Manufactured fine aggregates are a product created when rocks are crushed using a mechanical crusher. With the depletion of sources of natural sands, the usage of manufactured fine aggregates has increased. Manufactured fine aggregates have properties that differ from natural sands; for this reason, the plastic and hardened properties of concrete produced using manufactured fine aggregates differ from the properties of concrete made with natural sands. The main concrete properties affected by the usage of manufactured fine aggregates are skid resistance, workability, and finishability. The aim of this research project was to investigate how manufactured fine aggregates could be used in concrete pavements without causing workability or skid related issues. To improve the workability of concrete made with manufactured fine aggregates, the use of the optimized mixture proportioning method developed by the International Center for Aggregate Research (ICAR) was investigated. Results obtained from this testing were used to make recommendations on how the ICAR method for pavement concrete could be improved The goal of this research was to also develop laboratory tests that could reasonably predict skid performance of concrete pavements made with different types of sand. For this purpose concrete slabs made with different sands were evaluated for friction and texture using a circular texture meter (CTM), a dynamic friction tester (DFT), and a polisher. To ensure that the values obtained at the laboratory related to field performance, test sections constructed with 100% limestone sand and blended sands were evaluated. Laboratory and field test results for skid were used to identify aggregate tests that best correlates with concrete performance. Results show that the micro-Deval test for fine aggregates could be used to predict the polish resistance of concrete laboratory specimen. Results from field testing has shown that if limestone fine aggregates are not blended with siliceous sands, PCC pavements made with limestone sands on truck lanes could experience a large drop in skid resistance within a year of service. Results obtained from laboratory testing showed that blending a small quantity of siliceous sand with limestone sands considerably increased the skid resistance of concrete specimens. / text

Calcium nitrite as a corrosion inhibitor is mainly used to protect steel reinforcement in concrete by reducing its corrosion rate. Hence the effectiveness of calcium nitrite depends on its availability as a free nitrite in the pore solution. The present research work aims to determine the concrete mixture component mostly responsible for nitrite binding in concrete. Firstly, the experimental program included testing of nitrite binding in cement paste. Secondly, the effect of adding the fine aggregate (mortar mix) on nitrite binding was assessed. Finally, the mix with coarse aggregate (concrete mix) was evaluated. In-situ leaching method was used to obtain the pore solution that was needed. Measurement of pore solution with the In-situ leaching method and after an average of 48 days showed that concrete specimens have the most nitrite binding capacity. Then, the binding of nitrite was less in mortar and paste specimens respectively. Therefore, concrete specimens bind more nitrite compared to the paste and mortar specimens. The binding ratio increased whenever the nitrite addition level increased. Nevertheless, the free nitrite were similar in the case of the lowest nitrite addition for all types of mix. The pH levels for the mixes with nitrite present, were lower than those of the control mixes.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The use of foamed asphalt as a technique that incorporates recycled bases stabilized with RAP is known, because it achieves important structural contributions. However, the component of aggregates, belonging to the fine fraction (through the # 200 mesh) takes special importance. This article seeks to develop a comparative analysis between the stabilizations of recycled foamed asphalt bases and asphalt emulsion. The importance of this study lies in analyzing the structural contribution of the fines fraction when comparing both stabilizations. For the present investigation, 48 pits were examined, where the combined granulometry of the RAP plus the granular base was evaluated. Here it was possible to identify a minimal presence of fines even within the recommended spindle for foamed asphalt mixtures, evidencing a deficit in indirect traction strength (ITS). The results obtained show, that a dry stability of 484.7 kg is achieved, and a conserved strength of 45% in the foamed asphalt. While in the asphalt emulsion a dry stability of 1862.1 kg and a conserved resistance of 70% is achieved. This demonstrates the impact on the structural behavior that have the fines fraction in stabilizations with foamed asphalt.

O concreto autoadensável (CAA) é um concreto especial com a capacidade de fluir e preencher completamente todos os espaços das fôrmas pela ação de seu peso próprio, sem que haja ocorrência de bloqueio e segregação da mistura. Contudo, para alcançar essas características, normalmente esse concreto é dosado com um maior teor de materiais finos e/ou com aditivo modificador de viscosidade. Os agregados provenientes de Resíduos de Construção e Demolição (RCD) já estão sendo utilizados na produção de concretos, porém o uso dos materiais finos de agregados reciclados não é recomendado para a produção de concretos convencionais. Entretanto, acredita-se que em CAA esses materiais finos podem ser uma oportunidade interessante, tanto para a questão da reutilização desses resíduos, conseguindo uma destinação nobre para esses materiais com baixa demanda no mercado, como na manutenção das propriedades deste concreto, sendo os principais agentes do controle de segregação. Desta forma, o presente trabalho consistiu em estudar a influência da utilização de finos de RCD (concretos, argamassas e tijolos cerâmicos), separadamente, em substituição parcial ao agregado miúdo natural, nas principais propriedades do concreto autoadensável no estado fresco (fluidez, habilidade passante e resistência à segregação) e no estado endurecido (resistência à compressão e módulo de elasticidade), bem como avaliar seu desempenho quanto à durabilidade (absorção de água e penetração de íons cloretos). Os resultados demostraram perda de fluidez e boa coesão nos concretos autoadensáveis que empregaram agregados reciclados. No entanto, ainda conferem boas características de autoadensabilidade, atendendo as condições normativas para uso em estruturas correntes de engenharia. No que tange às propriedades mecânicas, foi observado aumento de resistência à compressão e decréscimo do módulo de resistência para concretos com finos de RCD. No quesito de durabilidade, os concretos com agregados reciclados apresentaram valores mais elevados para absorção de água por capilaridade e penetração de íons cloretos em comparação aos concretos de referência. / Self-compacting concrete (SCC) is a special concrete with the ability to flow into and completely fill all spaces within the formworks only by the action of their own weight, without blocking and segregation of the mixture. However, to achieve these characteristics, normally this concrete needs to be mixed with more content of fine materials and/or viscosity modifiers additives. The aggregates from Construction and Demolition Wastes (CDW) are used for concrete production, but the use of fine recycled aggregate is not recommended for the production of conventional concrete. Although, it is believed that in SCC these fine aggregates can be an interesting opportunity for the reuse of these wastes, achieving a noble destination for these materials with low demand in the market, as for the maintenance of the properties of this concrete, being the main agents of segregation control. So, the present research consisted in studying the influence of the use of CDW fines aggregates (concretes, mortars and ceramic bricks, separately) to replace the natural sand in the main properties of the self-compacting concrete in the fresh state (flowability, passing ability and segregation resistance) and in the hardened state (compressive strength and modulus of elasticity), as well as to evaluate its performance in terms of durability (water absorption and chloride penetration). The study results showed loss of flowability and increased cohesion in the self-compacting concretes that used recycled aggregates. However, they still confer good characteristics for self-compacting concrete, taking into account the normative conditions for using current engineering structures. With respect to the mechanical properties, it was observed an increase of compressive strength and decrease of the modulus of elasticity for concrete with CDW fines aggregates. In terms of durability, concretes with recycled aggregates presented higher values for capillarity water absorption and penetration of chloride ions compared to the references concretes.

The desire of the minerals industry to be more sustainable has led towards the increasing development of by-products. One such industry is the production of Alumina. The Alumina industry in Australia is the major producer of alumina in the western world with over 25 million tonnes of Bauxite Residue per annum. Alcoa World Alumina (Alcoa) has three refineries in Western Australia producing approximately 20,000 tonnes of Mud and a similar level of Red Sand each day. These as yet unutilised potential resources are being stockpiled, occupying a significant footprint. It is widely recognised within industry that there would be economic, environment and social benefits if a sustainable use for these materials were found. One such potential by-product is the production of coarse bauxite residue (Red Sand), neutralised and washed low in salt. The main purpose of this research was to establish a potential market for this material, through scientific evaluation of Red Sand as a replacement of natural fine aggregate (Natural Yellow Sand) in concrete mixes. For this research, the mixed stream of Bauxite Residue (fine and coarse) obtained in the Bayer process was neutralized by a process of carbonation then washed using cyclones and counter current wash towers to a value added byproduct. The coarse particles (Washed and Carbonated Sand-WCS) of the stream were separated by Wet High Intensity Magnetic Separation technique (WHIMS) so that different segments such as High Iron Sand (HIS) and Low Iron Sand (LIS) were formed. Physical, chemical and mineralogical properties of these materials have been tested and compared with that of natural sand. Several mixes of concrete were then designed using Red Sand as a fine aggregate in order to verify their effects on strength and durability indicators of concrete. / The comparative analysis between normal mix proportions and the mix proportions utilizing Red Sand was also achieved. In addition, the impact of marine environment on concrete mix design and properties of manufactured concrete were evaluated with a series of standard laboratory tests. The findings were promising in terms of both mechanical properties and durability and suggested that Red Sand, in particular Low Iron Sand is likely to be effective in place of fine aggregates and can be used within marine grade concrete with no major differences when compared to normal concrete. From the results obtained, it can be deduced that this material can be used in a wide range of concrete applications in Civil Engineering and Construction.

Fatigue cracking and moisture damage are two important modes of distresses in asphalt pavements. Recently, the Dynamic Mechanical Analyzer (DMA) was used to characterize fatigue cracking and evaluate the effects of moisture damage on the Fine Aggregate Matrix (FAM) portion of asphalt mixtures. The FAM specimens should be properly fabricated to represent the composition and structure of the fine portion of the mixture. The objective of the first phase of this study was to develop a standard test procedure for preparing FAM specimens such that it is representative of the mixture. The method consists of preparing loose full asphalt mixtures and sieving through different sizes. Then, the ignition oven was used to determine the binder content associated with the small size materials (passing on sieve #16). Sieve #16 is used to separate fine aggregates from the coarse aggregates. The applicability of this new method will be evaluated using a number of asphalt mixtures. The objective of the second phase of this study was to develop software to analyze the data from DMA test. Such software will enable engineers and researchers to perform the complex analysis in very short time. This is Microsoft Windows ® based software, executable in any hardware configuration under this operational system.

Current Texas Department of Transportation (TxDOT) procedures for evaluating coarse aggregate for portland cement concrete (PCC) have been in place for over 39 years. Item 421 in the TxDOT "Standard Specifications for Construction and Maintenance of Highways, Streets, and Bridges" describes the tests and test limits that must be met by aggregates before they can be approved for use in portland cement concrete applications. The intention of Item 421 is to ensure that only strong, durable aggregates are used in concrete so that the life of concrete is not cut short by common distress mechanisms which ultimately lead to costly repairs and replacements. The two main tests currently used by TxDOT to evaluate aggregates are the magnesium sulfate soundness test and the Los Angeles abrasion and impact test. These tests are meant to characterize the overall soundness and resistance to abrasion and impact of an aggregate respectively. Unfortunately, past research has shown that the magnesium sulfate soundness and test and the Los Angeles abrasion and impact test are not able to successfully predict the field performance of an aggregate in concrete. The requirements of item 421 have thus far done a reasonably good job of ensuring long-lasting concrete; however the current tests and test limits may be unnecessarily precluding the use of some local materials. As high quality aggregate sources are depleted and transportation costs increase, it will become more necessary to distinguish good performers from marginal and poor performers in the future. If aggregate tests can be found that demonstrate better correlations with field performance, it may be possible to use more local aggregate sources and still provide the desired level of reliability for pavements, bridges, and other TxDOT concrete applications. Researchers are in the processing of collecting coarse and fine aggregates commonly used in Texas and testing these aggregates on a variety of alternative tests. Researchers will attempt to relate this test data to concrete behavior and ultimately recommend tests for improved TxDOT aggregate specifications. / text

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-12T16:05:55Z No. of bitstreams: 1 GUILHERME COSTA DE OLIVEIRA - TESE PPGEQ 2016.pdf: 2637788 bytes, checksum: 666ee4637bd3109b74c369b5faba3164 (MD5) / Made available in DSpace on 2018-03-12T16:05:55Z (GMT). No. of bitstreams: 1 GUILHERME COSTA DE OLIVEIRA - TESE PPGEQ 2016.pdf: 2637788 bytes, checksum: 666ee4637bd3109b74c369b5faba3164 (MD5) Previous issue date: 2016-08-31 / Capes / Dentre os diversos minerais extraídos, no Brasil, o caulim é um dos principais. Esse mineral de da família das caulinitas, apresenta uma grande versatilidade quanto ao seu uso. Porém, durante o processo de beneficiamento, altas quantidades do material extraído são rejeitadas, chegando a 70% do montante. Esse resíduo é disposto a céu aberto, causando transtorno às populações circunvizinhas e ao ecossistema da região. Esse trabalho objetivou utilizar o resíduo gerado nesse processo como matéria prima para o desenvolvimento de argamassas. O resíduo foi caracterizado, e utilizando a difratometria de raios X (DRX) verificou-se que é, basicamente, constituído de caulinita e mica. O resíduo foi testado quanto à sua pozolanicidade e verificouse que não apresentava potencial adequado para ser utilizado como substituinte parcial do cimento. Entretanto, suas características físicas indicaram que o resíduo de caulim apresentava propriedades para ser utilizado como agregado miúdo. Traços de argamassas colantes foram realizados substituindo o agregado miúdo natural, areia, pelo resíduo do caulim em proporções de 0 a 100 %. Essas argamassas foram testadas de acordo com as especificações contidas na norma ABNT NBR 14081. Os resultados indicaram que, à medida que se aumentou a quantidade de resíduo, a argamassa necessitou de uma maior quantidade de água para se obter a trabalhabilidade adequada. Com relação aos dados de resistências mecânicas, verificou-se um decaimento linear nos dados. Para o Tempo em Aberto (TA), observou-se uma redução de, aproximadamente, 90% na resistência mecânica do material; com relação às Resistências de Aderência à Tração (RAT), houve diminuição de 87% nas resistências mecânicas dos traços curados ao ar e, 81 %, nas argamassas curadas em meio aquoso. O traço que continha 25 % de seu agregado natural substituído por resíduo de caulim, apresentou valores dentro dos limites estabelecidos pela NBR 14081 e uma demanda de água próxima à das argamassas colantes industrializadas disponíveis no mercado. Dessa forma, o resíduo oriundo do processo de beneficiamento de caulim, apresentou-se como uma opção viável para a redução do uso de areia no desenvolvimento de argamassas colantes. Essa substituição foi favorável tanto para dar uma destinação ao resíduo, como também para a diminuição do uso de areia como agregado miúdo, uma vez que sua extração acarreta em diversos problemas ambientais. / Among various minerals extracted in Brazil, kaolin is one of most important. This mineral from the kaolinite family has great versatility as its use and during its beneficiation process, high amounts of the extracted material are rejected, reaching values as 70%. This residue is disposed on the environment with no treatment, causing inconvenience to surrounding communities and to the region ecosystem. This work aimed to use this residue as raw material for the construction industry, more specifically in the development of AC-I type adhesive mortars. The residue was characterized and by X-ray diffraction verified that it is basically constituted of kaolinite and mica. Based on Brazilian standards, the residue was tested for its pozzolanic and it was found that showed no suitable potential for using as a partial replacement for cement. However, its physical characteristics indicate that the kaolin residue had properties to be used as fine aggregate. Traces of adhesive mortars were made by replacing the fine natural aggregate, sand, by kaolin residue in proportions from 0 up to 100 %. The results indicated that, as it increased the amount of residue, the mortar required a larger amount of water to obtain adequate workability. Due to mechanical resistance data, there was a linear decay in. For the Open Time (TA), there was a reduction of approximately 90% in the mechanical strength of the material; and about to Resistance Adhesion Tensile (RAT), a reduction of 87 % in the mechanical strength of the admixtures air-cured and 81 % in the mortar cured in an aqueous medium. The admixtures that contained 25 % of its fine aggregate replaced by kaolin residue, showed values within the limits established by the NBR 14081 and a water demand close by the demand in industrialized adhesive mortars. Thus, the residue derived from kaolin beneficiation process, proved to be a viable option for reducing the use of sand in the development of adhesive mortars. This substitution is in favour both to give a destination to residue, also to reduce the use of sand as fine aggregate, since its extraction brings several environmental problems in.

abstract: The fatigue resistance of asphalt concrete (AC) plays an important role in the service life of a pavement. For predicting the fatigue life of AC, there are several existing empirical and mechanistic models. However, the assessment and quantification of the ‘reliability’ of the predictions from these models is a substantial knowledge gap. The importance of reliability in AC material performance predictions becomes all the more important in light of limited monetary and material resources. The goal of this dissertation research is to address these shortcomings by developing a framework for incorporating reliability into the prediction of mechanical models for AC and to improve the reliability of AC material performance prediction by using Fine Aggregate Matrix (FAM) phase data. The goal of the study is divided into four objectives; 1) development of a reliability framework for fatigue life prediction of AC materials using the simplified viscoelastic continuum damage (S-VECD) model, 2) development of test protocols for FAM in similar loading conditions as AC, 3) evaluation of the mechanical linkages between the AC and FAM mix through upscaling analysis, and 4) investigation of the hypothesis that the reliability of fatigue life prediction of AC can be improved with FAM data modeling. In this research effort, a reliability framework is developed using Monte Carlo simulation for predicting the fatigue life of AC material using the S-VECD model. The reliability analysis reveals that the fatigue life prediction is very sensitive to the uncertainty in the input variables. FAM testing in similar loading conditions as AC, and upscaling of AC modulus and damage response using FAM properties from a relatively simple homogenized continuum approach shows promising results. The FAM phase fatigue life prediction and upscaling of FAM results to AC show more reliable fatigue life prediction than the fatigue life prediction of AC material using its experimental data. To assess the sensitivity of fatigue life prediction model to uncertainty in the input variables, a parametric sensitivity study is conducted on the S-VECD model. Overall, the findings from this research show promising results both in terms of upscaling FAM to AC properties and the reliability of fatigue prediction in AC using experimental data on FAM. / Dissertation/Thesis / Doctoral Dissertation Civil and Environmental Engineering 2016

In order to reduce the use of landfilling within waste management great emphasis is being placed on waste reduction and recycling. Each year in the UK approximately 2.5 Mt of waste glass is produced and approximately half of this waste is not recyclable. Therefore alternative ways need to be found for using waste glass and one possibility is to use it within concrete as a replacement for cement and/ or aggregate. In the research programme concrete mixes were tested which had 0%, 25%, 50% and 100% of the fine aggregate replaced by crushed waste glass. All glass was originally in bottle form and was crushed to produce ‘sand’ which had a grading curve more-orless identical to fine aggregate obtained from a commercial supplier. Three colours of glass were studied, i.e. flint (clear), amber and green. Concretes were also made which contained a mixture of colours (in proportion according to the weight of each type of waste glass produced annually within the UK) and also a mixture of unwashed waste glasses. The overall concrete mix adopted for investigation, i.e. 1:2:4, was selected because of its wide use within industry, and all concrete was made with a water:cement content of 0.6 without the addition of plasticiser or ASR-retarding agents. The suite of laboratory tests included; slump, flow, initial and final setting time, ultrasonic pulse velocity, water absorption by immersion and capillarity rise, ASR measurement (volumetric and linear), compression strength at ages from 7 days to 365 days. Techniques of developed digital imaging and processing have been applied to the glass aggregate to quantify various particle shape factors, i.e. aspect ratio, percentage concavity, Riley inscribed sphericity and surface texture index. Statistical analysis has been used to compare the distribution of particle forms present within the fine aggregate materials used in the experimental work. Dimensional changes (in three orthogonal directions) were measured as concrete cubes hardened over a period up to 365 days. The length changes of concrete prisms were also measured over the same period of time. The resultant data indicated that a fine aggregate which comprised 25% glass and 75% sand would be categorised as “non-expansive”, i.e. the same as the sand on its own. As the proportion of glass in the fine aggregate became greater than the aggregate became more expansive but it did not exceed recommended limits.