EFFECTS OF AGGREGATE SIZE ON FLEXURAL STRENGTH AND DENSIFICATION OF CEMENTITIOUS MATERIALS PRODUCED BY EXTRUSION MOULDING

Grouts have numerous applications in construction industry such as joint sealing, structural repair, and connections in precast elements. They are particularly favoured in rehabilitation of structures due to penetrability and convenience of application. Grouts for repair applications typically require high-performance properties such as rapid strength development and superior shrinkage characteristics. Sometimes industrial by-products referred as supplementary cementitious materials (SCM) are used with neat cement due to their capabilities to provide binding properties at delayed stage. Micro silica, fly ash and metakaolin are such SCMs, those can modify and improve properties of cement products. This study aims at investigating long-term mass loss and linear shrinkage along with long-term compressive and flexural strength for grouts produced from ultrafine cement and SCMs. A series of mixtures were formulated to observe the effect of SCMs on these grout properties. Properties were determined after 365 days of curing at 23oC and 55% relative humidity. The effect of SCMs on the properties are characterised by statistical models. Response surfaces were constructed to quantify these properties in relation to SCMs replacement. The results suggested that shrinkage was reduced by metakaolin, while micro silica and fly ash had positive effects on compressive and flexural strength, respectively.

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Enhancing the Flexural Strength of Concrete using Recycled Iron and Steel Slag Aggregate

LAUTECH Journal of Civil and Environmental Studies ◽

10.36108/laujoces/1202.70.0140 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

A. A Raheem

Keyword(s):

Tensile Strength ◽

Flexural Strength ◽

Concrete Beams ◽

Steel Slag ◽

Aggregate Size ◽

Mineralogical Composition ◽

Maximum Aggregate Size ◽

Considerable Effort ◽

Iron And Steel ◽

Coefficient Of Uniformity

Concrete is strong in compression but weak in tension hence, considerable effort is required to improve concrete’s tensile strength by the use of pre-stressed concrete and addition of admixtures or additives. In this study, the use of recycled iron and steel slag (RISS) aggregate to improve the tensile strength of concrete was considered. The paper assessed the mineralogical composition of RISS and granite aggregates, and gradation. It also determines the effects of RISS aggregate on the flexural strength of concrete beams of 150 × 150 × 600 mm containing 0, 10, 20, 40 and 60% RISS aggregate replacement in mix ratios 1:1½:3, 1:2:4 and 1:3:6 with water cement ratios 0.65,0.60 and 0.55 respectively. Diffractograph of RISS and granite aggregate showed that RISS contains Magnetite, Ilmenite and Quartz, while granite contains Quartz, Annite, Microcline and Albite as the predominant minerals. The coefficient of uniformity and concavity of RISS and granite aggregate for maximum aggregate size of 37.5 mm are 4.35 and 1.33; and 4.64 and 1.76 respectively. Both aggregates contain quartz as the predominant mineral and are well graded. The result of the Flexural strength at 28 days curing is within 0.135 – 0.250 MPa specified byBS8500 – 2:2015. Flexural strength of concrete beams cast with RISS aggregate is relatively higher than concrete cast with granite aggregate. Flexural strength, a measure of tensile strength of concrete is improved as percentage RISS aggregate increased.

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Effect of Aggregate Max Size on the Rheological Properties of Self Consolidating Concrete

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.853.193 ◽

2020 ◽

Vol 853 ◽

pp. 193-197

Author(s):

Samer Al Martini ◽

Ziad Hassan ◽

Ahmad Khartabil

Keyword(s):

Blast Furnace Slag ◽

Aggregate Size ◽

Maximum Size ◽

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Self Consolidating Concrete ◽

Granulated Blast Furnace Slag ◽

Concrete Mixtures ◽

Time Period ◽

Furnace Slag

The effects of aggregate size and supplementary cementitious materials (SCMs) on the rheology of self-consolidating concrete (SCC) were studied in this paper. Two main concrete mixtures with different maximum aggregate sizes were prepared and investigated. The first mix had a maximum size aggregate of 5 mm and the second mix was with 20 mm max size aggregates. All mixes incorporated different dosages of Ground granulated blast furnace slag (GGBS). The rheology of all mixes investigated was measured over 2 hour time period. It was found that the size of aggregates and GGBS dosage have influence on the yield stress of studied concrete mixes.

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Stress-Strain Behavior of Cementitious Materials with Different Sizes

The Scientific World JOURNAL ◽

10.1155/2014/919154 ◽

2014 ◽

Vol 2014 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Jikai Zhou ◽

Pingping Qian ◽

Xudong Chen

Keyword(s):

Flexural Strength ◽

Size Effect ◽

Cement Mortar ◽

Strain Curve ◽

Cementitious Materials ◽

Test Results ◽

Stress Strain ◽

Strain Behavior ◽

Modified Equation ◽

Good Agreement

The size dependence of flexural properties of cement mortar and concrete beams is investigated. Bazant’s size effect law and modified size effect law by Kim and Eo give a very good fit to the flexural strength of both cement mortar and concrete. As observed in the test results, a strong size effect in flexural strength is found in cement mortar than in concrete. A modification has been suggested to Li’s equation for describing the stress-strain curve of cement mortar and concrete by incorporating two different correction factors, the factors contained in the modified equation being established empirically as a function of specimen size. A comparison of the predictions of this equation with test data generated in this study shows good agreement.

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The Effect of Sisal Juice Extract Admixture on Compressive and Flexural Strength of Cement Concrete

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.4030 ◽

2021 ◽

Vol 11 (2) ◽

pp. 7041-7046

Author(s):

M. O. Eloget ◽

S. O. Abuodha ◽

M. M. O. Winja

Keyword(s):

Compressive Strength ◽

Flexural Strength ◽

Cementitious Materials ◽

Strength Development ◽

Concrete Durability ◽

Flexural Test ◽

Concrete Compressive Strength ◽

Cement Concrete ◽

Shrinkage Cracking ◽

Lower Permeability

The characteristics of concrete are influenced by the ratio of water to cementitious materials (w/c) used in the mixture. An increase in paste quality will yield higher compressive and flexural strength, lower permeability, increased resistance to weathering, improve the bond between concrete and reinforcement, reduced volume change from drying and wetting, and reduced shrinkage cracking tendencies. Admixtures are used to improve the properties of concrete or mortar. The current study investigates the effect of Sisal Juice Extract (SJE) as an admixture on concrete durability. SJE contains unrefined minerals which can be used as organic retarders to increase the rate of strength development at an early age. A total of 84 concrete cubes were produced in 7 sets of 12 samples each. One set was the control mix which had zero SJE content. The remaining sets had varying dosages of SJ namely 5%, 10%, 15%, 20%, 25%, and 30%. Twelve beam specimens were also cast and subjected to the three-point flexural test. To establish the effect on strength of concrete, compressive strength was tested at 7, 14, 28, and 56 days while flexural strength was tested at 28 days. The highest compressive strength was achieved at 5% dosage beyond which a decrease in strength occurred for all the higher dosages.

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Compressive and Flexural Strength Property Enhancement for Fibre Reinforced Standard Concrete (FRSC), High Strength Concrete (FRHSC) and High Performance Concrete (FRHPC) using Foundry Sand (FS) and Crushed Concrete Waste (CCW)

Journal of Construction Research ◽

10.30564/jcr.v2i2.2594 ◽

2021 ◽

Vol 2 (2) ◽

Author(s):

Pruthviraj S R ◽

Ravi Kumar C M ◽

Yajnodbhavi H M ◽

Maruthi T ◽

Raghavendra S

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

High Performance ◽

High Performance Concrete ◽

Research Work ◽

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Specific Test ◽

Foundry Sand ◽

Crushed Concrete

Now days, many research works are carried for all grades of concrete to make the concrete most economical and durable there by adding the supplementary cementitious materials and alternative replacement aggregates. In this research work deals with the experimental investigation of mechanical properties of the M30, M50 and M80 grade concrete by replacing the fine and coarse aggregate by foundry sand and crushed concrete waste respectively. Mix design procedures were followed as per IRC44:2017 guidelines and recommendation. Proper dosage of super plasticizer (SP) was maintained in the concrete to make it better performed. In this present investigation, a Poly Propylene fibre (PPF) of 0.3% by weight of the cement is used. Mechanical properties such as Compressive strength and Flexural Strength were determined by preparing the respective mould sizes for specific test and are cured for 7, 14 and 28 days and result obtained for respective days were tabulated and discussed.

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Bamboo Sawdust as a Partial Replacement of Cement for the Production of Sustainable Cementitious Materials

Crystals ◽

10.3390/cryst11121593 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1593

Author(s):

Yunyun Tong ◽

Abdel-Okash Seibou ◽

Mengya Li ◽

Abdelhak Kaci ◽

Jinjian Ye

Keyword(s):

Flexural Strength ◽

Lightweight Concrete ◽

Mechanical Performance ◽

Cold Water ◽

Cementitious Materials ◽

Cementitious Material ◽

Hot Water ◽

Partial Replacement ◽

Cement Matrix ◽

Masonry Construction

This paper reports on the utilization of recycled moso bamboo sawdust (BS) as a substitute in a new bio-based cementitious material. In order to improve the incompatibility between biomass and cement matrix, the study firstly investigated the effect of pretreatment methods on the BS. Cold water, hot water, and alkaline solution were used. The SEM images and mechanical results showed that alkali-treated BS presented a more favorable bonding interface in the cementitious matrix, while both compressive and flexural strength were higher than for the other two treatments. Hence, the alkaline treatment method was adopted for additional studies on the effect of BS content on the microstructural, physical, rheological, and mechanical properties of composite mortar. Cement was replaced by alkali-treated BS at 1%, 3%, 5%, and 7% by mass in the mortar mixture. An increased proportion of BS led to a delayed cement setting and a reduction in workability, but a lighter and more porous structure compared to the conventional mortar. Meanwhile, the mechanical performance of composite decreased with BS content, while the compressive and flexural strength ranged between 14.1 and 37.8 MPa and 2.4 and 4.5 MPa, respectively, but still met the minimum strength requirements of masonry construction. The cement matrix incorporated 3% and 5% BS can be classified as load-bearing lightweight concrete. This result confirms that recycled BS can be a sustainable component to produce a lightweight and structural bio-based cementitious material.

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Properties of Mortar with Recycled Aggregates, and Polyacrylonitrile Microfibers Synthesized by Electrospinning

Materials ◽

10.3390/ma12233849 ◽

2019 ◽

Vol 12 (23) ◽

pp. 3849 ◽

Cited By ~ 1

Author(s):

Manuel J. Chinchillas-Chinchillas ◽

Manuel J. Pellegrini-Cervantes ◽

Andrés Castro-Beltrán ◽

Margarita Rodríguez-Rodríguez ◽

Víctor M. Orozco-Carmona ◽

...

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Flexural Strength ◽

Total Porosity ◽

Cementitious Materials ◽

Effective Porosity ◽

Recycled Aggregates ◽

Capillary Absorption ◽

Fine Aggregate ◽

Water Penetration

Currently it is necessary to find alternatives towards a sustainable construction, in order to optimize the management of natural resources. Thus, using recycled fine aggregate (RFA) is a viable recycling option for the production of new cementitious materials. In addition, the use of polymeric microfibers would cause an increase in the properties of these materials. In this work, mortars were studied with 25% of RFA and an addition of polyacrylonitrile PAN microfibers of 0.05% in cement weight. The microfibers were obtained by the electrospinning method, which had an average diameter of 1.024 µm and were separated by means of a homogenizer to be added to the mortar. Cementing materials under study were evaluated for compressive strength, flexural strength, total porosity, effective porosity and capillary absorption, resistance to water penetration, sorptivity and carbonation. The results showed that using 25% of RFA causes decreases mechanical properties and durability, but adding PAN microfibers in 0.05% caused an increase of 2.9% and 30.8% of compressive strength and flexural strength respectively (with respect to the reference sample); a decrease in total porosity of 5.8% and effective porosity of 7.4%; and significant decreases in capillary absorption (approximately 23.3%), resistance to water penetration (25%) and carbonation (14.3% after 28 days of exposure). The results showed that the use of PAN microfibers in recycled mortars allowed it to increase the mechanical properties (because they increase the tensile strength), helped to fill pores or cavities and this causes them to be mortars with greater durability. Therefore, the use of PAN microfibers as a reinforcement in recycled cementitious materials would be a viable option to increase their applications.

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Dynamic Compressive Strength of Cementitious Materials

MRS Proceedings ◽

10.1557/proc-64-119 ◽

1985 ◽

Vol 64 ◽

Cited By ~ 9

Author(s):

L. E. Malvern ◽

T. Tang ◽

D. A. Jenkins ◽

J. C. Gong

Keyword(s):

Compressive Strength ◽

Strain Rate ◽

Maximum Stress ◽

Dynamic Range ◽

Structural Response ◽

Aggregate Size ◽

Cementitious Materials ◽

Rate Dependence ◽

Maximum Aggregate Size ◽

Inertia Effects

ABSTRACTFinite-element codes for structural response of reinforced concrete use as a parameter the unconfined compressive strength of the concrete, fc', which is sometimes increased by an arbitrary factor for dynamic loading. The objective of this research is to determine the rate dependence of fc' and eventually to model the rate-dependent constitutive behavior. Results of tests with a small Kolsky bar system and of a newly built larger system on concrete with a maximum aggregate size 1/2 inch are reported with strain rates at the maximum stress from 50 to 800/sec for mortar and from 5 to 120/sec for concrete. An apparent rate dependence up to almost twice the static strength is observed for both. The mortar shows an apparent linear dependence, while the high-strength concrete shows an approximately logarithmic dependence on the strain rate at the maximum stress, over the dynamic range observed. Some questions about specimen size effects and about how much of the apparent strain-rate effect is really a lateral inertia confinement effect are as yet unresolved. Continuing research is focused on observation of the lateral motion to assess lateral inertia effects in unconfined specimens and on passive confinement by steel jackets. Future efforts will be directed toward constitutive modeling.

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Flow Behavior of Self Consolidating Concrete Mixes with Various Maximum Size Aggregates

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.803.233 ◽

2019 ◽

Vol 803 ◽

pp. 233-238 ◽

Cited By ~ 1

Author(s):

Samer Al Martini ◽

Ziad Hassan ◽

Ahmad Khartabil

Keyword(s):

Fly Ash ◽

Flow Behavior ◽

Aggregate Size ◽

Maximum Size ◽

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Binary Blends ◽

Self Consolidating Concrete ◽

Slump Flow

The paper investigates the effects of aggregate size and supplementary cementitious materials (SCMs) on flow behavior of self-consolidating concrete (SCC). The fresh performance of concrete mixes was evaluated through slump flow and V funnel tests. Some concrete mixes were prepared with 5 mm maximum size aggregates and other mixes with 20 mm maximum size aggregates. The effects of varying contents of SCMs (Fly ash F and GGBS) on flow behavior of SCC under binary blends were also studied. The results show that the maximum size of aggregates has effect on the flow behavior of SCC.

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