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.

Study on the Durability of Concrete with Mineral Admixtures to Sulfate Attack by Wet-Dry Cycle Method

2011 ◽  
Vol 295-297 ◽  
pp. 165-169
Author(s):  
Guan Guo Liu ◽  
Jing Ming ◽  
Xiong Wen Zhang ◽  
Ai Bin Ma
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sulfate Attack ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Partial Replacement ◽  
Change Environment ◽  
Physical Mechanisms ◽  
Chemical Attack ◽  
Tidal Area

Sulfate attack is one of several chemical and physical mechanisms of concrete deterioration. In actual situation, concrete structures always suffer from the coupled effects of multifactor such as wet-dry cycle and sulfate attack when exposed to tidal area or groundwater level change environment. Partial replacement of cement with mineral admixture is one of the efficient methods for improving concrete resistance against sulfate attack. In this regard, the resistance of concrete with fly ash and slag to sulfate attack was investigated by wet-dry cycle method. The degree of sulfate attack on specimens after different cycles was observed using scanning electron microscopy. The results of compressive strength and percentage of compressive strength evolution factor at various cycling times show an increase in the sulfate resistance of concrete with 60% of fly ash and slag than that only with 40% fly ash. The microstructural study indicates that the primary cause of deterioration of concrete under wet-dry cycle condition is swelling of the sulfate crystal rather chemical attack.

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.

Influence of Mixing Method of Mineral Admixture on Performance of Recycled Concrete

2012 ◽  
Vol 598 ◽  
pp. 612-617 ◽  
Author(s):  
Ying Li ◽  
Da Hu Dai
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Recycled Concrete ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Mixing Method

In order to improve the microstructure of recycled concrete, the mineral admixtures were mixed into recycled concrete by different mixing method in this paper. It is demonstrated that the early compressive strength of recycled concrete decreased when mixed by fly ash only, but its later strength increasing rate is higher than recycled concrete without fly ash. When mixed fly ash and silica fume in the recycled concrete, the compressive strength of recycled concrete with fly ash and silica fume is higher than the strength of recycled concrete with fly ash only, and its microstructure tend to be dense.

Effect of Different Mineral Admixtures on Properties of Sulphoaluminate Cement

2012 ◽  
Vol 174-177 ◽  
pp. 1173-1176
Author(s):  
Rui Ma ◽  
Xin Cheng ◽  
Chen Chen Gong ◽  
Shou De Wang ◽  
Ling Chao Lu
Keyword(s):  
Electron Microscopy ◽  
Compressive Strength ◽  
Fly Ash ◽  
Cement Hydration ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Hydration Products ◽  
Sulphoaluminate Cement ◽  
Slag Powder ◽  
Scanning Electron

Effects of superfine slag powder, fly ash and ultra-fine CaCO3 on compressive strength of sulphoaluminate cement were investigated. Cement hydration products were analyzed by using scanning electron microscopy (SEM). The results show that different fineness and additions of mineral admixture differ in compressive strength. When the amount of superfine slag powder, fly ash and ultra-fine CaCO3 are added by 10%, 10% and 3% (by weight), the compressive strength of the hardened paste of sulphoaluminate cement is highest, respectively. Meanwhile, it is concluded that the additions of superfine slag powder and ultra-fine CaCO3 facilitates hydration at early ages, while fly ash could accelerate hydration at later ages.

Mechanical Properties of Steam-Cured Concrete with Combined Mineral Admixtures

2010 ◽  
Vol 168-170 ◽  
pp. 1535-1538
Author(s):  
Zhi Min He ◽  
Jun Zhe Liu ◽  
Tian Hong Wang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Precast Concrete ◽  
High Volume ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Splitting Strength ◽  
High Volume Fly Ash ◽  
Tensile Splitting Strength

In precast concrete elements manufacturing, steam-cured concrete incorprating 30% mineral admixtures encountered the problem of too low demoulding compressive strength. To resolve it, this paper mainly studied the influence of mineral admixtures on the compressive strength, the tensile-splitting strength and the flexural strength of the steam-cured concrete. The experimental results indicated that, compared with steam-cured concrete incorprating mineral admixtures, the later strength of steam-cured concrete incorprating 0% mineral admixtures has lower increment degree and its increment of tensile-splitting strength and flexural strength inverted to some extent. The demoulding compressive strength is too low for the high volume fly ash concrete mixtures. The problem of too low demoulding compressive strength is solved by incorprating composites of ground blast furnace slag(GBFS) and fly ash. Different varieties of mineral admixture used in the concretes can produce a certain degree of potentiation.

Research on the Proportion of Inorganic Binder Stabilize Materials with Soda Residue

2014 ◽  
Vol 629-630 ◽  
pp. 481-486
Author(s):  
Wen Ying Guo ◽  
Mei Ru Zheng ◽  
Yi Bo Yang ◽  
Heng Chang Wang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Chloride Ion ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Urgent Problem ◽  
Strength Performance ◽  
Inorganic Binder ◽  
Negative Effect

The soda residue pollutes the environment because of high contents of alkali ion and choleric ion in it. So how to treat the soda residue is an urgent problem to be solved. The mineral admixtures are added in traditional inorganic binder to improve the strength performance of inorganic binder stabilized materials and decrease the negative effect of soda residue is studied. And the results as followings: (1) Soda residue has different activated effect on mineral admixture; (2) Mineral admixture replace the cement with same dosage can improve the unconfined compressive strength greatly to meet the requirement of standard; (3) The choleric ion leaching rates of cement-mineral admixture-soda residue stabilized stone chip decrease with time. Mineral admixture has a better immobilization effect on the chloride ion except fly ash before 90d; (4) Ground granular blast-furnance slag is the best material to improve the strength performance of inorganic binder stabilized materials and decreases the negative effect of soda residue.

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.

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