• Journal of The Korean Society of Agricultural Engineers
• /
• v.57 no.4
• /
• pp.11-19
• /
• 2015

The important properties of EVA (ethylene vinyl acetate) redispersible polymer was waterproof, densification of internal pore space of concrete and ball bearing and micro filler. Also, the significant role of polypropylene(PP) fiber was crack control and blockade of movement for deterioration factors. The most studies for EVA were limited in the field of mortar and PP fiber reinforced concrete had been studied in the state of being restricted unit water content, rich mix and mixing much of the fiber without considering construction site. Therefore, the control mix design were applied in ready mixed concrete using 10 % fly ash of total cement weight used in batch plant. On the basis of control mix design, EVA contents ranging from 0 % to 10 % of total cement weight and PP fiber contents ranging from 0 % to 0.5 % of EVA concrete volume were used in the mix designs. The results showed the maximum compressive strength value was measured at EVA 5.0 % and PP fiber 0.1 %, the minimum water absorption ratio was at EVA 10 % and PP fiber 0 %, the durability factor for freezing and thawing resistance was at EVA 5.0 % and PP fiber 0.3 % and the minimum weight reduction ratio of resistance to sulfuric acid attack was at EVA 10 % and PP fiber 0.5 % after curing age 42days. Meanwhile, From these results, PP fiber reinforced EVA concrete would be very benefit, if each optimal mix types were used in hydraulic structures, underground utilities and agricultural structures.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.773-776
• /
• 2008

Restraining cracks on concrete structures can be the basic condition to improve the durability, so in this research, the resistibility on the drying shrinkage of concrete structures in the long period was being confirmed and as the reason of this shrinkage, the density of minute textures was being analyzed using a wooden prototype of a full scale produced with ready-mixed concrete and agents of glycol which can be used as a surfactant. As result of those tests, PFB technology can reduce the drying shrinkage by approximately $-100{\sim}200{\times}10^{-6}$ on a wooden prototype of a full scale and can also reduce the pore volume as the obstruction to the movement of gas or liquid by approximately $2.4{\sim}3.5$% so that PFB technology can be used to assure the resistibility on the drying shrinkage.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2010.09a
• /
• pp.295-297
• /
• 2010

본 연구에서는 GIS, GPS, Web기술을 이용하여 레미콘 차량의 운행상황과 이동경로 등을 실시간으로 파악 한 후 차량의 위치와 목적지 도착시간, 복귀예정시간 등을 예측하는 레미콘 차량 관제 시스템을 레미콘 배치플랜트의 도입 시 효율성을 평가하였다. 그 결과 공사현장에서 복귀하는 레미콘 차량의 도착시간이내 복귀거리등을 사전에 미리 차량관제서버로 전송해 주는 알림기능으로 인해 배치플랜트의 다음 배차를 위한 레디믹스가 반자동적으로 작동하여 차량의 대기나 다음 배차를 위한 차량 위치 파악 등의 지연시간이 현저히 감소되었다. 이는 1일 8시간을 기준 20대의 레미콘 차량을 분석 한 결과 실시간 운행정보를 통한 배치플랜트의 가동으로 인해 1일 155분의 시간이 절감되어 일 평균 2.5대의 레미콘 차량의 추가적 운행이 가능하였으며, 이를 비용으로 환산시 일 평균 90만원, 월 약 1920만원의 추가적인 이익이 발생하여 레미콘차량 관제 시스템에 따른 배치플랜트의 작동은 기업차원에서의 경제적 측면을 고려할 때 매우 효율적인 것으로 판단되었다.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2005.05a
• /
• pp.33-36
• /
• 2005

Recently, Trouble of sand supply is occurred according to exhaustion of natural sand resources. therefore, various measures are proposed for solution of trouble of sand supply. also the government settled trouble of sand supply through application of EEZ sand and crushed sand. but because both EEZ sand and crushed sand are poor against general sand, they lead to lowering of quality of ready-mixed concrete. Therefore, this study evaluated physical properties of mortar using EEZ sand and crushed sand and applied evaluation result to fundamental data The result of this study have shown that quality of mortar using EEZ sand and crushed sand independently is poor against general mortar. but, mortar flow and compressive strength is increased in case of mixing 222 sand and crushed sand properly.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2019.11a
• /
• pp.153-154
• /
• 2019

In this study, the fluidity and compressive strength of lightweight mortar using recycling water for pre-wetting of artificial lightweight aggregate were compared and analyzed to maximize the utilization of the recycling water, which is a by-product of the Ready-Mixed Concrete industry. For this purpose, the pre-wetting water was replaced with recycling water at the ratio of 0, 2.5, 5, 7.5 and 10%.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.210-211
• /
• 2017

According to KS F 2560, water-reducing agents used when mixing concrete are to undergo quality evaluation testing slump, air contents, setting time, etc., when delivered from the admixture factory to the ready mixed concrete site. Yet in actual acceptance testing this could be substituted by the score report of the admixture company, in which a possibility of low reliability lies. Therefore this study sought to analyze whether by artificially changing the solid content rate of lignin- and naphthalene-based water-reducing agents and using a liquid densimeter evaluate the quality of the admixture. The results showed that the Type B liquid densimeter was most appropriate and 50cc the most appropriate capacity for the mass cylinder. Also, judging from the changes in density and pH according to the changes in solid content rate, it concludes that a rapid appraisal of the quality of lignin- and naphthalene-based water-reducing agents would be possible using a Type B liquid densimeter.

• Journal of the Korea Institute of Building Construction
• /
• v.16 no.6
• /
• pp.561-569
• /
• 2016

Concrete is cheap, easy to deal with, and the quality is satisfactory. Also, it is one of the easiest materials to get because chemical composition of cement is similar to chemical composition of surface. On the other hand, it is so vulnerable to transform because of weak binding capacity and low binding energy that it produces cracks. Cracks decline durability, usability, safety of structures and damage exterior. In order to decline drying shrinkage crack, this study used shrinkage reducing typed Superplasticizer, which is combination of and water-reducing agent for convenience, different with existing study using AE agent, water-reducing agent, shrinkage reducing agent,. Considering SRS field application possibility, this study planned to mix concrete and mortar generally used in ready-mixed concrete company and did basic experiment depending on a change of SRS content ratio and admixture. Based on the experiment result. It is judged that SRS admixture 2% is proper ratio when Given the intensity and length change. Also mass combination will conduct follow-up studies.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.2
• /
• pp.78-85
• /
• 2020

Shotcrete concrete is generally used in the form of ready-mixed concrete products using type I ordinary portland cement(hereinafter referred to as OPC) and about 5% of accelerator mixed separately in the field. In this study, we tested the effect of OPC fineness and SO₃ content on a penetration resistance, compressive strength of binder for shotcrete using calcium aluminate type accerlerator. And we analysed hydrates and pore structure effects on mortar performance. In the future, it is expected to be useful for manufacturing optimized OPC as a binder for shotcrete.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.2
• /
• pp.86-93
• /
• 2020

Shotcrete concrete is generally used in the form of ready-mixed concrete products using type I ordinary portland cement(hereinafter referred to as OPC) and about 5% of accelerator mixed separately in the field. In this study, we tested the effect of addition of slag powder(SP) and limestone powder(LSP) on a penetration resistance, compressive strength of binder for shotcrete using calcium aluminate type accerlerator. And we analysed hydrates and pore structure effects on mortar performance. In the future, it is expected to be useful for manufacturing optimized composite cement as a binder for shotcrete.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.761-764
• /
• 2008

Most of ready-mixed concrete plants have the problem of construction waste sludge, which pollutes environment and causes economic loss due to the discard and increasing the cost of concrete. Thus, a recycling of the cement sludge has been strongly desired as one of their solution. This research is to the study on the recycling of the cement sludge, especially the study on the hydration control by the sodium gluconate as a set-retarder. The set-retarder can delay the hydration of the cement included in the sludge water, so that the sludge water can be substituted with some of new cement without the property of the cement. And it invests the effect of the sodium gluconate to the hydration of the cement in suspension. The degree of hydration of cement may be controlled by adding the sodium gliconate. The hydration delay time is observed that depends on the concentration of residual sodium gloconate, not how long the cement has been hydrated before the addition of the sodium gluconate.