Esta guía para,oyecto y la ejecución de micropilotes en obras de carretera forma parte de una serie de un documento de divulgación tecnológica elaborados. See details and download book: Ebookers Free Download Guia Para El Proyecto Y La Ejecucion De Micropilotes En Obras By Aavv Fb2. Cálculo de micropilotes de cimentación y dimensionado de su longitud, según guía del Ministerio de Fomento. ESFUERZOS Y REACCIONES. Cálculo de Viga .
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Climent Universidad de Alicante, Spain. Spanish and European codes on micropiles 23 call for a day or micropiloyes age when the micropile is loaded, if prior to that time compressive strength of micropilotez least 25 MPa mlcropilotes cylindrical specimens. In this study, effective porosity was the parameter used to assess durability, for water is the main vehicle for the ingress of aggressive agents in cement-based materials Slag-blended cement grout exhibits more favourable long-term durability properties than portland cement grout.
The samples were extracted from the 1 cm thick disks. This parameter was determined microopilotes the capillary absorption method described in Spanish standard UNE It also provides that in grout used as anti-corrosion protection for the reinforcement the w: Grouts were prepared with two commercial cements, a type I The legislation on soil anchors 45in turn, stipulates no specific geometry for the specimens to be used in compressive strength tests.
In this study, the variation in the diffusion coefficient D s was monitored through the age of 90 days. This very well known method is widely used in cement-based materials 20 This research aimed to characterise durability-related properties and compressive strength in cement grout prepared with a commercial cement blended with blast furnace slag at different w: This result concurs with previous reports micropiilotes28according to which blast furnace slag refines the cement pore network but such refinement does not translate into any material reduction in total porosity.
Ten-centimetre diameter cylindrical specimens measuring 5 cm thick were tested by sealing the bottom half of the side surface of the specimen with adhesive tape to ensure that only one of the flat surfaces of the specimen was in contact with the water Rilem TC PCD The cm diameter samples were used to study the variations in electrical resistivity and the cm specimens to determine compressive strength and the penetration of water under pressure.
Nonetheless, in the earliest tests, pressurised water was observed to leak out of the cracks formed, particularly in the CEM III specimens, rendering the findings invalid. Abstract Special foundations, most prominently micropiles and soil anchors, are frequently used in construction today.
While the legislation on micropiles 1 — 3 establishes certain minimum compressive strength values, the codes on soil anchors 45 leave this decision to the designer’s discretion. After 28 days, however, porosity was substantially lower in the former. This procedure has been used in the past for fly ash- and blast furnace slag-blended cement Norma UNEMadrid.
Electrical resistivity rose with time for both types of cement studied see Figure 2denoting the progressive refinement of the pore network as a result of ongoing clinker and slag hydration 6 Note that in both the and day specimens, at the w: The findings for this parameter are depicted in Figure 3. Their day strength is, however, lower than observed for the portland cement grouts. The results of this test for each type of cement and w: Two and two day specimens were tested for each type of cement and w: At longer hardening times, these adverse consequences of high temperature drying would be mitigated by mifropilotes refinement of the CEM III pore network, jicropilotes shown by the electrical resistivity results discussed earlier.
The mechanical property studied was compressive strength, since as noted above, this is the main parameter used in codes and standards for determining whether a cement is apt for such applications.
Study by impedance spectroscopy, en: Those texts also establish a range of acceptable micro;ilotes Article Tools Print this article. US manual FHWA-SA guisin turn, stipulates that the compressive strength of grout used to build micropiles should be determined on 5-cm cubic specimens, which were not tested in this study.
Other cylindrical specimens were cast to diameters of 10 and 15 cm and a height of 30 cm. Moreover, the fact that in soil anchors and micropiles the reinforcing steel is embedded in cement grout cement paste distinguishes these members from other civil engineering structures, where it is embedded in concrete. In the present study, this property was analysed in terms of the steady state chloride diffusion coefficient, found indirectly from electrical resistivity data Grout chloride resistance was also analysed, inasmuch as these ions gjia among the primary inducers of steel corrosion, particularly in micropiles and soil anchors in contact with aggressive water or soil.
These members, which transfer surface tensile stress to the undersoil 4consist essentially of a head and a free and a fixed micropilotez 45as shown in Figure 1 b.
Electrical resistivity readings furnish information on pore connectivity and size in materials, both of which parameters are associated with durability.
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The high short-term effective porosity observed for CEM III may be related to the slower reaction rate that characterises slag hydration, as discussed earlier in connection with the electrical resistivity and absorption findings.
Chloride resistance in grout is an area of particular interest, since these ions are among the most aggressive corrosion inducers in reinforcement embedded in micropiles and soil anchors, particularly in marine environments or structures in contact with high chloride- or sulfate-content water. Soil anchors are another type gjia special geotechnical application. Effective porosity, in turn, is directly related to the volume of pores accessible to water and therefore to aggressive agents such as chloride ions, which may corrode micropklotes steel used to reinforce micropiles and soil anchors.
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This parameter is an indirect measure of connectivity and pore size in a material. Special foundations for buildings and civil works are becoming increasingly common in gguia today.
Keywords Ground granulated blast-furnace slag; Cement grout; Special geotechnical applications; Durability; Compressive strength. Tests were conducted on 2-,and day specimens. Tests were conducted on 2- 7-,and day specimens. Effective porosity was determined from the following equation [ 1 ], further to standard UNE A comparison of the findings for the aforementioned semi-prisms to the FHWA-SA 1 compressive strength requirement reveals that all the grouts studied would be code-compliant the minimum strength recorded was The post-submersion absorption values were very similar in the day specimens for the two types of cement.
The coefficient was calculated with Equation [ 2 ] below, proposed by Andrade et al. Despite these considerations, the difference in day strength between the two types of cement was not overly large.
Although this test is actually designed for hardened concretes cured under water 29it microppilotes applied here to the cement grout because the standards on micropiles 2 and soil anchors 4 refer to the provisions of Spanish Structural Concrete Code EHE for characterising most grout properties Upon conclusion of the test, the specimens were split along the centreline and the depth of water penetration was measured in each half.