Mechanical and Microstructure Characterization of Fresh High- and Normal- Strength Concrete with Non-Contact Electrical Resistivity Measurement

2011 ◽  
Vol 250-253 ◽  
pp. 122-130
Author(s):  
Ye Tian ◽  
Xian Yu Jin ◽  
Yuan Zhan ◽  
Nan Guo Jin
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Resistivity Measurement ◽  
Electrical Resistivity Measurement ◽  
Normal Strength Concrete ◽  
Design Quality ◽  
Bulk Resistivity ◽  
Archie’S Law ◽  
Strength Concrete ◽  
Normal Strength

This paper reports the investigation on both high and normal strength concrete using a non-contact electrical resistivity facility. The bulk resistivity development (ρ(t)-t curves) of the fresh concretes was evaluated from casting to 72h. The relationship between the electrical resistivity and the pore structure obtained from mercury intrusion porosimetry (MIP) method was analyzed. And the compressive strength evolution of fresh high- and normal- strength concrete was studied based on the bulk resistivity at early ages. The experiment results indicated a linear relationship between the fractional porosity and electrical resistivity. A further correlation between the compressive strength and electrical resistivity was analyzed with Archie’s law. Based on these studies, it appears that the electrical resistivity test could provide information for the design, quality control, quality assurance, and utilization of both high- and normal- strength concrete.

In Situ Inspection of Ultra Durable Concrete Using Electrical Resistivity Technique

2011 ◽  
Vol 368-373 ◽  
pp. 1989-1992
Author(s):  
Tze Yang Darren Lim ◽  
Bahador Sabet Divsholi ◽  
Susanto Teng
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Normal Strength Concrete ◽  
Strength Concrete ◽  
Chloride Diffusivity ◽  
Concrete Quality ◽  
Concrete Resistivity ◽  
Normal Strength

In today’s rapid construction, a reliable method for quick evaluation of concrete quality during construction is very important. The compressive strength of concrete has been used to evaluate the mechanical properties of concrete; however compressive strength may not represent the durability of concrete. Rapid Chloride Migration Test (RCMT) and electrical resistivity can be used to evaluate the durability of concrete. Obtaining the coefficient of chloride diffusivity from RCMT usually requires a testing duration of 24 hours or less for normal strength concrete. With the inclusion of supplementary cementitious materials and lower water/cementitious ratio to achieve a higher strength and more durable concrete, testing of the concrete becomes an elaborate affair which might takes at least four to five days of testing. Electrical resistivity technique has been used to evaluate the quality of normal strength concrete. However the suggested classification of concrete quality is not applicable to ultra durable concrete. In this work, the effectiveness of using the concrete resistivity test results from electrical resistivity technique is studied. With the use of direct and four points Wenner probe methods, the concrete resistivity results were obtained and compared with the coefficient of chloride diffusivity from RCMT. Six mixes of three different grades with the inclusion of 30% granulated ground blast-furnace slag and 10% undensified silica fume were designed and tested; and high correlation coefficients (>0.94) for all the mixes were achieved. This represents the effectiveness of using the electrical resistivity technique to carry out fast and accurate in-situ test to determine the quality of the ultra durable concrete.

Possibility of using recycled waste medical-glass as fine aggregate in normal-strength concrete

2021 ◽  
Vol 15 (3) ◽  
pp. 93-108
Author(s):  
Huynh Thi My Dung ◽  
Huynh Van Hiep ◽  
Huynh Trong Phuoc
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Drying Shrinkage ◽  
Dry Density ◽  
Fine Aggregate ◽  
Normal Strength Concrete ◽  
Strength Concrete ◽  
Normal Strength ◽  
Recycled Waste ◽  
Medical Glass

The possibility of using recycled waste medical-glass aggregate (RGA) as a fine aggregate in the production of normal-strength concrete was investigated in this study. The influence of RGA as crushed sand (CS) replacement at different levels (by volume) of 0 – 100% (an interval of 20%) on the engineering properties and durability of concrete was also studied. Results show that the replacement of CS by RGA insignificantly affected the workability and unit weight of fresh concrete mixtures. Besides, using RGA to replace 20 – 60% CS was beneficial in terms of compressive strength, drying shrinkage, and ultrasonic pulse velocity (UPV). At these replacement levels, the dry density values were found to increase and the water absorption values were reduced as well. However, replacing CS with RGA up to 80% and 100% caused a reduction in compressive strength, dry density, and UPV and an increase in water absorption and drying shrinkage of concretes. Closed correlations among the above-mentioned concrete properties were also found in this study. All of the concrete samples obtained compressive strength values higher than the target strength (≥ 25 MPa) and they were classified as very good quality concretes with UPV values of above 4100 m/s. The experimental results demonstrate a high possibility of producing normal-strength concrete with a fine aggregate of RGA as either partially or fully replacement of CS. This also provides an environmentally-friendly solution for recycling waste medical glass in construction materials for sustainable development.

scholarly journals Experimental Study on Electrical Resistivity of Cement-Stabilized Lead-Contaminated Soils

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Zhiguo Cao ◽  
Lian Xiang ◽  
Erxing Peng ◽  
Kai Li
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Contaminated Soils ◽  
Unconfined Compressive Strength ◽  
Cement Content ◽  
Resistivity Measurement ◽  
Lead Content ◽  
Electrical Resistivity Measurement ◽  
Fundamental Parameter ◽  
Curing Time

Geotechnical applications based on soil resistivity measurement are becoming more popular in recent years. In order to explore the potential application of the electrical resistivity method in stabilization/solidification of contaminated soils, two kinds of lead-contaminated soils stabilized with cement were prepared, and the electrical resistivity and unconfined compressive strength of specimens after curing for various periods were measured. The test results show that a high lead content leads to a low value of electrical resistivity of cement-stabilized soils, and increasing cement content and curing time result in a significant increase in electrical resistivity. The reduction in porosity and degree of saturation, as a result of the cement hydration process, leads to an increase in electrical resistivity. The ratio of porosity-lead content/cement content-curing time, combining together the effect of lead content, cement content, curing time, and porosity on electrical resistivity of stabilized soils, can be used as a fundamental parameter to assess electrical resistivity of cement-stabilized lead-contaminated soils. Archie’s law can be extended to apply to cement-stabilized lead-contaminated soils by using this ratio, replacing the porosity. The new resistivity formula obtained in this paper is just empirical. There is a power function correlation between unconfined compressive strength and electrical resistivity of lead-contaminated soils stabilized with cement. Electrical resistivity measurement can be used as an economical and time-effective method to assess the quality of cement-stabilized lead-contaminated soils in practice.

Superplasticizer for High Strength Concrete

2015 ◽  
Vol 1768 ◽  
Author(s):  
Luis E. Rendon Diaz Miron ◽  
Maria E. Lara Magaña
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
High Strength Concrete ◽  
High Strength ◽  
Mineral Admixtures ◽  
Normal Strength Concrete ◽  
Strength Concrete ◽  
Normal Strength ◽  
Ready Mixed Concrete ◽  
Mixed Concrete

ABSTRACTIn the early 1970s, experts predicted that the practical limit of ready-mixed concrete would be unlikely to exceed a compressive strength greater than 90 MPa [1]. Over the past two decades, the development of high-strength concrete has enabled builders to easily meet and surpass this estimate. The primary difference between high-strength concrete and normal-strength concrete relates to the compressive strength that refers to the maximum resistance of a concrete sample to applied pressure. Although there is no precise point of separation between high-strength concrete and normal-strength concrete, the American Concrete Institute defines high-strength concrete as concrete with a compressive strength greater than 45 MPa. Manufacture of high-strength concrete involves making optimal use of the basic ingredients that constitute normal-strength concrete. When selecting aggregates to obtain high-strength concrete, we consider strength, optimum size distribution, surface characteristics and a good bonding with the cement paste that affect compressive strength. Selecting a high-quality Portland cement and optimizing the combination of materials by varying the proportions of cement, water, aggregates, and admixtures is also necessary. Any of these properties could limit the ultimate strength of high-strength concrete. Pozzolans, such as fly ash and silica fume along with silicic acid, are the most commonly used mineral admixtures in high-strength concrete. These materials impart additional strength to the concrete by reacting with Portland cement hydration products to create additional Calcium Silicate Hydrate (CSH) gel, the part of the paste responsible for concrete strength; finally the most important admixture is polycarboxylate ether as super plasticizer. It would be difficult to produce high-strength ready-mixed concrete without using chemical admixtures. In this paper we study the use of high performance concrete (HPC) to obtain very narrow strong pre-fabricated elements for water conducting channels.

scholarly journals Influence of local rice husks ash on compressive strength of normal-strength concrete

2019 ◽  
Vol 1402 ◽  
pp. 022004
Author(s):  
B A L Fanggi ◽  
M Moata ◽  
A Mata ◽  
F Liem ◽  
T Woenlele ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Rice Husks ◽  
Normal Strength Concrete ◽  
Strength Concrete ◽  
Normal Strength ◽  
Rice Husks Ash

Activity Evaluation of a Tailing in a Cementitious System

2017 ◽  
Vol 726 ◽  
pp. 515-520 ◽  
Author(s):  
Bing Hao Li ◽  
Lian Zhen Xiao ◽  
Ya Qing Fu
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Fly Ash ◽  
Activity Index ◽  
Resistivity Measurement ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Electrical Resistivity Measurement ◽  
Activity Evaluation ◽  
Two Peaks

Hydration activity of a tailing is evaluated by the hydration rate obtained from the electrical resistivity measurement and compressive strength in a cementitious hydration system as a mineral admixture. A plain paste and the pastes with tailing or fly ash by replacement of cement at water-binder ratio of 0.4 are prepared. The electrical resistivity of the paste samples was measured in 168h(7d) by a non-contact resistivity technique. Hydration activity of the tailing was also evaluated by measuring the compressive strength at the curing ages of 3d~90d to confirm the results from the electrical resistivity. It is found that the addition of a mineral admixture delays the occurrence of two peaks on the electrical resistivity differential curve and the delayed times are 3.32h and 6.10h for the sample with tailing, and 0.78h, 3.49h for the sample with fly ash. The rate values on the two peaks are decreased with incorporation of the tailing or fly ash. The activity evaluation results on the mineral admixtures from the resistivity measurement are consistent with the strength results before 7d. The resistivity as an activity index can provide a simple and fast way to evaluate mineral material activity at early ages. The effect of tailing and fly ash on compressive strength for a long term was also analyzed and the micro-structure of the pastes at 7d and 28d were observed by SEM.

scholarly journals Effect of Maximum Aggregate Size on the Strength of Normal and High Strength Concrete

2020 ◽  
Vol 6 (6) ◽  
pp. 1155-1165
Author(s):  
Gaith Abdulhamza Mohammed ◽  
Samer Abdul Amir Al-Mashhadi
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Coarse Aggregate ◽  
Design Method ◽  
High Strength ◽  
Maximum Size ◽  
Normal Strength Concrete ◽  
Normal Concrete ◽  
Strength Concrete ◽  
Normal Strength

Aggregates form 60% to 75% of concrete volume and thus influence its mechanical properties. The strength of (normal or high-strength) concrete is affected by the maximum size of a well-graded coarse aggregate. Concrete mixes containing larger coarse aggregate particles need less mixing water than those containing smaller coarse aggregates, In other words, small aggregate particles have more surface area than a large aggregate particle. In this research, about twenty-two mixtures were covered to study the effect of the MSCA, on compressive strength of (normal strength concrete) and Sixteen mixtures to study the effect of the maximum size of coarse aggregate on compressive strength for (high strength concrete). The concrete mixture is completely redesigned according to the maximum size of coarse aggregate needs and maintaining uniform workability for all sizes of coarse aggregate. The American design method was adopted ACI 211.1, for normal concrete. ACI 211-4R, the design method was adopted for high strength concrete. And use the MSCA with dimensions (9.5, 12.5, 19, 25, 37.5, and 50) mm for normal strength concrete and the MSCA (9.5, 12.5, 19, and 25) mm for high strength concrete. The slump was fixed (75-100) mm for normal strength concrete. Slump is fixed to (25-50) mm for high strength concrete before added Superplasticizer high range water reducer (HRWR). With Fineness Modulus (F.M) fixed to 2.8 for both normal concrete and high-strength concrete. According to the results of the tests, the compressive strength increases with the increase in the MSCA, of the normal concrete and also high – strength concrete. And the effect of the MSCA, on the compressive strength of normal concrete, is higher than that of high-strength concrete.

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