Journal of Cement Based Composites (CEBACOM)

Fatih Celik Andaç Batur Çolak Oğuzhan Yıldız Samet Mufit Bozkır

The effects of n-TiO2 additions at different amounts by mass (0.0%, 0.3%, 0.6%, 0.9%, 1.2% and 1.5%) on rheological properties (plastic viscosity and yield stress) of cement-based grouts incorporated with fly ash as mineral additive at different constitutes (0%-for control purpose, 5%, 10%, 15%, 20%, 25% and 30%) were investigated by analysis of experiments in this study. To prepare all samples, w/b ratio was defined as 1.0. To prevent sedimentation of TiO2 nanoparticles in free water and to supply uniform distribution of TiO2 nanoparticles in water with help of removing of these nanoparticles from each other, Ultrasonication method was applied by using a Horn type Ultrasonic Homogenizer in this experimental study. All experimental viscosity values of the cement-based grout samples were also obtained by using Coaxial Rotating Cylinder Rheometer test machine. Modified Bingham analytical model was used to investigate on this study for reference grout samples because of it shows dilatant (shear-thickening) flow behavior. Test results show that plastic viscosity values of the grout samples obtained by addition of FA remarkably decrease with rising amount of n-TiO2. Yield stress of fresh grout mixtures increases with respect to increase amount of FA content in all grout mixtures with different proportions of n-TiO2. the usage of FA as a mineral additive in cement-based grouts has improved the yield stress value of the samples. Since n-TiO2 has such a low specific surface area, the water requirement of the grout matrix tends to increase. Therefore, this situation causes increasing of cohesion. The developed ANNs model has been able to predict the plastic viscosity and yield stress of cement-based grouts containing TiO2 nanoparticle doped fly ash with very low error rates and high accuracy

https://doi.org/10.36937/cebacom.2022.5624

Fayza Eisa E.Hekal Manar M.Abdel Naby Faten Selim

In the present study, field examinations are explored on diversed blended cement mixes. The hardened blended pastes are prepared using ordinary Portland cement (OPC), fine metakaolin (MK) and brine chlorine sludge (CLS). Cement fouling features and the attack by SO4-2 ions are studied on the blended samples that are immersed in the marine environment up to 9 months. The performance of the cured specimens was explored via studying the compressive strength, the percent of mass change and the volume expansion at various curing durations. Beside, the total chlorophyll colonized on the surface of the cured specimens was determined by using spectrophotometeric technique . XRD and SEM techniques are used for studying the phase compositions and the morphology of the formed cement hydrates. The results illustrate that the blended mixes show an antifouling behavior higher than the neat OPC. This is related to acquiring a more compact structure of reduced porosities upon OPC blending. Additionally, OPC-MK specimens showed a high resistivity to attack by SO4-2 ions than OPC-CLS or neat OPC pastes. This is related to the high pozzolanic properties of MK in contrary to brine sludge

https://doi.org/10.36937/cebacom.2022.5625

SAEID MOGHIMI HASAN ERİNÇ KESER KAMBİZ RAMYAR

This paper reports the results of laboratory work on the flow and strength of cement mortars containing binary and ternary blends of portland cement, silica fume (SF), Class C fly ash (CFA) and Class F fly ash (FFA). The cement was partially replaced with 20 and 40 wt.% of fly ash (FA) and 5 wt.% of SF as binary mixtures. Besides, the ternary mixtures contained 15%FA+5%SF and 35%FA+5%SF in place of 20% and 40% cement respectively. Both fly ashes were used in the ternary mixtures, thus, 4 mixtures containing ternary binders were prepared. Two sets of mortar mixtures having either same flow or same water/binder (W/B) ratio as those of the control mixture (containing no mineral admixture) were investigated. In total, 15 mortar mixtures were taken into constitution in the present study. The flow of mixtures was measured immediately after casting. In addition, the 7-and 28-day flexural and compressive strength of the mortar mixtures were determined. The use of SF in binary mixtures with constant W/B ratio provided the highest compressive strength (68 MPa). In ternary mixtures the use of 20%FA+5%SF mixture with constant W/B ratio showed the highest 28-day compressive strength (65 MPa). Among the mixtures with constant W/B ratio, ternary mixtures showed the lowest flow values. Besides, in the mixtures with constant flow, once again, the ternary mixtures had the highest W/B ratio. Both in binary and ternary specimens, the mixtures prepared with FFA had a higher flow than that of the CFA mixtures.

https://doi.org/10.36937/cebacom.2022.5626

Mohamed Julyes Jaisingh.S Kannan V

This current exploration manages the streamlining investigation of biocement concrete made of silica rage, lime, fly debris and metakaolin squander powder to lessen the concrete substance up to 40 wt.%. The primary reason for this current review was to enhance the pozzolanic substance, for example, silica smolder, lime, fly debris and metakaolin molecule in the setting time and consistency and pressure strength of biocement mortar and how these pozzolanic materials go to important material. The pozzolanic particles by sieving interaction to affirm the uniform molecule size equivalent to 1 µm. The pressure strength, consistency, and last setting time were estimated after the fruitful maturing of concrete blocks for around 28 days. As indicated by Taguchi's investigation, the exploratory arrangement Level10 gives the general best position among other trial designs with the GRG of 0.805. Besides, the weight level of metakaolin straightforwardly impacts the general exhibition of concrete substantial shapes rather than silica smoke, lime, and fly debris particles. The affirmation concentrate on uncovered improvement in the dark social grade of 1.92%, which is equivalent to the high-pressure strength of 51.285 MPa, consistency territory between 29.5 to 38.5, and lower last setting season of 525 min. the impact of different pozzolanic substances on the concrete's consistency and setting time. It uncovered that by supplanting the 40% normal Portland concrete (OPC) with bio concrete, the concrete's consistency improves and the level of pozzolanic materials comparative with the level of OPC can build the concrete consistency restricts and lessen the use of bio concrete with minimal expense

https://doi.org/10.36937/cebacom.2022.5627

Pankaj Goel Rakesh Kumar Bishwajit Bhattacharjee

Reinforcement of cement concrete using a hybrid combination of fibers is one of the recent developments in the concrete composite. This study used a hybrid combination of micro polypropylene graded fiber (up to 6 mm in length) and macro hooked end steel fiber (60 mm in length). The polypropylene fiber was optimized targeting a 20-25% reduction in drying shrinkage and abrasion loss. The steel fiber dosage was optimized for an enhancement of 15-20% in the flexural strength in bending over a conventional pavement concrete. The hardened state properties relevant to pavement concrete such as strengths and durability in terms of abrasion loss and drying shrinkage were investigated. Additionally, flexural behaviour (toughness indices and residual strength factors) and impact resistance were also studied. A minimum improvement of 19% in flexural strength, and 12% in splitting tensile strength, but a reduction in compressive strength (≈ 10%) was noted. A significant reduction in drying shrinkage (53%) and abrasion loss (31%) were noticed for the hybrid fiber reinforced concrete composite (HyFRCC) mix in comparison with the control concrete. Further, a significant improvement up to 14 times in toughness indices, 66-74 units in residual strength factors, and up to 27 times in impact resistance for HyFRCC were encountered. The study finally suggests that a hybrid combination of polypropylene fiber (0.1%) and steel fiber (0.5%) can be used in the construction of a long-lasting, economical, and sustainable concrete pavement including concrete overlays such as bridge deck slabs and white topping pavements.

https://doi.org/10.36937/cebacom.2022.5630