Nowadays Portland cement concrete is the most widely used building material. Its mechanical properties, the quality/price ratio, performance in general, have contributed to the success ofthis material along 20th century. However the process of fabrication of Portland cement involves some problems (energetically and environmentally speaking) qffecting the general opinionn ofmodern societies on thepotential risks ofsuch a process of fabrication: Very high temperatures need to be reached (J400"C- 1500°C); natural quarries are destroyed during the extraction of raw materials; CO2 and NOX are emitted to the atmosphere. Finally, traditional concrete also presents some durability problems, which are currently difficult to overeóme. This paper offers some resulls obtained in an ongoing investigation. The investigation is related with the elaboration ofalkaline concrete: concrete in which the Portland cement is completely replaced (100%) byfly ash and the mixing water by an alkaline dissolution. This new alkaline concrete may reach a compressive strength of50 -60 MPa at 20 hours after the mixing. Additionally, alkaline concrete has a very good dimensional stability (it hardly undergoes shrinkage). Also, the adherence between the matrix and the steel reinforcement is very good; and because ofthe very similar chemical and mineral composition ofalkaline cements with natural zeolites, it is expected that the new concrete will have very good durability properties. Finally the pnce ofthe new concrete is competitive with Portland cement concrete prices and the application ofthe new material in theprecast industry could be done with almost no problems.
The main objective ofthis paper is to document the Chilean experience on the application oj'the postensioned super fíat floors construction technology. The advantages of this solution are presented and compared with other types of slabs on grade, highlighting the need of super fíat floors in warehouses with high racks for storage. The construction process and the required tools to adequately apply this technology are described, and three cases of actual construction Jobsperformed in Chile are analyzed. Also problems appearing during the construction process are presented and the adopted solutions are described. Finally, subjects requiring further research on the long temi behavior, performance and durability of postensioned superflat floors are recommended.
This paper summarizes thejirst Chilean experience\ in place cola recycling project, using foamed bitumen technology. This technology is applied on flexible pavement I rehabilitation, using speciaüzed equipment that crushes and I blends the existingpavement section, resulting in a base course (stabilized). The work describes the pavement befare the rehabilitation, the pavement structural design solution and the mix design solution. Also, explains the recycled layen construction process oblained from the field observation:\ equipment, procedures, performance and material control. \ Finally, the work explains the construction technol advantages and difficulties.
Structural safety analyses based on reliability provide a direct link with risk evaluation and economic decision. The term "partial reliability" allows for actual conditions ofthe state ofa civil work, e.g. degradation, deficiency, failure, etc, and actual traffic loads, but it does not include earthquake, wind, flood or scour effects. The model developed in this paper is a combination of Structural analysis based on discrete finite elements and Montecarlo simulation techniques using Matlab® software.
The Nueva Granada Military University and Javeriana University implemented an investigation aimed at determining the viability qfthe use ofwastes generated by the iron and steel industry qf Boyacá (Colombia), with a view to improve thephysical mechanical properties of granular bases and subbases in the constmction of pavements. The tests performed to determine the changes in the mechanical properties qfthe granular material were the standard and modified Proctor and C.B.R. tests As a conclusión, U was established that the resistance índex (C.B.R.) and the density qfthe material increasedby up to a 15%.
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