scholarly journals Infrared spectr of SP–2VU superplastifying agent and a cement mortar with additive

Author(s):  
L. A. Vinogradova ◽  
Y. P. Rusakova

To improve the concrete properties, various technological methods are used, the most accessible ones being the introduction of chemical additives into the concrete mixture, which can significantly reduce the costs level per unit of production; these additives improve concrete quality and effectiveness and reinforced concrete structures as well as increase their service life and buildings and structures in whole. This paper presents the results of studying the effect of introducing a superplasticizer with stabilizing effect of Polyplast SP – 2VU LLC Polyplast Novomoskovsk into concrete by analyzing the IR spectra of the additive in pure form and as part of hardened cement mortar (0.1–0.9%). Portland cement CEM I 42.5 B of Mordovcement OJSC was used as a binder; the aggregates were enriched with quartz sand from the Khromtsovsky deposit with a size of 2.4 and granite crushed stone of the Orsk deposit of 5–20 mm with water absorption of 0.2% . In the course of the work, the chemical composition of the additive SP2-VU itself and the hardened modified concrete composition were analyzed. Thus, the introduction of a modifier into a concrete composition leads to the change in its structure and strength characteristics. It was established with the help of IR spectra, that when the content of the additive in the cement mortar is 0.5%, a more ordered and stable hardened structure is formed. The reliability of the data obtained is confirmed by the identification of the main peaks. Due to the modification of concrete (at 0.3-0.5% in the concrete mix regulator concentration), the increase in the strength of the samples is more than 40%.

2013 ◽  
Vol 482 ◽  
pp. 118-122
Author(s):  
Jing Bo Sun ◽  
Yong Zhi Zuo ◽  
Hai Wen Teng ◽  
Tao Zhang ◽  
Huan Liu

The reason of most accidents in the construction engineering are due to the complicated nature of concrete composition, shortcomings during the construction process, equipment and many other reasons. Reinforced concrete quality account for a large percentage of engineering accidents. In this paper, reinforced concrete structures accident type and its causes were classified and summarized through the summarizing and sorting of different cases, and the relationship between them was analyzed and expounded.


2020 ◽  
Vol 309 ◽  
pp. 114-119
Author(s):  
Ekaterina S. Gerasimova ◽  
Elizaveta Gumirova

The paper is devoted to research of influence of “MC-Bauchemie” additions on the fine-grained concrete properties, namely compressive strength. The results of testing of fine-grained concrete made on the basis of two different natural sands are presented. Characteristics of the initial materials used in the work (Portland cement, sands and additions-plasticizers) are given. The basic methods of preparation of mixes and testing of hardened cement stone and concrete are described. The optimal quantity of the selected additions on the example of cement paste and stone are established. Mobility dependences of concrete mixes on a type and quantity of plasticizers are received. The dependence of the additions effectiveness on the mobility of the concrete mix on the quality of the fine aggregate is shown. It is established that the most effective additive is PowerFlow 3100, its optimal amount for obtaining fine-grained concrete on the basis of JSC “Kar’er Myisyi” sand is 0.2 %.


Author(s):  
Любовь Виноградова ◽  
Lyubov' Vinogradova ◽  
Юлия Русакова ◽  
Yuliya Rusakova

Chemical additives, namely, plasticizers and superplasticizers are effective modifiers of the concrete mix properties and structures. The additives allow to control properties of the concrete mix and to obtain its optimal structure, acting on the surface phenomena and microstructure of the cement paste. In the course of the study, the effect of introducing the superplasticizer SP-2VU into the concrete mix is studied. This allows to modify the construction and engineering properties of concrete. Analysis of the data obtained in determining the setting speed of the system based on cement and various concentrations of the regulator shows that the introduction of SP-2VU into the cement mortar leads to a significant slowdown in the process of setting the binder composition in comparison with additive-free cement, slowing the cement setting from ~ 2 hours to ~ 12.5 hours. In addition, the superplasticizer in an amount of up to 0.5 % contributes to some preservation of the cement mixture mobility to ~5 h, while in the absence of an additional composition - up to ~2.5 h. The SP-2VU (to a concentration of 0.7 %) increases the strength of modified concrete compared to conventional. Moreover, the optimal concentration of the additive (0.5 %) is established, which contributes to the set of the required speed of structure formation of the system and the formation of strong hardening structures with a more ordered, stable solidified structure and certain performance characteristics. At the same time, the strength of samples containing 0.5 % of the modifier in the concrete mixture increases by 40 %.


Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 267
Author(s):  
Tomasz Rudnicki

The article presents a new functional method of designing self-compacting concrete (SCC). The assumptions of the functional method of designing self-compacting concrete were based on the double coating assumption (i.e., it was assumed that the grains of coarse aggregate were coated with a layer of cement mortar, whereas the grains of sand with cement paste). The proposed method is composed of four stages, each of which is responsible for the selection of a different component of the concrete mix. The proposed designing procedure takes into consideration such a selection of the mineral skeleton in terms of the volumetric saturation of the mineral skeleton, which prevents the blocking of aggregate grains, and the designed liquid phase demonstrated high structural viscosity and low yield stress. The performed experimental studies, the simulation of the elaborated mathematical model fully allowed for the verification of the theoretical assumptions that are the basis for the development of the method of designing self-compacting concrete.


2013 ◽  
Vol 857 ◽  
pp. 3-9
Author(s):  
Zi Yi Hou ◽  
Peng Peng ◽  
Jin De Xie ◽  
Shao Peng Zheng ◽  
Ye Zhen Yuan

A test method for monitoring of cement mortar quality has been devised and an empirical relational equation between cement mortar fluidity and torque has been worked out. A test method for monitoring of indoor fresh cement concrete quality has been devised and a relational equation between fresh cement concrete and torque has been worked out. A test method for monitoring of fresh cement concrete in a mixing plant has been devised and a relational equation between fresh cement concrete and current property has been worked out. By means of online observed torque and current data, relevant fluidity and slump can be predicted to provide test methods and relevant theoretical basis for intelligent monitoring of fresh cement mortar and cement concrete quality in actual engineering.


2014 ◽  
Vol 941-944 ◽  
pp. 730-733 ◽  
Author(s):  
Maciej Gruszczyński

Numerous concrete and reinforced concrete structures (industrial floors, petrol station or manoeuvring park pavements, elements of sewage system) are subjected to danger of permanent or periodical action of petroleum liquids that often causes the considerable reduction in concrete strength as well as decrease of bond between concrete and steel, which usually results in structure damages. The subject of the paper is estimation of influence of polymer dispersion additive (styrene-acrylic co-polymer and styrene-butadiene latex) onto durability of concrete subjected to action of different types of light liquids. The influence of polymer dispersion additive was confronted with the action of silica fume usually applied for sealing the structure of concrete. In the paper there are presented tests results for different types of light liquids onto such cement-polymer concrete properties as: strength, penetration depth of light liquids into material structure.


2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Luoxin Wang ◽  
Junshuai Mei ◽  
Jing Wu ◽  
Xingyang He ◽  
Hainan Li ◽  
...  

The workability and mechanical performance of coral sand-cement mortar (coral mortar, for short) and the modification effects of mineral admixtures on the coral mortar were studied in this paper. The results showed that the strength of coral mortar was lower than that of standard mortar, but the strength of coral mortar was improved by compositing with the mineral admixture, which can be attributed to the improvement of the microstructure and interface transition area. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to explore the microscopic mechanism involved in the mechanical properties, volume stability, and hydration of mortar. The analyses revealed that the internal curing effect of coral sand improved the mechanical properties of mortar and its ability to resist shrinkage. The uneven surface of coral sand formed a meshing state of close combination with the hardened cement mortar, which helped to improve the volume stability of mortar. The Ca2+ and Mg2+ ions from coral sand participated in the hydration reaction of cement, which contributed to generating more hydration products. Moreover, the microaggregate filling and pozzolanic effects of fly ash and slag improved the mechanical properties of coral mortar and resistance to chloride ion diffusion.


2019 ◽  
Vol 9 (21) ◽  
pp. 4519
Author(s):  
Klus ◽  
Václavík ◽  
Dvorský ◽  
Svoboda ◽  
Botula

This paper presents the results of research dealing with the use of recycled waste sludge water from a concrete plant (CP) as partial or complete replacement of mixing water in cement mixtures. The need to recycle waste sludge water generated as a by-product (waste sludge water) during the production of fresh concrete in the concrete plant results from the environmental and economic problems associated with the operation of the concrete plant. Mixing water was replaced with recycled waste sludge water in the amount of 25%, 50%, 75%, and 100%. In order to determine the effect of partial or complete replacement of mixing water with waste sludge water from the concrete plant in the production of cement composites, laboratory tests of waste sludge water were carried out to determine whether the waste sludge water complies with the requirements for mixing water defined in CSN EN 1008. The tests also determined the properties of fresh cement mortar and hardened cement composites. These were tests of the beginning and end of cement mortar setting, and the strength characteristics (flexural strength, compressive strength). The results of these tests show that it is possible to replace the mixing water by waste sludge water from the concrete plant in the amount of up to 25% without significantly affecting the tested properties, in comparison with the formula containing pure mixing water.


1996 ◽  
Vol 26 (11) ◽  
pp. 1619-1627 ◽  
Author(s):  
Osman N. Oktar ◽  
Harun Moral ◽  
Mehmet A. Taşdemir

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