• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.11a
• /
• pp.61-62
• /
• 2012

This study is for analyzing possibility of utilizing as cement from waste concrete. The scrapped fine powder which contains a large amount of hydrate of cement can supercede lime stone, and greenhouse gas reductions are expected. However, Fine Aggregate powder efficient separation technology development is essential for that limestone substitution effect and reduce greenhouse gas emissions in order to facilitate through the recycling of the scrapped fine powders.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2005.05a
• /
• pp.69-72
• /
• 2005

Recently, there have been many studies seeking towards the utilization of cementitious powder from concrete waste as recycle cement. However, most of the studies actually have been researches about the reuse of mortar or paste, not concrete waste. In fact, either mortar or paste is quite different from a real concrete waste in terms of age and mixture. Thus the purpose of this study is to examine basic physical properties of recycle cement, manufactured with cementitious powder from concrete waste, and analyze differences in chemical and hydraulic properties of the cement and its tested model. As a result of the chemicai analysis, recycle cement is composed mainly of CaO and SiO2, and that it is even lower in the content of CaO than Portland cement, which is also supported by previous studies. But, Differently from previous studies, plastic working at the temperature of 650 was found an optimal condition under which cementitious powder from concrete waste could restore its hydraulic properties.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10c
• /
• pp.36-41
• /
• 1998

Recently, it has been reported that recycling of wasted glasses should be a hot issue in related business field. Thus, the purpose of this experimental research is to recycle wasted glasses by substituting for the cement in mortar and concrete. As a pilot test, workability and the strength of mortar with recycled glass have been tested and analyzed according to replacement ratio of recycled glass with grain size of them. As a result, considering the workability and the strength of mortar containing recycled glass, the existence of the optimum replacement ratio and grain size of them have been obtained.

• Magazine of RCR
• /
• v.14 no.1
• /
• pp.22-28
• /
• 2019

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.14 no.4
• /
• pp.289-295
• /
• 2008

The disposal of constructive waste is emerging as a national and social issue and the recycled powder generated by the production of reproductive aggregate is all being abolished or buried Analysis on the harmful effect of recycled powder indicated that because it contained massive cytotoxicity, it could derive secondary pollution to soil and subterranean water. This study set on an idea that one way to recycle recycled powder was to use it as a compound of concrete. In order to study that prospect, recycled powder, instead of cement, was mixed and a comparative analysis was conducted on the mechanical properties and workability. From experimental results, it was judged that application of recycled powder of cement replacement ratio below 20% was available with chemical admixtures. Also application of recycled powder was available to high strength concrete.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.3
• /
• pp.246-252
• /
• 2021

The basic properties and volume stability of the ultra-rapid setting cement mortar containing low-quality recycled aggregate with a higher water absorption and lower specific gravity than relavent Korea Standard were experimentally confirmed. The mix proportion without recycled aggregate followed that of the general repair mortar used in the fields. 15% and 30% of the fine aggregate was substituted by the recycled aggregate in the mixtures with and without latex emulsion, and properties and characteristics of the mortar including mortar flow, setting time, compressive and flexural strength, and linear deformation under sealed and unsealed conditions were evaluated. It was confirmed that when low-quality recycled aggregate was used by 30%, there were risks of decrease in the early-age strength by up to 50% within 24h and increases in drying shrinkage by up to 2 times for 2 weeks compared to the the mixtures without the recycled aggregate.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2005.05a
• /
• pp.65-68
• /
• 2005

This paper investigated the engineering properties of cement mortar mixed with more than 2 kinds of sand. For fresh mortar properties, unit volume weight is constant regardless of mixing content and type of sand. An increase in contents of river and crushed sand resulted in an increase in flow, whereas an increase in recycled sand contents reduced flow. Gap between maximum flow in N3C0R0 and minimum flow in N0C0R3 exhibited about $12\%$. Compressive strength at 28 days ranged from 32 to 36 MPa in order for crushed sand, river sand and recycled sand. Mortar with mixed sand along with river sand and crushed sand showed compressive strength comparable to crushed sand. An increase of fraction of recycled sand in mixed sand resulted in a decrease in compressive strength. For drying shrinkage, N0C0R3 had the largest drying shrinkage among various mixture type. The combination of large contents of recycled sand and small contents of river and crushed sand had a large amount of drying shrinkage.

• Journal of the Society of Disaster Information
• /
• v.8 no.3
• /
• pp.204-212
• /
• 2012

Lightweight soils are very economical and environment friendly materials that are valuable in field without wasting construction materials, dredged soils and clay/ silty soils during construction. Recently, the research of lightweight soils mixed with recycled material (recycled tire powder, rice husks) have been investigated. In this study the mix design factors (i.e., weight of soil, water content, foaming agent and added water) were analyzed and optimized mix design was suggested using cement content for revealing strength. For the analysis the stress-strain behavior, strength with respect to time, and experimental strength for the component of recycled material were analyzed. Finally, target strength was determined to calculate reasonable and economical mix ratio and the optimized cement content was suggested.

• Advances in concrete construction
• /
• v.13 no.1
• /
• pp.101-111
• /
• 2022

The rapid development of the construction industry in the world causes a rapid increase in the consumption of aggregate resources, which leads to the depletion of existing aggregate reserves. The use of recycled aggregate in the production of concrete and mortar may be a good solution to reduce the use of natural raw materials and to reduce demolition waste in the environment. In this study investigating the use of recycled aggregate in mortar production, mortar mixtures were produced by substituting 0%, 25%, 50% and 100% fine recycled aggregate (FRA) instead of natural aggregate. The effect of 20% and 40% fly ash (FA) substitutes on cement mortar performance was also investigated. Compressive and flexural strength, drying shrinkage, abrasion resistance, water absorption and capillary water absorption were investigated on the produced mortars. The increase in the use of FRA reduced the compressive and flexural strengths of mortars. While the capillarity coefficients, water absorption, rapid chloride permeability and drying shrinkage of the mortars increased with the increase in the use of FRA, the effect of the use of fly ash on the rate of increase remained lower. The increased use of FRA has improved abrasion resistance as well.

• Journal of the Korea Concrete Institute
• /
• v.19 no.2
• /
• pp.233-239
• /
• 2007

The main objective of this study was to evaluate the effect of recycled PET fiber made from waste PET bottle on the control of plastic shrinkage cracking of cement based composites. PET is blown as a plastic material and used in a variety products such as a beverage bottle. However, waste PET bottles are thrown after the usage, raising huge problems in terms of the environment. Thus, the research on the method to recycle the PET bottles indicates important aspects in environment and economy. The method to recycle waste PET bottles as a reinforcing fiber for cement based composites is one of effective methods in terms of the recycle of waste PET bottles. In this research, the effect of recycled PET fiber geometry and length on the control of plastic shrinkage was examined through thin slab tests. A test program was carried out to understand the influence of fiber geometry, length and fiber volume fraction. Three type of recycled PET fibers including straight, twist crimped and embossed type. Three volume fraction and two fiber length were investigated for each of the three fiber geometry. Test results indicated that recycled PET fibers are effective in controlling plastic shrinkage cracking in cement based composites. In respect to effect of length of fiber, longer fiber was observed to have efficient cracking controlling with low volume fraction in same fiber geometry while shorter fiber controled plastic shrinkage cracking efficiently as addition rate increase. Also, embossed type fibers were more effective in controlling plastic shrinkage cracking than other geometry fiber at low volume fraction. But, for high volume fraction, straight type fibers were most effective in plastic shrinkage cracking controlling in cement based composites.