João Castro-Gomes

Different combinations of mining waste mud, grounded waste glass, Portland cement, metakaolin and expanded cork were mixed together with alkaline activators (sodium silicate and sodium hydroxide solution) and as well aluminum powder or hydrogen peroxide to produce foamed lightweight materials. The size of the mineral materials is under 500 µm and expanded cork particles size is between 2 to 4 mm. The expanded cork added to the mixes changed between 10 to 40% volume of total solids. The influence of expanded cork on compressive strength was investigated. Precursors and activators were mixed together to produce a homogeneous mixture, which was placed into a cubic mold (40 x 40 x 40 mm 3), and cured at a temperature of 60°C, for 24 hours. After curing process, samples without foaming agents achieved the maximum compressive strength of 14.7 and 19.5 MPa for 7 and 28 days respectively. The porosity was observed by the naked eye of large voids in range of 4 mm in size. Microstructure analyses were carried on by SEM. Samples made with aluminum powder showed higher volume increase about 358% compared with samples made with hydrogen peroxide that presented a 141% volume increase. This preliminary study shows the feasibility to produce new improved lightweight foamed alkali activated materials incorporating expanded cork with potential applications in artistic, architectural, and historical heritage restoration.

This work reports an experimental study regarding the energy saving potential of an innovative concept of thermal energy storage, which consists in embedding more than one type of Phase Change Material (PCM) into cement-based mortars to apply as renderings in façade walls of buildings. The mortar simultaneously incorporates three distinct phase change materials and is termed HPCMM (Hybrid PCM mortar). The total mass percentage of PCMs in HPCMM can reach as high as 20%, while maintaining satisfactory performance in terms of mechanical properties/behavior of the mortar. The experimental program comprises two laboratory scale prototypes, materialized by two hollow boxes of outer dimensions 46×46×46cm 3 , internally coated with HPCMM or REFM (reference mortar without PCM) and externally subjected to realistic daily temperature profiles. The prototypes were internally equipped with a heater that was programmed to keep the inside of the box within the acceptable range of comfort temperature, in correspondence to the simulation of a winter scenario (heating season). By monitoring the energy consumption of the heater, it was possible to infer that the prototype rendered with HPCMM led to a reduction of energy consumption of nearly 20% as compared to the prototype rendered with REFM.

The asphalt industry has been under pressure to reduce its emissions. This can be achieved, from one hand, by decreasing the mixing and laying temperatures of asphalt mixtures. On the other hand, recycling of Reclaimed Asphalt Pavement (RAP) is a viable solution that allows reducing waste production and resources consumption. This paper presents a study that combines Warm Mix Asphalt with the use of RAP aggregates. These mixtures, while being produced at lower temperature than traditional Hot Mixtures contain 100% RAP. Several Warm Mix Recycled Asphalt (WMRA) were prepared with 100% RAP and different emulsion contents and their behaviour was assessed by means of laboratory tests such as water sensitivity, stiffness, fatigue resistance and rutting resistance. The obtained results show that these WMRA may be successfully used in road pavements in substitution of conventional Hot Mix Asphalts.

PCM vacuum impregnation is very successful for expanded clay lightweight aggregate. Polyester resin coating is able to retain all of the impregnated PCM from leakage. Resin coating is chemically stable and neutral, also improving thermal conductivity. Novel combination of geopolymer and thermal energy storing aggregates evaluated. ME-LWA has a high energy storage capacity of 157 J/g. a b s t r a c t Macro-encapsulated aggregates (ME-LWAs) consisting of expanded clay lightweight aggregates (LWAs) impregnated with a paraffin wax phase change material (PCM) was produced. To fully exploit the thermal energy retaining properties of PCM, it is fundamental to retain as much of the PCM as possible within the pores of the LWA. This paper investigates 3 different commercial materials to create a total of 14 different coating regimes to determine the most efficient coating method and material regarding its ability at retaining the PCM. The ME-LWAs are then further used as aggregates in geopolymer binders made from a combination of aluminosilicate rich mud and waste glass. Physical properties such as thermal conductivity and mechanical strength are determined for the geopolymer binder with and without the addition of the ME-LWA. A polyester resin was determined to be the most suitable choice of coating material for the ME-LWA, producing a practically leak-proof coating. The ME-LWA was also determined to be chemically neutral, showed a 42% higher thermal conductivity than the LWA in their raw state and maintained a latent heat of 57.93 J/g before and after being used in the geopolymer binder. Carbon fibres and graphite spray were used to improve the thermal conductivity of the resin coating, however no significant increase was detected. Finally, the compressive strength and thermal conductivity results achieved are acceptable for applications in buildings for enhancement of their energy efficiency.

This paper proposes a methodology for improvement of energy efficiency in buildings through the innovative simultaneous incorporation of three distinct phase change materials (here termed as hybrid PCM) in plastering mortars for façade walls. The thermal performance of a hybrid PCM mortar was experimentally evaluated by comparing the behaviour of a prototype test cell (including hybrid PCM plastering mortar) subjected to realistic daily temperature profiles, with the behaviour of a similar prototype test cell, in which no PCM was added. A numerical simulation model was employed (using ANSYS-FLUENT) to validate the capacity of simulating temperature evolution within the prototype containing hybrid PCM, as well as to understand the contribution of hybrid PCM to energy efficiency. Incorporation of hybrid PCM into plastering mortars was found to have the potential to significantly reduce heating/cooling temperature demands for maintaining the interior temperature within comfort levels when compared to normal mortars (without PCM), or even mortars comprising a single type of PCM.

This paper presents results of mechanical tests on the prototype of innovative structural strengthening in form of self-monitoring fabric. Smart textile employs carbon fibers conductivity for measuring strains while monitoring changes of electric resistance under increasing load. General solution was tested in series of calibrating tests on strengthening of small size concrete slabs. Promising results of simple specimen encouraged researching team to performed next tests with use of mastered carbon fibre reinforced fabric. Main tests were performed on natural scale RC beam. Smart textile proved its efficiency in both: strengthening and monitoring of strains during load increase. New strengthening proposal given 10% increase of loading capacity and the readings of strain changes were similar to those obtained in classical methods. In order of calibration of the prototype and define limits of the range of usability of this solution, textile sensor was tested in areas of large deformations (timber beam) and very small strains (bridge bearing block). In both cases prototype demonstrated excellent performance, in the range important for structural engineering. Paper presents also example of use of the smart strengthening in situ, in real life conditions.

Analytical results of ceramic materials of new production from waste of tungsten in Portugal Panasqueira mines are presented. We reaffirm the validity of such waste as raw material for ceramics, through the identification of neo minerals formed in high-temperature ceramics, such as: mullite and hematite. Analytical techniques in identification have been x-ray (XRD) diffraction, both raw ceramic pastes, as well as ceramic products studied at different temperatures (from 800 °C to 1250 °C), and morphological analysis by electron microscopy and chemical analysis by EDX. The results highlight the progressive trend of the ceramic to form new compound materials (mullite and hematite) when the working temperature is increased, as well as the greater presence of glassy phase. Both mullite and hematite, especially the first, are indicative of high quality ceramic in the obtained material. At the same time the vitreous matrix shows a volume of pores with diameters macro and mega, which favor the use of these new ceramic products in special industrial and technical applications. Resumo Se presentan los resultados analíticos de materiales cerámicos de nueva producción, a partir de residuos de minería de tungsteno de las minas de Panasqueira en Portugal. Se reafirma la validez de estos residuos como materia prima para cerámicas, mediante la identificación de minerales neoformados en el seno de cerámicas de alta temperatura, como son: mullite y hematite. Las técnicas análiticas en su identificación han sido difraccion de rayos x, tanto de las materias primas conformadoras de las pastas, como posteriormente de los productos cerámicos estudiados a diferentes temperaturas (desde 800 ºC, hasta 1250 ºC) y análisis morfológico mediante microscopia electrónica de barrido y análisis químico por EDX. Los resultados ponen de manifiesto la tendencia progresiva de las cerámicas para formar nuevos compuestos minerales del tipo mullita y hematita, a medida que se incrementa la temperatura de trabajo, así como la mayor presencia de fase vítrea. Tanto la mullita como la hematita, en especial la primera, son indicativas de alta calidad cerámica en lo materiales cerámicos obenidos. Paralelamente en la masa fundida se aprecia un volumen de huecos con diamétros macro y mega, los cuales posibilitan la utilización de esos nuevos productos cerámicos en aplicaciones industriales y técnicas especiales.

This research work aimed at the experimental investigation of mortars, comprising Phase Change Materials (PCM) embedded into lightweight aggregates, with the goal of highlighting behavioral differences in regard to the reference mortars that do not include PCMs. In fact, the presence of phase change materials in the cementitious mix, with freezing temperatures that are near the freezing point of water, are bound to contribute for the minimization of potential freeze-thaw effects upon application in pavements. Three mortars were prepared and tested under controlled environmental conditions: one conventional mortar; and two with PCM. All samples were monitored when subjected to freezing temperature profile, in order to understand the effect of the PCM incorporation. Experimental studies on the impregnation method and thermal performance of the composites led to conclude that the impregnation method is simple but very effective for embedding PCMs into porous materials such as mortar or concrete. This research work has further confirmed that the embedded PCMs provide the mortars with a large thermal energy storage capacity due to the quantities of PCM that can actually be incorporated. The results indicate that additionally PCM composites improve the thermal inertia as well as delayed freezing in the sub layer. This technique may help to extend the service life of pavement structures, by reducing freezing damage through the incorporation of phase change materials (PCMs). However, it should be stressed that the development of PCM composites for this purpose is still in its infancy, and there are many questions that will need to be answered in the future before such composites are ready for real-world applications. This research will help to serve as part of a foundation for such studies. Fotografia Autor 4 30 mm x 40 mm Kheradmand et al., Experimental assessment of lightweight aggregate composites impregnated with phase change materials for pavement structure applications 2 Keywords: phase change materials (PCMs), lightweight aggregates (LWAs), mortar, thermal energy storage. 1. INTRODUCTION Phase Change Materials (PCMs) are substances with a high thermal storage capacity that can be used to assist thermal control, as a consequence of their ability to store and release thermal energy during phase change processes (melting and freezing) [1]. During the process of solidification, PCMs release energy in the form of latent heat, and conversely, when PCMs melt, they absorb thermal energy from the surroundings. The magnitude of energy stored in a given PCM subject to a certain environmental condition strongly depends on its transition temperatures. PCMs with a phase change temperature within the range of human thermal (~20ºC) have been investigated in plastering mortars for buildings through numerical and experimental studies in order to reduce energy consumption by maintaining comfortable temperatures, [1-3]. In cold regions, roadway surfaces may collect snow and ice during the winter time, creating hazardous driving conditions for vehicles. To address this problem, chemical de-icing materials are used to counteract ice build up [4]. However, these de-icing materials have environmental impacts in the sense that they reduce service life of construction materials such as: steel, concrete and asphalt [5]. The effectiveness of a PCM at delaying or preventing freezing is complex and depends on the value of latent heat and the phase change temperature of the PCM, thermo-physical properties of the mortar with PCM, weather conditions and the way of incorporation methods [6]. Mortars with PCM have been previously used within buildings to moderate temperature at comfort level (nearly 22ºC). However, using such a mortar with PCM for extended roadway de-icing/delaying application is not recommendable. For such purpose, the melting temperatures of PCM should be lower melting as to approach the melting temperature of water as well. The application of PCMs in mortars for roadway pavements is thus bound to delay or even avoid the passage to negative temperatures, thus keeping the pavement warmer and partially avoiding thermal fatigue effects associated to freezing/thawing, as well as deleterious effect of de-icing agents. This paper focuses on the production of a mortar into which PCM is embedded through soaking of lightweight aggregates (LWA), which are in turn sealed. The conducted research encompasses mechanical assessment of the mortar and study of its thermal behaviour. The study further includes experimental simulation of heat transfer throughout the tested specimens as to better understand the behaviour of the system. It is also worth to remark that more than one dosage of PCM embedded into the mortar was studied.

In this study, Portland/calcium aluminate blended cement (PC/CAC) was combined with citric acid or lactic acid as additives to investigate the effects of the aforementioned carboxylic acids on the hydration reactions of PC/CAC as a potential fast hardening and low cost repair material for concrete. Mortar specimens with the carboxylic acid additives of either 0.5%, 1% or 3% by weight, prepared with a binder:sand:water ratio (by weight) of 1:3:0.5, were subjected to flexural and compressive strength tests at early ages up to 28 days. In order to understand the phase composition of the hydrates in the PC/CAC systems, XRD analyses were conducted on ground PC/CAC mortars with and without carboxylic acid at 7, 14 and 28 days. In combination with this, SEM images of selected mortar specimens were also taken at the same times for visual analyses of hydrates. Citric acid did not have any beneficial effect on enhancing the calcium silicate phase as initially assumed and instead reduced the strength of PC/CAC cement at all levels of concentration. The experiment analyses revealed that Portlandite crystals were the major hydrate phase in PC/CAC with lactic and citric acids. Lactic acid below 2% wt. improved both compressive and flexural strength gained at early ages due to improved crystallinity of the calcium hydroxide crystals. Combined with its inherent rapid setting time, PC/CAC blended cements have a potential to be developed into a suitable repair material for concrete.

This paper presents a study of the electrical and mechanical behavior of several continuous carbon fibers epoxy composites for both strengthening and monitoring of structures. In these composites, the arrangement of fibers was deliberately diversified to test and understand the ability of the composites for self-sensing low strains. Composites with different arrangements of fibers and textile weaves, mainly unidirectional continuous carbon reinforced composites, were tested at the dynamometer. A two-probe method was considered to measure the relative electrical resistance of these composites during loading. The measured relative electrical resistance includes volume and contact electrical resistances. For all tested specimens, it increases with an increase in tensile strain, at low strain values. This is explained by the improved alignment of fibers and resulting reduction of the number of possible contacts between fibers during loading, increasing as a consequence the contact electrical resistance of the composite. Laboratory tests on strengthening of structural elements were also performed, making hand-made composites by the "wet process", which is commonly used in civil engineering for the strengthening of all types of structures in-situ. Results show that the woven epoxy composite, used for strengthening of concrete elements is also able to sense low deformations, below 1%. Moreover, results clearly show that this textile sensor also improves the mechanical work of the strengthened structural elements, increasing their bearing capacity. Finally, the set of obtained results supports the concept of a textile fabric capable of both structural upgrade and self-monitoring of structures, especially large structures of difficult access and needing constant, sometimes very expensive, health monitoring.

ABSTRACT Geopolymerization is a chemical process in which aluminosilicate materials are precursors to obtain binders that have a low environmental impact. Fly ash has been used as a precursor for the development of these binders. However, thermal curing is needed to accelerate the polycondensation of aluminosilicate, which limits the application of this new binder in the construction industry. Thus, the objective of this study was to evaluate the feasibility to obtain such binders with good mechanical properties when cured at room temperature. The precursor material consisted of different mixtures of fly ash and metakaolin that were activated using combined sodium hydroxide and sodium silicate alkaline solutions. The effect on the compressive strength of different proportions of the alkaline solutions was studied. Compressive strengths of about 40 MPa were achieved at 91 days for the samples containing 70% fly ash and 30% metakaolin, activated using an alkaline solution of 50% sodium hydroxide and 50% sodium silicate. X-ray diffraction analysis showed the formation of natrite in geopolymeric samples, as well as the presence of crystalline compounds, such as quartz, mullite and hematite, in fly ash and metakaoline. Scanning electron microscopy analysis showed that in geopolymeric mixtures with higher compressive strength dissolution of fly ash and metakaolin particles occurred almost completely and that aluminosilicate dense gel has been formed extensively.

ABSTRACT Alkali-activated matrices can attain compressive strengths of the order of 30 MPa to 120 MPa, primarily depending on the mix formulation. The objective of this study is to evaluate compressive strength development by testing, at different ages, fly-ash-based mortars alkali-activated with activating solutions containing varying proportions of a combination of NaOH and Ca(OH)2. The NaO/SiO2 ratio was constant for all samples (N/S = 0.3). Three different CaO/SiO2 molar ratios of the total quantity of CaO to the total quantity of SiO2 present in the mix were studied; specifically: 0.05 (C/N = 0.033) – M5; 0.15 (C/N = 0.370) – M15; and 0.25 (C/N = 0.700) – M25. The M25 mix attained compressive strength of 30 MPa at 7 days. However, after periods of 28 and 91 days, M25 compressive strength had decreased to 22 MPa and 16 MPa respectively. The M15 matrices exhibited similar compressive strength results. In contrast, the M5 mix exhibited increasing compressive strength over time. The SEM micrographs of M5 and M25 matrices showed the presence of two different aluminosilicate gels: the M5 sample developed a massive aluminosilicate gel over time, while the M25 sample began to exhibit a spongy gel at 28 days, resulting in a weaker material. Therefore, the reduction in compressive strength appears to be related to increasing amounts of CaO (higher C/S and C/N) for the alkali-activated matrices tested in this study.

The use of passive cooling techniques has been seen as one of the solutions that can help to reduce energy consumption in the building sector. An innovative element that allows the combined use of two passive cooling techniques, evaporative cooling and night ventilation, is proposed in the present work. In order to optimize the use of those techniques it was decided to include in the element configuration a core component with latent heat storage capabilities. Briefly it can be said that the element is composed by the accumulating core, consisting of a cement mortar vertical panel impregnated with paraffin, with two adjacent channels for air circulation. The element, whose configuration should allow its integration into the buildings envelope, has a parallelepiped shape with one air inlet and one air outlet in each of its opposite faces, the exterior and the interior ones. The core surface adjacent to the exterior channel is maintained continuously wetted by a water sprinkler system integrated in the element. The airflow in each channel is provided by tangential fans mounted on top of the element. The paraffin wax used corresponds to a commercial wax with phase transition range near 21  C, slightly below typical comfort temperatures. A prototype of the element was constructed and subjected to a series of experimental studies that aim to know its response in operating conditions similar to real ones. These studies took place in a climate chamber for a wide range of conditions. The results suggest that the proposed element exhibits the potential for passive cooling of buildings. It was concluded that the paraffin wax incorporation in the cement mortar core has substantially improved the capacity of thermal energy accumulation of the element, that the evaporation process on the outside surface of the core provides a substantial temperature reducing of the core, and that its use also during night-time periods allows to cool the core well below the outside temperatures, thus maximizing the possibility of application of night ventilation.

O artigo apresenta um estudo experimental no qual se exploram variáveis relacionadas a uma fibra acrílica desenvolvida para reforçar argamassas de construção. O objetivo foi identificar as variáveis mais influentes das fibras acrilicas através de modelos de representação do desempenho das argamassas. A partir das variáveis: comprimento
diâmetro e volume de fibras, misturas de argamassas reforçadas com fibras acrílicas definidas por um plano fatorial 23 foram ensaiadas no estado fresco e no estado
endurecido. Ensaios de consistência, de massa volúmica, de resistências mecânicas, módulo de elasticidade, de retração livre e de absorção de água por capilaridade compuseram o plano de ensaios. O volume e o comprimento das fibras tem influências significativas tanto na resistência à flexão como na resistência à compressão. O volume de fibras também diminui ligeiramente a massa volúmica da argamassa endurecida favorecendo a redução do módulo de elasticidade. O diâmetro das fibras contribuem para o aumento da retração e a diminuição do coeficiente de capilaridade.

The objective of this experimental study was to examine the possibility of reusing ceramic materials waste from container glass, bricks and tiles of red-clay ceramic industry in Portugal as partial cement replacement in mortar and concrete. The  different types of waste were finely ground to specific sizes
(0–45 lm, 45–75 lm and 75–150 lm) and its pozzolanic activity was determined. The reduction of glass and ceramic waste particle size was accomplished in the laboratory by crushing and grinding using a ball jar mill. After gridding, the fine waste materials were characterized by the determination of density,
Blaine fineness and particle morphology using scanning electrical microscope. The compressive strength activity index, at 7, 28 and 90 days, was determined in mortars produced with each finely grounded waste ceramics and different percentages of partial cement replacement. Standard ASTM accelerated
mortar bar tests and a modified test carried on in 40 ! 40 ! 160 mm size mortar specimens were performed to investigate the potential expansion caused by the alkali–silica reaction of finely grounded waste glass as partially cement replacement.
The results obtained confirm the pozzolanic activity of the grounded waste, collected in the central region of Portugal, making feasible their incorporation as cement mortars and concrete components.

The ventilated double window, as a passive heating system, acts as a heat reclaiming device. Part of the heat loss from inside through the window is returned back to the room by the air flow, acting as a heat recoverer. Incident solar radiation upon the window warms its components being part of that heat removed by the air flow delivering it into the room, acting as a solar collector. The effect of these two functions were analysed in this study, through numerical simulation based on outdoor tests under real weather conditions. It was found that solar collector function plays a small role in the pre-heating of the air. First of all this is due to the system’s transparency, which allows most of the solar radiation to enter directly to the indoor space. Secondly, in a 24 hour period there are only some hours of sunshine. Instead, heat recovery works all the time, the conclusion being that this passive heating device can be used on any facade orientation.

The permeability and ability for capillary absorption of concrete are usually served as criteria for assessing the long-term performance (durability) of concrete. In order to know the long-term performance (durability) of concrete, the permeability or capillary absorption test is usually required. However, a long term preconditioning procedure prescribed in RILEM TC 116-PCD is unavoidable if one wants to carry out the permeability or capillary absorption tests. An attempt is made in this paper to address the possibility of simplifying the RILEM preconditioning procedure. The RILEM preconditioning method and a simplified preconditioning procedure were carried out on several sets of specimens which were cut from the same concrete slab. Thereafter, capillary absorption and gas permeability tests were carried out on these same specimens. Results of these two tests were compared between RILEM procedure and the simplified procedure and the results indicate that the two procedures provided similar results and as thus comparable to one another.

About 30% of European citizens are concentrated in 500 largest cities of the continent. Most of these cities are now subjected, or will be in the near future, to significant modification of their urban texture, brought about by the exploitation of new areas and by redevelopment of old industrial sites or the construction of big and pervasive infrastructure.
Urban areas modernization, underground exploration of minerals and natural calamities (floods, earthquakes, etc.) bring the change of the work conditions of urban infrastructure – in many cases historical buildings. The consequence of this change is the necessity of strengthening them. It has been observed, that traditional methods of strengthening buildings subjected to complex load layout do not always act in most effective way, oppositely, sometimes they have caused hazardous situations.
Recently, researchers and industry seek for other, more universal ways of buildings’ protection. In 2009 scientists from Silesian University of Technology (Gliwice, Poland), Universidade da Beira Interior (Covilha, Portugal) and specialists from enterprises: FIDIA (Perugia, Italy), Europrojekt (Wrocław, Poland) and FISIPE (Lavradio, Portugal) joint their efforts to prepare and propose new approach. Their ideas met approval of European Commission, which granted 4 years lasting project INSYSM. Material presented in this book was collected during realization of this project and is one of the main results.
The Handbook was created in the form of the toolbox of the procedures for retrofitting, strengthening, real time monitoring and maintenance of structures, specifically those impacted by complex situation of loads (i.e. seismic, paraseismic, mining deformations of subsoil, floods, transport, etc.). The toolbox focused on innovative techniques of structural upgrade with fibre-reinforced materials. It adapted the form of a handbook including description of reasons of structural damages, material properties, design methodology together with structural design procedures and examples, technological procedures for strengthening applications with examples, requirements and practical tips as well as methods of control.

A PRESENTE INVENÇÃO CONSISTE NUM CONJUNTO ACOPLÁVEL DE PEÇAS MODULARES DE REVESTIMENTO DESCONTÍNUO E GEOMETRIA IRREGULAR, PARA EXECUÇÃO DE SUPERFÍCIES
AJARDINADAS CONTÍNUAS HORIZONTAIS, VERTICAIS, CURVAS OU INCLINADAS. ESTAS PEÇAS MODULARES DESTINAM-SE AO REVESTIMENTO DE SUPERFÍCIES EXTERIORES OU INTERIORES, DE ESTRUTURAS EDIFICADAS OU À EXECUÇÃO DE SUPERFÍCIES AJARDINADAS INDEPENDENTES DE QUALQUER ESTRUTURA EDIFICADA. CADA PEÇA MODULAR É COMPOSTA POR UMA PLACA BASE (1) FIXA A UMA PLACA SUPERIOR (2), COM ABERTURAS (3) DE FORMA CILÍNDRICA E COM FURAÇÕES
LATERAIS DE DRENAGEM (4) O CONJUNTO ACOPLÁVEL DE PEÇAS MODULARES INTEGRA UMA ESTRUTURA DE APOIO (5), COM PEÇAS DE FECHO (6) E TAMPAS DE FIXAÇÃO (7) ESTES ELEMENTOS SITUAM-SE NOS ESPAÇOS INTERSTICIAIS ENTRE PEÇAS MODULARES, PERMITINDO QUE AS PEÇAS MODULARES SEJAM INSTALADAS E SUBSTITUÍDAS DE FORMA INDIVIDUAL E MANUALMENTE.

Parâmetros que dependem das condições de mistura e de cura, em especial da razão água/cimento, da temperatura de cura e do grau de hidratação do cimento. No entanto, a micro estrutura do cimento hidratado é muito complexa. Modifica-se com o tempo e depende de multiplos parâmetros, sendo por isso de difícil caracterização objectiva.