Illinois' Experience with Cement Strength Uniformity

About 3.5 billion tons of mining waste is generated annually in Russia. The task of their utilization is urgent in connection with the accumulation of large-tonnage waste of simultaneously mined rocks, enrichment waste and crushing screenings. The problem can be solved by using these wastes as mineral additives to artificial cement-based conglomerates. According to the study results it was found, that the compressive strength of hardened cement paste increased during all hardening periods, when finely dispersed mining wastes were introduced. In the early stages of hardening, limestone had a predominant effect. Introduction of diopside led to the greatest hardening together with the hardening period increase. Linear and nonlinear mathematical models, describing the dependence of cement strength on the type and amount of mineral additives, were constructed. The highest strength values of hardened cement paste, both after hardening under normal conditions for 28 days, and after heat and moisture treatment could be achieved with 7% dispersed diopside. At the same time, the hardening effect (increase in the strength of cement by 35–40%) was retained when 1/3 of the diopside in the complex additive was replaced by dispersed limestone. An increase in the content of limestone in the complex additive composition over 1/3 was impractical.

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A Study on Optimum Mixture Ratio of Reactive Powder Concrete

Advances in Materials Science and Engineering ◽

10.1155/2018/7196873 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

Mingyang Chen ◽

Wenzhong Zheng

Keyword(s):

Compressive Strength ◽

Steel Fiber ◽

Raw Materials ◽

Reactive Powder Concrete ◽

Mixture Ratio ◽

Curing Methods ◽

Main Components ◽

Cement Strength ◽

Reactive Powder ◽

Design Factors

To optimize the main components of reactive powder concrete (RPC) for various curing methods, based on the fluidity and compressive strength, an inclusive experimental research is conducted on 58 different mixture ratios. The results indicate that owing to the increase of the cement strength, the RPC fluidity decreases and the cement strength is not proportional to the compressive strength. The addition of the fly ash and the nano-microbead is an effective way to improve the fluidity, and it is required at the low W/B ratio. However, the influence of the SF grade on the strength and fluidity is almost negligible. By considering the fluidity, strength, and economy of RPC as crucial design factors, SF90 is suggested. The contribution of the steel fiber to the compressive strength cannot be ignored. The upper envelope value of the steel fibers is required for the structure to resist appropriately against the fire. According to the test results, the mixture ratio formula is proposed through considering the characters of different compositions and curing methods. The strength coefficient k1 is introduced to verify the influence of the steel fiber content, and the parameters fb, αa, and αb in the formula are reevaluated. A reasonably good agreement between the calculated strength and those obtained from the tests is reported, except for the case of W/B = 0.16 with P.O.52.5 cement. The basic steps for preparations of different RPC strengths are given, which provide a valuable reference to choose appropriate raw materials and mixture ratio design for different strength values.

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MODERN THREE-DIMENSIONAL TECHNOLOGY AND FACTORS LIMITING THEIR

Bulletin of Belgorod State Technological University named after V G Shukhov ◽

10.12737/23011 ◽

2016 ◽

Vol 1 (12) ◽

pp. 22-30 ◽

Cited By ~ 1

Author(s):

Кучерова ◽

Anna Kucherova ◽

Дребезгова ◽

Mariya Drebezgova ◽

Чернышева ◽

...

Keyword(s):

Setting Time ◽

Three Dimensional ◽

High Strength ◽

Improve Performance ◽

Three Dimensional Printing ◽

Reducing Costs ◽

Manufacturing Technologies ◽

Strength Uniformity ◽

Dimensional Printing ◽

Strength Of Adhesion

The article presents information on the modern three-dimensional technologies and the main factors constraining their development. In recent decades there has been revolutionary new approaches to construction, in particular three-dimensional printing technology construction features, allowing you to abandon the traditional formwork, which significantly reduces costs and allows to create various architectural forms of buildings and structures. For the development of construction of next generation technologies requires the development of new materials with desired controlled properties: quick setting time, high strength, uniformity and strength of adhesion between the various layers. The use of additive manufacturing technologies for the construction of buildings and structures will significantly reduce costs by reducing costs of materials and improve performance, discover new creative approaches to create a variety of architectural shape of our cities.

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