This master thesis has investigated the performance of a deep excavation with a jet grout bottom plug used to prevent bottom heave and hydraulic uplift failure. The concept of a jet grout plug as a structural and sealing component in a specific case was studied, namely one of the tunnel sections of The West Link tunnel project in Gothenburg. The section was to be built as a cut-and-cover tunnel with the excavation shaft consisting of secant pile walls, struts and a jet grout bottom plug. It is to be established where there are a lot of sensitive buildings and constructions close to the excavation site. This makes it important not to disturb the surroundings during construction with, for example, settlements.The study was carried out by doing a literature study, analytical calculations and numerical simulations in the finite element software PLAXIS 2D. More specifically, the checks evaluated were uplift equilibrium of the jet grout plug and of the whole structure, structural performance of the jet grouted plug and hydraulic conductivity of the jet grouted mass.The results show a design of a jet grout plug that together with the additional structures works sufficiently enough to make a secure construction for a deep excavation below the ground water table. The structural performance of the jet grouted plug to function as a strut level is fulfilled even if the jet grout is not perfectly performed. To work as a sealing component the jet grout column pattern and the centre-to-centre distance between the columns are important factors together with the alignment and diameter of the jet grout columns. To make a completely watertight construction is however almost impossible in this case since the jet grout plug is located at a large depth (around 20 m). To work properly against failure by uplift it does not need to be completely watertight. Instead, the use of relief wells makes sure that the pore water pressure is not larger than the vertical stress from the soil, otherwise failure by uplift is a real danger. Furthermore, to work properly against settlements it is not only the water tightness of the jet grout plug that decides whether it will work properly. Instead, it is also the pumping and infiltration system together with the, in this case, sensitivity of the lower aquifer that decides the risk of settlements.

No description available.

The Concrete Masonry Association of California and Nevada in conjunction with Brigham Young University devised a masonry prism testing scheme to aid in the determination of whether prisms constructed with grouts possessing high levels of supplemental cementitious materials could meet minimum masonry compressive strength requirements. ASTM standards, identical to that of concrete, place restrictions on quantities, by weight, of supplemental materials that can replace ordinary Portland cement. For an all fly ash replacement, up to 40% of Portland cement can be replaced while up to 70% can be replaced by a fly ash-slag combination. Research is focused on class F fly ash and ground granulated blast furnace slag replacing Portland cement in larger quantities. Manufacturing grouts with increasing incremental amounts help to establish higher use limitations associated specifically with masonry grout. Masonry prisms, concrete masonry units, type M mortar, and variations of grout were tested for their respective compressive strengths at age intervals of 14, 28, 42, 56, and 90 days. Grouts were designed to support the discussion of whether non-traditional grouts can achieve acceptable masonry compressive strength in prisms while not possessing adequate grout compressive strength. The control grout consisted of one mix design containing a cementitious materials content of 100% Portland cement. Three grouts replaced Portland cement with fly ash and three grouts replaced Portland cement with a fly ash-slag combination without modifying the cementitious material weight contribution. Class F fly ash replaced Portland cement at rates of 45%, 55%, and 65%. Class F fly ash-ground granulated blast furnace slag combinations replaced Portland cement at rates of 65%, 75%, and 85% where the combinations consisted of 25% fly ash and 40%, 50%, and 60% slag. Results indicate that all prisms exceeded the 10.3 MPa (1500 psi) minimum compressive strength requirements before the mandated 28-day age period. Neither 55% and 65% fly ash replacements nor the 85% fly ash-slag combination achieved grout strength minimums at the typical specified age. The grout mixtures manufactured with exceeding addition rates which attained greater than the minimum strength at the 28-day age were the 45% fly ash and 65% and 75% fly ash-slag combination. All grouts did, eventually, extend their strength gain beyond 13.8 MPa (2000 psi) through the course of testing and all but 65% fly ash achieved this strength within 42 days.

Light-weight aggregate has been used successfully for structural and non-structural applications, and its most common use has been in light-weight concrete. Limited research has been done on light-weight grout though and there are no standards in place. The research performed in this study is intended to increase the knowledge of light-weight grout specifically made with expanded shale aggregate. The research presented herein is a pilot study and consists of preliminary aggregate and grout testing that resulted in the mix design of six grout types: three fine grout designs and three coarse grout designs. Conventional normal-weight aggregate was employed in the first grout mix. A light-weight aggregate batch was made with the same material proportions, as well as the same target water-cement (w/c) ratio and cement content. The weight of the cement was increased by 30 percent in the third grout type of each set to determine the effect on strength. The slump, component temperature, unit weight, air content, segregation, cement content, w/c ratio, and compressive strength for each grout type was gathered throughout testing. Correlations between grout testing results are examined and discussed. In addition, the effectiveness of expanded shale grout, other light-weight grouts, and normal-weight grout with respect to compressive strength to cement content ratio are determined. Results of the testing show that all six grout types studied in this research reached the minimum 28-day strength of 13.8 MPa (2000 psi) ASTM standard. In addition, the results indicate that the cement content in expanded shale light-weight grout would need to be increased to reach comparable compressive strengths to that of the normal-weight grout. The comparison between the compressive strength to cement content ratio of the different grouts indicate that normal-weight grout is more efficient. In addition, light-weight grout made with blast furnace slag grout is slightly more efficient than that made with expanded shale; however, this observation was only possible after several crucial assumptions were made about an existing blast furnace slag study. These strength-cement ratios do not account, however, for the benefits of reduced dead loads, improved thermal insulation, and improved sound insulation that could potentially influence the choice of the material used in and the life-cycle cost of the construction. Additional research should be done to verify the results of the ratios and the assumptions made herein. Furthermore, a life-cycle analysis needs to be conducted before a definite conclusion is made about which type grout is more efficient.

No description available.

Reinforced masonry grouted using self-consolidating grout (SCG) is a relatively new and economically competitive option for construction, providing advantages such as reduced construction time, decreased noise and vibration, and reliable consolidation. However, SCG has different properties than conventional grout and its performance should be verified using current governing code requirements. The purpose of this research program was to determine the development length of spliced reinforcing bars in masonry grouted with SCG.Twelve masonry panels, four courses high and two and a half blocks wide, were constructed using 8-inch concrete masonry units, each with two pairs of vertically spliced #6 reinforcing bars. Six of the panels had splice lengths that met current code provisions to verify that the code requirements are adequate for use with SCG. The remaining panels had shorter splice lengths than required to investigate the possibility of shorter splices in SCG. The ultimate bond strengths were compared to the design requirement for a splice to develop 125% of the yield strength of the rein-forcing bars.All lap splices developed the required stress, including those with shorter lengths. This indicates that the current code provisions are adequate to determine the development length of reinforcement splices in masonry grouted with SCG and reinforced with #6 bars in the specific configurations tested. According to this study, a development length reduction factor may be viable when SCG is used in masonry.

No description available.

Student Number : 7439270 - MSc research report - School of Mining - Faculty of Engineering and the Built Environment / In tabular mining, common in South African gold and platinum mines, the removal of the tabular ore body by mining operations leaves behind excavations known as stopes. These stopes form the production areas of a mine and have to be supported in order that a safe working environment is created. Stopes generally have widths of close to a metre but, in some areas and on certain reefs, may be much wider. Prior to the 1980s, a combination of in-stope pillars and timber was used to support these stopes, but innovations from the 1970s have produced grout packs as a viable support option. These packs are cast in situ through the use of cemented classified tailings gravitated from surface and placed in reinforced geotextile bags at the stope face. As these packs cure and become rigid they are able to bear load when compressed by stope closure. In this way, the packs keep the working areas open. To quantify the load-bearing capacity of grout packs, a range of sizes and designs was tested in a laboratory press and, thereafter, a select few were tested underground. Initially, two aspects of grout packs that had not been adequately quantified previously were addressed. These were: the in situ load / compression characteristics of different forms of grout packs; and the relationship between laboratory test results and in situ performance. The laboratory test programme was extended to allow for an investigation into methods of improving the yieldability of grout packs and the possibility of using them to replace in-stope pillars. It was found that the factors that most affect the initial strength and post-failure characteristics of a grout pack are: the grout strength; the amount and type of steel reinforcement; the inclusion of ancillary columnar support; and the height and diameter of the pack. It was also found that grout packs could be used to replace in-stope pillars, but that pack strength and spacing should be conservatively calculated before implementation. A provisional relationship between the behaviour of packs tested in a press and those placed underground was determined.

The objective of this thesis is to investigate the photocatalytic activity in nanosized TiO2 structures. Two different structures were used for two different reaction systems. In the first part of the study, TiO2 coated on glass beads by a sol-gel procedure were used to test the photocatalytic CO2 reduction reaction with H2O and H2 in the gas phase. The results of photocatalytic CO2 reduction reaction revealed that CO2 reduction step of the overall reaction proceeds in dark / while illumination is required for water splitting reaction. In the second part of the study, Photocatalytic oxidation activity of the commercial TiO2 powders mixed with grout and plaster were studied for a potential commercial self cleaning material. A method based on gas phase benzene oxidation was developed for testing TiO2 added cement based self cleaning surfaces. This method was used to screen 15 commercial TiO2 samples with and without cement. Based on this method a commercial TiO2 sample (S9) was selected for further use. Surface of 15 commercial TiO2 samples were characterized by using NO and CO2 as probe molecules. Photocatalytic benzene oxidation experiments showed that using TiO2 on the surface lead to more effective surfaces in terms of photocatalytic activity. TiO2 was bound to surface by inorganic materials without much activity loss. This kind of amount optimization is of commercial importance.

Neste trabalho foram realizados estudos referentes ao comportamento mecânico e ao contato nata-rocha de dois arenitos da Serra do Espigão, no estado de Santa Catarina, localizados em um trecho de 700m na BR-116 km 108 com histórico de problemas de instabilidade de encostas. No local, observam-se duas formações geológicas, a Formação Rio do Rastro, composta por sedimentos transicionais em pacotes de arenitos e lamitos, e a Formação Botucatu, composta por arenitos eólicos. Neste estudo foram obtidas mais de uma centena de amostras que foram submetidas a análises de lâmina delgada e difratometria de raio X, além de ensaios de granulometria, compressão simples e ensaios CCBT (Composity Cylinder Bond Test). As amostras foram extraídas diretamente da face do talude e também de blocos remanescentes de rupturas no bordo da pista através de uma perfuratriz manual. Para o arenito Botucatu, foram realizados cortes em posição paralela, perpendicular e angular em relação ao plano de estratificação natural da rocha sedimentar. No ensaio de compressão simples avaliou-se a influência da estratificação do arenito Botucatu, bem como a variação na resistência de amostras embebidas e, ainda, a relevância da profundidade amostral na resistência. Os resultados revelaram que a estratificação do arenito Botucatu apresenta forte influência na resistência desta. Para o arenito Rio do Rastro não foram observados planos de estratificação em escala amostral. Ambos os arenitos apresentam considerável queda de resistência ao serem embebidos. Os resultados dos ensaios CCBT puderam ser comparados com ensaios de arrancamento em campo, apresentando valores numéricos muito próximos. A adesão obtida através do ensaio CCBT representa o limite inferior de resistência de contato, podendo ser utilizado diretamente como parâmetro de projeto da adesão nata-rocha. Observou-se em laboratório que o material pulverizado do corte dos corpos de prova compostos tem influência na adesão nata-rocha uma vez que este material promove a colmatação da superfície porosa. As análises de lâmina delgada e difração de raio X contribuíram para a caracterização e identificação geológica dos materiais estudados, bem como para a interpretação dos resultados. / In this research, the grout-rock contact and the mechanical behavior of two sandstones were studied. The samples were collected from a highway cut slope (700m long) at km 108 of BR- 116 from Serra do Espigão in the State of Santa Catarina, which has an history of instability problems. There are two geological Formations: Rio do Rastro Formation, composed of transitional sediment packages of sandstones and mudstones and the Botucatu Formation composed of eolian sandstones. In this work more than one hundred samples were taken for optical thin section microscopy and X-ray diffraction, and tests of grading, uniaxial compression tests and CCBT (Composity Cylinder Bond Test). Samples were taken directly from the slope and also from rock blocks toppled by the road using a portable hand drill. For sampling Botucatu sandstone cuts were made in order to obtain specimens with the natural stratification parallel, perpendicular and angular in relation to its axis. Uniaxial compression test were used to evaluate the influence of these angles of stratification of Botucatu sandstone and the influence of previous soaking. For Rio do Rastro sandstone specimens no bedding planes were observed at the sample scale. The results showed that the Botucatu sandstone strength has a strong influence with respect to its stratification. Both sandstones exhibit considerable loss in strength due to soaking. Pullout field test results which compared well with CCBT. The CCBT results represents the lower limit of rock-grout contact strength and can be used directly as the bond strength design parameter. In the laboratory tests it was also observed that the powdered material resultant from the specimens cutting operations have a considerable influence on the grout-rock bond strength as this material promotes clogging of the porous surface. The grading and the microscopic and diffraction analyses contributed to the characterization and identification of geological materials studied and the results interpretation.