Properties Of Self-compacting Mortars Research Articles

Enhancing the performances of self-consolidating composite mortars with Alfa fibers and slag: A combined Taguchi-ANN optimization

Alfa fiber-reinforced self-compacting mortars (SCMs) offer enhanced workability. Thus, the potential of combining natural Alfa fibers and ground granulated blast furnace slag (GBFS) to optimize the rheological and mechanical properties was ascertained. The effect of fibers and GBFS on the properties of SCMs after treatment with linseed oil and NaOH was also evaluated. Partial substitution of cement by slag (10 % and 30 %.) was achieved. Mini cone spreading, V-funnel flow tests as well as compressive and bending tests at 7 days and 28 days were performed on the prepared mixtures. For optimization and predictive purposes, both Taguchi optimization and Artificial Neural Network modeling were employed. Our results indicated that, according to Taguchi experimental design, the use of 1 % fiber in the initial mixture achieved a good distribution within the paste and improved flexural strength. In addition, the treatment of fibers with NaOH actually improved the structure and bonding surface. Fiber content and GBFS replacements achieved the desired rheological and mechanical characteristics. Prediction of both compressive and flexural strengths was successfully achieved by an accurate application of machine a learning algorithm based on six inputs, one hidden layer and four outputs. The combined ANN-Taguchi approach provided accurate predictions of SCM performances and identified a robust mix-design that was less prone to fluctuations in the initial material properties. Alfa fibers and GBFS promoted both fresh and hardened properties. This study demonstrated the effectiveness ML and statistical optimization in developing high-performance, sustainable-SCMs with superior workability and strengths, making them ideal for various construction applications.

Effect of the incorporation ratio of recycled concrete aggregate on the properties of self-compacting mortar

This paper investigates the effect of the addition of recycled concrete aggregate (RCA) on the properties of self-compacting cement-based materials at the mortar scale, at the incorporation ratios of 0, 25, 50, and 100 %. The results showed that the yield stress and the plastic viscosity of the mortar increased with the incorporation ratio of RCA. Slump flow and V-funnel time were used to assess these properties. The mechanical strength of the mix also increases with the RCA incorporation ratio. A quantitative analysis of the data demonstrated that the effect of the addition of RCA on the mortar's rheological properties can be attributed to a decrease of the aggregate's packing density (morphology effect), a decrease of the effective water-to-cement ratio of the mix (water-to-cement ratio effect), and an increase of the aggregate's effective volume fraction (volume fraction effect). The latter two effects are caused by the aggregate's high water absorption, whose impact on mechanical strength is stronger than that caused by the morphology effect. In addition, the increase of the mix's strength can also be attributed to the increase of the effective water-to-cement ratio of the mix and to the bonding quality between the aggregate and the cementitious matrix. The increment in the incorporation ratio of RCA causes a reduction of the effective water-cement ratio of the mix and an increase of the bonding quality.

Improving mechanical/colorimetric properties of self-compacting mortar using an intensively colored-nanoparticle containing polymeric paste

Colored self-compacting mortars (C-SCMs) are important decorative materials for construction and building industries. It has been found that using inorganic/organic pigments for coloring the SCMs causes considerable decrement in the mechanical and aesthetic properties. In the last decade, latex modified C-SCMs were developed that showed improved color properties with lower effects on the mechanical properties. In present work, high performance-water based colored pastes were prepared using SBR latex (as binder), phthalocyanine blue (as organic pigment at 1.5 and 3 wt%) and CaCO3 nanoparticles (as reinforcement). The pre-fabricated pastes were added to a SCM mix design as coloring agent. The prepared samples were evaluated for colorimetric (i.e. L*, C* and H*) and mechanical (i.e. compressive and flexural) properties. For comparison, the organic pigment (at 0.25, 0.5, 0.75 and 1.5 wt%) and SBR latex (at 5 wt%) were also used to prepare latex modified C-SCM samples. The results showed that addition of 3 wt% of CaCO3 nanoparticles to the pre-fabricated colored paste caused improvement in the flexural strengths (by 28%) and flexural toughness (by 86%) of the prepared mortars compared to the latex modified C-SCM. Despite of using an organic pigment, the colorimetric properties (i.e. color difference and uniformity) and the pigment saturation point (by 100%) of the prepared C-SCMs were also improved using the nano-based coloring pastes.

The effect of different viscosity modifying additives on the mechanical and flow properties of self-compacting mortars

Some requirements are needed in the rheology design of special concretes such as self-compacting concrete, underwater concrete, shotcrete. For example, in the design of the desired concrete flow, some viscosity modifying agents (VMA) are used with various plasticizer additives. However, studies are needed to determine which of these additives used to design flow parameters is more appropriate. Herein, the mechanical and rheological effects of two commercially used VMAs on self-compacting mortars were investigated. For this purpose, compressive-flexural strength tests and mini-slump, mini-V funnel tests were conducted to determine the effects of welan gum (WG), and xanthan gum (XG) included in the mixtures at various ratios (0.01-0.1%) by weight of cement. The study supported by FE-SEM analysis concluded that WS had a positive effect on mechanical behavior, while XG had a negative effect, but XG was more effective on flow properties than WG.

INFLUENCE OF TEMPERATURE EFFECTS ON NANO-SILICA BLENDED SELF-COMPACTING GLASS MORTAR

Self-compacting mortars are achieving a great deal in the construction industry due to their remarkable characteristics and due to their advantages over conventional concrete. The main drawback associated with self-compacting mortars is the high cost associated with the ingredients used in the production of self-compacting mortars. This research aims to overcome this by combining the effects of nano-silica and glass powder on the properties of self-compacting mortar at normal and higher temperatures. The experiments were conducted to determine the split tensile strength over a range of curing periods and after being subjected to various temperatures. Durability properties of the self-compacting glass mortar, such as sorptivity, were also studied and compared with the properties of the control mortar. In addition, the chloride penetration resistance of the self-compacting mortars were also studied. The microstructure properties, such as X-ray diffraction and FTIR studies, were also performed to analyze the characteristics of self-compacting glass mortars at the micro level. The proposed mortar design can solve the problem of the disposal of waste glass, prevent the the depletion of natural river aggregates and also prove to be cost effective for massive construction purposes.

Properties of self-compacting mortars using blends of limestone powder, fly ash, and zeolite powder

The present study investigates the influence of limestone powder, fly ash, zeolite powder, and their blends on some fresh and hardened properties of self-compacting (SC) mortars. Blends of supplementary cementitious materials (SCMs) perform better than a single SCM in cementitious systems. The motivations for the present study include the introduction of novel blends of SCMs like limestone and zeolite powders to provide efficient SC mortars and potential alternatives of fly ash in a period of its short supply. The investigated properties include flow characteristics, shrinkage, pore pressure, hydration kinetics, compressive strength, microstructural characteristics using MIP and SEM, compositional analysis using thermo-gravimetric analysis, hardened density, and relative water absorption. The experimental results indicate that 20% replacement of cement with blend of limestone and zeolite powders led to the most improved response and provided better performance than other studied compositions.

Effect of superplasticizer and silica fume on the properties of self-compacting mortars

Self-compacting concrete is a highly flowing concrete that compact under self-weight without any vibration effort. The mortar phase of self-compacting concrete determines its rheological, strength characteristics, and durability. This paper discusses the effect of superplasticizer and silica fume on the properties of self-compacting mortars. Mini-slump flow diameter tests were conducted to determine the rheological properties of mortar mixtures, and compressive strength, density, water absorption, porosity experiments to assess the hardened properties of mortar specimens. Analysis of regression models shows that the use of superplasticizer reduces the water demand of mortar mixtures by up to 40 %, and the addition of silica fume leads to the densification of cement stone structure and reduces the porosity of concrete to 24 %. The maximum compressive strength at 2 days can be achieved with a superplasticizer content of 0.8-1.0 % and 0-5 % silica fume by binder weight, and at 28 days – with 1.0-1.2 % superplasticizer and 10-15 % silica fume content. According to X-ray phase analysis in a cement stone containing superplasticizer and silica fume, the degree of cement hydration increases and reduces the amount of portlandite, which leads to an increase in the strength and durability of the concrete.

Properties of Self-Compacting Cementitious Composite Materials Containing Cement Kiln Dust Powder

This paper aims to investigate the influence of utilization micro cement kiln dust as a sustainable materials additive in order to reduce the voids and micro cracks in the cementitious mortar materials which cause a drastic reduction in the load carrying capacity of the element. Its therefore very important to decrease the pores and enhance the mechanical strength of the cementitious composite materials. In this article, the properties of self-compacting mortar containing micro cement dust additive was experimentally assessed. Micro cement dust powder was added to the self-compacting mortar in (1, 2, 3, 4 and 5 %) percentage by weight of cement to be used as cementitious sustainable materials. The experimental results indicated that the modification and enhancement of the workability of fresh mixture and the mechanical strengths of self-compacting mortar were increased as micro cement dust additives increases. Also; the water absorption and total porosity were decreased with increases of micro cement dust powder.

Erratum: The effects of silicon dioxide, iron(III) oxide and copper oxide nanomaterials on the properties of self-compacting mortar containing fly ash

Erratum: The effects of silicon dioxide, iron(III) oxide and copper oxide nanomaterials on the properties of self-compacting mortar containing fly ash

The use of plastic waste as fine aggregate in the self-compacting mortars: Effect on physical and mechanical properties

This work aims to study the possibility of recycling waste plastic (polyethylene terephthalate (PET) used for the bags manufacture) as a fine aggregate instead of sand in the manufacturing of the self-compacting mortars. For this, an experimental study was carried out to evaluate physical and mechanical properties of the self-compacting mortars (SCMs) with plastic wastes. The sand is substituted with the plastic waste at dosages (0%, 10%, 20%, 30% and 50% by weight of the sand).The physical (bulk density, porosity, water absorption and ultrasonic pulse velocity testing) and mechanical (bulk compressive and flexural strength) properties of SCMs were evaluated and a complementary study on micro-structural of the interface of cementitious matrix and plastic waste. The measurements of physical and mechanical properties show that, in term of the density for materials, the mortars with 50% of plastic waste give better results than other proportion of the waste. Those mortars have a mechanical strength acceptable for lightweight materials. According to results obtained a reduction of 15% and 33% for mortar containing 20–50% plastic waste. A microscopic study of the interfacial zone (plastic–binder) has shown that there is an adhesion between plastic and cement paste (case 28days of hydration).

Properties of self-compacting mortars with binary and ternary cementitious blends of fly ash and metakaolin

The link between flow properties and the formulation is actually one of the key-issues for the design of self-compacting concretes (SCC). As an integral part of a SCC, self-compacting mortars (SCMs) may serve as a basis for the design of concrete since the measurement of the rheological properties of SCCs is often impractical due to the need for complex equipment. This paper discusses the properties of SCMs with mineral admixtures. Portland cement (PC), metakaolin (MK), and fly ash (FA) were used in binary (two-component) and ternary (three-component) cementititios blends. Within the frame work of this experimental study, a total of 16 SCMs were prepared having a constant water-binder (w/b) ratio of 0.40 and total cementitious materials content of 550 kg/m3. Then, the fresh properties of the mortars were tested for mini-slump flow diameter, mini-V-funnel flow time, setting time, and viscosity. Moreover, development in the compressive strength and ultrasonic pulse velocity (UPV) of the hardened mortars were determined at 1, 3, 7, 14, and 28 days. Test results have shown that using of FA and MK in the ternary blends improved the fresh properties and rheology of the mixtures when compared to those containing binary blends of FA or MK.

The effect of chemical admixtures and mineral additives on the properties of self-compacting mortars

Mortar serves as the basis for the workability properties of self-compacting concrete (SCC) and these properties could be assessed by self-compacting mortars (SCM). In fact, assessing the properties of SCM is an integral part of SCC design. The objective of this study was to evaluate the effectiveness of various mineral additives and chemical admixtures in producing SCMs. For this purpose, four mineral additives (fly ash, brick powder, limestone powder, and kaolinite), three superplasticizers (SP), and two viscosity modifying admixtures (VMA) were used. Within the scope of the experimental program, 43 mixtures of SCM were prepared keeping the amount of mixing water and total powder content (portland cement and mineral additives) constant. Workability of the fresh mortar was determined using mini V-funnel and mini slump flow tests. The setting time of the mortars, were also determined. The hardened properties that were determined included ultrasonic pulse velocity and strength determined at 28 and 56 days. It was concluded that among the mineral additives used, fly ash and limestone powder significantly increased the workability of SCMs. On the other hand, especially fly ash significantly increased the setting time of the mortars, which can, however, be eliminated through the use of ternary mixtures, such as mixing fly ash with limestone powder. The two polycarboxyl based SPs yield approximately the same workability and the melamine formaldehyde based SP was not as effective as the other two.