Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 206-219). Available also in a digital version from Dissertation Abstracts.

Vid byggprojekt har det uppdagats fuktproblem i betongplattor där plastmattor har släppt från underlaget. Ett av problemen som beskyllts i media är förändringen från byggcement till bascement. Bascement är en cementsort som 14 % flygaska blandat med portlandklinker. Anledningen till att cementtillverkarna använder flygaska, som är en restprodukt från pulvereldade kolkraftverk, är att det ger minskade mängder portlandklinker som vid tillverkningen släpper ut stora mängder koldioxid. Cement är bindemedlet i betong och när flygaska används binds mindre mängd i vatten i betongens hydrationsprocess. För att undersöka vilken skillnad i uttorkning det finns i betong med bascement och byggcement gjöts två betongprover med samma betongrecept och VCT, men med respektive bascement och byggcement som bindemedel. Dessa betongprover förvarades i en uppvärmd lokal med låg relativ fuktighet. Fuktmätningarna utfördes enligt rådet för byggkompetens fuktmätningsmanual som är det gällande regelverket. Dessa resultat jämfördes med fuktprognoserna från TorkaS och BI Dry, som är de vanligaste fuktberäkningsprogrammen som används. Samtidigt intervjuades olika aktörer från byggbranschen för att undersöka hur de uppfattade problemet med uttorkning i betong. Fuktmätningarna visade ingen markant skillnad mellan betong med bascement och byggcement. Vid jämförelse med de prognosticerade värdena från fuktberäkningsprogrammen framkom att TorkaS värden var väldigt nära de uppmätta fuktvärdena, medans BI Dry:s värden låg långt under de uppmätta värdena. Vid intervjuerna framkom att byggbranschen har många frågor kring uttorkning i betong. Däremot finns svårigheter att avgöra vad som ligger till grund för problemen. Om det är bytet från byggcement till bascement eller om hanteringen av betongen i ett tidigt skede efter gjutningen som påverkar. Däremot om fuktfrågan tas upp i ett tidigt stadium i byggprocessen går det att bespara både tid och pengar. Byggbranschen behöver utbildas hur uttorkningens process ser ut för att öka förståelsen för problemet. / In construction projects, moisture problems have been discovered in concrete slabs where plastic mats have been released from the substrate. One of the problems reported in the media is the change from Portland cement to fly ash cement. Fly ash cement is a cement with 14% fly ash mixed with portland clinker. The reason that cement manufacturers use fly ash, which is a residual product from powder-fired coal power plants, is that it reduces the amount of portland clinkers that release large amounts of carbon dioxide during production. Cement is the concrete binder and when fly ashes are used, less amount of water is bound in the concrete's hydration process. To investigate the difference in dehydration found in concrete with fly ash cement and Portland cement, two concrete samples were obtained with the same concrete recipe and VCT numbers, but with different cement types. These concrete samples were stored in a heated local with low relative humidity. Moisture measurements were carried out according to the current regulations. These results were compared with the moisture predictions from TorkaS and BI Dry, which are the most commonly used moisture calculation programs. At the same time, various actors from the construction industry were interviewed to investigate how they perceived the problem of dehydration in concrete. The moisture measurements showed no significant difference between concrete with base cement and building cement. When compared with the forecasted values from the moisture calculation programs, it was found that the Dry values were very close to the measured moisture values, while BI Dry's values were well below the measured values. The interviews revealed that the construction industry has many questions about dehydration in concrete. On the other hand, there are difficulties in determining what is the basis for the problems. If there is a change from the portland cement to the fly ash cement, or the handling of the concrete at an early stage after the casting affects. However, if the moisture issue is taken up early in the construction process, it is possible to save both time and money. The construction industry needs to be educated how the process of desiccation works to increase understanding of the problem.

Se viene buscando optimizar la elaboración del concreto lanzado, pero en el proceso se deja de lado el control de calidad por lo cual es indispensable comparar la influencia de un componente primario como el cemento tipo IP y HE. La presente tesis tiene por objetivo realizar el estudio comparativo de concreto lanzado con cemento portland puzolanico tipo IP vs tipo HE en el revestimiento del túnel de la mina Orcopampa–Arequipa. Nos ha impulsado a investigar la necesidad de obtener la relevancia en el desempeño y las implicancias del cemento para shotcrete desde una visión técnica, a través de ensayos de campo y laboratorio. Considerando el enfoque técnico al determinar las diferencias entre el concreto lanzado con cemento Tipo IP y Tipo HE desde el análisis de resistencia a tenacidad y resistencia a la compresión. Realizando un tipo de Investigación básica, cuantitativa, descriptivo, aplicada, de campo con un diseño experimental, según el estudio es cuasi experimental, prospectivo por la cronología de observación, transversal según el número de mediciones, descriptiva, comparativa y explicativa. Los resultados estadísticos nos demuestran que si existen diferencias significativas de 62 % entre los resultados de la resistencia a la compresión del concreto lanzado cemento Tipo HE sobre el concreto lanzado con cemento Tipo IP en su totalidad de edades ensayadas. En el análisis estadístico de los ensayos de tenacidad se observa que el cemento Tipo HE tiene una mejor capacidad para absorber energía ya que tiene la característica de desarrollar resistencias a edades tempranas. It has sought to optimize the development of the shotcrete, but in the process neglects quality control so it is essential to compare the influence of a primary component such as cement type IP and HE. This thesis aims to conduct a comparative study of shotcrete with IP pozzolanic Portland cement type HE vs kind in the lining of the tunnel Arequipa Orcopampa mine. It has prompted us to investigate the need for relevance in the performance and the implications of cement shotcrete from a technical view, through field and laboratory tests. Whereas the technical approach to determine the differences between the shotcrete cement type HE type IP and from the analysis of toughness and resistance to compression. He made a type of Basic, quantitative, descriptive research, applied field with an experimental design, the study is quasi-experimental, prospective timeline for observation cross as the number of measurements, descriptive, comparative and explanatory. The statistical results show that if there are significant differences between the results 62% of the compressive strength of cement Type HE shotcrete shotcrete on cement type IP fully tested age. In the statistical analysis of toughness tests it shows that the cement type HE has a better ability to absorb energy and which has the characteristic of developing resistance at early ages.

The work is focused on the possibilities of using FBC fly ash for composite cements, monitoring their hydration processes, especially the creation of AFt phase. The possibility of preparing synthetic ettringite and thaumasite and their detection.

One of the most prominent measurable parameters of the development of phases and phase transformations in inorganic systems are undoubtedly the volume changes of silicate matrix. The study of volume changes is crucial in the terms of usable durability of final product. They represent shrinkage or expansion of the material and may lead to significant decrease of technological and ecological parameters and often to complete destruction of these materials. Most often the volume changes can be observed when cement is used as a binder and in concretes, mortars, artificial aggregates and other similar materials. There are many methods to detect, define and determine the volume changes qualitatively or quantitatively. The development of phases was investigated as a part of the dissertation thesis and hence the volume changes were observed under the conditions closest to the real state in the construction industry. The raw materials and admixtures were selected which model the content of hazardous components present in conventional materials (both natural and secondary), used in construction and the relationship with volume changes was searched and demonstrated. The contacts for measuring the volume changes were attached to test surfaces of specimens and the physical - mechanical tests (volume changes, phase changes, strength, etc.), chemical analysis and ecotoxicity tests depending on the length of hydration were performed.