Mortar Flow Research Articles

Waste glass powder as partial replacement of cement for sustainable concrete practice

Abstract Million tons of waste glass is being generated annually all over the world. Once the glass becomes a waste it is disposed as landfills, which is unsustainable as this does not decompose in the environment. Glass is principally composed of silica. Use of milled (ground) waste glass in concrete as partial replacement of cement could be an important step toward development of sustainable (environmentally friendly, energy-efficient and economical) infrastructure systems. When waste glass is milled down to micro size particles, it is expected to undergo pozzolanic reactions with cement hydrates, forming secondary Calcium Silicate Hydrate (C–S–H). In this research chemical properties of both clear and colored glass were evaluated. Chemical analysis of glass and cement samples was determined using X-ray fluorescence (XRF) technique and found minor differences in composition between clear and colored glasses. Flow and compressive strength tests on mortar and concrete were carried out by adding 0–25% ground glass in which water to binder (cement + glass) ratio is kept the same for all replacement levels. With increase in glass addition mortar flow was slightly increased while a minor effect on concrete workability was noted. To evaluate the packing and pozzolanic effects, further tests were also conducted with same mix details and 1% super plasticizing admixture dose (by weight of cement) and generally found an increase in compressive strength of mortars with admixture. As with mortar, concrete cube samples were prepared and tested for strength (until 1 year curing). The compressive strength test results indicated that recycled glass mortar and concrete gave better strength compared to control samples. A 20% replacement of cement with waste glass was found convincing considering cost and the environment.

Modification of water retention and rheological properties of fresh state cement-based mortars by guar gum derivatives

The present study examines the influence of chemical composition and structure of guar gum derivatives on water retention capacity (WR) and rheological behavior of fresh state cement-based mortars. The investigation was also completed by adsorption isotherms. For this, original guar gum, three HydroxyPropyl Guars (HPG) and two hydrophobically modified HPGs were selected. The effect of the molar substitution (MSHP) and of hydrophobic substitution (DSAC) was investigated. The results highlight that chemical composition of HPGs has a remarkable effect on fresh state properties of mortars. The original guar gum does not impact on neither WR nor rheological behavior. Increasing MSHP leads to an improvement of the WR and the stability of mortars while the hydrophobic units further enhance WR and lead to a decrease in the yield stress and an increase in the resistance to the flow of admixed mortars.

Evaluation of fly ash geopolymer mortar incorporating calcined wastepaper sludge

This study evaluates fresh and hardened properties of fly ash geopolymer mortars incorporating calcined wastepaper sludge cured under ambient conditions. The calcined sludge geopolymer mixtures were characterized by XRD, XRF, and SEM–EDS techniques. It was observed that addition of up to 40 wt% calcined sludge in geopolymer mortars at a fixed liquid/solid mass ratio of 0.2 reduced flow of mortars from 112 to 61%, while the corresponding setting time was shortened from 113 h to just under 1 h. At the maximum calcined sludge loading of 40 wt%, the compressive strength at 7 days was 29.0 MPa, a significant increase from 3.8 MPa for reference mortar samples with no addition of sludge. Correspondingly, a nearly fourfold reduction in 56-day drying shrinkage measured at 3600 microstrains was observed, compared to reference mortars. The plausible reaction mechanisms, in particular, apparent concurrent formation of C-A-S-H/N-(C)-A-S-H phases alongside geopolymer gel networks are discussed in detail.

Influence of GGBS on Rheology of Cement Paste and Concrete with SNF and PCE based Superplasticizers

Limestone and clay which are the major ingredients of the cement production are non-renewable resources. Therefore, it is essential to identify a sustainable material to replace cement. The by-product from the steel plant is subsequently granulated to desired fineness and is termed as Ground Granulated Blast furnace Slag (GGBS). Superplasticizers (SP) are used to improve the workability of concrete at low water-cement ratios and increase the compressive strength by reducing it. But, this workability is sometimes lost rapidly as time progresses after contact between the cement and water. Therefore, it is necessary to understand the mechanisms that influence the cement-super plasticizer interaction for selecting an appropriate type of admixture at an optimum dosage. In this present research the compatibility study, between six combinations of cement using different percentages of GGBS with two different SPs were investigated. The optimum dosage was found using marsh cone test. The cement mortar flow test was conducted to find out the setting time and compressive strength of the mortar. It is found that the increase in addition of GGBS decreases the dosage of Superplasticizers to achieve the desired workability. The target mean strength of the M40 concrete was achieved with replacement of 50% GGBS using PCE based SP.

Performance of Softwood Soda-Anthraquinone Lignin–Polyethylene Glycol Derivatives as Water-Reducing Admixture for Concrete

We have developed a high-performance lignin-based water-reducing admixture. In this study, softwood soda-anthraquinone lignin was modified with mono-epoxide polyethylene glycols having chain lengths of 10, 25, and 50 mol (the number of repeating units of ethylene oxide). The mortar flow and concrete slump flow tests were used to investigate the performance of the lignin derivatives as a water-reducing admixture. All tested lignin-PEG derivatives performed considerably better than a commercial lignosulfonate water-reducing admixture in the mortar flow test. In particular, the derivative with a PEG chain length of 50 mol performed excellently in both tests. The optimum PEG content for mortar dispersion was approximately 40% for lignin derivatives with a PEG chain length of 50 mol; this content exhibited a dispersing effect that was four times higher than that of the lignosulfonate water-reducing admixture. The strength of concrete containing the lignin derivatives was almost the same strength as that of concrete containing the commercial lignosulfonate water-reducing admixture.

The use of seashells as a fine aggregate (by sand substitution) in self-compacting mortar (SCM)

The aim of this study is to see the possibility to use or to recycle wastes of Marin’s origin, in particular seashells in a self-compacting mortars (SCMs) as a fine aggregate by sand substitution. An experimental study was conducted to evaluate the properties in the fresh (fluidity and flowability) and hardened properties (bulk density, porosity/water absorption, flexural and compressive strength and elastic modulus) of self-compacting mortars (SCMs) with the partial and total substitution of sand (S) by seashells (Sh) crushed at different ratio (Sh/S=0%, 10%, 20%, 50% and 100%) by weight. The obtained results show that the crushed seashells (0/5mm class), can be used as the fine aggregate for self-compacting mortar, without affecting the essential properties of mortar. However, the flowability of mortars based 100% of seashells, was better and is suitable for a fluid concrete (as a self-compacting concrete). Also, up to 100% replacement of sand by the crushed seashells has caused a slight reduction in compressive strength and elastic modulus of studied mortars. The macrostructural study by optical microscope of the interfacial zone (seashells–binder) has shown that there is a good adhesion between seashell and cement paste and the angular form of the seashells has significantly improved the distribution of this latter in the cementitious matrix.

Effect of Corrosion Inhibitor on the Compressive Strength of Polymer-Modified Cement Mortars

This study examined initial flow and compressive strength development of polymer-modified cement mortar according to the addition of corrosion inhibitor. Test results showed that with the increase of the amount of corrosion inhibitor, the initial flow of mortars increased whereas compressive strength decreased. The strength development of mortar specimens could be reasonably predicted using the modified ACI 209 equations.

Friction Influence between Particles in the Behavior of Flow of Lime-Rendering Mortars

The behavior and properties of rendering mortars, in the fresh state, are influenced primarily by particle grading, amount of water employed, and the shape and surface texture of particles. Production processes and application of rendering mortars demand an appropriate adjustment in their materials so that the plasticity and consistency need to be optimized allowing an appropriate execution of rendering. The friction between particles of sand is decisive in the rheological behavior of mortars. In this context, the present study evaluates the mortar flow behavior focusing on the influence of microfine content and grading of sands on friction angle of mortars. For experimental development, mortars that differ according to binder/aggregate ratios and aggregate grading distributions were used, in addition to using sands with different microfine contents. The mortar consistencies were established based on the cone penetration test. The mortars were tested to determine the internal friction angle using the direct shear test. The yield stress was obtained from the Vane test. The results indicate a relationship between the microfine content and the internal friction angle of the mortars, identifying a strong influences of friction under the behavior of flow of the rendering mortars.

The effect of using high strength flowable system as repair material

The maintenance and the repair of concrete structures have become more needed in the field of Civil Engineering. The selection of repair materials for concrete structures requires an understanding of the material behavior. Therefore, this research is conducted to provide a clear indication and understanding of the behavior and structural performance in engineering construction. The combined system of substrate concrete with different mix proportions of flowable high strength system reinforced by hybrid fibers was used to study its mechanical properties. The experimental tests are: compressive strength, splitting tensile strength, flexural strength and pull-out test. It was found that the high strength flowing concrete (HSFC) provides the best performance when the compressive strength of the repaired system is needed, whereas the high strength flowable mortar (HSFM) has the best performance when the tensile strength of repaired system is required. The best value of pull out test was obtained from using the flowable high strength mortar reinforced with 1.5% steel fiber +0.25% palm fiber +0.25% Barchip fiber as the repair material, whereas, the least value of pull-out test was obtained from samples using epoxy.

Performance of Softwood Soda-Anthraquinone Lignin as Water-Reducing Chemical Admixture in Concrete

We have attempted to establish a new process for producing a concrete chemical admixture prepared with by-product lignin of bioethanol production. In our pretreatment process of bioethanol production, soda-anthraquinone (AQ) cooking was applied to remove lignin from softwood chips. Soda-AQ lignin was recovered as precipitate by acidifying the black liquor. Five kinds of soda-AQ lignin were isolated by selecting the pH value of the precipitation. Each of the isolated soda-AQ lignins was used in the mortar fluidity test as concrete admixture. With the exception of the soda-AQ lignin at higher pH (pH 10.5) precipitation, the isolated lignin gave about two times’ higher mortar flow values than that of the widely used commercial lignosulfonate admixture. Size exclusion chromatography (SEC) data showed that the isolated lignin at higher pH value gave higher molecular weight. Functional group chemical analysis suggested that the isolated lignin of lower molecular weight had a higher phenolic hydroxyl group and higher alpha-carbonyl group content.

Mix design method for self compacting metakaolin concrete with different properties of coarse aggregate

This study deals with a proposed mix design method for SCC utilizing different properties of coarse aggregate. The work was conducted in three phases, i.e. paste, mortar and concrete to facilitate the mix design process. Initial investigation on cement paste determined the basis for water cement ratio and superplasticizer dosage for the concrete. For the study on mortar, metakaolin (MK) as pozzolan was used at replacement levels of 5%, 10%, 15%, and 20% by weight of cement. Self compactability of mortars was obtained by adding suitable materials such as mineral admixtures and superplasticizer which provided a sufficient balance between flowability and viscosity of the mix. The optimum MK replacement level for cement was 10% from the viewpoint of workability and strength. Flowability of mortar decreased with the use of metakaolin. Moreover, strength of mortar increased when the optimum replacement level of pozzolan was used. Different fresh concrete tests were adopted. The results obtained for fresh concrete properties showed that flowability of concrete increased with increase flowability of mortar. The mixes which contained coarse aggregate with lower volume, small size, and continuous grading affected positively the fresh properties of SCC. Finally, the mix design method used was successful in producing SCC with different coarse aggregate properties.

Influence of curing conditions on properties of high calcium fly ash geopolymer containing Portland cement as additive

This paper investigated the mechanical properties and microstructure of high calcium fly ash geopolymer containing ordinary Portland cement (OPC) as additive with different curing conditions. Fly ash (FA) was replaced with OPC at dosages of 0%, 5%, 10%, and 15% by weight of binders. Setting time and microstructure of geopolymer pastes, and flow, compressive strength, porosity and water absorption of geopolymer mortars were studied. Three curing methods viz., vapour-proof membrane curing, wet curing and temperature curing were used. The results showed that the use of OPC as additive improved the properties of high calcium fly ash geopolymer. The strength increased due to the formation of additional C–S–H and C–A–S–H gel. Curing methods also significantly affected the properties of geopolymers with OPC. Vapour-proof membrane curing and water curing resulted in additional OPC hydration and led to higher compressive strength. The temperature curing resulted in a high early compressive strength development.

Particle shape analysis of fine aggregate using a simplified digital image processing method

The use of manufactured fine aggregates in Portland cement concrete has been increasing in the last years owing to environmental and economic reasons. This type of aggregate normally has flaky and elongated particles that negatively affect workability. Producers have been making efforts to overcome this problem by the use of better crushers capable of improving particle shape. However, even using modern crushers, the particle shape depends on the rock mineralogy and the production variables. Thereby, it is of foremost importance to determine a shape index that can be used both as a production control parameter and for improvements on the aggregate performance. Hence, this paper presents a simplified digital image processing method to measure a particle shape index for fine aggregates based on the concept of volumetric coefficient recommended by French standard AFNOR XP P18-54. The validation tests were undertaken in coarse aggregate samples and showed a very good agreement with manual measurements. Experimental tests were also carried out on mortar samples produced with three different manufactured fine aggregates with distinct shape index measured by the proposed method. The results showed that mortar flow is strongly influenced by the particle shape measured by the proposed method.

硫酸アルカリが急硬性セメント組成物の物性に及ぼす影響

The properties of cement quick-hardening additive are influenced depending on the quality of cement used. However, little is known concerning the influences of miner constituents on the properties of cement additives. One of miner constituents contained in cement is an alkali compound. In this report, the authors have studied about the influences of alkali sulfate on the properties of quick-hardening cement compound. As a result, they found the following influences；1）Mortar flow became larger or smaller depending on dosage or kind of alkali sulfate. The authors assumed that larger or smaller mortar flow is because of the interaction of alkali with not only cement, but also quick-hardening additive. 2）Workable time tended to become shorter. They confirmed that workable time is associated with the formation of ettringite. 3）Compressive strength at early age became slightly higher, but that after 7 days became lower. The authors have assumed that higher compressive strength at early age is associated with the formation of ettringite and lower compressive strength after medium age is associated with sparseness of compositions of hardened cement compound by the presence of alkali. 4）Expansion strain became larger. The authors assumed that high concentration of sulfate and hydroxide ion promotes topochemical reaction and increases the amount of ettringite formed. 5）Ettringite formation reaction was promoted if alkali sulfate was contained in quick-hardening cement compound.硫酸アルカリが急硬性セメント組成物の物性に及ぼす影響を検討した。その結果、①モルタルフロー値は、硫酸アルカリの添加率や種類によって、大きくなる場合や小さくなる場合があった。②可使時間は短くなる傾向があった。③初期材齢の圧縮強さは、やや高くなったが、材齢7日以降の圧縮強さは、低くなった。④膨張率は大きくなった。⑤硫酸アルカリが急硬性セメント組成物中に存在すると、エトリンガイトの生成反応が促進されることを確認した。

Compressive Strength of Blended Portland Cement Mortars Incorporating Fly Ash and Silica Fume at High Volume Replacement

Fly ash has been widely used as a replacement of Portland cement at high content levels, but the compressive strength of Portland cement blended with fly ash is lower at early ages. Thus, this study compares the compressive strength of ternary blended Portland cement mortars incorporating fly ash (40-70 wt%) and silica fume (5-10 wt%) with binary blended Portland cement mortars incorporating fly ash only. Blended Portland cement mortars were designed with a constant water/binder ratio of 0.485 and the flow table tested was carried out. A fine aggregate to binder ratio of 2.75 was used. The compressive strength of all blended Portland cement mortars that cured in water at 23 °C was tested at 28 days. The results show that the flow of blended Portland cement mortars increased with increasing fly ash content and tended to decrease with increasing silica fume content, at the same replacement level. Moreover, the compressive strength of blended Portland cement mortars decreased with increasing fly ash content. However, compressive strength gains were obtained from ternary blended Portland cement mortars incorporating silica fume, tending to increase with increasing silica fume content.

Impact of metakaolin characteristics on the rheological properties of mortar in the fresh state

Abstract This study investigated the flow properties (slump, flow time, apparent viscosity at different shear rates) of cement/metakaolin-based mortars. The mix proportion that was used per weight was 3:1:0.5 (sand:binder:water), and the binder was composed of either 100% cement (OPC) or combinations of cement and metakaolins (MKi). Replacement rates of cement with MK were 12.5% and 25% per weight. Four metakaolins produced in two areas with two processes of calcination (fluidized bed and flash calcination) were employed. Their chemical and mineralogical compositions, physical properties, size distribution and morphology were fully characterized. Relationships between various MK properties and the flow properties of mortars were studied. Results show that metakaolins can produce significant differences in the flow of mortars, depending on their physical and chemical properties. In particular, the nature and content of impurities are key factors acting directly on the morphology of the distribution of the constituting particles and the water demand of MK. All these parameters control the rheological properties of the resulting cementitious suspensions. The mode of calcination is a second order factor influencing the shape of particles, since the flash process can smooth the surface of the smallest particles. More specifically, the high quartz content present in flash MK as rounded particles is minimally or not at all affected by the calcination process, and maintains flow properties more successfully than mortar incorporating cement only.

Flowable high strength cementitious matrices for ferrocement applications

Laboratory investigation was undertaken to develop high strength cementitious matrices for casting thin ferrocement laminates ideally suited for structural repair/retrofit. The developed high strength mortar matrices contain various combinations of silica fume and fly ash, and provide a good balance between flowability and strength. The matrices developed had a 28-day compressive strength range from 48 to 64MPa with a corresponding flow range from 129% to 138%. The developed high strength mortar was used in producing ferrocement jackets for cylindrical stubs to examine its performance and efficiency when the stubs are subjected to axial loads. The developed high strength ferrocement laminates seem to provide appreciable increase in load carrying capacity, lateral confinement and ductility. In terms of ferrocement efficiency, the stubs wrapped with the laminates containing 2 and 4 layers of welded wire meshes, WWM, showed about 16% and 29% increase in axial stress respectively, with a corresponding increase in axial strain of about 32% and 70% respectively. Based on the findings of the present investigation, high strength ferrocement laminates containing a specific number of welded wire meshes can be considered as a promising material for maintenance and rehabilitation of concrete structures, especially when using high strength and flowable mortar with WWM complying with ferrocement specifications.

Viscoplastic Particle Method for Flow Simulation of Highly Flowable Mortar and Concrete

Viscoplastic Particle Method for Flow Simulation of Highly Flowable Mortar and Concrete

Flow and Engineering Properties of Fiber Reinforced Hwangtoh Mortars

In this study, six mortar mixes were tested in order to examine the significance and limitations of hydrophilic fiber in terms of its capacity to enhance the tensile resistance of Hwangtoh mortar. Lyocell, polyamide and polyvinyl alcohol (PVA) fibers were selected for the main test parameters. The tensile capacity of mortars tested was evaluated based on the splitting tensile strength and the modulus of fracture, while their ductility was examined using the toughness indices specified in ASTM. Test results showed that the addition of lyocell and PVA fibers had little influence on the flow of the Hwangtoh mortars. To enhance the tensile capacity and toughness index of Hwangtoh mortar, it is proposed that fiber spacing above 0.0003 is required, regardless of the type of fiber.

Evolution of Durable High-Strength Flowable Mortar Reinforced with Hybrid Fibers

The production and use of durable materials in construction are considered as one of the most challenging things for the professional engineers. Therefore, this research was conducted to investigate the mechanical properties and the durability by using of different percentages of steel fiber with high-strength flowable mortar (HSFM) and also the use of the hybridization of steel fibers, palm fibers, and synthetic fiber (Barchip). Different experimental tests (compressive strength, splitting tensile strength, flexural strength, and static modulus of elasticity among others) were determined after 90 days of normal water curing and 180 days of seawater exposure. The results indicate that hybrid fibers of 1.5% steel fibers + 0.25% palm fibers + 0.25% Barchip fibers provide significant improvement in the different mechanical properties of HSFM. Besides, the hybridization of fibers was found to be effective in the terms of durability (exposure to seawater). Therefore, the minimum reduction in static modulus of elasticity, compressive, splitting and flexural strength was obtained for the HSFM mixes of hybrid fibers using steel fibers with palm fibers and also for the use of steel, palm, and Barchip fibers.