Synthesis of Organosilicon Polymers Based on Carbamide Formaldehyde Resin

The article presents the synthesis of organosilicon compounds based on industrial secondary raw materials of urea-formaldehyde resin and tetraethoxysilane. The structural characteristics of the synthesized hydrophobic polymer have been studied. Compositions of hydrophobic compositions based on synthesized poly (oligomers) have been developed and tested in concrete mixtures.

Enhancing corrosion resistance of RC pipes using geopolymer mixes when subjected to aggressive environment

The durability of reinforced concrete (RC) pipes depends upon the corrosion resistance of the reinforcing steel and the resistance of concrete mixes against an aggressive environment. This research paper aims to compare the performance of R.C. pipes made of ordinary Portland cement (OPC) concrete mixtures with others made of two different geopolymer concrete mixes based on different ratios of granulated blast furnace slag (GBFS), fly ash (FA), and pulverized red brick (RB) subjected to three different environments, ambient, tap water (TW), and an aggressive environment, and a solution of 10% magnesium sulfates + 5% chloride (MS-CL). An accelerated corrosion setup has been applied to accelerate the corrosion process in the tested samples. The evaluation of change of compressive strength of concrete and microstructure of different mixes was investigated too. Fourier transform infrared (FTIR) spectroscopy has been studied on all pipes. Geopolymer concrete mixes based on 90% GBFS and 10% RB show better results in all cases. Geopolymer concrete mixes based on 63% GBFS, 27% FA, and 10% RB increase the concrete compressive strength in the magnesium sulfate and chloride environment by 5% compared to tap water. It can be concluded that the geopolymer concrete mixes produced of 90% GBFS and 10% RB perform well under all environments, and its microstructure shows stable behavior in an aggressive environment.

Seashells and Oyster Shells: Biobased Fine Aggregates in Concrete Mixtures

The construction industry is the largest global consumer of materials, among which sand plays a fundamental role; now the second most used natural resource behind water, sand is the primary component in concrete. However, natural sand production is a slow process and sand is now consumed at a faster pace than it’s replenished. One way to reduce consumption of sand is to use alternative materials in the concrete industry. This paper reports the exploratory study on the suitability of aquaculture byproducts as fine aggregates in concrete mixtures. Seashell grit, seashell flour and oyster flour were used as sand replacements in concrete mixtures (10%, 30% and 50% substitution rates). All the mixtures were characterized in fresh and hardened states (workability, air content, compressive strength and water absorption). Based on compressive strength, measured at 7 and 28 days, seashell grit provided the most promising results: the compressive strength was found to be larger than for conventional concrete. Moreover, the compressive strength of the cubes was larger, when larger percentages of seashell grit were used, with the highest value obtained for 50% substitution. However, for oyster flour and seashell flour, only 10% sand substitution provided results comparable with the control mixture. For the three aggregates, workability of concrete decreases with fineness modulus decrease. For mixtures in which shell and oyster flour were used with 30% and 50% substitution percentages, it was necessary to increase the quantity of mixing water to allow a minimal workability. In conclusion, considering the promising results of the seashell grit, it is suggested to study further the characteristic of the material, also considering its environmental and physical properties, including acoustic and thermal performances. Higher substitution percentages should also be investigated. This research adds to the relevant literature in matter of biobased concrete, aiming at finding new biobased sustainable alternatives in the concrete industry.

Development of Prediction Model to Predict the Compressive Strength of Eco-Friendly Concrete Using Multivariate Polynomial Regression Combined with Stepwise Method

Concrete is the most widely used building material, but it is also a recognized pollutant, causing significant issues for sustainability in terms of resource depletion, energy use, and greenhouse gas emissions. As a result, efforts should be concentrated on reducing concrete’s environmental consequences in order to increase its long-term viability. In order to design environmentally friendly concrete mixtures, this research intended to create a prediction model for the compressive strength of those mixtures. The concrete mixtures that were used in this study to build our proposed prediction model are concrete mixtures that contain both recycled aggregate concrete (RAC) and ground granulated blast-furnace slag (GGBFS). A white-box machine learning model known as multivariate polynomial regression (MPR) was developed to predict the compressive strength of eco-friendly concrete. The model was compared with the other two machine learning models, where one is also a white-box machine learning model, namely linear regression (LR), and the other is the black-box machine learning model, which is a support vector machine (SVM). The newly suggested model shows robust estimation capabilities and outperforms the other two models in terms of R2 (coefficient of determination) and RMSE (root mean absolute error) measurements.

Effect of Zeolite on the Compressive Strength of Concrete with Different Types of Cement

Concrete is a material component in coastal area construction. With the increasing demand for concrete for construction purposes, there have been various innovations in concrete mixtures to improve the quality of the concrete, including the compressive strength value of concrete. In the concrete mixture, the researchers also add additive to the concrete mixture, one alternative is natural zeolite which is widely found in the earth. Research by testing concrete samples with variations of the zeolite mixture 0%, 15%, and 25% uses cement type V. The test results are then compared with the results of other studies using different types of cement. Comparative studies of zeolite concrete test with different types of cement show that the optimum proportion of zeolite is around 10% to 20% of the weight of cement to get the best compressive strength value.

Resistance under Marshall monotonic load for asphalt concrete mixtures

The dense hot MDC-19 type asphalt mixes are considered, by the “Instituto Nacional de Vías” in Colombia, as continuous grading asphalt mixes (asphalt concrete). These constitute most of the surface course, in the structures of in-service pavements, being the object of study and research in different projects to ensure their durability. In the present investigation, unlike other investigations, the mechanical behavior under Marshall monotonic load was studied in the laboratory between MDC-19 dense type asphalt mixtures, comparing plant-produced and laboratory-produced asphalt mixtures. To carry out this process, samples of uncompacted asphalt mixtures were taken, produced in four fixed plants, with which Marshall-type briquettes were compacted. Likewise, samples of mineral aggregates and asphalt cement were obtained from the same plants, which constitute the mixtures raw material produced there. With these materials, briquettes with the same characteristics were mixed and compacted. Subsequently, the resistance under Marshall monotonic load was determined on the briquettes manufactured in plant and laboratory. The optimal asphalt cement content was compared between plant and laboratory- produced mixtures. An increase in Marshall Stability was found in the briquettes made with plant-produced mixtures, while these required a greater amount of asphalt cement for their production.

Enhancement of Electrical and Mechanical Properties of Modified Asphalt Concrete with Graphite Powder

A large number of additives are introduced in asphalt concrete mixtures in purpose of improving the properties of resistance, facing the increasing traffic and more severe climatic conditions. This will guarantee the good comfort for a longer exploitation time. In this article we used graphite powder as an unconventional additive, and then investigate its effect mainly on the electrical resistivity which is in context of our research work on conductive asphalt (with a resistivity around 106 Ω m), As well as on its mechanical properties evaluated using the new Fenix test that gives many information of mechanical especially dissipated energy. A significant improvement was noticed in the reduction of resistivity by reaching 1.7 × 106Ω m and also greater resistance to cracking based on variation of dissipated energy as a result we concluded that introducing graphite powder with an appropriate amount enhance both mechanical and electrical properties asphalt concrete. Doi: 10.28991/CEJ-2022-08-01-09 Full Text: PDF