Effect of cement types on carbonation depth of concrete

Reinforced concrete as a building material is the most used in most civil engineering structures. This one is exposed to several attacks (physical, chemical and mechanical). Among these attacks, we can cite the phenomenon of carbonation, which leads to corrosion of the reinforcements and consequently reduces the service life of reinforced concrete structures. In addition, this phenomenon generates additional repair costs, which can sometimes exceed the initial cost of the building. Furthermore, it depends on the type and class of cement, two main classes of cement are used for the formulation of concrete in Algeria, ordinary Portland cements and cements with additions.  This paper enters in the option of sustainable development, in order to study the behavior of these two types of cements against accelerated carbonation. For this purpose, two concrete compositions (based on ordinary Portland cements and cements with additions) were formulated, from these two formulations, samples were made in order to subject them to accelerated carbonation in a chamber rich in CO2 according to the recommendations of the AFPC-AFREM. The results obtained clearly show that concretes based on ordinary Portland cements (OPC) are less sensitive to the phenomenon of carbonation compared to concretes based on blended cements. &nbsp

A Scalable and Participatory Sustainable Rangeland Management Toolkit with a Holistic and Multidisciplinary Approach to Rehabilitate Degraded Rangelands

Rangelands contribute significantly toward improving livelihoods, offering food security, trade and tourism for pastoral communities. Numerous challenges include poor government policies, loss of indigenous knowledge and top-down approaches toward sustainable rangeland rehabilitation that often fail to consider local development adoption and sustainability. In such situations, effective management is needed for sustainable rangeland ecosystem goods and services in a context characterized by rainfall unreliability, poor soil nutrient status and high uncontrolled grazing. This paper presents a new comprehensive toolkit for identifying and combining suitable and site-specific interventions aimed at reversing the trend of degraded arid rangelands. This toolbox is founded on science-based evidence and experienced practitioners. For severely degraded arid rangelands, the preference of applying an isolated technology may be insufficient to halt degradation. Through targeting a landscape scale that uses an integrated and multidisciplinary approach, this promising tool/approach aims to address the biophysical and socioeconomic linkages and trade-offs existing between the different land uses. The approach highlights the important role of rangeland governance. It also underscores the need to base decision-making on both indigenous knowledge and modern science, in order to empower communities to make good choices based on the best information available

The effect of alleviating the sand concrete by wood shavings on wall time lag and decrement factor

In the arid regions, such as the city of Laghouat in the south of Algeria, the major preoccupation is how to build a well insulated building. While taking into account the now days requirements of « sustainable construction ». In this context the sand concrete alleviated by wood shavings, in order to improve its thermo-physicals properties, is an environmental and sustainable approach, which can be a promising alternative in the domain of the building industry. However, the importance of this study is limited to the experimental research of a better thermo-physical performance and to the reduction of the shrinkage while ensuring good mechanical properties.  Finally, and in order to get closer results to the reality, a theoretical study by simulation is conducted in order to appreciate the thermo-physical behavior of the concrete studied for the construction of an exterior wall in a specific region.  Two different parameters have been varied in this study: the thickness of the wall (with and without cavity) and the thermo-physical properties of the studied concrete.  The results show that the thermo-physical properties of the concrete studied such: the thermal conductivity, the specific heat and the density have a great effect on the time lag ? and the decrement factor ƒ.  Grater time lag and lower decrement factor minimize the effects of the outside environment on the inside one.  The value of time lag and decrement factor for 20cm wall made by sand concrete elevated by wood shavings were 6hours, 0.305, and for the same wall with 5cm cavity were, 8hours, 0.084. The results obtained are useful for designing low energy consumptions buildings

Barley breeding for quality improvement in Tunisia

This study was initiated to assess the effectiveness of three selection procedures applied in the early  segregating generations of barley crosses for quality traits. The selection procedures were pedigree selection (PS), bulk selection (BS) and single seed descent selection (SSD). Selection was operated in F2’s crosses. Field trials were conducted with 19 F3 crosses of barley in two different environments, a sub-humid  environment at Beja and a semi-arid one at Kef. Heading date (HD), thousand kernel weight (TKW), protein  content (PC), â-glucan content (BG) and husk percentage (HP) were evaluated. Data were subjected to an  additive main effects and multiplicative interaction (AMMI) model to determine the efficiency of each method of selection for the proper environment. The results show that the AMMI model generated predictive  optimizing selection method. The pedigree selection was more efficient in high input environment, while the bulk method was very effective for the selection of kernel weight in target environment.Key words: Additive main effect and multiplicative interaction (AMMI) model, Barley, breeding methods, efficiency of selection, quality traits

How vegetation in flows modifies the turbulent mixing and spreading of jets

While studies on vegetated channel flows have been developed in many research centers, studies on jets interacting with vegetation are still rare. This study presents and analyzes turbulent jets issued into an obstructed cross-flow, with emergent vegetation simulated with a regular array of cylinders. The paper presents estimates of the turbulence diffusion coefficients and the main turbulence variables of jets issued into a vegetated channel flow. The experimental results are compared with jets issued into unobstructed cross-flow. In the presence of the cylinder array, the turbulence length-scales in the streamwise and transverse directions were reduced, relative to the unobstructed crossflow. This contributed to a reduction in streamwise turbulent diffusion, relative to the unobstructed conditions. In contrast, the transverse turbulent diffusion was enhanced, despite the reduction in length-scale, due to enhanced turbulent intensity and the transverse deflection of flow around individual cylinders. Importantly, in the obstructed condition, the streamwise and transverse turbulent diffusion coefficients are of the same order of magnitude

A Repository of Books by Women from the Arab World Translated to English

The translation of women writers from the Arab world in the West contributes to the harmful and inaccurate stereotyping of women from the region in the Global North as oppressed and silenced. In this paper, I describe the rationale and building process for “The repository of books by women from the Arab world translated to English”, a digital project built to counter this flattened image of women from the Arab world by shedding light on the books translated so far and exposing the patterns in the choice and translation of books from Arabic to English. I start by discussing the problem with translating books by women from Arabic to English and the need to do it more broadly as a way to show more diversity in the topics discussed. I then describe the database compilation process and the website development process while explaining the design choices

Effect of High-Intensity, Short-Duration Grazing on Species Density and Botanical Composition of Arid Rangelands

Rangelands are the mainstay of pastoral and agropastoral livelihoods worldwide. They have provided forage for livestock and wildlife for centuries, but steady degradation of rangelands is causing increasing concern. Many rangeland managers believe exclusion of livestock grazing for extended periods would allow degraded rangelands to recover. The purpose of this current ongoing research is to evaluate the effect of high-intensity short-duration grazing on plant density, species richness and botanical composition on arid rangelands during favorable years. The site, which is protected for two years in southern Tunisia and covers an area of 6 ha, was grazed by a flock of about 150 heads of sheep for one week. The grazing took place towards the end of the spring season just after seed dispersal. The measurements were taken before and after grazing using the quadrats method. Preliminary findings revealed no significant difference in plant density, richness, and botanical composition of perennial species. On the contrary, the annual species decreased. In conclusion, short-duration grazing systems do not affect perennial plants that permit greater forage selectivity. As temperatures start rising in late spring, livestock is forced to select annual plants due to their higher palatability and higher water content without damaging perennial plants. In addition, grazing removes oxidized plant material from perennial species that would otherwise remain on top of the plants, prevent photosynthesis, and cause the plant’s death after several years

Is the Tunisian Central Bank following a Linear or a Nonlinear Augmented Taylor Rule?

The political transition in the Arab Spring countries has been accompanied by a deterioration of economic and financial indicators like in the Tunisian case. This paper aims to get a deeper understanding of the nature of the rule that reflects the behavior of the Tunisian monetary authority in the current dominance of economic and financial instability. In particular, this paper assesses whether the Tunisian Central Bank is indeed following a linear or a non linear augmented Taylor rule. For our purpose, we use a forward looking version of Taylor rule augmented by including the effect of exchange rate to estimate the linear and the nonlinear models. A smooth transition regression model is used to estimate the nonlinear rule. The results obtained imply that the Tunisian Central Bank follows a nonlinear Taylor rule in the conduct of monetary policy. In addition, our evidence suggests that the reaction of  monetary authority in Tunisia  to the deviation of forecasts of inflation rate, output gap and exchange rate changes in terms of magnitude and statistical significance across the high and low interest rate regimes. In particular, when the lagged interest rate is above the threshold level of 4.76%, the main objective of the policy makers is to fight the inflation rate and to limit the depreciation of exchange rate rather than to boost the economic activity. Keywords: Taylor rule, smooth transition regression model, interest rate reaction function, nonlinearity JEL Classifications: C22, E17, E43, E52, E58 DOI: https://doi.org/10.32479/ijefi.897