Crushed Limestone Sand Research Articles

Effect of partial and total replacement of siliceous river sand with limestone crushed sand on the durability of mortars exposed to chemical solutions

This study presents a part of different works carried out on a context of local materials valorization and industrial wastes reuse. The main objective of this investigation is to substitute silica river sand (M’zi river) by crushed limestone sand (residues quarries) in the mortar, so as to valorize the crushed limestone sands that are found (in waste form) in large quantities in the region of Laghouat (Algeria), to protect the environment against this waste and to unlock the local construction projects, especially after the ban on local sand extraction from river for environmental reasons. Indeed, the aim of this work is to study the effect of this replacement on the durability of mortar exposed to different chemical environments. In fact, we have to study the behavior of the obtained mortars into three different environments: in open air, in a solution containing lime and in another one containing hydrochloric acid (HCl). For replacement 0%, 50% and 100%, the results showed that, compared to open air environment, conservation in a lime solution has a positive effect on the durability of mortars. In fact, it furthermore improves their physical and mechanical properties such as the mechanical strength, the dimensional variations, etc. In addition, and compared to silica sand, it has been noted that these properties were much higher in the presence of crushed limestone sand in mortar. Concerning the HCl-solution, it has been recorded a negative effect on the durability of mortars. But, it should be noted that this effect was considerably reduced in the presence of crushed limestone sand in the materials. Finally, with introduction of limestone sand in mortar, the improvements were higher: decrease in the permeability, reduction in the mass and strength losses, reduce in the phenomenon of capillary rise and less attack by acid.

改質フライアッシュを混入したモルタルの収縮ひび割れ特性に関する研究

改質フライアッシュを混入したモルタルの乾燥収縮ひび割れに対する抵抗性について、混合砂と石灰砕砂を使用し、内部拘束型による一軸拘束試験を行った。その結果、混合砂はすべての供試体においてひび割れが発生したが、石灰砕砂にはひび割れが発生しなかった。また、フライアッシュがひび割れ発生に及ぼす影響については明確な結論を得ることが出来なかった。さらに、筆者らが行った既往の研究で得られたコンクリートの実験結果と比較を行った。その結果、コンクリートに比べモルタルは割裂引張強度が大きく、ひび割れ発生時の拘束応力も大きくなることが分かった。

A Comparative Study of Concretes Containing Crushed Limestone Sand and Natural Sand

This paper describes the effects of high temperatures on the strength characteristic of crushed limestone sand concrete (CLSC). To compare, natural (river) sand concrete (NSC) and CLSC specimens were exposed to the three different high temperatures. Visual color-change and weight loss were also carefully examined through the tests. The test results indicated that the decreasing rate of compressive strength of CLSC after exposure to high temperature is slightly lower than that of NSC while the splitting tensile strength of CLSC indicated a very similar rate compared to NSC. Therefore, the strength variations of crushed limestone sand concrete after exposal to high temperature can be similarly treated as that of the natural sand concrete. Also it can be seen that the CLSC can use 0.5 power law equation to represent the relationship between compressive and splitting tensile strength before and after exposal to high temperature.

Rheological, Mechanical and Structural Performances of Crushed Limestone Sand Concrete

The crushed limestone sand is an abundant material in Tunisia, which induces many environmental problems. Indeed, available stocks of siliceous sand drastically decrease because of its massive use in hydraulic concrete. Some recent research works, carried out in Tunisia, concluded that crushed limestone sand may be used in concrete manufacture instead of siliceous sand traditionally used. In this context, an experimental study was achieved in order to quantify the influence of a partial or total substitution of siliceous sand by crushed limestone sand on hydraulic concrete performances. Preliminary chemical and physical tests on crushed sand indicated that it presented the minimum requirement for its use as aggregate in hydraulic concrete. 79 concretes were then prepared with siliceous sand, crushed limestone sand and a mix of the two sands. Their slump value and compressive strengths were measured on plain concretes. Complementary structural tests on reinforced concrete beam were also performed. The results proved that crushed limestone sand concretes showed workability and mechanical performances closed to those of siliceous sand concretes.

Chloride Diffusion in Mortars - Effect of the Use of Limestone Sand Part II: Immersion Test

Part I of this study was devoted to the electrical accelerated chloride diffusion in mortars. In this second part, natural chloride diffusion has been investigated for four types of mortars under exposure to a 0.5 mol/L NaCl solution for a period of up to 35 days. Two different types of sand were used for the production of test samples: siliceous sand (used as a reference) and limestone sand (used in this study). The effect of water to cement ratio and exposure time on the diffusion coefficients of mortars was also investigated. In this study, the total and free chloride content and penetration depth of mortar were measured after immersion, and Fick's second law of diffusion was fitted to the experimental data to determine the diffusion coefficient. Their results show that the use of crushed limestone sand in mortar had a positive effect on the chloride resistance. The apparent diffusion coefficient in all specimens was smaller than that in siliceous sand mortar. However, the chloride penetration of these mortars was increased as exposure time progressed.

Influence of Aggregate Type and Size on Ductility and Mechanical Properties of Engineered Cementitious Composites

The influence of aggregate type and size on engineered cementitious composite (ECC) mechanical and ductility properties was investigated and the results presented in this paper. A micromechanically-based high-performance fiber-reinforced cementitious composite, ECC enjoys improved durability and high ductility due to tight crack width. Microsilica sand (200 μm [0.008 in.] maximum aggregate size) is typically used to produce standard ECC mixtures. There was investigation of ECC mixtures containing either gravel sand or crushed dolomitic limestone sand with maximum sizes of 2.38 or 1.19 mm (0.094 or 0.047 in.) in this study. Three different ECC mixtures with 1.2, 2.2, and 4.2 fly ash/portland cement (FA/C) ratios were cast for each aggregate type and maximum aggregate size. There was experimental determination of crack development, drying shrinkage behavior, and the effects of FA/C, aggregate type, and maximum aggregate size on compressive, flexure, and unixial tensile properties. Experimental results show that strain-hardening behavior with strain capacities, provided that the matrix employs a high FA content, can be compared with the standard microsilica sand ECC mixtures, in ECC mixtures produced with gravel sand and crushed dolomitic limestone sand with higher maximum aggregate sizes. Tensile strengths of these mixtures can be 3.57 to 5.13 MPAa (0.52 to 0.74 ksi), and tensile ductility can maintain, at 28 days of age, 1.96 to 3.23%. Material behavior can be further improved by using crushed dolomitic limestone sand and gravel sand, since they can be drying-shrinkage arrestors in the paste.

Strength and durability of concrete incorporating crushed limestone sand

In recent years, there is a growing interest in the use of crushed sand obtained from limestone quarries in some countries where river sand is not widely available. The fines content is usually high in crushed sand which can adversely affect concrete properties. The influence of fines in crushed sand on physical and mechanical properties of concrete has been widely investigated. The results proved that up to 15% of fines content in crushed sand could be used without adversely affecting concrete strength. However, little work has been done so far on the effect of fines in crushed sand on the durability of concrete. This paper examines the influence of limestone fines in crushed sand on concrete properties. Properties include strength, water, gas and chloride-ion permeability and capillary water absorption. Four different cement types were used while maintaining a constant water/cement ratio. The results show that concrete containing 15% of limestone fines as replacement of crushed sand reduces the water permeability and increases the gas and chloride-ion permeability.

A comparative study on the performance of sands rich and poor in fines in self-compacting concrete

Self-compacting concrete (SCC) as a special concrete, has practical advantages due to its mechanical performance and application easiness. However, a more careful study is needed at the stage of mixture proportioning. In order to produce SCC, a more voluminous but also a more viscous matrix is needed compared to concrete of normal workability. This may be achieved by using additional fillers with pozzolanic or inert nature. The employment of sands rich in fines may be a second alternative source of filler. However, the physical properties of sands rich in fines affect the performance of SCC in dual ways. In this study, the effects of the changes in the physical properties of sands (in particular the fine material content and type), on concrete performance were investigated. SCC mixtures containing four different sands (washed natural (WN) sand, washed crushed limestone (WCL) sand, crushed limestone sand with silt powder (CLS) and crushed limestone sand with clay powder (CLC)) were produced and the admixture requirements for each type of SCCs were determined. Test results suggest that, in order to produce SCC with the same consistency, admixture requirement may change with the physical properties of sands used. When compared to SCCs prepared with washed sand (poor in fines), approximately similar compressive strengths have been obtained by using CLS sand. On the other hand, CLC sand caused strength loss and increased the admixture demand for a targeted slump-flow of SCC. Due to the increased admixture content, setting times of SCCs prepared with CLC sand were also lengthened. The methylene blue adsorption value is a good indicator of clay content of sand. This test method was efficiently used for the selection of appropriate sand type incorporating high volumes of fine materials. Additionally, microstructural studies revealed some clues about the poor performance of SCCs prepared with CLC sand.

Long-term compressive strength and some other properties of controlled low strength materials made with pozzolanic cement and Class C fly ash

Controlled low strength material (CLSM) is a flowable mixture that can be used as a backfill material in place of compacted soils. CLSM (or flowable fill) require no tamping or compaction to achieve its compressive strength and typically has a load carrying capacity much higher than that of compacted soils, but can be proportioned to allow future excavation. In this study, several different CLSM mixtures containing Class C fly ash (FA) obtained from Soma Thermal Power Plant in Turkey, crushed limestone sand (CLS), and a minimal amount of pozzolanic cement (PZC) were produced. The mass of PZC was kept constant for all mixtures at 5% of FA by mass. The mechanical and physical properties of CLSM mixtures such as unconfined compressive strength, water absorption by capillarity and EP toxicity were investigated by a series of laboratory tests. CLSM mixtures with low PZC contents and high Class C FA and CLS contents can be produced with excellent flowability and low unconfined compressive strengths in the range of 1.16–2.80MPa at 365-days age when re-excavation at later ages might be needed. The results presented here show a new field of application for Soma FA in CLSM mixtures, resulting in great advantages in waste minimization, as well as, conservation of resources and environment.

Properties of Controlled Low-Strength Material Containing Foundry Sand

Highway engineers, contractors, and state regulatory officials have been skeptical about using foundry sand in construction because of the lack of engineering data and the perceived risks associated with any nontraditional material's technical and environmental performance. This research study was performed to document and evaluate engineering properties of controlled low-strength material (CLSM) containing byproduct foundry sand. Mixtures containing clay-bonded and chemically bonded sand were compared in the plastic and hardened states to CLSM mixtures containing uniformly graded crushed limestone sand. The data show that byproduct foundry sand can be successfully used in CLSM, and it provides similar or better properties to that of CLSM containing crushed limestone sand. The foundry sand assisted in keeping the strength from exceeding the desired upper limit of 700 kPa. Clay-bonded sand retarded the setting time, and chemically bonded sands required a reduction in water to control bleeding. CLSM containing a combination of fly ash and chemically bonded sands was shown to have excellent characteristics for flowable backfill and excavatable base material.

The fracture characteristics of crushed limestone sand concrete

The use of crushed sand as a fine aggregate has rapidly increased due to a shortage of river sand. Accordingly, research on crushed sand concrete is required. In this research, the fracture characteristics of crushed limestone sand concrete were experimentally investigated through a wedge splitting test, and the results were compared with those of crushed granite sand concrete and river sand concrete. The strength of crushed limestone sand concrete was also investigated. It was shown that the fracture energy of concrete was little influenced by the type of fine aggregate. In addition, the fracture energy of crushed sand concrete was slightly higher than that of river sand concrete. This seems to be due to very fine sand (VFS) included in crushed sand, which tends to improve the cohesion between cement paste and aggregate. Also, the fracture energy was not proportionally increased with an increase of concrete strength. The characteristic length of crushed limestone sand concrete was almost the same as that of river sand concrete or crushed granite sand concrete. The characteristic length greatly decreased as the strength of concrete increased.

Sables calcaires à fines calcaires et argileuses: influence et nocivité dans les mortiers de ciment

On a realise un programme de recherches assez exhaustif dans le but de rassembler des donnees pour une prochaine revision de la Norme Espagnole du Beton sur la teneur en fines des sables, actuellement fixee, sans exception, a 5%. On presente les resultats de l'influence des differentes teneurs en fines calcaires et argileuses sur les proprietes mecaniques des mortiers, prelablement a l'etude de cette influence sur des betons confectionnes avec des granulats calcaires de broyage. Cette phase est en cours d'execution a l'heure actuelle. Avant de se livrer a ces travaux experimentaux, on a realise une prospection generale de toutes les carrieres de broyage de calcaire dans la zone nord-est de la peninsule correspondant au Pays Basque. D'apres les resultats obtenus, il semble que la limite pourra s'elever jusqu'a 12 a 15%, a condition d'assurer la presence d'argile a un taux defini par des essais. To obtain data for the next revision of the Spanish Concrete Standard, with regard to the content of sand fines, presently set at 5%, an exhaustive research project was undertaken. The results show the influence of different contents of calcareous and clay fines in the mechanical properties of mortars made with crushed limestone sand, prior to studying the corresponding influence on concrete prepared with this type of aggregate, which is presently being examined. Prior to this research work, a general survey was carried out of all the quarries with crushed limestone in the northwest of the peninsula corresponding to the Basque Country. From these analyses carried out in 44 quarries, an average value of 13%, taken from a range between 7 and 23%, was deduced for its contents in fines, the most frequent value being between 11 and 12%. In this study, we have seen that for clay contents in sand below 2%, 20% of total fines can be achieved with a tendency to increase resistance in cement mortars of equal plasticity. For any set contents of total fines, the increase in proportion of clay in the sand is what really makes the resistance to mortar compression drop noticeably and linearly. It has been verified for example, that a jump of 2% in the contents of clay in sand influences the resistance just as much as a modification in the contents of fines from 3 to 20%. In short, it is important to limit the contents of clay in sand, either by the sand equivalent or methylene blue (analogous to NF P 18-301, Dec. 1983). In this way, calcareous crushed sands with fines much higher than the present 5% specified could be allowed. We think that this amount could be set between 12 and 15% after carrying out the present tests on concrete.