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This article discusses the effects of glass powder (GP) replacements and sodium hydroxide (NaOH) molarity on the rheological, fresh, mechanical and microstructure characteristics of slag-based mechanochemical geopolymer (MG) grout. A conventionally activated geopolymer grout and an ordinary Portland cement (OPC) grout were also investigated for comparison. Four glass powder replacement ratios were used (0%, 10%, 20% and 30% by the total precursor weight) to prepare slag-based mechanochemical geopolymer at three NaOH concentrations (1.25, 2.5 and 3.75 molars). The experimental results showed that the rheological behaviour of MG grouts was considerably reduced, whereas the setting time and the bleeding capacity value increased when slag was substituted with 0%–30% GP. However, after 28 days, the unconfined compressive strength (UCS) improved by 2%–13% when 10%–20% GP was used as a slag replacement, then dropped by 4% when 30% GP was substituted. The results confirmed that both geopolymer grouts irrespective of the activation method had shorter setting time and more stable bleeding capacity than OPC grout. The results also revealed that the UCS of geopolymer grout is enhanced by 18% when the source materials are activated by the mechanochemical method compared to the conventional activation of geopolymer grout. The microstructure results revealed that the activation method had a considerable effect on the microstructure of geopolymer grout because the ball milling process increased the surface area and reduced the particle size of slag compared to conventionally activated geopolymer grout. [ABSTRACT FROM AUTHOR]

This paper evaluates the unconfined compressive strength (UCS), stability (bleeding), modulus of elasticity and failure patterns of cement-based grout mixtures that were prepared by placing of rice husk ash (RHA) with cement at various water to binder (w/b) ratios. In order to investigate these parameters, UCS and bleeding tests were conducted on the soilcrete samples that prepared at 5, 10, 20 and 30% replacement level of RHA with cement for.75, 1.00 and 1.25 w/b ratios. Test results showed that the UCS values of the samples for 28 day curing are higher than 1 MPa and E/qu ratios obtained from soilcrete mixtures were less than the corresponding value from slurry clay–cement mixes given in the literature. In addition, all bleeding test results are lower than the level of.5%. Finally, most of the mixtures prepared for this study failed along foliations. [ABSTRACT FROM AUTHOR]

Peat is found in many countries throughout the world where it can be generally seen in thick layers in limited areas. Peat is an extreme form of soft soil and is considered problematic due to the low shear strength and large compressibility. This project presents laboratory finding on the compressibility and shear strength characteristics of fibrous peat with sand column. The peat used in the study is classified as fibrous peat and H1–H4 in Von Post scale. Its liquid limit is 119%. In all tests, the peat used for the tests passing 2 mm and remain on.15 mm. The rounded sand used for making sand column is poorly graded passing from 2 mm sieve size and retaining on 1 mm sieve size. The tests conducted to investigate effect of area ratio of sand column on shear strength and compressibility of the peat. Three different area ratios were used for both compressibility and shear strength tests. Consolidation test results showed that when the area ratio increases compressibility characteristic of the peat improved. Shear strength of the organic soil was also affected from the sand column. [ABSTRACT FROM AUTHOR]

In order to provide a fast and cost-effective solution, particularly for preliminary evaluations in many design situations of constructions, a number of numerous empirical equations for estimation of compression index simply established with soil index properties are intensively used for consolidation settlement. However, they may not be appropriate when considered for different regions dependent upon local site conditions. Thus, it is important to know the performances of the empirical equations with local data. This paper investigates the performances of some of the empirical equations for estimation of compression index for fine-grained soils of Baghdad City along the Tigris River. Four criteria including error and ranking measurement were employed as bases of evaluation: root mean square error, the ratio of estimated to measured (laboratory) compression index, ranking index and ranking distance (RD). The last two (ranking index and RD), a relatively new approach of ranking measurement, involve with the accuracy and precision of estimated result with actual data. The assessment ultimately has been done regarding the RD, since it is a comprehensive statistical parameter that gives equal weight to the accuracy (mean) and precise (standard deviation) of estimation, as compared with others. It is found from the analysis results that the overall best estimation of compression index for the data of Baghdad was obtained by the empirical equations established with liquid limit proposed by Cozzolino and Azzouz, Krizek, and Corotis. The results indicate that the most reliable equation correlates compression index with liquid limit. [ABSTRACT FROM AUTHOR]

Sixty four tests were performed in a steel tank to investigate the axial responses of piles driven into organic soil prepared at two different densities using a drop hammer. Four different pile materials were used: wood, steel, smooth concrete, and rough concrete, with different length to diameter ratios. The results of the load tests showed that die shaft load capacity of rough concrete piles continuously increased with pile settlement. In contrast, the others pile types reached the ultimate shaft resistance at a settlement equal to about 10% of the pile diameter. The ratios of base to shaft capacities of the piles were found to vary with the length to diameter ratio, surface roughness, and the density of the organic soil. The ultimate unit shaft resistance of the rough concrete pile was always greater than drat of other piles irrespective of soil condition and pile lengtii. However, the ultimate base resistance of all piles was approximately close to each other. [ABSTRACT FROM AUTHOR]