Detection of Inherent Heterogeneities in Cement Strength Records by Means of Segmentation

2008 ◽  
pp. 42-42-24 ◽  
Author(s):  
LR Taerwe
Keyword(s):  
Cement Strength

Hardening Cement Conglomerates by Mining Industries Waste

2021 ◽  
Vol 316 ◽  
pp. 1061-1066
Author(s):  
Lilia V. Ilina ◽  
Irina N. Mukhina ◽  
Mariya M. Semenova
Keyword(s):  
Cement Paste ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Period Increase ◽  
Complex Additive ◽  
Nonlinear Mathematical Models ◽  
Study Results ◽  
Cement Strength ◽  
Heat And Moisture ◽  
Mineral Additives

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.

scholarly journals A Study on Optimum Mixture Ratio of Reactive Powder Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
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.

Variability of Cement Strength in Saudi Arabia

2008 ◽  
pp. 80-80-13
Author(s):  
MS Taryal ◽  
MK Chowdhury
Keyword(s):  
Saudi Arabia ◽  
Cement Strength

Preparation and Mechanism of High Dosage Fly Ash Cement

2012 ◽  
Vol 152-154 ◽  
pp. 52-56 ◽  
Author(s):  
Rui Gang Wang
Keyword(s):  
Fly Ash ◽  
Testing Methods ◽  
Comparative Tests ◽  
Activate Effect ◽  
Composite Mixture ◽  
Cement Strength

The activate effect of various activator on fly ash was studied according to the comparative tests of cement strength. The result shows that the sulfate activator and alcohol amine activator composite mixture has the best activate effect under the reasonable mix ratio. The composite mixture can obviously affect fly ash cement strength, and under the 50% mixing amount of fly ash, the 3d strength of cement is improved by 30% to 50%, and the 7d strength of cement is improved by 20% to 30%. Activate mechanism of the composite activator was studied through the XRD, SEM and other microscopic testing methods.

The Slag Influence on High Temperature Resistance of Aluminophosphate Cementfor Heavy Oil Thermal Recovery

2014 ◽  
Vol 33 (4) ◽  
pp. 325-328 ◽  
Author(s):  
Zaoyuan Li ◽  
Yan Wang ◽  
Xiaowei Cheng ◽  
Xiaoyang Guo
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Low Temperature ◽  
Heavy Oil ◽  
Thermal Recovery ◽  
Temperature Resistance ◽  
High Temperature Resistance ◽  
Zonal Isolation ◽  
Cement Strength ◽  
Isolation Performance

AbstractThe sharp strength recession of silicate cement in high temperature is the crucial reason of casings damage and zonal isolation failure in heavy oil thermal recovery. Although aluminophosphate cement has a better high temperature resistance in comparison with silicate cement, its compressive strength recession in high temperature slightly recessed. The results show that adding slag into aluminophosphate cement can not only develop compressive strength of cement at low temperature, but it can also improve the high temperature resistance of the cement. After adding slag, the formation of C2ASH8 conduces to develop cement strength at low temperature, and C3AS2H2 conduces to high temperature resistance. To increase temperature resistance of aluminophosphate cement, C3ASH4 generation and Al(OH)3 decomposition should be avoided. Crystal structure of cement after high temperature is well developed with compactly and neatly arranged, allowing cement to maintain good mechanical properties to help protect the casing and improve zonal isolation performance.

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