Hasan Firat Pulat

Suction characteristics of compacted zeolite-bentonite and sand–bentonite mixtures

Soil suction is one of the most important parameters describing soil moisture conditions for unsaturated soils used in landfill liners. However, few studies have been conducted on the suction characteristics of compacted zeolite–bentonite mixtures (ZBMs) and sand–bentonite mixtures (SBMs), which are proposed for use as liner materials. Nevertheless, zeolite is known for its microporous skeleton containing cages and tunnels and it has a great physical affiliation to water uptake. Zeolite and bentonite, in a mixture, are thought to be in competition for water uptake and this may alter the distribution of water content for each soil in the mixture. The present study investigated the suction properties of compacted ZBMs and SBMs for varying mixing ratios and compaction water contents. The soil suction measurement technique chosen was the filter-paper method. The suction characteristics of powdered, granular, and block zeolites, as well as 0, 10, and 20% bentonite in ZBMs and SBMs were measured and compared with each other. Contaminated compacted ZBMs are compared with those of uncontaminated compacted ones at the optimum water content for the 10% and 20% mixtures. The results show that suction capacity of zeolite increases with grain size. As bentonite content increases, both matric and total suction increase for both mixtures. ZBMs have higher matric suction values than SBMs, but not total suction values. Contaminated total suction values are found to be higher than those of uncontaminated samples due to an increase in dissolved ion concentration.

The effect of soil mineralogy and pore fluid chemistry on the suction and swelling behavior of soils

Soil suction is one of the most important parameters for describing the moisture condition and engineering behavior of unsaturated soils. Therefore, changes in suction behavior of soils in the presence of saline waters are important for engineered barriers. The aim of this study was to determine the change in suction and swelling behavior of soils, which were exposed to salt solutions (NaCl, CaCl2, natural seawater) with respect to distilled water. The three soil samples were gathered with different mineralogy and plasticity characteristics and tested for determining matric and total suction values and for obtaining free swelling characteristics in the presence of salt solutions. The bentonitic soil sample had the highest total suction value in the presence of seawater. Kaolinitic and zeolitic soil samples had the highest total suction values in the presence of NaCl solution. The highest modified free swell index value of the samples was obtained in the presence of NaCl solution for all the soil samples. No relationship was found between the total suction, matric suction and the modified free swell index value of the tested soils.

Compaction behavior of synthetic and natural MSW samples in different compositions

Compaction is the one of the most important stages of the storage process in landfills. Well-compacted municipal solid waste (MSW) occupies less volume than an uncompacted MSW sample of the same weight and provides a safer storage area. The composition of MSW changes in between countries and even cities. For that reason, for effective compaction, the composition effect should be investigated. In this study, effects of composition, degradation and energy on the compaction behavior of artificially-prepared and natural fresh and aged MSW samples were determined. Artificial samples were prepared in representative different compositions Europe (E-1), Turkey (T-1) and the USA (U-1) to examine the effect of the composition. In addition to the synthetic MSW samples, natural MSW samples were obtained from the municipal landfill area of Manisa, Turkey. The standard Proctor test results have shown that the highest maximum dry unit weight was observed with the U-1 composition, which has the lowest organic content and the highest metal content. The degradation effect was investigated on the natural samples. The degraded MSW sample (3–4 years) has significantly higher maximum dry unit weight than the fresh natural MSW sample because of its low organic content. According to the results of this study, with respect to the composition effect, the percentage of organic waste is the most important factor on the compaction behavior of MSWs. As paper, organic and plastic contents increase in the MSW composition the γdry-max value decreases and wopt increases. The ash content does it reversely, as such that any increase in γdry-max decreases the wopt value of the MSW.

On Shear Strength of Stabilized Dredged Soil from İzmir Bay

Dredging is the process of carrying out work such as protection of inland water and sea lanes, construction/deepening of port basins, opening/deepening of channels and regulation of coasts. As a result of the dredging, the large amount of dredged soil is removed and disposal or reuse of this material is very important for economically and environmentally. This material can be recycled in the civil engineering applications as construction material, road and foundation embankment. However, because of the high organic matter content, dredged soil has very different shear strength characteristic compared to inorganic soil. In this study physico chemical engineering properties and shear strength behavior of natural and stabilized Izmir Bay’s dredged soil were examined for four organic matter contents (0%, 4%, 7% and 11%). The index properties of natural samples were defined by sieve analysis, specific gravity, Atterberg limits and pH tests. The direct shear tests were conducted with natural and stabilized dredged soils for saturated loose and dense samples. The shear strength parameters of natural dredged soils were compared with lime and silica fume added (10% and 20%) samples. Test results have shown that specific gravity value decreased, the liquid and plastic limit increased with the organic matter content increasing for natural samples. Silica fume added samples have higher cohesion but lower internal friction angles. The highest internal friction angle belongs to natural dredged soil without organic matter.

Geotehnička svojstva i nosivost zgure iz visoke peći

U radu su analizirana geotehnička svojstva i nosivost zgure iz visoke peći. Ispitivanja CBR vrijednosti provedena su sa sitnozrnim i krupnozrnim uzorcima zgure iz visokih peći. Uzorci za ispitivanje CBR-a pripremljeni su standardnim i modificiranim energijama zbijanja. Za ispitivanje učinka fluida u porama na nosivost, pripremljeni su uzorci s vodom iz vodovoda i s morskom vodom. Rezultati ispitivanja pokazali su da sitnozrni uzorci imaju veće CBR vrijednosti u usporedbi s krupnozrnim, a energija zbijanja je bila parametar koji je najviše utjecao na vrijednosti CBR-a. Veće CBR vrijednosti pripadale su uzorcima koji su pripremljeni i njegovani s morskom vodom.

Influence of Seawater on the Suction and Swelling Behavior of Clayey Soils

The present study examines the suction characteristics and swelling behavior of clayey soils when exposed to natural seawater with respect to distilled water. The effects of saline waters on the engineering behavior of soils need to be determined since the salinity of the pore fluid of soils near coastal areas increases continuously. Six clayey soil samples with different mineralogy and characteristics were gathered and tested to determine the suction and swelling characteristics in the presence of natural seawater and distilled water. The results show that the total suction values of the samples are higher in the presence of seawater than in distilled water. The samples with high swelling potential have lower matric suction values than nonswelling soils. Moreover, in contrast to swelling-type soils, the matric suction values of the nonswelling soils remain similar in the presence both distilled water and seawater. The modified free swell index (MFSI) of the samples is well correlated with the liquid limit (LL), plasticity index (PI), and cation exchange capacity (CEC) in distilled water. However, coefficients of determination decreased in the presence of seawater. Also, there is no significant correlation existing between total and matric suction values and the MFSI values of the samples.