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Author(s):  
A. Abdalqader ◽  
Mohammed Sonebi ◽  
Neil Thornton ◽  
Su Taylor

Cement grouts have many purposes in various civil engineering applications such as precast construction, soil stabilization and structural rehabilitation. Using filler materials as a component in cement grouts has been increasingly implemented. The incorporation of such fillers not only does improve the fresh and hardened properties of grouts but also contributes to the decarbonization of grouts by reducing the amount of Portland cement, thereby lowering the carbon footprint of grouting materials. This study aims at assessing the influence of various filler materials on the properties of cement grouts. Three different fillers were used in this study: commercial limestone, commercial pure dolomite, dolomitic quarry dust. These fillers were assessed in terms of their effect on the spread, flowability, cohesion and compressive strength at 3, 7 and 28 days. The results show that fresh properties of the grout were dependent on the type of fillers. Dolomitic quarry dust improved the workability and flowability more than the commercial limestone and dolomite did. The compressive strengths of cement grouts did not change significantly with the incorporation of the fillers. However, cement grout samples including quarry dust exhibited slightly higher 28-d compressive strength than other samples although the same mix had lower 1-d compressive strength than other mixes. This study highlights the benefits of utilizing quarry dust in cement-based binders without compromising the performance.


Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 340
Author(s):  
Parthiban Kathirvel ◽  
Gunasekaran Murali ◽  
Nikolai Ivanovich Vatin ◽  
Sallal R. Abid

It appears that the awareness and intentions to use recycled concrete aggregate (RCA) in concrete are expanding over the globe. The production of self-compacting concrete (SCC) using RCA is an emerging field in the construction sector. However, the highly porous and absorptive nature of adhered mortar on RCA’s surface leads to reduced concrete strength, which can be removed with the application of various techniques, such as acid treatment. This study investigated the effect of the partial replacement of silica fume by cement and natural aggregate (NA) by RCA with and without steel fibre. The used RCA was treated with magnesium sulphate solution. It was immersed in solutions with different concentrations of 10%, 15% and 20% and for different periods of 5, 10 and 15 days. Sixteen mixes were prepared, which were divided into six groups with or without 1% of steel fibre content. The fresh properties, compressive strength, split tensile strength and impact resistance were examined. The results revealed that the strengths of the mixes with 20% RCA were marginally better than those of the control mixes. The compressive strength and split tensile strength were reduced by 34% and 35% at 60% RCA content, respectively, as compared to the control mixes.


Author(s):  
Mahmud Sami Döndüren ◽  
◽  
Mohammed Gamal Al-Hagri ◽  

There are some problems and weaknesses related to cement-based materials, such as their very low tensile strength, low chemical resistance and the huge contribution of cement production to industrial CO2 emissions. One possible method to reduce the impacts of such problems is the partial replacement of cement in cementitious materials with nano materials. This work provides a detailed review of incorporation of one of the most widely used nano materials, namely nano-titanium dioxide, and its effect on the properties of cementitious composites. Different properties have been considered in the current study, such as fresh properties, mechanical properties (compressive strength, split tensile strength and flexural strength), durability (permeability, ultrasonic pulse velocity (UPV), electrical resistivity, carbonation resistance, freeze and thaw resistance and sulfate attack resistance) and microstructural properties. This paper also investigates the optimum content of nano-TiO2 in cement-based materials. Moreover, the cost effectiveness of use on nano-titania in cementitious composites has been discussed. Nano titania reduces the workability and setting time of cement-based materials. It can be very effective in improving the mechanical properties, durability and microstructural properties of cementitious composites.


Author(s):  
Minakshi Uchibagle ◽  
B Ram Rathan Lal

Controlled low-strength material (CLSM) is a self-levelling cementitious material. It is not concrete nor soil-cement, however, it possesses properties similar to both. CLSM is widely used as a replacement for soil-cement material in many geotechnical applications such as structural backfill, pipeline beddings, void fill, pavement bases and bridge approaches. This paper study potential possibility of polypropylene fiber in CLSM. Harden and fresh properties compressive strength , flowability and density for the proposed CLSM were investigated. This CLSM mix design with different percentage of polypropylene fiber and pond ash, cement and water. EPS beats and polypropylene add 0 %, 0.5%, 1.0% and 1.5% of total weight is added in CLSM MIx. Results show that the CLSM incorporating EPS beats and polypropylene satisfies compressive strength requirement as per the requirements of ACI committee 229. polypropylene decreases the flowability of CLSM mix and at the same tine by adding EPS beats the density of CLSM mix are reduce which become lightweight CLSM mix. from this it can conclude that polypropylene fibers is less effective in CLSM mix and EPS beats make CLSM mix lightweight which create lightweight CLSM mix applicable for filling application.


2021 ◽  
Vol 14 (1) ◽  
pp. 183
Author(s):  
Ahmed Yasien ◽  
Ahmed Ghazy ◽  
Mohamed Bassuoni

The City of Winnipeg (COW) and the University of Manitoba (UM), Canada, have partnered since 2015 to conduct research on the use of portland limestone cement (PLC), comprising up to 15% limestone filler, in transportation infrastructure such as pavements and bridges. Laboratory tests have substantiated the equivalent or superior resistance of concrete made from PLC, relative to that made from general use (GU) cement (Type I) to durability exposures including acids, sulfate salts and chloride-based deicing salts. Subsequently, a field trial was done in 2018, which involved casting two concrete pavement sections made from PLC and GU cement in Winnipeg, Manitoba, Canada. The current paper reports on the construction and long-term (three years/winter seasons) properties of these pavement sections including fresh properties, strength, absorption and chloride ions penetrability, as well as microstructural features. Cores were taken from mid-slabs and at joints, which are the most vulnerable locations to damage in concrete pavements. The field trial results showed that concrete pavement sections made with PLC had equivalent or superior performance compared with those made of GU in terms of fresh, hardened and durability properties. Thus, it presents a viable option for sustainable construction of concrete flatwork in cold regions.


Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 81
Author(s):  
Zengqing Sun ◽  
Qingyu Tang ◽  
Xiaohui Fan ◽  
Min Gan ◽  
Xuling Chen ◽  
...  

Alkali-activated materials (AAMs) are considered to be alternative cementitious materials for civil infrastructures. Nowadays, efforts have been made in developing AAMs with self-compacting ability. The obtained self-compacting AAMs (SCAAMs) accomplish superior passing and filling properties as well as excellent mechanical and environmental advantages. This work critically revisits recent progresses in SCAAMs including mixture proportions, fresh properties, mechanical strength, microstructure, acid and sulfate resistance, high temperature behaviors, impact resistance and interface shear strength. To facilitate direct comparison and interpretation of data from different publications, mixture proportions were normalized in terms of the content of key reactive components from precursors and activators, and correlation with mechanical behaviors was made. Moreover, special attention was paid to current research challenges and perspectives to promote further investigation and field application of SCAAMs as advanced construction material.


Author(s):  
Г. С. Славчева ◽  
Е. А. Бритвина ◽  
М. А. Шведова

Постановка задачи. Рассмотрение закономерностей влияния вида цемента и модификаторов вязкости на технологические свойства смесей для 3D-печати определяется необходимостью одновременного обеспечения показателей пластичности и формоустойчивости смесей и декоративности композитов на их основе. Результаты. Представлены результтаты экспериментальных исследований основных реологических характеристик декоративного бетона для строительной 3D-печати. Выявлено влияние состава бетона на подвижность и формоустойчивость смеси. Установлено, что вид используемого цемента изменяет пластичность смеси и формоустойчивость под весом вышележащих слоев. Смеси с оптимальным компонентным составом декоративного бетона для строительной 3D-печати имеют следующие реологические характеристики: предел текучести K @ 1,0-2,2 кПа, структурная прочность s = 1,5-4,5 кПа, относительные пластические деформации Δ = 0,03-0,07 мм/мм. Данные характеристики определяют способность смеси к пластическому деформированию без разрушения структуры при течении, а также способность сохранять форму при печати слоя и нагружении вышележащими слоями. Выводы. Оптимальные диапазоны свойств смесей для 3D-печати могут быть изменены в 2-3 раза за счет использования цементов с различным гранулометрическим составом. Регулирование подвижности и формоустойчивости смесей с различными видами цемента главным образом обеспечивается применяемым модификатором вязкости. Statement of the problem. This paper present the rheological properties of 3D-printable decorative concrete. The effects of the mix proportion on its plasticity and shape stability are presented together. It has been established that a kind of cement changes the plasticity of fresh mixtures and its resistance to load during printing. Results. The fresh mixtures of 3D-printable decorative concrete with effective mix design had plastic yield value K @ 1.0-2.2 kPa, structural strength s = 1.5-4.5 kPa, value of plastic deformations Δ = 0.03-0.07 mm/mm. That has defined the ability of these mixes to plastically deform without any structure destruction and hold its shape, resist the deformation under compressions load during multi-layer casting. Conclusions. Shape stability of 3D-printable mix can be changed by 2-3 times by using cement with an efficient ranging of a particle size. The plasticity and shape stability of fresh mixes can be regulated using viscosity modifiers whose type depends on the type of cement.


Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7592
Author(s):  
Hengrui Liu ◽  
Zhenghong Tian ◽  
Haoyue Fan

In this paper, the effect of a newly developed superfine basalt powder (SB) on the fresh and mechanical properties of cement paste was studied. The concept of water film thickness (WFT) was cited to explain the influence of SB on fresh and mechanical properties and related mathematical model formulas were established. In addition, the relationship between the fresh properties and mechanical properties of paste was also explored. The results indicated that SB can improve the segregation resistance and cohesiveness. The maximum improvement rate relative to the control cement paste was 75.4% and 50.4%, respectively. The 5% SB and 10% SB reduced the fluidity in the range of 4.1–68.7% but increased the early and late compressive strength in the range of 1.2–25.7% compared to control cement paste under different water/cementitious materials (W/CM) ratios. However, the influence of 20% SB on fluidity and compressive strength was opposite to the above behavior, and the increase rate and decrease rate were 1.8–11.8% and 1.1–13.9% respectively. The WFT was the most important factor that determined the compressive strength, rheological parameters, and flow parameters of paste containing SB, while the substitute content of SB and WFT together determined the bleeding rate and cohesiveness. Among them, the correlation between bleeding rate and WFT increased with time. The empirical mathematical models between WFT, fresh properties, and compressive strength were established and verified by other mineral admixtures, which were successfully extended and applied to the entire field of cement-based materials


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3278
Author(s):  
Mehdi Chougan ◽  
Francesca Romana Lamastra ◽  
Eleonora Bolli ◽  
Daniela Caschera ◽  
Saulius Kaciulis ◽  
...  

The impact of extra-low dosage (0.01% by weight of cement) Graphene Oxide (GO) on the properties of fresh and hardened nanocomposites was assessed. The use of a minimum amount of 2-D nanofiller would minimize costs and sustainability issues, therefore encouraging the market uptake of nanoengineered cement-based materials. GO was characterized by X-ray Photoelectron Spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), and Raman spectroscopy. GO consisted of stacked sheets up to 600 nm × 800 nm wide and 2 nm thick, oxygen content 31 at%. The impact of GO on the fresh admixtures was evaluated by rheology, flowability, and workability measurements. GO-modified samples were characterized by density measurements, Scanning Electron Microscopy (SEM) analysis, and compression and bending tests. Permeability was investigated using the boiling-water saturation technique, salt ponding test, and Initial Surface Absorption Test (ISAT). At 28 days, GO-nanocomposite exhibited increased density (+14%), improved compressive and flexural strength (+29% and +13%, respectively), and decreased permeability compared to the control sample. The strengthening effect dominated over the adverse effects associated with the worsening of the fresh properties; reduced permeability was mainly attributed to the refining of the pore network induced by the presence of GO.


2021 ◽  
Vol 27 (12) ◽  
pp. 13-22
Author(s):  
Mohammed Fadhil Qasim ◽  
Zena K Abbas ◽  
Suhair Kadhem Abd

Recently times, industrial development has increased, including plastic industries, and since plastic has a very long analytical life, it will cause environmental pollution. Therefore studies have resorted to reusing recycled plastic waste (sustainable plastic) to produce environmentally friendly concrete (green concrete). In this research, some studies were reviewed and then summarized into several things, including the percentage of plastic replacement from the aggregate and the effect of this percentage on the fresh properties of concrete, such as the workability and the effect of plastic waste on the hardening properties of concrete such as dry density, compressive, tensile and flexural strength.


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