Resumen: Se investigó la factibilidad de utilizar el ensayo de flexión de vigas Semicirculares (SCB, del inglés Semi Circular Bending Test) para monitorear y controlar la calidad del hormigón para su aplicación en pavimentos. Se fabricaron dos mezclas de hormigón con resistencias a la compresión especificadas de 30 MPa y 40 MPa incorporando cemento de alta resistencia. Los resultados del ensayo SCB se correlacionaron con la resistencia a la flexión de vigas estandarizadas y la resistencia a la compresión de cilindros. Se realizó un análisis estadístico de bondad de ajuste de todos los modelos empíricos obtenidos para estudiar el grado de asociación entre las variables. El modelo de correlación potencial resultó ser el más apropiado para relacionar las propiedades mecánicas estudiadas, con coeficientes de correlación de Pearson superiores a 0,93. Estas ecuaciones pueden ser utilizadas para alimentar la base de datos de los niveles 1 y 2 del método de diseño Mecanicista-Empirico (ME) para pavimentos de concreto. También se hallaron modelos con valores únicos que permiten cálculos rápidos con buena precisión. Los resultados muestran que el ensayo SCB es una opción promisoria a la hora de estimar la resistencia a flexión del hormigón para uso en pavimento, así como para realizar su control y aseguramiento de calidad.

Abstract: The feasibility of using the Semicircular Bending (SCB) test to control the quality of concrete for application in pavements was investigated. Two concrete mixtures incorporating high-strength cement with specified compressive strengths of 30 MPa and 40 MPa were manufactured. The results of the SCB test were correlated with those of the flexural strength of standardized beams and the compressive strength of cylinders. A statistical analysis of the goodness of fit of all the empirical models obtained was conducted to study the degree of association between the variables. Power models were the most appropriate to relate the mechanical properties studied, with Pearson's correlation coefficients higher than 0.93. These equations can feed the database of levels 1 and 2 of the Mechanistic-Empirical (ME) design method for concrete pavements. Models with unique values that allow quick calculations with good precision were also found. The results show that the SCB test is a promising option when estimating the flexural strength of concrete for use in pavement, as well as carrying out its control and quality assurance.

Abstract: Rigid pavements are subject to vehicular load transmissions that produce fissures and cracks due to poor design. This affects vehicular traffic and the environment. The objective of the study is to know the influence of carob stem ash (CTA) for the design concrete f'c 210 Kg/cm2. In which, a series of dosages of 0 % (standard concrete), 5 %, 8 % and 12 % of CTA was incorporated. The study presents a quantitative technique and quasi-experimental design. A total of 60 concrete samples was made, divided into 36 cylindrical specimens of 15 x 30 cm for compression, 12 joists of 15 x 15 x 50 cm for bending and 12 concrete discs of 5 x 10 cm for abrasion. The results, after 28 days, were as follows: (0 %) 243 Kg/cm2, 5 % 247 Kg/cm2, 8 % 224 Kg/cm2 and 12 % 216 Kg/cm2; for compressive strengths. Standard concrete (0 %) of 26 Kg/cm2, 5 % of 29 Kg/cm2, 8 % of 30 Kg/cm2 and 12 % of 31 Kg/cm2; for flexural strengths, and pattern concrete (0 %) with a wear of 0.63 %, 5 % with a wear of 0.66 %, 8 % with a wear of 0.74 % and 12 % with a wear of 0.77 % for abrasion resistance. It is concluded that the optimal and ideal percentage is the partial addition of CTA at 5 %, where it improves the mechanical characteristics of concrete in the design of rigid pavement.

Resumen: Los pavimentos rígidos están sujetos a transmisiones de cargas vehiculares que producen fisuras y grietas, debido a un mal diseño. Esto afecta al tránsito vehicular y al medio ambiente. El objetivo del estudio es conocer la influencia de la ceniza del tallo de algarrobo (CTA) para el concreto de diseño f’c 210 Kg/cm2. En el cual, se incorporó una serie de dosificaciones del 0 % (concreto patrón), 5 %, 8 % y 12 % de CTA. El estudio presenta una técnica cuantitativa y diseño cuasiexperimental. Se realizó un total de 60 muestras de concreto: divididas en 36 probetas cilíndricas de 15 x 30 cm para compresión, 12 viguetas de 15 x 15 x 50 cm para flexión y 12 discos de concreto de 5 x 10 cm para abrasión. Los resultados, a los 28 días, fueron los siguientes: al (0 %) de 243 Kg/cm2, 5 % de 247 Kg/cm2, 8 % de 224 Kg/cm2 y 12 % de 216 Kg/cm2; para las resistencias a compresión. Concreto patrón (0 %) de 26 Kg/cm2, 5 % de 29 Kg/cm2, 8 % de 30 Kg/cm2 y 12 % de 31 Kg/cm2 para las resistencias a flexión. Concreto patrón (0 %) con un desgaste de 0.63 %, 5 % con un desgaste de 0.66 %, 8 % con un desgaste de 0.74 % y 12 % con un desgaste de 0.77 % para las resistencias a abrasión. Se concluye que el porcentaje óptimo e ideal es la adición parcial de CTA al 5 %; donde mejoran las características mecánicas del concreto en el diseño de pavimento rígido.

Abstract: The pavement sub-base requires suitable materials for the necessary support. Traditionally, borrow material has been used, this generates environmental impact. This study analyzed the potential for reusing industrial waste ashes deposited in landfills. Laboratory tests were conducted by mixing the soil with different proportions of ashes. The relationship between soil moisture and dry weight was determined, and the C.B.R. (California Bearing Ratio) test was performed. The pavement thickness was calculated, keeping the same sub-base thickness. As the percentage of ashes increased, the soil quality decreased, but it still met the requirements for use as a sub-base. It is recommended to consider industrial waste ashes as a viable recycling material in pavement construction, which would reduce the environmental impact associated with their disposal in landfills.

Resumen: La sub-base del pavimento requiere materiales adecuados para el soporte necesario. Tradicionalmente, se ha utilizado material de préstamo, lo que genera un impacto ambiental. Este estudio analizó el potencial de reutilizar cenizas de desecho industrial depositadas en vertederos. Se realizaron ensayos de laboratorio mezclando el suelo con diferentes proporciones de cenizas. Se determinó la relación entre humedad y peso seco del suelo, se realizó el ensayo C.B.R. (California Bearing Ratio) y se calculó el espesor de pavimentos, con un mismo espesor de sub-base. A medida que aumenta el porcentaje de cenizas, la calidad del suelo disminuye, pero sigue cumpliendo los requisitos para ser utilizado como sub-base. Se recomienda considerar las cenizas de desecho industrial como un material de reciclaje viable en la construcción de pavimentos, lo que reduciría el impacto ambiental asociado a su disposición en vertederos.

This research explored the denitrification potential of a submerged zone incorporated into the present permeable interlocking concrete pavement (PICP) design. The following three main factors controlling denitrification were investigated through a laboratory study: (i) detention time, (ii) inclusion of a carbon source (newspaper), and (iii) submerged zone depth. The study used 10 columns, each fully packed with 50-63 mm washed aggregate and including a 1.5 m deep submerged zone. Columns were paired according to detention time (1, 2, 5, 10 and 'varied' days) with one set including newspaper, the other set not. All columns were loaded with synthetic stormwater over a 4-month period. Samples were taken from different submerged depths (0, 300, 600, 900, 1200 and 1 500 mm) and analysed for concentrations of ammonia (NH3), nitrate (NO3-) and phosphate (PO4(3-)) every 10 days. This study found that 10 - or more - days detention and the provision of a carbon source had the most significant impact on denitrification - providing an overall mean NO3- and nitrogen removal above 41% and 59%, respectively. Moreover, a submerged depth of 300 mm was sufficient to achieve a minimum NO3- removal of 41% in columns which included a carbon source and had 10 days detention. Generally, an increase in detention time resulted in an increase in NH3 and PO4(3-) removal with overall mean values of 86% and 30%, respectively, achieved with 10-day detention periods.

The increased frequency of extreme weather events associated with climate change is a growing concern for road authorities, consultants, contractors and end users. Climate change adaptation is not yet incorporated into South Africa's transport design and planning. Current design methods for asphalt pavements include recently introduced performance-graded (PG) specifications for bitumen. Although the need exists to use future-projected temperature maps in the road industry, the hindrance to this adoption has been extracting the appropriate rising air temperatures from climate model projections. This study focuses on the integration of bias-adjusted historical and projected climate model temperature outputs between 1980 and 2060 to estimate changes in pavement temperatures throughout South Africa to inform a strategy for adaptive material selection. Differences in bitumen selection are observed for the PG 58 and PG 52 maximum temperature grade, and an introduction of PG 70 regions, as derived from climate model data in comparison with the SATS 3208 technical standard. The general trend is a gradual increase in maximum pavement design temperatures, mostly affecting the country's northern and central regions and corresponding road networks. This paper concludes that adjustments are required regarding climate projections for use in bituminous binder selection based on the current specification.

Abstract: The aging of asphalt binders has a great impact on the behavior of pavement. The specifications for performance grade include tests on short-term (RTFOT) and long-term (PAV) aged residues. However, aging is greater at the top of wearing course than deeper zones, long-term tests do not correlate accurately with field aging and in the latter, the incidence of local temperature is not considered accurately. The objective is to relate the aging of Ecuadorian asphalt at the laboratory level, applying different conditioning times in the PAV, with the field aging from asphalts recovered from the top of pavements surface in selected roads of the Andean and Coastal regions, with different construction times and cumulated degree-days (CDD), using certain rheological parameters. As a result, in the Ecuadorian asphalt, the RTFOT residue is equivalent to field aging of 1.1 years in the Coastal region and 1.7 years in the Andean region. On the other hand, the usual PAV of 20 hours corresponds to field aging of 5.8 years for the Coastal region and 9.3 years for the Andean region. The progressive evolution of damage to our roads, without considering traffic, corresponds to conditioning times in the PAV between 13.0 and 26.6 hours.

Resumen: El envejecimiento del asfalto impacta el comportamiento de los pavimentos. Las especificaciones por grado de desempeño incluyen ensayos a residuos envejecidos a corto plazo (RTFOT) y a largo plazo (PAV). Sin embargo, el envejecimiento es mayor en la parte superficial de la capa de rodadura, las pruebas a largo plazo no se correlacionan con precisión con el envejecimiento en el campo y la incidencia de la temperatura local tampoco se considera adecuadamente. El objetivo es relacionar el envejecimiento del asfalto ecuatoriano a largo plazo a nivel de laboratorio, aplicando en el PAV diferentes tiempos de prueba, con el envejecimiento en obra a partir de asfaltos recuperados de capas asfálticas en las regiones andina y costera del Ecuador, con diferentes tiempos de colocación y grados-día acumulados, empleando ciertos parámetros reológicos. Como resultados, el residuo del RTFOT equivale a un envejecimiento en obra de 1.1 años en la región costera y de 1.7 años en la andina. Por otra parte, al PAV de 20 horas le corresponden tiempos de envejecimiento de 5.8 años en la costera y 9.3 años en la andina. La evolución de los deterioros en nuestras vías, corresponden a tiempos en el PAV entre 13,0 y 26,6 horas respectivamente.

Abstract: The aging of asphalt mixes affects the durability of the pavement. The characteristics of the mixture interact in a complex way with the temperature and service time on site, so the use of the cumulated degree-days (CDD) criterion is possible. The work’s objective is to analyze the aging of the mixtures in the Coastal and Andean regions, through the application of the CDD related to the stiffness modulus at 20 °C in the NAT equipment, obtained from cores sampling in roads built in different years and to make observations regarding existing damages associated with durability. Seven sections were selected from similar mixtures placed between 0 and 14 years ago, made with crushed alluvial materials and AC-20 asphalt from the Esmeraldas refinery. The results show that the aging evaluated through the stiffness modulus presented a greater impact in the Coastal region than in the Andean region due to its higher temperatures, allowing the use of the CDD to unify the behaviors in the two regions into a single relationship. Observations show that the probable range of the progressive evolution of damages, from its beginning to its critical phase, is from 45.000 to 80.000 °C-days.

Resumen: El envejecimiento de las mezclas asfálticas afecta la durabilidad del pavimento. Las características de la mezcla interactúan de manera compleja con la temperatura y el tiempo de servicio en sitio, esta condición posibilita el uso del criterio de grados-día acumulados (CDD). El objetivo de este trabajo es analizar el envejecimiento de las mezclas en las regiones Costa y Andina, mediante la aplicación del CDD para el módulo de rigidez a 20 °C en los equipos NAT, obtenido a partir de testigos muestreados en caminos construidos en diferentes años, con el objeto de realizar observaciones respecto de los daños existentes asociados a la durabilidad. Se seleccionaron siete tramos de mezclas similares colocadas entre 0 y 14 años, elaboradas con materiales aluviales triturados y asfalto AC-20 de la refinería de Esmeraldas. Los resultados revelaron que el envejecimiento, evaluado a través del módulo de rigidez, presentó un mayor impacto en la región Costa que en la región Andina debido a sus mayores temperaturas, por lo que el uso del CDD posibilitó unificar el comportamiento de las dos regiones en una sola relación. Las observaciones muestran que el rango probable de evolución progresiva de los daños, desde su inicio hasta su fase crítica, es de 45.000 a 80.000 °C-día.

Overloading of heavy vehicles reduces pavement life and increases pavement life cycle costs. As part of Namibia's strategy to control heavy vehicle overloading on the road network, weighbridge facilities have been constructed at strategic locations on primary routes (trunk roads). The study analysed the extent of heavy vehicle overloading on Namibian trunk roads, as well as the effectiveness of existing overloading mitigation measures. The dataset comprised heavy vehicle loading information from the year 2015 to 2019, from ten static weighbridge facilities. The parameters investigated include overloading magnitude, the effect of overloading on road pavement life, and the effectiveness of current overload mitigation measures. The results showed that 13.3% of the vehicles weighed were overloaded, with a compounded decrease in overloading of approximately 0.5% per annum. Despite the overloading decrease, the study found that the estimated road service life was reduced by as much as nine years over the study period. High levels of weighbridge avoidance and poor stakeholder coordination in mitigating overloading were identified. The study recommends deploying high-speed weigh-in-motion systems, an increase in fines charged for overloading offenses, and developing a demerit point-based system for habitual offenders to strengthen mitigation measures.

ABSTRACT With a growing population, the construction sector is continually expanding due to societal demands. Hence, this research focused on implementing Lean Construction methodology in an urban pavement project. This non-experimental methodology relies on field data collection for measurements during specific timelines, leading to quantifiable results for analysis. Prior to implementing this methodology, the project experienced delays. However, with the application of Lean Construction methodology and its tools, objectives were successfully achieved. Planning was carried out using Look Ahead, organizing workflow, and achieving a plan fulfillment percentage exceeding 70% of the projected values. Consequently, favorable schedule indices were evident, surpassing budget projections in executed budgets. The application of Lean Construction methodology successfully completed the entire project within the set timeframe. Furthermore, productivity and crew performance improvements were observed in a specific task.

RESUMEN Con una población creciente, el rubro de la construcción día a día se va incrementado por las exigencias de la sociedad, por ello es por lo que la presente investigación se focalizó en la aplicación de la metodología Lean Construction en una obra de pavimentación urbana. Dicha metodología es no experimental y se basa en la recolección de datos en campo que permiten realizar mediciones durante la ejecución de las actividades en una línea de tiempo determinada y conlleva a cuantificar resultados para ser analizados. Antes de la aplicación de la metodología se presentaban atrasos en la ejecución de la obra, pero con la implementación y la aplicación de la metodología Lean Construction mediante sus herramientas, se lograron cumplir los objetivos trazados, con una planificación realizada mediante Look Ahead. Esto permitió ordenar los flujos de trabajo y obtener resultados como el del porcentaje del plan cumplido, el cual fue mayor al 70% de lo proyectado. Por consiguiente, se evidencia en los índices del cronograma que se lograron valores favorables para el avance de obra, cuyos presupuestos ejecutados superaron a los presupuestos proyectados. Por lo tanto, la aplicación de la metodología Lean Construction logró cumplir con la totalidad del proyecto en un plazo fijado. Además, se evidenciaron mejoras en la productividad y los rendimientos de las cuadrillas en una partida específica.

Resumo O trecho oeste do Rodoanel Governador Mário Covas foi aberto ao tráfego no ano de 2000. O pavimento era originalmente composto por placas de concreto com barras de transferência, com módulo de ruptura de projeto 4.5 MPa. Falhas prematuras foram observadas não somente por engenheiros e usuários, mas foram também relatadas pela imprensa. Placas de concreto começaram a ser demolidas e substituídas. Muitas das placas removidas foram levadas a uma planta de reciclagem local para britagem. Entretanto, os agregados produzidos não foram utilizados na produção das novas placas de concreto. O primeiro objetivo foi verificar a presença de fluorita como substância prejudicial no concreto existente, pois era uma suspeita entre os tecnologistas de concreto envolvidos no projeto de mistura durante a construção. As análises químicas por espectrometria de fluorescência de raios X não evidenciam a presença de componentes químicos prejudiciais à durabilidade do concreto. Portanto, o segundo objetivo foi aceitar o material para reciclagem e assim discutir proporções da mistura, resistência, rigidez, tenacidade à fratura e fadiga. Este documento apresenta um estudo de viabilidade da utilização de agregados reciclados na produção de novas placas de concreto, contudo mais espessas. O estudo inclui discussões sobre as proporções de mistura, resistência mecânica, fratura, fadiga, e composição química. A análise química com espectrometria de fluorescência de raios-X não detectou a presença de compostos químicos prejudiciais a durabilidade do concreto. O desempenho à fadiga de misturas recicladas impõe demandas por soluções de projeto mais espessas e custosas.

Abstract The west section of the Governor Mário Covas São Paulo Metropolitan Road Ring was opened to traffic in 2002. The original pavement was a jointed plain concrete pavement with dowelled joints and a design flexural strength (or modulus of rupture) of 4.5 MPa. Premature failure of the concrete slabs was observed not only by engineers and users, but also reported by the media. Concrete slabs soon started being demolished and replaced. Many of the removed slabs were taken to a nearby recycling plant for crushing. However, the resulting recycled concrete aggregate was not used in the manufacturing of the new slabs. There were concerns that the potential presence of detrimental chemical substances had caused the early deterioration of the slabs. If that were true, using recycled aggregates obtained from the original concrete could result in the same issues in the new mix. This paper describes a feasibility study on recycling the original concrete for use as aggregate in new concrete slabs. The first goal was to verify the presence of fluorite as detrimental substance in the existing concrete because there was a suspicion among concrete technologists engaged on mixture design during the construction. Chemical analysis using X-ray fluorescence spectrometry did not show the presence of chemical components detrimental to concrete durability. Therefore, the second goal was to accept the material for recycling and discuss mix proportions, strength, stiffness, fracture toughness, and fatigue. Although some of the concrete properties were affected by the inclusion of recycled aggregates in the mix, the results indicate that it is possible to use recycled aggregates produced from the original concrete to cast new concrete slabs, however requiring greater thicknesses. The fatigue performance of recycled mixtures points out the demand for thicker and eventually more expansive design solutions.

ABSTRACT The objective of this research was to assess the performance of pavement-quality concrete having 100% copper slag as fine aggregate in the presence of steel fibre. In this research, the crimped steel fibre of two lengths (30 mm and 50 mm) and different dosages such as 0.5%, 1.0%, 1.5%, and 2.0% by weight of concrete are included in the concrete having 100% copper slag as fine aggregate and compared with the concrete having river sand and copper slag as fine aggregate without fibre. The mechanical characteristics that are being examined include fatigue performance, bond strength, impact strength, flexural strength, stress-strain behaviour, abrasion resistance, and slabs exposed to both static and cyclic loading. According to the experimental findings, pavement concrete that contains 100% copper slag as fine aggregate and 1% crimped steel fibre in both 30 and 50 mm diameters performs better and is more optimal. An inventive way to manage copper slag waste and create durable, stiff pavement construction is with copper slag in concrete road construction. Utilising copper slag in concrete road construction offers a novel approach to waste management and the creation of environmentally friendly concrete road construction.

Abstract Laterite gravels have been successfully adopted as pavement materials in the field. Despite that, they are often rejected in material selection processes because of its base on traditional gradation and consistency limits requirements. To allow a deeper evaluation of such material found abundantly in tropical countries, along to characterizing traditional parameters, repeated load triaxial tests were performed in a Laterite Gravel from Acre/Brazil to evaluate its elastic and plastic behavior through Resilient Modulus (RM) and Permanent Deformation (PD), respectively. In addition, a simulation was conducted in the MeDiNa software, based on the test results considering stress states that are usually applied in pavement layers. The material showed RM values higher than 500 MPa, which was considered high compared to materials such as Quartz and Granite. It was also observed low permanent deformation (below 1 mm for higher tensions applied) and accommodation of displacement (shakedown) for most specimens. The simulation results showed low rutting prediction for the Laterite Gravel applied in highway pavement layers. Thus, the results indicated that the lateritic gravel can be adopted in the composition of base or subbase layers of flexible pavements, even though some limits of the parameters specified by traditional specifications were violated, as expected. In addition, we also highlight the need for adoption of new material selection strategies that are based on key mechanical characteristics to avoid discarding potentially well performing materials.

Resumo Em finais da década de 1960 engenheiros aeroportuários desenvolveram materiais de pavimentação especiais para reter trens de pouso de aeronaves em caso de avanço sobre a extensão final da área de segurança da pista. Tal material da superfície do pavimento, invertendo um conceito geral, deve ser esmagado na primeira passagem das rodas resultando no afundamento da aeronave que é prontamente retida, resultando em perda brusca de velocidade, de preferência evitando perdas de vidas e ferimentos, bem como riscos mínimos para a integridade estrutural do avião. Nesse estudo é analisada e discutida a possível aplicação do concreto permeável para tal tarefa, simulando uma situação real (aeroporto de Congonhas) e compreendendo os efeitos estruturais na camada superficial do concreto permeável, indicando tensões, deflexões e resistências requeridas para o material. As simulações consideraram a aeronave crítica A 320-200 bem como veículos de combate a incêndios sobre o pavimento. A análise atendeu aos requisitos da Federal Aviation Administration para estruturas de pavimento não padronizadas, bem como a simulação de tensões pelo método dos elementos finitos para placas medianamente espessas. Tensões de compressão juntamente com tensões excessivas de tração na flexão, além das tensões de cisalhantes (punção) previsíveis, permitiram concluir pela viabilidade do uso de concreto permeável de baixa resistência como alternativa para material de engenharia a ser construído como sistema de retenção de aeronaves.

Abstract From the late 1960’s airport engineers developed special paving material for arresting aircraft gears in event of overrun as a partial extension of a runway end safety area. Such pavement surface material, inverting a general concept, should be crushed over the first pass of gear wheels resulting the aircraft to sink and being promptly arrested resulting in abrupt loss of velocity, preferability avoiding loss of lives and injuries as well as with minimum risks for the airplane structural integrity. Herein is analyzed and discussed the possible application of pervious concrete for such a task by simulating an actual situation (Congonhas airport) and understanding the structural effects on the crushable concrete surface layer, pointing out stresses, deflections and required strengths for the material. Simulations regarded the critical aircraft A 320-200 as well as fire-fighters cars over the pavements. Analysis complied to Federal Aviation Administration requirements for non-standard pavement structures as well simulation of stresses trough the finite element method for medium-thickened plates. Compressive stresses along with flexural excessive stresses, besides predictable punching shear stresses allowed to conclude by the feasibility of using low strength pervious concrete as alternative for engineered material to be built as arresting system.

Resumo As principais causas do desempenho insatisfatório de bases de brita graduada tratada com cimento (BGTC) está relacionada à sua matriz cimentícia heterogênea, porosa e frágil que favorece o processo de degradação por fadiga. Assim, buscando melhorar as propriedades mecânicas e resposta estrutural da BGTC, o presente estudo avaliou diferentes faixas granulométricas (DER-SP, CBGM 2 EN 14227-1 e CCR-ACI) através de modelos clássicos de distribuição de partículas como Talbot & Richart e modelo analítico do empacotamento compressível (compressible packing model – CPM) para classificar e selecionar curvas granulométricas capazes de potencializar o empacotamento das partículas e melhorar a resistência mecânica da mistura. O efeito do teor de cimento (4 e 5%) foi avaliado, bem como o potencial de se utilizar sílica ativa em suspensão (em porcentagens de 5, 7 e 10% da massa de cimento) para modificar a zona de transição interfacial. Verificou-se que o CPM é uma poderosa ferramenta para a seleção e projeto de misturas bem graduadas; a curva média para a faixa CBGM 2 da norma Europeia EN 14227-1 apresentou a maior densidade de empacotamento. O efeito do aumento do teor de cimento de 4% para 5%, em termos de resistência mecânica, poderia ser compensado pela adição de 7% de sílica ativa à mistura com 4% de cimento. Por fim, misturas com 5% de cimento e 10% de sílica ativa apresentaram valores de módulo de elasticidade muito similares àqueles tradicionalmente obtidos para BGTC; contudo, a resistência à tração indireta da BGTCAD foi significativamente maior (em torno de 28%), levando à uma relação modular (Et,sp/fct,sp) menor, o que é promissor em termos durabilidade mecânica para esse tipo de concreto seco.

Abstract The main causes of poor performance of cement-treated crushed stones (CTCS) pavement layers are material-related heterogeneity, porosity, and brittle cementitious matrix, leading to fast fatigue degradation. Seeking to improve CTCS mechanical properties and structural response it was studied different grading curves such as DER-SP, EN 14227-1 CBGM 2 and RCC-ACI were studied. The aim of the laboratory study was to rank and select among the classical particle size distribution models like Talbot & Richart, and analytical models as compressible packing model – CPM, the best grading curve which was capable of producing mixtures with the best aggregate interlocking and improved mechanical resistances. The effect of cement content (4% and 5%) as well as the potential of using silica fume in suspension (percentages of 5, 7 and 10% of cement mass) to improve the interfacial transition zone were evaluated. It was found that CPM is a powerful tool for aggregates ranking aggregates and designing well-graded mixtures like CTCS; the CBGM 2 EN 14227-1 mean curve achieved the best packing density. The effect of increasing the cement content from 4 to 5% in terms of mechanical strength has the same result as the addition of 7% of silica fume in mixtures with 4% cement. Eventually, mixtures with 5% cement and 10% silica fume showed modulus of elasticity similar to traditional CTCS; nonetheless, the HP-CTCS (high performance CTCS) split tensile strength was significantly higher (about 28%), leading to a lower Et,sp/fct,sp relationship, which is a highly positive outcome to improve mechanical durability of this innovative dry compacted concrete.

Resumo Embora o desempenho em termos de colmatação de pavimentos de concreto porosos seja um tópico sensível na literatura técnica, a maioria dos estudos se refere a pesquisas laboratoriais em corpos de prova utilizando diferentes equipamentos para a simulação da perda de permeabilidade devido à inserção de detritos nos poros. Entretanto, medidas de taxa de infiltração são a base para a definição da necessidade de manutenção em pavimentos reais e devem ser realizados periodicamente para medir e endossar que a adequação da taxa de infiltração é o cerne do protocolo de gerenciamento da colmatação. Este estudo trata sobre um experimento em campo em uma calçada de concreto permeável circundada por um jardim arborizado com árvores nativas tropicais exóticas. Ao longo de quatro anos, onze medidas de monitoramento foram realizadas utilizando o teste do anel de infiltração recomendado pela norma ASTM C1701. A principal contribuição deste artigo é a proposição de um modelo linear misto considerando a distribuição exponencial condicionada para a taxa de infiltração e uma interceptação normal aleatória. Pela análise de resíduos e parcelas de diagnóstico, é possível observar que o modelo proposto apresenta uma boa adequação, permitindo prever a queda da taxa de infiltração devido à colmatação por matéria orgânica densa.

Abstract Clogging of porous concrete pavements is understood as a performance pathology within this peculiar concrete component. Albeit the clogging performance of porous concrete pavements is a sensitive topic in technical literature, most studies refer to laboratory investigations on concrete samples using different kinds of apparatus for the simulation of loss of permeability due to debris insertion on porous interstices. However, infiltration rate measurements are the basis for defining maintenance needs in actual pavements and shall be carried out periodically to measure and endorse infiltration rate adequacy as the kern of a clogging management protocol. This study dealt with a field experiment in a pervious concrete sidewalk surrounded by a wooded garden with tropical native and a variety of exotic trees. Over four years, eleven monitoring measurements were carried out using the ASTM C1701 infiltration ring test. The main contribution of this paper is a proposition of a mixed linear prediction model considering conditioned exponential distribution and a random normal intercept for the infiltration rate. From residual analysis and diagnosis plots, it can be seen that the proposed model presents a goodness of fit, allowing anticipation of infiltration rates reduction due to clogging by dense organic matter. Minimum infiltration rate is taken as 0.1 cm/s and such condition was achieved in a couple of months, awakening consciously to consider three to four intensive cleaning maintenance per year in dense wooded areas like public parks.