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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A number of environmental benefits derive from the use of active cement additions to manufacture concrete. Slag-blended cement grout exhibits more favourable long-term durability properties than portland cement grout.
Eight samples were tested per cement type and w: Electrical resistivity readings furnish information on pore connectivity and size in materials, micropilotess of which parameters are associated with durability. Other cylindrical specimens were cast to diameters of 10 and 15 cm and a height of 30 cm. Corrosion and Chloride Transport; T4. This would mean that at very early ages, the microstructure of CEM III would be less refined than at older ages and the volume of pores accessible to water would be greater.
Further to the electrical resistivity and post-submersion absorption findings for hardened grout designed for micropiles and soil anchors, when made from cements with a high blast furnace slag content the material has a more refined pore network than when prepared with a comparable portland cement.
In Spain, the grout for these special technical applications is generally prepared with portland cement, although the codes and standards in place stipulate only the minimum compressive strength required, with no mention of cement type.
Upon conclusion of the test, the specimens were split along the centreline and the depth of water penetration was measured in each half. Ortega Universidad de Alicante Spain. This improvement is related to the hydraulic properties of blast furnace slag. Durability and Degradation of Cement Systems: They are used in retaining structures, bridge abutments and landside control 4.
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: Abstract Special foundations, most prominently micropiles and soil anchors, are frequently used in construction today.
Moreover, strength gain in slag-blended cement is known to be slower than in portland cement 728requiring more time to reach comparable strength values.
The results observed for the properties related to durability studied consequently appear to indicate that the grout prepared with cement carrying a high slag content affords greater soil anchor and micropile durability than portland cement grout.
The products formed during slag hydration induce microstructural refinement in the mortar and concrete 67 Moreover, the fact that early age electrical resistivity values were similar in the two types of cement studied, but slightly higher for CEM I at w: Effective porosity was determined from the following equation [ 1 ], further to standard UNE Although the former procedure entails a lower risk of microstructural alterations due to the lower drying temperature, its implementation calls for fairly long test times on the order of at least one month for each condition tested.
In this study, the variation in the diffusion coefficient D s was monitored through the age of 90 days. 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. All the grouts studied here also met these specifications, with the exception of the CEM I materials with a w: That notwithstanding, as explained above, this test was conducted because the codes and standards on soil anchors and micropiles 24 explicitly provide that grout must be EHEcompliant 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 the steel used to reinforce micropiles and soil anchors.
As in micropiles, micropiootes cement micopilotes for soil anchors is normally prepared with type I portland cement, although neither standard UNE-EN Indeed, in the day specimens, all the CEM III grouts studied had similar or lower effective porosity, depth of water penetration under pressure and steady state chloride diffusion coefficients than the CEM I grout with a w: 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.
The post-submersion absorption values were very similar in the day specimens for the two types of cement.
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In the CEM I grout, effective porosity was fairly low in the 2- and day specimens. This parameter was determined with the capillary absorption method described in Spanish standard UNE The characterisation of cement grouts for soil anchors and micropiles is of cardinal importance for the prevention of reinforcement corrosion.
How to cite item. Soil anchors are another type of special geotechnical application.
This study, as micrlpilotes earlier, aimed to analyse the behaviour of cement grout, not concrete. At longer hardening times, these adverse consequences of high temperature drying would be mitigated by the refinement of the CEM III pore network, as shown by the electrical resistivity results discussed earlier. Most of the grouts prepared with slag-bearing cement meet the compressive strength requirements laid down in the various codes and standards for micropiles and soil anchors, whether measured on cm diameter, micropilottes high cylindrical specimens or 4-cm square, cm deep prismatic specimens.
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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 Pastor Universidad de Alicante – Consulteco, S. Tests were conducted on 2- 7-,and day specimens.
This finding could have practical consequences, since the Spanish guide for designing and building soil anchors in road works 4for instance, stipulates that the cement grout used for anti-corrosion protection in contact with reinforcing steel i. The code also establishes a series of maximum depth values, depending on the type of environment to which the concrete is exposed.
The results of this test for each type of cement and w: