This thesis is focused on the description and evaluation of the status of existing reinforced concrete and of the prefabricated overhanging structures. The first part describes the solution overhanging structures, followed by a description of selected diagnostic methods for determining the properties of concrete in the structure and to determine the degree and extent concrete reinforcement. The main objective is to determine the status of overhanging structures on the case static analysis and critical points of the support structure for the purpose of the planned revitalization of the object.

The diploma thesis deals with development of high resistant composite, which brings its properties closer to the melted basalt products. This fact will allow substitution of basalt elements in hostile chemical environment by newly developed material and completes its product line. High resistant composite also consists of secondary raw material in highest possible amount. Material that is being evolved carries high strength, abrasion resistance and is also resistable in hostile chemical environment.

In der vorliegenden Untersuchung wurden Messungen der Veränderungen der Ultraschallgeschwindigkeit in Betonproben verwendet, um die Entwicklung der Schädigung in Betonen der Festigkeitsklassen C80/C95 und C120/135 während Ermüdungsversuchen unter verschiedenen Beanspruchungsniveaus zu quantifizieren. Die Ergebnisse zeigten die Abhängigkeit der Entwicklung von Ermüdungsschäden von den Belastungsbedingungen und den Betoneigenschaften. Eine der wichtigsten Schlussfolgerungen aus den hier vorgestellten Forschungsergebnissen ist, dass die Druckfestigkeit des Betons allein keinen Hinweis darauf gibt, ob ein Beton unter Ermüdungsbeanspruchung ein abruptes Versagen oder ein progressives und angekündigtes Versagensverhalten zeigt.

Con el actual incremento en las construcciones, el empleo de concreto cada vez es más frecuente y con ello la búsqueda por su mejora, encontrando variedad de alternativas de incorporaciones para este. Por ello, se propone el uso de un absorbente de humedad, similar a la función de un polímero superabsorbente, denominado gel de sílice (G.S.); pretendiendo analizar su influencia en algunas propiedades de concreto con relación a/c de 0.555 y 0.6, incorporando porcentajes de 0.1%, 0.5% y 1% de este material en función al peso de cemento. Resaltando que, con la relación a/c más alta, se presentan temperaturas más bajas, disminuye el tiempo de fragua, aumentos en trabajabilidad, resistencias a la compresión iniciales significativas con aumentos progresivos en el tiempo, mayor rigidez, disminuye la permeabilidad y presenta un mejor desempeño ante ataque de sulfatos, a medida que la cantidad de G.S. aumenta. Por otro lado, con la relación a/c más baja, se encontró aumentos en la temperatura, disminución en tiempo de fragua, disminución en trabajabilidad, incrementos en la resistencia a la compresión con algunas excepciones y disminuciones en la rigidez, a medida que la cantidad de G.S. disminuye. Sugiriendo que el porcentaje óptimo de G.S. varía en función de la relación a/c; una mezcla con una relación a/c de 0,6 se beneficia de mayores porcentajes de G.S., mientras que una mezcla con una relación a/c de 0,555 se beneficia de menores porcentajes de G.S. / With the current increase in construction, the use of concrete is becoming more and more frequent and with it the search for its improvement, finding a variety of alternative incorporations for it. Therefore, the use of a moisture absorber, similar to the function of a superabsorbent polymer, called silica gel (S.G.), is proposed; trying to analyze its influence on some properties of concrete with a w/c ratio of 0.555 and 0.6, incorporating percentages of 0.1%, 0.5% and 1% of this material according to the weight of cement. It should be noted that, with the highest w/c ratio, lower temperatures are presented, setting time decreases, increases in workability, significant initial compressive strengths with progressive increases over time, higher stiffness, decreased permeability and better performance against sulfate attack, as the amount of S.G increases. On the other hand, with the lowest w/c ratio, increases in temperature, decreases in setting time, decreases in workability, increases in compressive strength with some exceptions and decreases in stiffness were found as the amount of S.G decreases. Suggesting that the optimum S.G. percentage varies as a function of the w/c ratio; a mix with a w/c ratio of 0.6 benefits from higher S.G. percentages, while a mix with a w/c ratio of 0.555 benefits from lower S.G. percentages.

Esta investigación tiene como objetivo principal determinar los porcentajes más óptimos del vidrio molido incoloro y del RCD reemplazando estos agregados reciclados por los agregados naturales en un concreto simple de f’c = 175 kg/cm2, sustituyendo en un 5%, 10% y 15% la arena por el vidrio y en un 10%, 20% y 30% la piedra chancada por el concreto triturado (RCD). El procedimiento se inició determinando las características de los agregados naturales y reciclados para realizar así el diseño de mezcla y posterior a ello producir las probetas del concreto patrón y del concreto modificado. Los ensayos que se realizaron fueron Resistencia a la compresión a los 7, 14 y 28 días de curado; resistencia a la tracción indirecta y flexión a los 28 días de curado y finalmente un ensayo de durabilidad por abrasión al concreto que también se realizó pasando los 28 días de curado. Se obtuvo de resultado que el mejor porcentaje de vidrio y RCD que se puede reemplazar es el de 10% de Vidrio y 20% de RCD ya que dio una resistencia a la compresión de 251 kg/cm2; para el ensayo a tracción indirecta el mejor resultado fue el del concreto con 5%Vidrio y 10%RCD ya que al aumentar el agregado reciclado más iba bajando la resistencia y finalmente para el ensayo a flexión el mejor porcentaje fue el de 10%Vidrio y 30%RCD. Cabe mencionar que en el ensayo por abrasión al concreto el menor porcentaje de desgaste fue el concreto con 5%Vidrio y 30% de RCD. / The main objective of this research is to determine the most optimal percentages of colorless ground glass and RCD, replacing these recycled aggregates with natural aggregates in a simple concrete of f'c = 175 kg/cm2, substituting 5%, 10% and 15 % sand for glass and 10%, 20% and 30% crushed stone for crushed concrete (RCD). The procedure began by determining the characteristics of the natural and recycled aggregates in order to carry out the mix design and, after that, produce the standard concrete and modified concrete specimens. The tests that were carried out were Compression resistance at 7, 14 and 28 days of curing; indirect tensile strength and flexion at 28 days of curing and finally a concrete abrasion durability test that was also carried out after 28 days of curing. The result was obtained that the best percentage of glass and RCD that can be replaced is 10% Glass and 20% RCD since it gave a compressive strength of 251 kg/cm2; For the indirect tensile test, the best result was that of concrete with 5% Glass and 10% RCD, since as the recycled aggregate increased, the resistance decreased, and finally, for the flexural test, the best percentage was 10% Glass and 30% RCD. It is worth mentioning that in the concrete abrasion test the lowest percentage of wear was concrete with 5% Glass and 30% RCD.

Self-consolidating concrete (SCC) has wide use for placement in congested reinforced concrete structures in recent years. SCC represents one of the most outstanding advances in concrete technology during the last two decades. In the current work a great deal of cognizance pertaining to mechanical properties of SCC and comparison of fracture characteristics of notched and unnotched beams of plain concrete as well as using acoustic emission to understand the localization of crack patterns at different stages has been done. An artificial neural network (ANN) is proposed to predict the 28day compressive strength of a normal and high strength of SCC and HPC with high volume fly ash. The ANN is trained by the data available in literature on normal volume fly ash because data on SCC with high volume fly ash is not available in sufficient quantity. Fracture characteristics of notched and unnotched beams of plain self consolidating concrete using acoustic emission to understand the localization of crack patterns at different stages has been done. Considering this as a platform, further analysis has been done using moment tensor analysis as a new notion to evaluate fracture characteristics in terms of crack orientation, direction of crack propagation at nano and micro levels. Analysis of B-value (b-value based on energy) is also carried out, and this has introduced to a new idea of carrying out the analysis on the basis of energy which gives a clear picture of results when compared with the analysis carried out using amplitudes. Further a new concept is introduced to analyze crack smaller than micro (could be hepto cracks) in solid materials. Each crack formation corresponds to an AE event and is processed and analyzed for crack orientation, crack volume at hepto and micro levels using moment tensor analysis based on energy. Cracks which are tinier than microcracks (could be hepto), are formed in large numbers at very early stages of loading prior to peak load. The volume of hepto and micro cracks is difficult to measure physically, but could be characterized using AE data in moment tensor analysis based on energy. It is conjectured that the ratio of the volume of hepto to that of micro could reach a critical value which could be an indicator of onset of microcracks after the formation of hepto cracks.