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This study aims to determine the braking performance of limestone as a filler in brake friction materials.

Samples containing limestone material (30-35-40%), which can be an alternative to brake friction material filler, were produced. The samples were weighed on precision scales, mixed homogeneously and produced using the hot molding method. The physical and tribological properties of the produced samples were determined, and their microscopic analyzes were made with scanning electron microscopy.

As the amount of limestone increased, the density of the samples decreased. The friction coefficient and wear rates were close to each other and within the optimum limits for all samples. Limestone materials can be used instead of barite materials studied in the literature on brake linings. Microcracks were observed only in samples containing 30% and 35% limestone in microscopic images.

In this study, the wear rate, coefficient of friction and microstructures on the friction surfaces of brake friction materials containing limestone were investigated. The usability of limestone as a filler in brake friction materials provides valuable information to researchers and industrial organizations in the brake friction material field.

Modern construction methods have been developed with the goal of reducing construction time as much as possible, which results in some situations during construction and within the first few days after it, when concrete is subjected to exceptionally high loads. The precast concrete, which is the concrete in very early ages, may result in severe cracks or damages. In conventional construction projects, sometimes working with concrete, which had not reached its ultimate strength, is an unavoidable matter of fact. This paper aims to discuss these issues.

Researchers in the field of construction materials have done their best to make some changes in the different parts of the concrete in order to bring about reforms, based on the existing needs, and achieve new quality and primacy from concrete. One kind of concrete, the emergence of which dates back to many years ago, is self-compacting concrete. Thanks to its high efficiency for the parts with complex forms of high-density steel, this kind of concrete suggests new prospects.

This study aims at evaluating the effect of early loads on the 28-day compressive strength of concretes with zeolite and limestone powder under different curing conditions (wet or dry). In this regard, two self-compacting concrete mix designs with the same ratio of water to cementations materials and 0.4 percent and 10 percent zeolite have been considered; therefore, concrete cube samples with zeolite and limestone powder in different curing conditions at ages of three, one and seven days under preloading with 80–90 percent of compressive strength are damaged, and after curing in different conditions, their 28-day compressive strength is measured. According to the results, the recovery of the 28-day compressive strength of damaged samples, compared to that of intact samples, is possible in all curing conditions. The experiments that have been performed on concrete samples under dry and wet curing conditions show that the full recovery of compressive strength of damaged samples compared to that of intact ones happened only in preloaded samples at the age of one days, and in other ages (three and seven days) the 28-day strength reduction has occurred in damaged samples compared to the that in intact samples. The results of concrete samples with zeolite and without limestone powder at the age of one day indicate the greatest impact on other samples on the 28-day compressive strength of damaged samples compared to that of intact ones, occurring under dry condition.

This research analyzed and studied the influence under wet and dry curing conditions and the presence of limestone powder and zeolite fillers in recovering of the 28-day compressive strength of preloaded concrete samples at early stages (one, three and seven days) after the construction of the concrete.

By its high fluidity, great deformability and rheological stability, the self-compacting mortar (SCM) is capable of ensuring the ability to be easily implemented without vibration. However, its formulation requires a large volume of fine materials with a high dosage of cement, which is necessary to ensure adequate workability and mechanical strengths, which is necessary to allow its flow. Current environmental considerations encourage reducing the production of cement, it is essential to use additions to replace the cement, because of their great availability and their moderate price. On another side, their use contributes to an economic sort to solve the problems related to the environment.

The formulations and characteristics of SCM made with two types of mineralogical sources (silica and limestone) were investigated. Different materials were used separately and in binary combinations; silica river sand (SRS), limestone quarry sand (LQS), silica fillers (SF) and limestone fillers (LF). The formulation starts with the self-compacting pastes (SCPs) then the SCMs at the SRS and the LQS whose the cement is partially replaced by volume contents of SF and LF with 15%, 30% and 45%.

The results obtained prove that the incorporation of LQS instead of SRS has a negative effect on the fluidity and deformability and a positive effect on the mechanical strengths of SCM. In addition, the incorporation of the SF and LF reduces the need for water and the saturation dose of superplasticizer in the pastes. Thus, the addition of the SF and LF in specific voluminal contents (15% SF and 30% LF) in the binder can have a beneficial effect on the parameters of the workability and the mechanical strengths of SCM. These results are very interesting to aspects such as technological, economic and environmental.

Influence of the different type of sands and fillers in improvements the properties of SCM made from various mineralogical sources.

This paper aims to study the effect of mineral additions on the mortars’ physical, mechanical and durability properties. Two local mineral additions, considered inert, are chosen: limestone fillers from North-East of Algeria and natural dune sand from Algerian desert areas.

Two local additions are finely crushed to a fineness greater or equal to that of the used cement and incorporated into the mortars with predetermined rates; (0, 10%, 15% and 20%) compared to the cement weight to examine their effects on the mortars’ properties at different ages. Two conservation environments are chosen: freshwater as a neutral area and rising water table as an aggressive area to appreciate the effect of the two additions on physical and mechanical properties and durability.

The results showed the beneficial effect of these additions on compactness, mechanical resistance and durability toward the rising water table. The results have also allowed us to make an experimental comparison between the limestone addition which is commonly used in the Algerian cement industry and the dune sand, which is not yet well explored and exploited.

The added value of this study is the use of crushed dune sand which is a local addition of southern Algeria for improving the resistance of mortars and concrete toward the aggressiveness of rising water table which presents a major problem for the infrastructure of civil and public construction.

This research aims to study the influence of limestone filler on rebar corrosion.

Mortar samples containing 35% calcareous filler and with a rebar inserted in the axis, were cast. Specimens were cured at the open air and during 28 days in lime water. After curing, they were submerged in two electrolytes (tap water and 3% NaCl) and corrosion parameters (corrosion potential and corrosion current) were monitored over time by d.c. techniques. Simultaneously, electrochemical noise measurements were carried out. After corrosion tests, rebars were pulled out by lateral compression, and their surface observed by scanning electron microscopy.

In general, carbonate additions impaired mortar protective properties, especially in the presence of chloride and changed the nature of the protective layer on rebars. The curing process did not introduce significant differences except for mortars with a high water cement ratio cured in lime water for which the beneficial effects of the simultaneous presence of carbonate and lime in the pore solution could be appreciated. The role of carbonate additions is to provide carbonate anions to passivate rebars. This passivation process caused corrosion rates not to be so high. Carbonate anions also deposited on oxide spots which were rendered passive but this process was not uniform. Certain areas on the rebar underwent intense carbonation while others showed increased corrosion rates.

There are not many corrosion studies about the influence of limestone filler on rebars corrosion. Particularly, this paper deals with mortars containing high percentages of carbonate additions. Results showed that the presence of this type of admixture changes the structure of the passive layer and, sometimes, may increase corrosion rates.

The purpose of this paper is to elucidate if there is a loss in bond strength between galvanized steel used as reinforcement, and concrete of water‐to‐cement (w/c) ratio of 0.4 and 0.5, after both types of sample were cured for seven, 21 and 28 days in saturated calcium hydroxide solution, and without curing. The air permeability of the concrete was investigated at the interfacial zone.

Structural low‐carbon steel and galvanized steel were embedded in concrete samples, prepared with Portland cement type I and limestone (calcite 94‐97 percent) aggregates. The bond strength between the concrete and the reinforcing bars was measured by means of pull‐out tests.

In concrete of w/c=0.4 the bond for galvanized steel was 5.4±0.5 MPa, while the bond for black steel was 5.8±0.5 MPa, which is 7 percent higher than bond strength measured for samples with galvanized steel rebars. The bond strength for galvanized steel in concrete with a w/c ratio 0.5 was 5.5±0.6 MPa, which was 9 percent higher than the values obtained for black steel, which was 5.0±1 MPa. The total average bond strength of galvanized steel in concrete of w/c ratio 0.4 (5.4±0.5 MPa) and w/c ratio 0.5 (5.5±0.6 MPa) was very similar. They differed by only 2 percent. No decrease in the air permeability at the interfacial zone concrete/galvanized steel was found due to curing.

This research gives quantitative data on the behavior of galvanized steel used as reinforcing bars in concrete, prepared with limestone aggregates. The results might help to increase the reliability of galvanized reinforcing steel used in infrastructure exposed to very aggressive tropical humid marine environments.

The purpose of this paper is to prove and qualify the influence of textured surface substrates morphology and chemical composition on the growth and propagation of transplanted corals. Use additive manufacturing and silicone moulds for converting three-dimensional samples into limestone mortar with white Portland cement substrates for coral growth.

Tiles samples were designed and printed with different geometries and textures inspired by nature marine environment. Commercial coral frag tiles were analysed through scanning electron microscopy (SEM) to identify the main chemical elements. Raw materials and coral species were selected. New base substrates were manufactured and deployed into a closed-circuit aquarium to monitor the coral weekly evolution process and analyse the results obtained.

Experimental results provided positive statistical parameters for future implementation tests, concluding that the intensity of textured surface, interfered favourably in the coralline algae biofilm growth. The chemical composition and design of the substrates were determinant factors for successful coral propagation. Recesses and cavities mimic the natural rocks aspect and promoted the presence and interaction of other species that favour the richness of the ecosystem.

Additive manufacturing provided an innovative method of production for ecology restoration areas, allowing rapid prototyping of substrates with high complexity morphologies, a critical and fundamental attribute to guarantee coral growth and Crustose Coralline Algae. The result of this study showed the feasibility of this approach using three-dimensional printing technologies.

This paper examines the influence of seasonal changes on stripping of overburden in West African Portland Cement (WAPCO) Shagamu, Nigeria. In order to achieve this tonnage of overburden moved per mouth, tonnage of exposed and workable limestone available for blasting were determined during dry and rainy season for 3 years. The results showed that overburden stripped vary from 292,000 tons to 303,000 tons and 195,000 tons to 211,000 tons during dry and rainy seasons respectively. Also, the tonnage of exposed and workable limestone varies from 2.07 million tons to 2.61 million tons and 1.5 million tons to 1.517 million tons during dry and rainy season respectively for 2004-2006. Therefore, stripping of overburden should be compensated during dry season to maintain the level of production.

The purpose of this paper is to find the relationship of palaeontology, palaeobotany and coal thickness of Taiyuan Formation during Late Carboniferous – Early Permian Period in Shanxi Province.

This paper selects three regions, namely, Baode, Xishan and Lingchuan, to analyse the distribution characteristics of palaeontology, palaeobotany and variation of coal thickness.

It was found that in a certain period of geological history, palaeontology and palaeobotany play a dominant role in shaping of a coal-bearing basin. Coal seam thickness changes largely from the northwest to the southeast, gradually thinning in Taiyuan Formation.

Palaeontology and palaeobotany play a dominant role in the shaping of a coal-bearing basin.