This research investigates the incorporation of eco-friendly materials, namely fly ash and artificial interior stone sludge into cement grouts. The study aims to establish the correlation between the microstructural properties and the compressive strength, providing a comprehensive behavior of fly ash and artificial interior stone (AIS) sludge on the cement grouts. A multifaceted experimental approach encompassing compressive strength testing, mercury intrusion porosimetry, thermogravimetric analysis, and scanning electron microscopy is employed. The result indicated that incorporating fly ash and artificial interior stone sludge into cement grouts led to a reduction in the porosity and refinement of the pore size. The thermogravimetry analysis revealed a notable impact of fly ash and artificial interior stone sludge on hydration and phase transition. The scanning electron microscopy findings of the microstructural enhancement confirmed that the combined incorporation of fly ash and AIS sludge densified the structure.

Phosphorus (P) is a limited, essential, and irreplaceable nutrient for the biological activity of all the living organisms. Sewage sludge ash (SSA) is one of the most important secondary P resources due to its high P content. The SSA has been intensively investigated to recover P by wet chemicals (acid or alkali). Even though H2SO4 was mainly used to extract P because of its low cost and accessibility, the formation of CaSO4 (gypsum) hinders its use. Heavy metals in the SSA also cause a significant problem in P recovery since fertilizer needs to meet government standards for human health. Therefore, P recovery process with selective heavy metal removal needs to be developed. In this paper some of the most advanced P recovery processes have been introduced and discussed their technical characteristics. The results showed that further research is needed to identify the chemical mechanisms of P transformation in the recovery process and to increase P recovery efficiency and the yields.

Phosphorus is an essential and irreplaceable element for all living organisms and its resource is limited. Significant amount of used phosphorus is collected in sewage treatment plant as sludge. Sludge ash after incineration contains about 10% of phosphorus in dry mass basis, which is comparable to phosphate rocks, and it is an important source of phosphorus recovery. Acid and alkali were used to leach phosphorus from sludge ash and compared for their leaching kinetics and performance. Phosphorus leaching by NaOH was fast and 0.2 N and 2 N NaOH leached 49% and 56% of the total phosphorus in the sludge ash at the L/S ratio of 100. Phosphorus leaching by sulphuric acid and hydrochloric were very fast and most of the phosphorus was leached in 5 minutes. In case of sulphuric acid 95% of the total phosphorus in the sludge ash was leached by 0.2 N at the L/S ratio of 100 and 93% was leached by 1 N at the L/S ratio of 10. 1 N hydrochloric acid leached 99% of the total phosphorus at the L/S ratio of 10. The results showed acids were more effective than alkali for phosphorus leaching from sludge ash and hydrochloric acid leached more phosphorus than sulphuric acid.

We investigated the effects of leaching concentration (0.1 ~ 1.0 M) and time (1 ~ 120 min) on the phosphorus recovery from ash and dried sewage sludge produced by titanium tetrachloride (TiCl4) flocculation by acidic (H2SO4 and HCl) or alkaline (KOH and NaOH) leaching. The extraction efficiencies of dried sludge were 2.7 ~ 12.6% for H2SO4, 2.5 ~ 10.5% for HCl, 3.6 ~ 9.6% for KOH, and 7.1 ~ 9.9% for NaOH with 1 M, and the maximum efficiency was obtained within 45 min. The maximum %P extracted of sludge ash was 83.1 for H2SO4, 80.2 for HCl, 51.2 for KOH, and 51.2 for NaOH with 1 M, obtained within 45 min. The rate constants (min−1) for the leaching of P from sludge ash were found to be 1.199 for H2SO4, 1.026 for HCl, 0.264 for KOH, and 0.622 for NaOH. The P leaching increased with the increase in leaching concentration, and the maximum leaching for ash was obtained within 0.3 M, regardless of acidic or alkaline leaching. The overall results indicate that the ash of TiCl4 flocculated sewage sludge can be treated with H2SO4 to efficiently recover P.

The quantities of low-grade reject fly ash (RFA) and paper sludge ash (PSA) generated are increasing annually and causing a serious social problem. In this study, the utility of these by-products was analyzed by using RFA and PSA as mineral admixtures. RFA-PSA blended mortar was fabricated and evaluated for use as a cement additive. RFA was milled to improve workability and the hydration reaction, and PSA was mixed with anhydrite to create the ettringite. As the RFA-PSA blended powder replaced 10% of the cement by weight, compressive strength of the mortar exceeded that of ordinary mortar prepared with Portland cement (OPC). Length change (28 days) of the RFA-PSA mortar with a 10% replacement rate was 68% of the OPC mortar and was 62% with a 30% replacement rate.

아스팔트 포장이 최초로 시공된 이후로 눈부신 경제발전과 함께 도로의 신설, 확장 및 포장과 동시에 기존 포장도로의 유지보수는 국가건설 산업의 중요한 부분이 되었다. 근래에는 교통량의 증가 및 교통하중의 증가로 인하여 아스팔트 포장은 설계수명을 다하지 못하고 급속히 파손되는 결과를 가져와 폐아스콘의 발생량이 기하급수적으로 증가하고 있는 추세에 있다. 천연자원 고갈 및 훼손에 따른 문제 해결을 위하여 최근 ｢건설폐기물의 재활용촉진에 관한 법률｣ 제38조제3항에 따른 ‘순환골재의무사용건설공사의 순환골재 사용용도 및 의무사용량 등에 관한 고시’ (환경부 고시 제2009-138호, 국토해양부 고시 제2009-713호, 2009.8.25)에 따라 1km 이상의 도로를 건설할 경우 반드시 재생아스콘을 사용해야한다. 환경부는 공공기관이 발주하는 건설공사에 사용하는 의무사용 비율을 현재 15％에서 40%로 높여갈 계획에 있다. 이러한 정부의 정책에도 불구하고 재생아스콘의 사용 실적이 저조한 이유에는 그 기능성 및 가격경쟁력의 문제가 크다고 할 수 있고 재생아스콘의 사용 공법에는 포장 시 가열의 유무에 따라 가열재생아스콘과 상온순환아스콘으로 구분되어 진다. 환경부하저감과 자원절약의 의미로 시행되는 재생아스콘은 가열시 발생되는 이산화탄소 및 에너지 소비측면에서 적합하지 않으며, 특히 가격 경쟁성에서 시장성이 떨어진다. 따라서 상온순환아스콘의 확대보급을 위한 기술개발이 필요하며 이에 본 연구는 최근 저탄소 녹색생산 및 경제성 향상을 위한 자원재활용과 고부가성을 요구하는 시멘트 업계의 동향을 고려하여 무기계 순환자원인 제지슬러지, 고로슬래그 및 탈황석고 등의 자원을 재활용하여 시멘트를 전혀 사용하지 않고 고온의 소성과정 없이 상온에서 제조가 가능한 상온순환아스콘 채움재 개발과 그 특성평가를 진행하였다. 본 연구는 KS L 5105에 명시된 시험방법으로 실험을 진행하였으며 각각의 배합에 따른 유동성, 압축강도, 기타 물성 등을 시험하였으며 제지애시를 혼입한 채움재의 물성을 확인하였다.

산업화의 영향으로 에너지 수요 증가에 따라 석탄수요의 증가 및 산업부산물인 재(Ash)의 발생량 또한 급증하는 추세이며, 재(Ash)의 재활용량은 지속적으로 증가하고 있으나 재활용에 의한 수익은 점차 감소하고 있어 재(Ash)의 재활용 부가가치가 점점 낮아지고 있는 실정이다. 본 연구는 산업부산물인 슬러지와 비산재 혼합에 따른 조경골재 생산을 하고자 하며, 하수슬러지 20~25%, 비산재 30~35%과 첨가제로서 물유리 및 알칼리제를 혼합한 후 소성온도 700~1000℃에서 1시간 동안 반응시켜 제조하여 화산석 대체의 조경골재 사용을 위한 가능성 연구를 하고자 한다. 소성시킨 멀칭용 조경재 제조 후 성분분석을 해본 결과 Si 성분이 20.77%으로 가장 많이 함유되어 있는 물질로 나타났으며 조경재의 구조에 영향을 미치는 Al, Ca, Fe 등의 원소로 구성되어 있는 것으로 나타났다. 주사 전자현미경(SEM)분석을 한 결과 다공성이 발달된 구조가 형성되어 토양에 통기성을 높일 수 있는 구조로 발달되어져 있음을 확인할 수 있었으며, 적정 배합비 및 소성온도 등의 특성을 보다 연구하여 화산석과 유사한 조건의 특성을 함유한 멀칭용 조경재를 제조할 수 있을 것으로 판단된다. 슬러지와 비산재의 혼합을 통한 조경골재 제조에 따른 결론은 폐자원을 활용하여 다양한 분야에서의 재활용 가능성을 높여줄 수 있을 것으로 사료되며, 이에 따른 기업 간의 협력을 통해 자원화 네트워크를 구축할 수 있는 방법을 통한 산업부산물의 다용도화가 가능하다.

Carbon dioxide has steadily increased in atmosphere since the industrial revolution, and it is the main cause of the global warming. In this study, carbon dioxide is stored in the form of insoluble calcium carbonate through indirect carbonation using paper sludge ash (PSA) as a raw material and acids (acetic acid and hydrochloric acid) as solvents. Acid is very efficient to extract calcium from PSA, which is as high as 55%. However, since the pH of calcium extractant obtained using acid is as low as 6 and carbon dioxide is not present in the form of CO32- at the low pH, carbonation reaction does not occur to form calcium carbonate. Sodium hydroxide, therefore, is added into the calcium extractant to increase pH up to 13. The amount of sodium hydroxide is calculated based on the equivalent of calcium in the extractant. Then, carbon dioxide is injected into the calcium extractant for 30 minutes at a flow rate of 0.05 L/min. The calcium extractant is prepared in advance using 40 g of PSA and 1L of 0.7 M acid, and 35mL of 50% sodium hydroxide is added into the extractant to adjust pH. During carbonation, liquid samples are taken at designated intervals to measure pH and calcium concentration. After the carbonation is completed, white solids are collected to dry at 105℃ for 12 hours, which weigh 30.0 g and 33.1 g from the extractants using acetic acid and hydrochloric acid, respectively. The white solids are found to be highly pure calcite by XRD analysis. Based on the solid mass, the amounts of carbon dioxide sequestrated in PSA are calculated to be 330.4 kg CO2/ton PSA and 363.7 kg CO2/ton PSA using acetic acid and hydrochloric acid as solvents, respectively.

Incinerated sewage sludge ash (ISSA) is regarded as a valuable resource having great potential for the recycling ofphosphorus. The P content of ISSA is known as around 10% as a P. Therefore, this study was undertaken to investigatethe precipitation and separation characteristics of phosphorus from the acid-extracted solution of ISSA. The incineratedsewage sludge ash was leached by 1N sulfuric acid with solid/liquid ratio of 10 for 30min. The extracted solutioncontained about 1.1% of P and other metals, Al, Fe, Ca and Mg, with over than 1,000mg/L. Some heavy metals suchas Cu, Pb and Cr are presented as impurities as well. Most of Al and Fe in the extracted solution were precipitated withP when titrating it to pH 3.6. The precipitated form were assumed to AlPO4, FePO4·2H2O respectively, and Pb and Crwere precipitated in this stage as well. At this experiment, about 62.9% of the initial P was precipitated and removedfrom the solution. It was also find that all of the P extracted can not be recovered as a precipitate with a simple additionof NaOH, even though titrated to pH 11.6. The precipitated P also contained some impurities such as Al, Fe, and someheavy metals, which means that further researches are needed for the efficient separation and recovery of P from ISSA.

The main objective of this research was to evaluate the effects of process variables which were forming ability, flow displacement, effective stress, effective strain, fluid vector and products defects on manufactured artificial lightweight aggregate made of both incinerated sewage sludge ash and clay by means of the numerical analysis of a rigid-plastic finite element method. CATIA (3D CAD program) was used for an extrusion metal mold design that was widely used in designing aircraft, automobile and metallic molds. A metal forming analysis program (ATES Co.) had a function of a rigid-plastic finite element method was used to analyze the program. The result of extrusion forming analysis indicated clearly that a shape retention of the manufactured artificial lightweight aggregate could be maintained by increasing the extrusion ratio (increasing compressive strength inside of extrusion die) and decreasing the die angle. The stress concentration of metal mold was increased by increasing an extrusion ratio, and it was higher in a junction of punch and materials, friction parts between a bottom of the punch and inside of a container, a place of die angle and a place of die of metal mold. Therefore, a heat treatment as well as a rounding treatment for stress distribution in the higher stress concentration regions were necessary to extend a lifetime of the metallic mold. A deformity of the products could have made from several factors which were a surface crack, a lack of the shape retention and a crack of inside of the products. Specially, the surface crack in the products was the most notably affected by the extrusion ratio.