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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These results are consistent with the findings on effective porosity, electrical resistivity and post-submersion absorption and can be attributed to the more highly refined pore network in the blast furnace slag-blended material.
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: Abstract Special foundations, most prominently micropiles micropiltoes soil anchors, are frequently used in construction today.
How to cite item. Both cements were compliant with reference guide 24 minimum strength class requirements Pre-trial specimen conditioning may have also affected these short-term effective porosity findings. This parameter was determined with the capillary absorption method described in Spanish standard UNE Their day strength is, however, lower than observed for the portland cement grouts. Keywords Aggregate Characterization Composite Compressive guai Concrete Durability Mechanical properties Mortar Portland cement Waste treatment cement characterization compressive strength concrete corrosion durability fly ash mechanical properties microstructure mortar physical properties.
Corrosion and Chloride Transport; T4.
The use of one such special geotechnical application, micropiles, has grown significantly in recent microplotes in light gia its adaptability to all manner of terrains and its aptness for underpinning existing foundations, among others 12. In the CEM I grout, effective porosity was fairly low in the 2- and day specimens. 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.
This parameter is an indirect measure of connectivity and pore size in a material.
Tests were conducted on 2-,and day specimens. This micropilotew has been used in the past for fly ash- and blast furnace slag-blended cement The appearance of these cracks, in combination with a scantly refined early age pore network, might explain the high effective porosity values observed for the CEM III material.
Two and two day specimens were tested for each type of cement and w: For exposure classes IIIc, Qc and Qb, in contrast applicable to prestressed members such as soil anchors onlythe code 30 stipulates that the maximum penetration depth must be under 30 and the mean under 20 mm.
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.
Micro;ilotes and European codes on micropiles 23 call for a day or the age when the micropile is loaded, if prior to that time compressive strength of at least 25 MPa in cylindrical specimens.
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Cylindrical specimens 10 cm in diameter and 15 cm high were moulded and then cut into disks 1 to 5 cm thick to study post-submersion water absorption and determine effective porosity. 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.
The samples were extracted from the 1 cm thick disks.
Cement grout for micropiles is generally prepared with a w: Here it was determined in cement paste specimens using the Wenner four-point test 20 described in Spanish standard UNE The findings also indicate that the w: 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 These findings are likewise consistent with the results of the other parameters studied.
The findings therefore indicate that in the short term the total pore volume was higher in the CEM III grout, whereas the long-term volume was very similar in the micropilptes materials.
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The aforementioned findings appear to show that the use of cements with a high blast furnace slag content in cement grout for soil anchors and micropiles leads to a more refined microstructure in the hardened grout than observed in the portland cement-based material, although the pore volume was not observed to decline significantly. 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.
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. Keywords Ground granulated blast-furnace slag; Cement grout; Special geotechnical applications; Durability; Compressive strength. 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.
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. Micropiles are cylindrical members with diameters of under mm, drilled and grouted with cement grout or mortar injected in one or two phases, reinforced with steel tubing and sometimes strengthened with one or several ribbed bars 12.
The penetration of water under pressure is a test 29 recommended in Spanish Structural Concrete Code EHE 30 to measure water permeability in concrete. The Spanish guide for designing and building micropiles in road works 2 envisages w: Standard test method for specific gravity, absorption, and voids in hardened concrete, Philadelphia.
For soil anchors, the Spanish guide for designing and building soil anchors in road works 4 provides that grout compressive strength is to be defined in the design.
Ten-centimetre diameter cylindrical specimens measuring 5 cm thick were tested by sealing the bottom half of the mmicropilotes 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 results show that slag grout exhibits greater durability than the portland cement material and complies with the compressive strength requirements laid down in the respective codes.
Note that the fixed anchor transfers the load to the terrain across cement grout, which can also be used to fill the rest of the bore hole. Nonetheless, the effect on the in-service properties durability and mechanical strength of the slag cement grout used in special geotechnical applications such as micropiles and soil anchors has not been researched.
Three specimens were tested per cement type and w: Ortega Universidad de Alicante, Spain.
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In this study, the variation in the miropilotes coefficient D s was monitored through the age of 90 days. The protocol for monitoring soil anchor construction laid down in the aforementioned guide 4 suggests that compressive strength should be determined in 7- and day grout.
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: Upon conclusion of the test, the specimens were split along the centreline and the depth of water penetration was measured in each half. Climent Universidad de Alicante Spain.