Impact of Severe Climate Conditions on Loss of Mass, Strength, and Stiffness of Compacted Fine-Grained Soils–Portland Cement Blends

Compaction and Portland cement addition are amongst promising ground improvement procedures for enhancing the mechanical properties of gold tailings. The present investigation intends to compute the impact of Portland cement content and dry density on the properties (durability, stiffness, and strength) of compacted gold tailings – cement mixes. Its main significant addition to knowledge is the quantification of accumulated loss of mass (ALM) after wetting–drying cycles, shear modulus at small strains, and unconfined compressive strength (qu) as a function of the porosity/cement index. In addition, the existence of an exclusive relation connecting ALM divided by the number of wetting–drying cycles and porosity/cement index is revealed empirically. This broadens the applicability of such an index by demonstrating that it controls not only mechanical but also endurance performance of compacted gold tailings – Portland cement mixes.

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Properties of cement composites based on limestone depending on their granulometric composition

Vestnik MGSU ◽

10.22227/1997-0935.2020.7.999-1006 ◽

2020 ◽

pp. 999-1006

Author(s):

Svetlana V. Samchenko ◽

Olga V. Alexandrova ◽

Anton Yu. Gurkin

Keyword(s):

Composite Materials ◽

Portland Cement ◽

Granulometric Composition ◽

Coarse Grained ◽

Cement Matrix ◽

Cement Composites ◽

Construction Costs ◽

Initial Strength ◽

Fine Grained ◽

Additional Formation

Introduction. The use of limestone in cement compositions as an additional cementing agent solves both environmental and economic problems, namely, reduction of construction costs. In this regard, the study of the properties of the granulometric composition and volumetric content of cement composites, containing limestone, becomes increasingly important. The mission of this research is to optimize the properties of composite materials containing Portland cement and limestone by changing the granulometric composition of flour limestone. Materials and methods. Limestone, having three different Blaine milling fineness values of 250, 300 and 450 m2/kg, was used; its content reached 10, 15, 25 and 35 %. Cement and sand mortars were applied for testing purposes. The influence of the granulometric composition of limestone on the workability and compressive strength of composite cement was determined. Results. The effect of limestone on the limit shear stress becomes more pronounced when the amount of limestone increases to 25 and 35 %. This is most noticeable for limestone with a high content of fine fractions of 5–20 µm. The use of finely milled limestone increases the initial strength of the composite material. By adding 10 and 15 % of such limestone we can increase the strength by 16–20 %, and supplementary 25–35 % of limestone increases strength by 5–8 %. Strength enhancement is due to the reactivity of limestone and formation of calcium hydrocarbon aluminate 3CaO∙Al2O3∙СаСО3∙12H2O, which promotes formation of the crystal framework of the cement matrix. Additional formation of crystalline hydrates in the initial coagulation structure deteriorates the mortar workability, but increases its strength. Conclusions. The use of coarse-grained limestone significantly improves mortar workability, while the use of fine-grained limestone increases its content without reducing its strength. The granulometric composition of ground limestone shall be as close as possible to the granulometric composition of cement for the properties of composite materials containing Portland cement and limestone to be optimized.

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AN EFFECTIVE WAY TO RECYCLE 3D PRINTING CONCRETE SCRAP

Construction Materials and Products ◽

10.34031/2618-7183-2021-4-2-12-18 ◽

2021 ◽

Vol 4 (2) ◽

pp. 12-18

Author(s):

D.A. Tolypin ◽

N. Tolypina

Keyword(s):

Compressive Strength ◽

3D Printing ◽

Portland Cement ◽

Quartz Sand ◽

Raw Materials ◽

Electricity Consumption ◽

Cement Matrix ◽

Fine Aggregate ◽

Fine Grained ◽

Control Samples

the article proposes a rational method for processing 3D printing concrete scrap using vibration equipment, which allows obtaining a multicomponent building material with minimal electricity consumption. As a crite-rion for the degree of grinding of concrete scrap, it is proposed to use the specific surface area of the finely dispersed part of concrete scrap, which should correspond to 400-500 m2/kg. The possibility of reusing the resulting product instead of the traditional fine aggregate of quartz sand is shown. It was found that the con-crete scrap without the addition of Portland cement hardens, reaching up to 48% of the compressive strength of the control samples by 28 days. When 10% of the binder CEM I 42.5 N was added to the concrete scrap processing product, the compressive strength of fine-grained concrete increased by 106.6%, and 20% of Portland cement - by 112.2 %, compared to the strength of control samples of a similar composition on tra-ditional quartz sand after 28 days of hardening. It is noted that this is primarily due to the weak contact zone of quartz sand and the cement matrix of concrete. The use of the product of processing concrete scrap al-lows obtaining building composites based on it with the complete exclusion of natural raw materials

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Modeling the composition of fine-grained modified concrete elaborated with vibropressing technology

MATEC Web of Conferences ◽

10.1051/matecconf/201929800133 ◽

2019 ◽

Vol 298 ◽

pp. 00133 ◽

Cited By ~ 2

Author(s):

E. R. Pyataev ◽

A. Y. Ushakov

Keyword(s):

Portland Cement ◽

Experimental Research ◽

Frost Resistance ◽

Building Materials ◽

Road Construction ◽

Average Density ◽

Optimal Composition ◽

Fine Grained ◽

Main Components ◽

Modifying Additive

The article analyzes the property requirements of small-piece products used in road construction, specially those related to water and frost resistance. It describes the main features of the vibration technologies involved in the manufacture of building materials, in particular, paving slabs. The article presents conclusive results, obtained through scientific research, which allow us to establish the influence of both, the costs of the main components and the parameters of vibration compression, on the properties of the final product. Combining the analysis of classical methods with the results of experimental research, a methodology has been developed for reaching an optimal composition of fine-grained vibropressed concrete modified with active additives. It is shown that the particular strength achieved from the combination of vibroformed fine-grained concrete, whose average density is 2270–2320 kg/m3, with polymer multifunctional modifiers, is mainly due to the use of Portland cement, a modifying additive, and the pressure conditions employed during the experiment..

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Mathematical Model for Improvement of Concrete Quality

Materials Science Forum ◽

10.4028/www.scientific.net/msf.952.356 ◽

2019 ◽

Vol 952 ◽

pp. 356-362

Author(s):

Ksenia Domnina ◽

Elena Pivarčiová

Keyword(s):

Portland Cement ◽

Fiber Reinforced Concrete ◽

Concrete Durability ◽

Compression Tests ◽

High Quality ◽

Maximum Increase ◽

Fine Grained ◽

Concrete Quality ◽

Pet Fibers ◽

Fine Grained Sand

To obtain high-quality concrete constructions it is not enough to execute it only in concrete of high class. One of the effective ways to improve the reliability and durability of concrete is its reinforcing by various kinds of fibers. The article presents the researching results of the influence of brands of portland cement and disperse reinforcing by polyethylene terephthalate fibers (PET-fiber) on concrete durability. Standard compression tests of the cubical prototypes of fine-grained sand concrete made of two brands of portland cement – PC400 and PC500 with different percentage of PET-fibers have been conducted. The optimum content of PET-fiber, wherein there is a maximum increase of durability of fine-grained fiber-reinforced concrete, has been set.

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Increasing Density and Cement Content in Expansive Soils Stabilization:Conflicting or Complementary Procedures for Reducing Swelling?

Canadian Geotechnical Journal ◽

10.1139/cgj-2019-0855 ◽

2020 ◽

Author(s):

Nilo Cesar Consoli ◽

Mariana Tonini de Araújo ◽

Suéllen Tonatto Ferrazzo ◽

Vinícius de Lima Rodrigues ◽

Cecilia Gravina da Rocha

Keyword(s):

Moisture Content ◽

Portland Cement ◽

Significant Influence ◽

General Equation ◽

Cement Content ◽

Expansive Soils ◽

Dry Density ◽

Loss Of Mass ◽

Porosity Index ◽

Swelling Model

Present study makes three contributions to the literature of expansive soils: (i) it proposes equations to predict soil swelling based on dry density and cement content, (ii) it checks the developed general equation by predicting the swelling of different expansive soils from literature and (iii) it designs experiments that investigate factors that have a significant influence on swelling. An experimental programme was carried out to analyse the expansion of bentonite-kaolin-cement blends. Different proportions of bentonite-kaolin, cement content, dry density and moisture content were evaluated. A unique relation of the cement/porosity index was obtained for cement stabilized expansive soils swelling; this index has been used before to portray strength, stiffness and loss of mass of stabilized soils and is now shown to be applicable to describe swelling of expansive soils treated with Portland cement. In the present research, cement content and dry density are seen as conflicting parameters regarding the swelling of expansive soils, since increasing Portland cement amount reduces swelling and increasing density (through compaction) causes higher expansion. A general swelling model was proposed and successfully checked with data from the literature, being able to predict the swelling of expansive soils with different densities, expansive mineral, moisture and cement contents.

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Light fine-grained fibrous concrete for small architectural forms

MATEC Web of Conferences ◽

10.1051/matecconf/201821201008 ◽

2018 ◽

Vol 212 ◽

pp. 01008 ◽

Cited By ~ 1

Author(s):

Albina Baranova ◽

Margarita Badenikova ◽

Pavel Shustov ◽

Christina Rudykh ◽

Anna Bobrova

Keyword(s):

Portland Cement ◽

Bending Strength ◽

Basalt Fiber ◽

Strength Characteristics ◽

Concrete Mixture ◽

Optimal Ratio ◽

Fine Grained ◽

Fibrous Concrete ◽

Selection Of

The selection of the composition of a highly mobile concrete mixture for manufacturing small architectural forms has been performed, and the strength characteristics of light fine-grained fibrous concrete have been studied. It has been experimentally established that the optimal ratio of the Portland cement to microsilica is 1: 1. The introduction of basalt fiber in the amount of 0.5% of the mass of solids contributes to the increase in bending strength of fine-grained concrete to 70%.

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