Compressive Strength Of Mixtures Research Articles

Effect of AR-glass fibers and natural micronized zeolite on mechanical and permeability properties of concrete exposed to normal, sodium chloride, and magnesium sulfate environments

This article investigates the effects of AR glass fibers and micronized natural zeolite on reducing permeability and increasing compressive strength. However, there is little detailed information about the impact of the interaction of zeolite and AR glass fibers on the mechanical properties and their comparison in normal environments with Chloride (NaCl) and sulfate (MgSO4). According to the results of the tests, the compressive strength of mixture 9 (1 % by volume of concrete, glass fibers, and 12 % by weight of cement, zeolite) and mixture 11 (2 % by volume of concrete, glass fibers, and 8 % by weight of cement, zeolite) in normal environments, Chloride and sulfate increased by 43.2, 34.8, and 30.1, 64.1, 68, and 58.8 %, respectively, compared to the control sample of its environment. The permeability of mixtures 9 and 11 has decreased by 68.42, 66.67, 42.31, 47.37, 61.9, and 55.77 %, respectively, compared to the control sample of its environment. Finally, SEM images have been used to investigate the microscopic structure.

Optimizing the mechanical behavior of clay using cement and PVC aggregates with the application of a mixture design method

The present research work aims to use the mix design approach to develop some models that can predict the mechanical properties of clayey soil. For that, the proctor compaction test, direct shear test, and uniaxial compression test were performed on bentonite (B) and other mixtures incorporating different proportions of polyvinyl chloride (PVC) aggregates stabilized with cement (C). The experimental and modeling results indicated that a good correlation existed between the three factors (B, C, and PVC) and the values of the maximum dry density, cohesion, and compressive strength responses. It was also found that the majority of models gave relatively good correlation coefficients (R2 ≥ 0.90) for all the responses under study. The results obtained indicated that this bentonite had a compressive strength 180.24 kPa, with a cohesion 64.71 kPa, and a maximum dry density equal a 1.571 gr/cm3. In addition, the experimental and modeling findings showed that the mixture including C (55% ± 10%), PVC (35% ± 10%), and B (10% ± 10%) exhibited a quite high cohesion of 103 kPa (more than one and half times that of unreinforced samples), while the highest compressive strength of 445 kPa (two and half times more than that of unreinforced samples) was obtained for the mixture comprising of C (50% ± 10%), PVC (25% ± 10%) and B (25% ± 10%). In addition, it turned out that these results are very encouraging in terms of environmental protection because this technique allows recycling and valorizing huge quantities of PVC waste produced throughout the world. It has been revealed that PVC wastes can be utilized in the geotechnical field to improve the mechanical behavior for clay soils, and to assess the values of maximum dry density, cohesion, and compressive strength of mixtures not made in the laboratory using the derived statistical models.

Laboratory study on the properties of concrete pavement containing blast furnace slag and Gilsonite

This study evaluated the mechanical properties and abrasion resistance of the concrete pavement when cement was replaced by the blast furnace slag (BFS) and Gilsonite at levels of 20%, 25%, and 30%, as well as 5%, 7%, and 9%, respectively. For this purpose, a total of ten mixing designs were made and cured for 28 days. The results showed that the compressive strength of mixtures containing two additives decreased. In contrast, the BFS20-G7 mixture satisfied the proposed minimum compressive strength. However, the flexural strength and tensile splitting of the BFS20-G7 containing 20% BFS and 7% Gilsonite increased by about 4 and 7 percent. The Wide Wheel Abrasion Test results showed that the mixture containing 20% BFS-7% Gilsonite increased the abrasion resistance by about 5% and 17% in 100 and 300 revolutions, respectively. Conclusively, using BFS20-G7 in low-traffic areas such as parks and driveways can be suggested.

Preparation and characterizations of hydroxyapatite microcapsule phase change materials for potential building materials

This paper aims to develop a novel thermal storage cement-based material (TSCM) with good service performances using rigid phase-change microcapsules. Microcapsules were made of hollow HAP incorporated with capric acid (CA). The fabricated composite phase change material (CA/HAP) was characterized by using various techniques, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), thermogravimetry (TGA) and differential scanning calorimeter (DSC). The basic properties of TSCM mortars with varying amount of CA/HAP including workability, hydration heat, compressive strength and thermal regulating ability were also assessed. The test results showed that CA/HAP is small and regular in spherical shape and exhibits high absorption ratio and good physicochemical stability. The incorporation of CA/HAP in cement-based materials leads to a decrease of workability, acceleration of hydration process and significant improvement of thermal regulation property. The compressive strength of mixtures containing CA/HAP is noted to be increased when incorporating 10% of CA/HAP by volume.

RECYCLING OF CONSTRUCTION AND DEMOLITION WASTE AS AGGREGATE FOR PAVEMENT BLOCK PRODUCTION

The objective of this paper is to evaluate the performance of recycled concrete aggregate for use in the production of pavement blocks. For this research project, aggregates were obtained from various sources of recycled waste, including wall plaster, ceramic tiles and concrete flooring. The concrete mixtures were prepared using three different quantities of recycled aggregate: 25%, 50% and 100% of the total aggregate weight. The structural properties of the concrete mixtures were analyzed using slump cone measurements and compressive strength tests (cube tests) at 3, 7 and 28 days. The results obtained indicated that the compressive strength of all mixtures increased with time. However, it was also noted that the compressive strength of the concrete mixtures decreased as the quantity of recycled aggregate increased. The maximum compressive strength was achieved at 28 days by the concrete mixture comprised of 25% recycled aggregate, which was obtained from concrete floor waste. This illustrates that the use of this type of recycled aggregate allows engineers to obtain concrete mix designs which meet the structural requirements for application in pavement blocks.

Influence of Curing Media and Mixing Solution on the Compressive Strength of Laterized Concrete

Concrete has been a major building material over the centuries due to its strength, durability and versatility. However, despite the numerous advantages of concrete, it is still plagued with several limitations in addition to its high use of raw materials. In order to improve the resilience of concrete mixtures, this study was carried out to investigate the effect of curing media and mixing solution on the compressive strength of concrete mixtures incorporating different proportions of laterite as partial replacement of the conventional fine aggregate. The laterite content in the concrete was varied at 0%, 15% and 30% of fine aggregate, and mixed with bacteria solution or water. The compressive strength of the mixtures was evaluated at 7, 14 and 28 days for concrete mixtures cured in water, bacteria solution, nutrient broth and combined bacteria and nutrient broth. Results from this study indicate concrete mixtures cured in nutrient broth plus bacteria solution have the highest compressive strength followed by bacteria, nutrient broth and water. The improvement in compressive strength due to Bacillus sp. CT-5 (i.e. bacteria used in this study) can be attributed to the precipitation of CaCO3 at the cell surface as well as within the concrete matrix. This provided a nucleation site which made it to become less porous and permeable and thereby increasing the compressive strength of the concrete cubes. The results of this study can be used to understand how various solutions incorporating bacteria can be used to enhance the performance of concrete. In addition, this study exhibits the viability of using locally available materials such as laterite in concrete mixtures.

Applicability of Palm Oil Fuel Ash in Interlocking Compressed Earth Brick – A Preliminary Assessment

This paper presents the preliminary assessment on the applicability of palm oil fuel ash (POFA) as one of the materials used to produce interlocking compressed earth brick (ICEB). Ultrafine size POFA was used to replace the main ingredient for ICEB production which is the clay soil. The percentages of replacement were limited to 0%, 10%, 20%, 30%, 40%, 50%, and 60% by weight of the total clay soil material. The main purpose of conducting the experiment is to identify the most desirable mix through compressive strength test. Result showed that, at the curing age of 28 days, the compressive strength of mixture that substituted with 30%–60% of ultrafine POFA achieved higher strength than the control mixture. Meanwhile, the highest compressive strength was obtained by batch series CP50 (50% clay soil + 50% ultrafine POFA). The experimental studies specified that ultrafine POFA has significant possibilities for application in manufacturing ICEB.

Evaluating steel fiber‐reinforced self‐consolidating concrete performance

AbstractThe fiber‐reinforced self‐compacting concrete (FR‐SCC) is considered a high‐performance material, clustering characteristics of SCC combined with steel fibers. This paper assessed fresh and hardened state properties of a reference SCC and a FR‐SCC with fibers of three types and three quantities of reinforcement, totalizing 10 mixtures. Fresh state properties of the mixture were evaluated through the tests of slump‐flow, flow rate, filling ability, plastic viscosity by V‐funnel, passing ability by J‐ring and by L‐box; and hardened properties comprised compressive strength, flexural strength, and flexural toughness. Overall, it was observed that increasing the amount and length of fibers hindered the mixture workability. Also, the flexural strength and flexural toughness increased as the length and the amount of fibers increased. Regarding mechanical properties, it was not possible to identify an equivalence between the types of fibers evaluated and the compressive strength of mixtures. The flexural was proportional to the amount of fibers, with increases of up to 30% for concretes with fibers.

Mechanical and physical behavior of cement paste and mortar incorporating nano‐CaO

The aim of this work is to experimentally investigate the effect of properties of nano‐CaO in cement‐based materials. Mortars and paste samples were produced by using nano‐CaO in 2.5, 5, and 7.5% ratios instead of cement. The initial and final setting times and volumetric autogenous shrinkage tests of paste samples and 7, 28, and 360 days’ compressive strength, the ultrasonic pulse velocity, heat of hydration, and linear autogenous shrinkage of mortar samples were determined. In addition, the micro‐structures of paste samples were characterized by X‐ray‐diffraction and SEM. As a result, the shrinkage and setting times were reduced with the increase of nano‐CaO content. CaO with nano size increased the compressive strength (about 10–22%) and the heat of hydration. The compressive strength of mixture containing 7.5% nano‐CaO was lower than that of 2.5 and 5% nano‐CaO at 360 days of curing duration. The heat of hydration increased for all the mixtures containing nano‐CaO at an early stage and very rapidly between 4 and 16 hr.

Durability and microstructure properties of SBR-modified concrete containing recycled asphalt pavement

The road and building industry are the largest material consumers of the earth and the largest producer of solid waste. Recycling and reusing waste materials such as construction and asphaltic waste is one of the practical remedies in order to reduce the consumption of mineral materials. In this study, the effect of silica fume, styrene butadiene rubber (SBR) latex, and recycled asphalt pavement (RAP) on the mechanical properties (compressive, flexural and splitting tensile strength, module of elasticity and toughness), permeability characteristics (water penetration depth, rapid chloride ion penetration, electrical resistivity) were assessed. Additionally, microstructure properties were investigated via scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). In this regard, 33, 66 and 100 wt% of coarse aggregates were replaced by RAP. Furthermore, three different curing methods were applied to evaluate the mechanism of latex effect on compressive strength of mixtures. The results showed that the replacement of SBR latex and silica fume led to a significant increase in mechanical properties and reduction of the permeability of concrete mixtures. The interfacial transition zone (ITZ) between the cementitious matrix-aggregate using SEM images indicated that mixtures containing SBR latex and silica fume had a uniform structure at the cementitious matrix-aggregate interface. EDX analysis also indicated the reduction of ITZ thickness and the calcium to silica ratio. It was also found that the compressive strength of the concretes cured in high temperature condition increased remarkably, which exhibits the heat contribution to the formation of a polymer membrane in specimens with latex.

Influence of pumice and zeolite on compressive strength, transport properties and resistance to chloride penetration of high strength self-compacting concretes

This paper investigates the effect of two different natural pozzolan (pumice and zeolite) on compressive strength (fc), transport properties and resistance to chloride penetration both in immersion and tidal conditions when used in high strength self-compacting concrete (HSSCC). First, the chemical and mineralogical composition as well as the microstructure and the pozzolanic activity of the natural pozzolan are studied. Then, two percentages, 10% and 15%, of pumice and zeolite instead of Portland cement in HSSCC are investigated. Five concrete mixtures with a control mixture without any pozzolan are prepared and tested in both fresh and hardened states. The results show that the studied zeolite is a clinoptilolite that presents higher pozzolan activity compared to pumice. However, the compressive strength of mixtures containing zeolite remains low compared to control mixture. On the contrary, mixtures with pumice present compressive strength values close or higher than the ones of the control mix at both early and long term ages with a remarkable increase at long term. For durability purposes, the transport properties of the different mixtures are studied through capillary absorption, water absorption, water penetration, electrical resistivity, chloride migration and diffusion tests. The results show that, both pumice and zeolite pozzolan are found to have a significant effect on the increase of the resistance to chloride penetration in both immersion and tidal conditions. However, zeolite mixtures exhibit better resistance. This research shows that, the substitution of Portland cement by 15% of pumice or 10% of zeolite in HSSCC is affordable in all aspects.

フライアッシュを使用した調合における初期強度に及ぼすアミン系強度増進剤の効果

For utilization of flyash which is one of byproducts, authors focus on flyash cement having relative lower consumption, even specified in JIS. One of the reasons for lower consumption is slower early strength development than ordinary Portland cement (OPC) in case of much replacing ratio of flyash in flyash cement. Therefore in this study, strength enhancers as cement additives are studied on the effect of strength development, especially for early age. Firstly, the compressive strength of mixtures using OPC and flyash corresponding to JIS Type-B and Type-C are measured to confirm the effect of the strength enhancers. Additionally, the heat of hydration by isothermal calorimeter of cement paste using amines as strength enhancers are measured for discussion of the effect of the strength enhancer for cement hydration and the hydration mechanism for early strength enhancement. The conclusions are as followings; 1) Two different strength enhancers Triisopropanolamine (TIPA) and Alkanolamine are evaluated for FA Type-B-mixture and FA Type-C-mixture replacing flyash to a part of the OPC. Alkanolamine shows higher strength than TIPA by FA Type-B-mixture and FA Type-C-mixture. Besides, Alkanolamine shows higher strength than OPC from 1day to 7days. This result shows the effect of strength enhancer differs for mixtures, and it suggests that TIPA and Alkanolamine have different hydration mechanism. 2) As a result of heat of hydration, Alkanolamine generates highest heat of FA Type-B-mixture and FA Type-C-mixture. The strength enhancers are considered to have acceleration effect for this heat of hydration. 3) In dissolution test using flyash and the strength enhancers, TIPA shows high elution amount of Fe2O3 from flyash. In contrast, Alkanolamine shows no effect for dissolution of Fe2O3. But when using TIPA and Alkanolamine for flyash, it was confirmed that the amount of effusion of the metal-ion was different than only flyash mixed. 4) C3S or C4AF is used for heat of hydration measurement to determine the hydration mechanism of the strength enhancers. Alkanolamine shows acceleration effect for C3S. However, TIPA shows the retarding effect constantly. For C4AF, Alkanolamine shows higher acceleration effect than TIPA. 5) As for estimated hydration mechanism for early strength enhancement, the strength enhancers would accelerate C3S and C4AF in OPC.

Response of Hybrid Waste Fiber-Self Compacted Reinforced Concrete Slabs Under Static Loading

This work aims atassessing thebehavior of self-compacted concrete (SCC) reinforced with hybrid recycled waste fibers (RWFSCC) in two-way slabs under static loading, Waste plastic fibers (PET) and metal cans fibers and hybrid fibers with aspect ratio (12.5) have been used with volumetric percentages (0.1%, 0.25% and 0.4%) for each type of recycled fibers respectively, in addition to the reference mixture (free of fibers) for the purpose of comparison.The current study has been divided into two parts , the first part is focused on studying the effect of recycled fibers on the specified mechanical properties, namely: the compressive strength and the splitting tensile strength of the hardened SCC, The second part included the study of the behavior of concrete slabs under static loading .The results showed a slightly improvement in the compressive strength of mixtures that containing volumetric ratio (0.1%) of waste recycled fibers , also showed that the plastic fibers have improved both the splitting tensile strength ,as the ratio of the recycled fibers has increased, and the bending strength and toughness of the concrete slabs that containing the hybrid recycled fibers ,whereas the increasing of the metal recycled fibers ratio caused to reduce this increasing and to give a negative effect on the structure of SCC .

Permeability properties of self-consolidating concrete containing various supplementary cementitious materials

In this study, permeability properties of 17 self-consolidating concrete (SCC) mixtures containing various supplementary cementitious materials (SCM) were investigated by different experimental approaches. The effects of SCM type and content on the compressive strength, rapid chloride ion permeability (RCPT), water penetration depth, water absorption and sorptivity were studied. For these purposes, various amounts of silica fume (SF), metakaolin (MK), Class F fly ash (FAF), Class C fly ash (FAC) and granulated blast-furnace slag (BFS) were utilized in binary, ternary, and quaternary cementitious blends. Results showed that partial replacement of PC by SCM increased the compressive strength of control mixtures at 28 and 90days (except for FAF at 28days). Mixtures containing MK presented a better performance compared to other SCM at 7days. The utilization of SCM reduced the RCPT results of almost all mixtures compared to the control mixtures and the reduction was more significant with an increase in the SCM content. All of the mixtures containing SCM had lower penetration depths when compared to reference mixtures at 28 and 90days. Good correlations were established between the percentage of permeable voids and water absorption. Moreover, there was an inverse but almost linear relationship between permeable voids content and compressive strength of the mixtures.

Research on the Performance of the Cement Stabilized Gravel with Rubber Particles

The primary objective of this paper was to study the mechanical properties and durability of the cement stabilized gravel which added rubber particles by using macroscopic and microscopic test. Through tests of compression, splitting and frost resistance, relationships between mechanical properties of samples and rubber particles content were studied. Scanning electron microscope (SEM) was applied to analyze the micro-morphology and elemental composition of samples, X-ray diffraction (XRD) was engaged to identify the product phases. The tests results showed that compressive strength of mixtures decreased with the rubber particles content increasing and the early strength effect was obvious, splitting strength decreased slightly. It also indicated that the addition of rubber particles can improve the frost resistance of the mixtures. As a result, the frozen stability coefficient (K) of samples was improved from 0.89 to 0.97. XRD and SEM analyses showed that calcium silicate hydrate (CSH) was resultant and the interface bonding between sand and CSH was better than rubber particles and CSH, which the latter had interface cracks.

Unified modeling of setting and strength development

The effect of temperature on the development of concrete compressive strength can be modeled by the maturity approach once the temperature sensitivity of the mixture, quantified by the activation energy ( E a) of its chemical reactions, is known. It is common in maturity applications to use a unique value of E a obtained for the hardening period, even though the effect of temperature is different on the rate of setting and hardening. E a-values presented in the literature suggest that the temperature sensitivity is lower before hardening. This paper proposes a new approach to the traditional maturity method unifying the distinctly different temperature sensitivities before final setting and during hardening. Results of setting and compressive strength of mixtures with different cementitious materials were analyzed with activation energy values calculated for the periods before final setting and during hardening. For the investigated mixtures, the new approach led to improved strength predictions, suggesting that it is useful to take into account setting behavior in the development of the strength–maturity relationship.

Characteristics and durability of cements containing fly ash and limestone subjected to Caron's Lake water

In most countries, limestone and pozzolanas are widely used in Portland cement because such additions increase the chemical resistance to sulfate and/or chloride attack, impermeability and lower the heat of hydration of concrete. This study aimed to investigate the effect of fly ash (FA) and limestone (LS) on the hydration and durability of ordinary Portland cement (OPC) subjected to Caron's Lake water. The results revealed that the increase of LS content increased the water of consistency (normal consistency) of cement pastes, whereas the initial and final setting times were reduced by up to 30%. The portlandite contents of mixtures containing FA decreased. At the same time, an increase of LS content from 10 to 20% decreased the portlandite content by up to 90 days. On the other hand, the portlandite content of 30% LS increased by up to 90 days. Cement pastes containing FA had the lower values of total sulfate and chloride contents than sulfate-resisting cement pastes. The compressive strength of mixture M.10 (20% FA and 10% LS) showed higher compressive strength values than the other cements when immersed in both curing media, namely tap and Caron's Lake water. It is recommended that cements that are to be used for underground concrete structures or marine structures that are exposed to sulfate-containing seawater do not contain more than 10–20% of LS.

New technique for improvement on reactivity of cement industry wastes

A new technique, in which fly ash was first ground before grinding together with cement kiln dust (CKD), was developed in order to activate reactivity of CKD–fly ash systems. Test results of particle size distribution, rate of heat evolution and compressive strength of mixtures made with the new technique are discussed and compared with those of mixtures made with previous technique, in which CKD and fly ash were ground together without prior grinding of fly ash. The test results showed that CKD–fly ash mixtures made with the new technique exhibited significantly improved performance in comparison with that of mixtures made with the previous process.

Impedance spectroscopy of chemically enhanced clays used for adobe construction

Sun-dried clay or mud bricks were one of the first building materials used by man. The main advantages of these materials are: their availability in dry regions, their low cost and their remarkable insulating properties. However, compared to other materials, the physical properties such as compressive strength and water absorption are very low and very high, respectively. The aim of this work is to develop high performance clay composition with the highest compressive strength and the lowest water absorption using chemically enhanced clay mixtures, which can find applications in the building industry. In the present work the impedance spectroscopy technique is used to study the development of both high compressive strength and low water absorption of different mixtures, namely: a) clay + water, b) clay + acrylic emulsion, and c) clay + asphalt emulsion + acrylic emulsion. Thus, for these mixtures it was shown that impedance spectra consisted of two semicircles: one describes the electrical properties of the clay and the other one represents those of the capillary porosity. In addition, it was found that the mechanical properties such as compressive strength of the mixtures are related to the amount of capillary porosity. The results obtained have shown that the mixture clay + acrylic emulsion + asphalt emulsion has the best combination of reasonable compressive strength and low water absorption, for a clay likely to be used for adobe construction.

Limestone Crusher-Run and Tailings in Compaction Concrete for Pavement Applications

Laboratory experimentation indicates that both limestone crusher-run and finely grained limestone tailings (by-products of the aggregate-mining industry) can be used in concrete made with an emerging technology for flatwork contruction known as roller compacted concrete (RCC). This paper reports on tests of laboratory specimens using various combinations of mix components and proportions. The unit cost of concrete progressively decreases as the graded coarse aggregate is substituted with the crusher-run and as the tailings are added. On the other hand, the compressive strength of mixtures including the crusher-run is better than that of graded coarse aggregate and is further improved by the addition of tailings.