures from two different companies which shows evenly dispersed of wasted form polyurethane. This research conducts a study on the effect of mixing ratio of admixture on the light-weight concrete used wasted form polyurethane. As a result of the test, increased mixing ratio of the admixtures results reduced fluidity of concrete. On the other hand, percentage of moisture content and compressive strength are increased slightly. Combustibility performance and sound insulation performance are also secured, as well.

• Journal of the Korea Institute of Building Construction
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• v.18 no.2
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• pp.117-123
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• 2018

The increase in energy efficiency has became a significantly important issue for building construction and maintenance. The energy efficiency is known to be achieved by using a material with lower thermal conductivity, and the best method is to increase the internal porosity of the material. Typical ways to increase internal porosity within cementitious composite are to use foaming agents or to use reactive powder such as aluminum. However, in this work, hydrogen peroxide was chosen as an alternative material to make lightweight cement mortar. The volume expansion of fresh cement mortar and unit weight, compressive strength and thermal conductivity of 28 day old cement mortar were measured. According to the experimental results, the incorporation of hydrogen peroxide increased internal porosity, and thereby reducing the compressive strength and thermal conductivities of cement mortar. It was found that hydrogen peroxide can be successfully used to produce lightweight mortar for thermal insulation purposes of buildings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.226-234
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• 2017

The physical properties of lightweight foamed concrete mixed with EPS waste and flame resistant EPS waste were investigated. For this purpose, the main variables considered were a cement content of 300 and $400kgf/m^3$ and an EPS replacement ratio of 0, 10, 20, 30, and 40% by the volume ratio of the foam. The water-cement ratio and the dilution concentration were fixed to 0.5 and 10% respectively. The test results showed that the apparent density meets degrees 0.5 and 0.6 of KS F4039, and they showed little difference between the two mixes of Type A and Type B, regardless of the unit cement content. The bending strength obtained through the compressive strength also met the degree of KS F 4039. The thermal conductivity was 1~3% higher for the mixes of EPS than the case of flame resistant EPS, but both mixes met the 0.4 degree of KS F4039. The absorption ratio showed the values above 20% with a 1~3% difference for the two mixes, which mean further studies will be needed to reduce the absorption ratio.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.183-184
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• 2020

This study evaluated the effect of foam volume ratio on shear friction behavior of bottom ash based lightweight aggregate concrete (LWA_BA). The LWA_BA with different foam volume ratio ranged between 8 and 25 MPa for compressive strength(f_ck), 17.3~62.5 kN for shear capacity at first shear crack(V_cr), 31.1~73.8 kN for shear friction capacity(V_n), and 0.01~0.03 mm for slip at maximum peak load(S₀). f_ck decreased with increase in the foam volume ratio, showing that this trend was also observed in V_cr, V_n, and S₀.

• Journal of the Korea Institute of Building Construction
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• v.9 no.5
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• pp.63-70
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• 2009

This study is part of an ongoing research project on the development of a sound-absorbing lightweight foamed concrete manufactured by a hydro-thermal reaction between silica and calcium. As the silica source, pulverized bottom ash was used, and as several cementitious powders of ordinary portland cement, alumina cement and calcium hydroxide were used. Manufacture of foamed concrete was accomplished using the pre-foaming method to make a continuous pore system, which is the method of making the foam by using a foaming agent, then making the slurry by mixing the foam, water, and powders. The experiment factors are W/B, foam agent dilution ratio, and foam ratio, and test items are compressive strength, dry density, void ratio, and absorption rate, as evaluated by NRC. The experiment results showed that the sound absorption of lightweight foamed concrete satisfied NRC requirements for the absorbing materials in most of the experiments. It is thus concluded that foam ratio was the most dominant factor, and significantly affected all properties of lightweight foamed concrete in this study. W/B rarely affected total void ratio and continuous void ratio as well as compressive strength, and dry density and foam agent dilution ratio also had little effect onalmost all properties. The analysis of the correlation between NRC, absorption time, continuous void ratio, and absorption time showed that the interrelationship of the continuous void ratio was high.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.216-223
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• 2019

The objective of this study is to propose a reliable stress-strain model in compression for lightweight concrete using bottom ash aggregates and air foam(LWC-BF). The slopes of the ascending and descending branches in the fundamental equation form generalized by Yang et al. were determined from the regression analyses of different data sets(including the modulus of elasticity and strains at the peak stress and 50% peak stress at the post-peak performance) obtained from 9 LWC-BF mixtures. The proposed model exhibits a good agreement with test results, revealing that the initial slope decreases whereas the decreasing rate in the stress at the descending branch increases with the increase in foam content. The mean and standard deviation of the normalized root-square mean errors calculated from the comparisons of experimental and predicted stress-strain curves are 0.19 and 0.08, respectively, for the proposed model, which indicates significant lower values when compared with those(1.23 and 0.47, respectively) calculated using fib 2010 model.