Influence of concrete strength evaluation method accuracy on reliability levels of geotechnical structures

Quantitative parameters of influence of grain composition of ground quartz sand and its quantity on the workability and segregation of self-compacting fresh concrete were determined at the constant amount of mixing water and water-cement ratio. Ground quartz sand in the amount of 50-150 kg/m3 was added instead of fine and coarse aggregates with changing the amount of polycarboxylate superplasticizer. It is stated that the use of ground quartz sand of finer grinding provides higher values of workability at the same quantity of water and superplasticizer. Segregation of the fresh concrete occurs when using increased amount of ground quartz sand of coarser grinding and increased amount of superplasticizer. Experimental studies have shown the effectiveness of the use of ground quartz sand to obtain self-compacting fresh concrete of different classes of workability SF1 and SF2 as well as classes of segregation resistance SR1 and SR2. The results of the experiments allow to state that the use of ground quartz sand of coarser grinding leads to segregation of fresh concrete at its low workability, while the use of ground quartz sand of finer grinding allows to obtain fresh concrete with resistance to segregation.

Section: Research Results and Discussionsupporting

confidence: 84%

Technological Properties of Self-Compacting Concrete Mixtures with Ground Quartz Sand

Kazanskaya¹,

Fadeeva²,

Isakovsky³

2019

“…The use of non-destructive methods reduces the accuracy of the test, so it is difficult to make a reasonable decision about the reserve of load-bearing capacity of masonry [25,[29][30][31]. The development of these methods seems to be effective in combination with destructive methods.…”

Section: Methodsmentioning

confidence: 99%

Methods of Assessing the Strength of Masonry to Ensure the Reliability of Reconstructed Structures

Kazanskaya¹,

Belentsov²

2019

The reliability of structures in the reconstruction of buildings depends on quality control methods that can be destructive and non-destructive. Directions for improving the accuracy of methods for assessing masonry as a complete construction system are proposed in the paper. The factors to be taken into account when assessing the bearing capacity of the operating buildings have been stated. Margin of errors of a number of parameters using different methods of strength assessment have been determined.

“…Historical masonry and plaster mixes, as a rule, are characterized by the strength class from M25 to M75. Accordingly the use of limestone is not limited to its lower strength in comparison with quartz sand [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Lime Based Dry Mixes with Carbonate Aggregates

Pukharenko¹,

Харитонова²

2019

 Abstract: The use of carbonate rocks as aggregates for cement concretes and mortars is limited due to their insufficient strength and the threat of corrosion. The use of quarry dust from crushing carbonate rocks are technically and economically feasible in building compositions based on air-hardening lime. The results of the study of the effect of replacing a part of quartz sand in lime mortar by limestone and dolomite fine aggregates on the basic physical and mechanical properties of lime mortars for restoration are presented in the paper. The matrix of planning experiments, which allows increasing the informativity of the research results in order to reduce the number of experiments in the search for optimal values, is proposed. The efficiency of replacement of the quartz sand with quarry dust of carbonate rocks in the production of dry mixes for restoration is shown.