Normal Concrete Mix Research Articles

PERFORMANCE OF CONCRETE MADE WITH CRUSHED CLAY BRICKS AS COARSE AGGREGATE

Because of economic considerations and thermal insulation requirements, it seems necessary therefor to produce lightweight concrete obtained by crushing an enormous tons of building demolition wastes have been produced. In this study, it is gintended to investigate smashed and the possibility of using crushed clay bricks to replace the coarse aggregate (gravel) in concrete mies. Four nominal normal concrete mixes and four more mixes of crushed clay brick aggregate were prepared and tested. The crushed clay brick aggregates were produced by crushing the brick units (locally available and manufactured in Iran) manually and collected into described size (20 mm). From the analysis of the results, it was found that the unit weight of the crushed brick concrete ranged from (1685-1760) kg/m3 and its compressive strength was about 61% of that of the natural aggregate concrete while the flexural strength was 70% of natural aggregate concrete. Also, the relation between compressive and flexural strength for the lightweight concrete produced is similar to that of normal concrete. Moreover, the results indicated the suitability of the crushed clay brick aggregate concrete to be used in buildings.

Effect of Partial Replacement of Slag and Nano Silica Infused Slag on Properties of Concrete

Investigations were carried out on the changes in properties of concrete when steel slag is used in concrete in its normal form and after modifying its properties by infusing it with nano-silica. The sand is replaced by steel slag and modified steel slag by 10%, 20% and 30% in M30 grade concrete. Tests results on compressive strength and workability of concrete revealed that compressive strength of concrete cubes after 28 days increased by 25.4%, 26.4% and 45.2% for 10%, 20% and 30% respectively after replacing sand by steel slag. After modification of steel slag properties by infusing it with nano silica, the 28 days compressive strength was observed to be increased by 38.19%, 35.80% and 27.89% for 10%, 20% and 30% as compared to traditional concrete mix respectively after replacement. Infusing steel slag with nano silica increased the compressive strength of concrete mix by 20.17%, 25.74% and 49.64% for 10%, 20% and 30% respectively when compared to normal steel slag concrete mix. It was also observed that using steel slag in concrete mix also influences on water consumption in concrete mix. Workability tests conducted using 0.45 and 0.5 w/c ratio and the inference was that the workability increased with the increase in percentage of steel slag but workability decreases with the increase in percentage of modified steel slag.

Tension stiffening approach for interface characterization in recycled aggregate concrete

This study proposes a comprehensive analysis on the structural performance of reinforced Recycled Aggregate Concrete members. Particularly, it summarizes the results of an experimental investigation aimed at analyzing the tension stiffening behavior of normal and high strength class concretes produced with Recycled Concrete Aggregates (RCAs). The mixtures were proportioned in order to achieve 25 and 65 MPa of compressive strength and, moreover, several recycled-to-natural coarse aggregates replacement ratios were considered: 0%, 25% and 50%. The results derived from this type of test furnish a comprehensive analysis on both the steel-to-matrix interaction and the crack formation and propagation on concrete elements as well as distributed cracking mechanisms. Using a finite difference numerical model, the experimental results are used to back-calculate and identify the steel-to-concrete bond slip law. Also, it is an alternative mean of developing the stress-crack-width law for concrete in tension. The results showed that the use of recycled concrete aggregate does not affect the resulting concrete performance and, therefore, the RCAs can be successfully employed, up to the levels analyzed herein, for the production of structural elements made with normal and high strength class concrete mix.

Compression Strength Concrete with Pond Ash Lati Berau

Handling of coal burning waste of thermal power plant in Lati, Berau district, East Kalimantan province, which is recommended by the department of environmental impact management is to dispose the coal ash into pools flowed water so that coal ash did not fly and cause air pollution. As known that coal ash waste is included hazardous and toxic waste, therefore managing it carefully is a necessity. Sediment or heap of coal ash in the sedimentation pond that is flowing with water is called Pond Ash. This study is conducted by utilizing the pond ash as a replacement material in the concrete mix. The effect of the use of pond ash as partial replacement of sand, fine aggregate in the concrete mix, is studied using cylindrical specimen with a diameter of 100 mm and a height of 200 mm. Specimens were made by taking the ratio of the percentage of pond ash of 0%, 5%, 10%, 15% and 20% of the mixture of concrete with the constant water cement ratio 0.49 which is based on the results of normal concrete mix design. The compressive strength test of concrete was conducted at ages 1, 3, 7, 14, 28 and 90 days. The test results of compressive strength of concrete obtained showed an increase in compressive strength in accordance with the addition of pond ash in the mix. The adding of pond ash in the mix affected the increasing in the compressive strength of concrete, and the optimum strength is obtained in the ratio of 17% pond ash, which increased to 26.08 MPa from 25.05 MPa for concrete with and without pond ash mixes respectively, or increased by 4.12%. This increase is not significant and cannot be used as a reference, however, by the results of this study it can be concluded that the pond ash waste can be utilized for the manufacture of concrete as a partial replacement of sand.

Overview of studies on the effect of recycled aggregates sourced from tested cylinders on concrete material and structural properties

The paper presents an overview of a two-phase research program that was designed at the American University of Beirut (AUB) to investigate the effect of replacing different percentages of natural coarse aggregates (NCA) with recycled coarse aggregates (RCA) on the properties of the produced concrete. The source of RCA was tested cylinders in batching plants which would help recycling and reusing portion of the waste products of the concrete industry. In the first phase, the fresh and hardened mechanical properties of the produced concrete mix were investigated. The variables were the concrete strength (28 or 60 MPa) and the percentage replacement of NCA with RCA from crushed tested cylinders [0 (control), 20, 40, 60, 80, or 100%). Normal strength tested cylinders were used as source of the recycled aggregates for the normal strength concrete (NSC) mix and high strength tested cylinders were used for the high strength concrete (HSC) mix. Tests included plastic state slump and hardened state mechanical properties including cylinder compressive strength, cylinder splitting tensile strength, modulus of elasticity, and standard beams flexural strength. The results indicated no significant effect on the slump and around 10% average reduction in the hardened mechanical properties for both investigated levels of concrete compressive strength. In the second phase, the structural behavior of normal strength concrete (NSC) reinforced concrete beams prepared by replacing different percentages of NCA with RCA from tested concrete cylinders was studied. For each of three modes of failure (flexural, shear, or bond splitting), three beams with different percentages replacement [0 (control), 40, or 100 percent] were tested. One replicate was prepared for each beam to validate the test results. Results indicated no significant difference in the ultimate load reached or load-deflection behavior that could be related to the percentage replacement of NCA with RCA.

Stress-Strain Relationship for Steel-Fiber Reinforced Polymer Modified Concrete under Compression

The present study, concern about an experimental work to study the stress-strain relationship of steel-fiber reinforced polymer modified concrete under compression. Four different mixes with weight proportions of (1:2:4) were used as; normal weight concrete (NC), polymer modified concrete (PMC) with (10%) of cement weight and two mixes of steel-fiber polymer modified concrete with (1%) and (2%) volume fraction of steel fiber, (SMPC). The influences of polymer and fiber addition on peak stress, strain at peak stress and the stress-strain curve were investigated for concrete mixes used. For all selected mixes, cubes (150×150×150mm) were made for compressive strength test at (28) days while stress-strain test was caried out on cylinders (150 mm  300 mm) at the same age. Results showed an improvement in compressive strength of polymer modified concrete (PMC) over reference mix, the maximum increase of it was (13.2 %) at age of (28) days. There is also an increase in compressive strength with increasing of steel fibers content with comparison to normal concrete, the maximum increases of it were (19.6% and 25.2%) of mixes with 1% and 2% fiber content by volume respectively. In terms of modulus of elasticity, the addition of polymer and the presence of fibers cause a significant increase in it. The peak of stress- strain curve for normal strength concrete (Mix No.1) was linear whereas it was more sharp for the other mixes. The behaviour of normal strength concrete (Mix No.1) was linear up to 20 % of ultimate strength, while for the mixes with the higher strength i.e. polymer modified concrete and fibers reinforced concrete (Mixes No.2, 3 and 4) the linear portion increases up to about 50 % of ultimate strength

Strength Characteristics of Groundnut Leaf/Stem Ash (GLSA) Concrete

Abstract The compressive strength properties of concrete are substantial factors in the design and construction of concrete structures. Compressive strength directly affects the degree to which the concrete can be able to carry a load over time. These changes are complemented by deflections, cracks etc., in the structural elements of concrete. This research investigated the effect of groundnut leaf/stem ash (GLSA) on the compressive strength of concrete at 0%, 5 %, 10 % and 15 % replacements of cement. The effect of the water-cement ratio on properties such as the compressive strength, slump, flow and workability properties of groundnut leaf/stem ash (GLSA) mixes with OPC were evaluated to determine whether they are acceptable for use in concrete structural elements. A normal concrete mix with cement at 100 % (i.e., GLSA at 0%) with concrete grade C25 that can attain an average strength of 25 N/mm2 at 28 days was used as a control at design water-cement ratios of 0.65 and grading of (0.5-32) mm from fine to coarse aggregates was tested for: (1) compressive strength, and the (2) slump and flow Test. The results and observations showed that the concrete mixes from GLSA at 5 – 15 % ratios exhibit: pozzolanic properties and GLSA could be used as a partial replacement for cement at these percentage mix ratios compared with the control concrete; an increase in the water-cement ratio showed a significant decrease in the compressive strength and an increase in workability. Therefore, it is important that all concrete mixes exude an acceptably designed water-cement ratio for compressive strength characteristics for use in structures, water-cement ratio is a significant factor.

Mechanical Properties of Self Compacting Concrete Made with Local Materials

The main objective of this research is to investigate the properties of fresh and hardened self-compacting concrete (SCC) made from locally available materials in Basrah governorate-Iraq. The study consists of investigation the influence of volume ratio of coarse aggregate, limestone powder (LSP) to total powder ratio, and powder/water ratio. This is to obtain more information which will contribute to a better understanding to the use of local materials in production of SCC.To achieve these aims, 18 different mixes (17 SCC mixes and one normal concrete (NC) mix were prepared, tested and evaluated. It has been noticed that, with the same W/C ratio, SCC mixes prepared with higher coarse aggregate volume ratio showed higher strengths and modulus of elasticity than mixes prepared with lower coarse aggregate volume ratio. The increment of LSP as a replacement of cement leads to lower strengths and static modulus of elasticity. For the same compressive strength at 28 days, SCC showed 11%, 20% and 26.4% higher flexural, splitting tensile and bond strengths than NC respectively

AN EXPERIMENTAL STUDY ON MUD CONCRETE USING SOIL AS A FINE AGGRGATE AND LD SLAG AS COARSE AGGREGATE

Aggregates are important ingredients of concrete. Sand is used abundantly after air and water. The extensive use of these natural resources is exploiting the environment every day. many alternative materials are being used, viz., slag sand, manufactured sand, quarry dust etc., as fine aggregates; Materials such as steel slag, blast furnace slag are being used as replacement for coarse aggregates. This paper reports the result of different mixes obtained by partial replacement of Natural coarse aggregates (NCA) and complete replacement of fine aggregates (FA) by alternative material such as LD slag and Natural soil respectively. This paper reports the result of different mixes obtained by partial replacement of natural coarse aggregates (CA) and complete replacement of fine aggregates (FA) by alternative material such as LD slag and Natural soil respectively. The wet compressive strength ranged from 16MPa to 20MPa for cubes made of Natural Sand and Natural Coarse Aggregates MIX-D. The wet compressive strength ranged from 18-26MPa for MIX-A; The value obtained for MIX-A was found to be 20% more compared to MIX-D. The split tensile strength ranged from 1.16-1.51MPa for MIX-A, it was concluded that, the mud concrete mix prepared with soil and LD slag gave the satisfactory result which was intended to achieve by normal conventional concrete mix MIX-D. The flexural strength ranged from 3.04-3.41MPa for MIX-A and 2.84-3.45MPa for M4, , it was concluded that, the mud concrete mix prepared with soil and LD slag gave the satisfactory result which was intended to achieve by normal conventional concrete mix. The mud concrete with Soil and LD slag cut down the cost of mix up to 43% when compared with normal conventional concrete of equivalent grade.

Impact resilience of multiscale fibre reinforced composites

This research considered cementitious composites reinforced with macroscale, microscale and nanoscale fibres. Ten test groups including a combination of the multiscale fibres (steel fibres, polyvinyl alcohol (PVA) fibres and carbon nanofibres (CNFs)) were studied. An experimental programme was developed to determine the compressive, tensile and flexural strength as well as impact toughness. This multiscale fibre reinforcement (steel, PVA and CNFs) in normal concrete mixes for practical applications led to a tenfold increase in impact resilience, based on a small-scale repeated impact test performed in this study, and also considerably enhanced the tensile strength of the cementitious composites. On the other hand, cementitious composites singly reinforced with nanoscale CNFs in normal concrete mixes including coarse and fine aggregates showed negligible improvements in impact toughness and tensile strength. Three-point bending tests on reinforced concrete beam specimens showed that the macroscale structural performance of the concrete members was enhanced with the addition of multiscale fibres. The toughness or energy absorption capability increased by 29%. It is therefore concluded that multiscale fibre reinforcement, including CNFs, has the potential to reduce the projectile–target collision force due to increased ductility of the concrete members and to alleviate concrete spalling resulting from projectile penetration on account of increased toughness.

Effect of Superplasticizer Dosage on Workability and Strength Characteristics of Concrete

The use of chemical admixtures in concrete is a common solution to achieve full compaction particularly where reinforcement congestion and shortage of skilled workers. The past researchers have been underscored the use of chemical admixtures imparts the desirable properties to concrete in both fresh and hardened state. This paper has been made an attempt to study the influence of superplasticizer dose of 400ml, 600ml, 800ml, 1000ml and 1200ml/100 kg of cement on performance of Concrete. The experimental tests for fresh and hardened properties of concrete for three mixes of 30 MPa grade are studied and the results are compared with normal concrete. The tests considered for study are, slump test, slump loss, flow table and compressive strength test The results show that for the constant water cement ratio, increase of superplasticizer dose in properties of concrete leads to gain of good workability. Moreover, there is also increase in compressive strength than that of normal concrete mix.

Design of Normal Concrete Mixtures Using Workability-Dispersion-Cohesion Method

The workability-dispersion-cohesion method is a new proposed method for the design of normal concrete mixes. The method uses special coefficients called workability-dispersion and workability-cohesion factors. These coefficients relate workability to mobility and stability of the concrete mix. The coefficients are obtained from special charts depending on mix requirements and aggregate properties. The method is practical because it covers various types of aggregates that may not be within standard specifications, different water to cement ratios, and various degrees of workability. Simple linear relationships were developed for variables encountered in the mix design and were presented in graphical forms. The method can be used in countries where the grading or fineness of the available materials is different from the common international specifications (such as ASTM or BS). Results were compared to the ACI and British methods of mix design. The method can be extended to cover all types of concrete.

Utilisation of Fly Ash and Fibre in Concrete

Strength of fly ash concrete made with 10, 15, 20 % and fibre made with 0.1, 0.15, 0.20 % of cement replacement was evaluated in terms of its relation with compressive strength and workability test. Comparison was made between ordinary Portland cement and fly ash concrete and natural fibre. Test results indicated that strength of concrete having cement replacement up to 15% of fly ash and 0.15% of fibre was comparable to the normal concrete mix without fly ash and fibre. The results confirm that fly ash concrete and fibre concrete is a promising material for long term strength development. This was due to the fact that early age strength of fly ash and fibre concrete was lower as compared to strength of control concrete. From the viewpoint of sustainable development, it is a strongly viable solution as a building material in the years ahead.

Lowering paste volume of SCC through aggregate proportioning to reduce carbon footprint

The production of SCC (self-consolidating concrete) generally requires a fairly high paste volume, ranging typically from 35% to 40%. This is to achieve the high flowability, high segregation resistance and high passing ability needed. However, a high paste volume would lead to low dimensional stability and high carbon footprint. Hence, increasing the paste volume of an otherwise normal concrete mix is not a good method of SCC production. There is a necessity to lower the paste volume of SCC so as to avoid the adverse effects of high paste volume and reduce the carbon footprint. Herein, it is proposed to adjust the aggregate proportions to maintain the performance of the SCC while lowering the paste volume. Trial concrete mixes are tested to demonstrate how the paste volume can be lowered through aggregate proportioning. Overall, the test results reveal that with suitable aggregate proportioning, the paste volume can be lowered to as low as 26% and that the volume of aggregate particles finer than 1.18mm has major effect on the passing ability of SCC.

Performance of Iron Ore Tailings as Partial Replacement for Sand in Concrete

This paper reports preliminary findings on the properties of concrete produced using iron ore tailings obtained from ZCM Minerals SDN BHD located in Kotta Tingi, Johor, Malaysia. The Iron Ore Tailings (IOT’s) a waste product, with particle size range from (850μm - 75μm) obtained from Iron Ore Processing was utilized as fine aggregate to produce concrete. Based on British Standard (BS) guidelines, normal concrete mix was designed. Five types of concrete samples (C0, C1, C2, C3, and C4) were produced, with the percentage of tailings used to replace sand as fine aggregate ranging from 0 to 40[%]. The reference sample is C0 with no tailings and the four others, containing tailings at 10[%] intervals. The effect of iron ore tailings on the consistency of the fresh concrete were studied, as well as the density, compressive strength, flexural strength and splitting tensile strength, of the hardened concrete. The results of the consistency tests on concrete shows that the slump values ranges from 81 to 53[mm] from concrete sample C0 to C4 respectively, while the compacting factor values ranges from 0.92 to 0.89 respectively. The density of the produced concrete cube samples falls within the range 2350 to 2430[kg/m3]. The concrete sample C3 gave the highest compressive strength value of 43.70[N/mm2]. The concrete sample C3 also gave the highest flexural strength value of 4.79[N/mm2], while the The concrete sample C4 gave the highest splitting tensile strength value of 4.0[N/mm2] after curing period of 28[days].

Porosity of Self-compacting Concrete

The construction industry demands more durable concrete with high performance. Self-compacting concrete (SCC) is developing gradually to meet many aspects of construction technology, especially reinforced concrete. On the other hand, durability properties still need some enhancements particularly in term of microstructure properties. Furthermore, there is a lack of research on non-destructive testing of self-compacting concrete. Question arises: are the contexts on the strength of conventional normal concrete (NC) extendable on the strength of SCC? Laboratory tests were carried out at the BME, Department of Construction Materials and Technologies. Aim of the research was to determine the service life of SCC with respect to normal concrete. Constant and variable parameters were determined to the concrete mixes. Constant parameters were: type of cement CEM III-A 32.5 N-MS and grading curve of the aggregate. Variable parameters were: water-cement ratio, content of cement, content of limestone powder. The purpose of this study is to analyze the implementation of economical non-pozzolanic filler additive (limestone) into the concrete matrix of SCC. Normal and Self-compacting concrete mixes were prepared to reach a correlation between porosity indicators. Results indicated that SCC mixtures had more reliable rebound index and lower total porosity values than NC; whereas water absorption in SCC was found to show considerably higher values than referred NC mixes.

Measuring static stability and robustness of self-consolidating concrete using modified Segregation Probe

Compared with normal concrete mixes, the segregation resistance of self-consolidating concrete (SCC) are more sensitive to small variations of properties such as gradation and moisture content of aggregates, type and dosage of superplasticizer, etc. To study segregation and design an SCC mix, which is robust against small variations in raw materials, it is critical to be able to quickly quantify static segregation and stability robustness. In this paper, a modified Segregation Probe is introduced as a simple and fast method for testing static segregation and stability robustness of fresh concrete. The modified Segregation Probe resolved the occasional tilting problem of the original design. The design of the modified Segregation Probe was explained based on rheology and mechanics analysis. The results of the modified Segregation Probe agreed well with the Penetration Test (ASTM C1712-09), the Column Segregation test (ASTM C1610/C1610 M-10), and the original Segregation Probe (when no tilting problem happened). Lastly, the procedure to test and quantify stability robustness using modified Segregation Probe is presented.

Fresh and Hardened Properties of Self- Compacted Concrete at Different Curing Regimes(eng)

The aim of this study is to compare the properties of three self-compacted concrete (SCC) mixes, with normal concrete mix. For the SCC mixes, the cement was replaced partially with either limestone dust or clinker waste dust. Compressive strength, tensile splitting, and flexural strength tests were conducted at ages of 3, 7, 14, 28, and 56 days to trace the strength development. Modulus of elasticity tests were conducted at 28-days. The test results showed that mixes containing lime-stone dust have better fresh properties than the other SCC mix. The compressive strength test results showed that the mix containing clinker waste powder give higher compressive strength. and mix containing eight percent limestone give higher tensile splitting strength and flexural strength than the mix has ten percent of limestone give for all curing regimes. The results showed that the modulus of elasticity is relatively lower than that for normal concrete and the voids volume in normal concrete is greater than that of SCC. Keywords: Clinker dust, Compressive strength, Concrete, Fresh properties, Lime-stone

Influence of Powder and Paste on SCC Using Recycled Concrete Aggregate

The use of recycled concrete aggregate is an important issue for preserving the natural resources, protecting the environment, saving of energy and for sustainable development. In this study, a unique simple mixture proportioning method was successfully adopted for developing SCC based on the absolute volume concept, starting with a volume of paste with maximum aggregate size of 20 mm. The method involved very few trials with different types of aggregate that can be advantageously used in field practice. The volume of paste chosen was 0.38 to 0.43 fraction of the total mix. Natural crushed angular granite and recycled demolished concrete waste were used as aggregate for making SCC with fly ash as filler. SCC and vibrated normal concrete mixes were made for varying cement contents of 300 kg/m 3 to 450kg/m 3 and for a constant water content of 185 l/m 3 . Cubes of 150 mm size were cast and tested for compressive strength at different ages of 7, 28 and 60 days. The results indicate that higher paste content not only makes the mix more cohesive with better lubrication of aggregates, but also increases the slump flow (reduces yield stress) and compressive strength. The 28 day compressive strength of SCC with both natural and recycled concrete aggregate showed higher compressive strength than vibrated normal concrete and significant increase at later age, possibly due to pozzolanic activity of the filler material (fly ash). However, the compressive strength of SCC mixes with recycled concrete aggregate has a lower value, when compared with SCC mixes of natural crushed angular granite aggregate at the same age. The study clearly shows the importance of paste in SCC and the advantage of using recycled concrete aggregate with better performance than the vibrated normal concrete with natural crushed aggregate and can go a long way in conserving the natural resources by the use of recycled concrete aggregate for sustainable development.

Performance of Fiber normal – weight concrete Exposed to Elevated Temperatures

The main rule of this search is determining the effect adding various types of fiber to normal concrete mixes on performance normal strength concrete ,it has been used three types of fibers (glass, short steel fibers& long steel fibers)with different contents in mixes(0.5,1.0&1.5%) respectively. It had been cast (210) cubes with dimensions (100×100×100m) mm,(160) cylinders with dimensions (100×200) mm , All concrete specimens heated under different temperatures (100,200,300,400,500 &600 C°) at age 28 days, so that it had been stayed under specified temperatures about two hours then , cooled in naturally in room temperatures and tested in compressive for cubes &splitting strength for cylinders. The results stated that the fiber improve the compressive strength under fire temperatures about (87%) compare with reference mixes, and the fiber glass take little differences than steel fiber in splitting strength when its content reach (1.0,1.5%) respectively and using this types of fibers improved the properties of concrete against the fire.