• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.825-830
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• 1999

The purpose of this study is to improve overall performance of prefoamed lightweight cellular concrete for On-Dol system floor. This study includes 4 sections as follows. \circled1 Analysis of the structural characteristics of On-Dol System focusing on the lightweight cellular concrete insulation layer. \circled2 Establishment of the mixing design equations. \circled3 Development of some admixtures used with foaming agent. \circled4 Improvement of the equipment for onsite production. This study has proven that, compared with the current existing one, the newly developed lightweight cellular concrete has been reduced the usage of cement by 20% and the cracks caused by cement drying shrinkage up to 80% but has shown the increased compression strength by 20% at 7 days curing period. The volume contraction of freshly prepared cellular concrete by the loss of foam was hardly found in newly developed lightweight cellular concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.393-400
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• 1997

It is possible to reduce dead load and cross section of structural members by use of lightweight concrete, and also reduce the cost of construction. The mechanical properties of lightweight concrete are lower than that of normal weight concrete having the same compressive strength, then it is necessary to make higher strength of lightweight concrete for structural use, and the objective of this paper is to development and application the highstrength lightweight concrete with lower than 2.0t/$\textrm{m}^3$ of unit weight and over than 350kg/$\textrm{cm}^2$ of compressive strength.

• Computers and Concrete
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• v.4 no.6
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• pp.499-510
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• 2007

The densified mixture design algorithm (DMDA) was employed to manufacture high-performance lightweight concrete (LWAC) using silt dredged from reservoirs in southern Taiwan. Dredged silt undergoing hydration and high-temperature sintering was made into a lightweight aggregate for concrete mixing. The workability and durability of the resulting concrete were examined. The LWAC made from dredged silt had high flowability, which implies good workability. Additionally, the LWAC also had good compressive strength and anti-corrosion properties, high surface electrical resistivity and ultrasonic pulse velocity as well as low chloride penetration, all of which are indicators of good durability.

• Structural Engineering and Mechanics
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• v.39 no.6
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• pp.833-847
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• 2011

We have developed a lightweight aggregate (LWA) concrete made by expanding fine sediments dredged from the Shihmen Reservoir (Taiwan) with high heat. In this study, the performance of the concrete and of prestressed concrete beams made of the sedimentary LWA were tested and compared with those made of normal-weight concrete (NC). The test results show that the lightweight concrete (LWAC) exhibited comparable time-dependent properties (i.e., compressive strength, elastic modulus, drying shrinkage, and creep) as compared with the NC samples. In addition, the LWAC beams exhibited a smaller percentage of prestress loss compared with the NC beams. Moreover, on average, the LWAC beams could resist loading up to 96% of that of the NC beams, and the experimental strengths were greater than the nominal strengths calculated by the ACI Code method. This investigation thus established that sedimentary LWA can be recommended for structural concrete applications.

• Magazine of the Korea Concrete Institute
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• v.9 no.1
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• pp.165-172
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• 1997

Lightweight foamed concrete is a concrete which is lighter than conventional concree by mixing ptetoamed foam in cement slurry. The objectives of this study are to develop optimal prefoarneti lightweight foamed concrete with high lightness. high flowability and enough strength fol special use of structural application by using the polymer foam agent. By mixing the admixtures such as silica-fume and fly-ash and the industrial by-product such as styrofoam for the purpose of practical use of industrial waste, lightweight foamed concrete shich has better lightness. flowability and strength than the conventional prefoamed lightweight foamed concrete is developed. This paper presents extensive data on characteristics of compressive strength and flowability of the concrete manufactured with the different factors in mix design and also presents optimum mix proportion.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.358-365
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• 1996

Lightweight foamed concrete is a concrete which is lighter than normal concrete by mixing prefoamed foam in cement slurry. The objective of this study are to develop prefoamed optimal lightweight foamed concrete using polymer foam agent and to obtain its mechanical characteristics experimentally. This paper presents extensive test data on young's modulus, poisson's ratio, stress-strain curve, the characteristics of strength of the foamed concrete and also presents the mechanical characteristics of the foamed concrete according to foam sizes.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.477-480
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• 2006

Normally, with all ensuring the fire resistance structure as a method of setting the required cover thickness to fire, the RC is significantly affected from the standpoint of its structural stability that the compressive strength and elastic modulus is reduced by fire. Especially, high strength concrete and lightweight aggregate concrete is occurred serious fire performance deterioration by explosive spalling. Thus, this study is concerned with explosive spalling of lightweight concrete using structural lightweight aggregate. From the experimental test result, lightweight aggregate concrete is happened explosive spalling. The decrease of cross section caused by explosive spalling made sharp increasing gradient of inner temperature.

• Computers and Concrete
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• v.16 no.3
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• pp.449-466
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• 2015

This paper aims to study the local bond stress-slip behavior of reinforcing bars embedded in lightweight aggregate concrete (LWAC). The experimental variables of the local bond stress-slip tests include concrete strength (20, 40 and 60 MPa), deformed steel bar size (#4, #6 and #8) and coarse aggregate (normal weight aggregate, reservoir sludge lightweight aggregate and waterworks sludge lightweight aggregate). The test results show that the ultimate bond strength increased with the increase of concrete compressive strength. Moreover, the larger the rib height to the diameter ratio ($h/d_b$) of the deformed steel bars is, the greater the ultimate bond stress is. In addition, the suggestion value of the CEB-FIP Model Code to the LWAC specimen's ultimate bond stress is more conservative than that of the normal weight concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.640-643
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• 2004

Synthetic lightweight aggregates are manufactured with recycled plastic and fly ash with 12 percent carbon. Nominal maximum-size aggregates of 9.5mm were produced with fly ash contents of 0 percent, 35 percent, and 80 percent by total mass of the aggregate. An expanded day lightweight aggregate and a normal-weight aggregate were used as comparison. Mechanical properties of the concrete determined included density, compressive strength, elastic modulus, and splitting tensile strength. Compressive and tensile strengths were lower for the synthetic aggregates; however, comparable fracture properties were obtained. Relatively low compressive modulus of elasticity was found for concretes with the synthetic lightweight aggregate, although high ductility was also obtained. As fly ash content of the synthetic lightweight aggregate increased, all properties of the concrete were improved.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.117-120
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• 2006

The purpose of this study is to efficiently treat the sewage sludge discharged from sewage treatment plants and evaluate the feasibility of the manufacture of lightweight aggregates(LWA) using a large quantity of sewage sludge. Sintered lightweight aggregate from sewage sludge is experimentally manufactured with various mass ratios of clay to sewage sludge by a pilot plant, and is tested for density, water absorption and crushing value. Their physical properties are compared to those of a commercial sintered lightweight aggregate. As a result, an experimentally manufactured lightweight aggregate is similar or superior in physical properties to the commercial lightweight aggregate. The manufactured lightweight aggregate could be used for structural concrete and non-structural concrete.