Investigation of Pore Structure for Manufactured Sand Mortar

2014 ◽  
Vol 534 ◽  
pp. 39-51
Author(s):  
Zheng Hong Tian ◽  
Jing Wu Bu
Keyword(s):  
Pore Structure ◽  
Pore Size ◽  
Water Saturation ◽  
Total Porosity ◽  
Threshold Region ◽  
Fine Aggregate ◽  
Test Results ◽  
Natural Sand ◽  
Manufactured Sand ◽  
Threshold Radius

This paper focuses on the pore structure parameters of mortars produced with manufactured sand and natural sand via water saturation and MIP methods. Test results show that, total porosity, as well as compressive strength, of manufactured sand mortar, is higher than that of natural sand mortar at fixed w/c and s/c ratio. Furthermore, considerable volume of large pores present in specimens of manufactured sand at higher w/c ratio rather not at the lower w/c ratio, which caused by the larger binder-aggregate interface. Manufactured fine aggregate in mortar probably accelerate hydrated reaction of cement, which result in the most probable pore size is finer than that of natural sand mortar. It can be concluded that the threshold region becomes flatten and threshold radius increases due to the aggregate volume concentration rises. Finally, a new theoretical model with a double-lognormal distribution function is demonstrated to be reasonable to fit pore size distribution in mortars.

scholarly journals Influence of Pore Structure on Compressive Strength of Cement Mortar

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Haitao Zhao ◽  
Qi Xiao ◽  
Donghui Huang ◽  
Shiping Zhang
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Pore Size ◽  
Cement Mortar ◽  
Natural Sand ◽  
Cement Ratio ◽  
Manufactured Sand ◽  
Mix Proportion ◽  
Mercury Porosimeter ◽  
Threshold Radius

This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure.

Petrographic and Petrophysical Characteristics of the Upper Devonian Three Forks Formation, Southern Nesson Anticline, North Dakota

2017 ◽  
Vol 54 (3) ◽  
pp. 181-201
Author(s):  
Rebecca Johnson ◽  
Mark Longman ◽  
Brian Ruskin
Keyword(s):  
Relaxation Time ◽  
Pore Size ◽  
Water Saturation ◽  
Average Pore Size ◽  
Total Porosity ◽  
Average Pore ◽  
Pore Sizes ◽  
Three Forks Formation ◽  
Three Forks ◽  
Intercrystalline Pores

The Three Forks Formation, which is about 230 ft thick along the southern Nesson Anticline (McKenzie County, ND), has four “benches” with distinct petrographic and petrophysical characteristics that impact reservoir quality. These relatively clean benches are separated by slightly more illitic (higher gamma-ray) intervals that range in thickness from 10 to 20 ft. Here we compare pore sizes observed in scanning electron microscope (SEM) images of the benches to the total porosity calculated from binned precession decay times from a suite of 13 nuclear magnetic resonance (NMR) logs in the study area as well as the logarithmic mean of the relaxation decay time (T2 Log Mean) from these NMR logs. The results show that the NMR log is a valid tool for quantifying pore sizes and pore size distributions in the Three Forks Formation and that the T2 Log Mean can be correlated to a range of pore sizes within each bench of the Three Forks Formation. The first (shallowest) bench of the Three Forks is about 35 ft thick and consists of tan to green silty and shaly laminated dolomite mudstones. It has good reservoir characteristics in part because it was affected by organic acids and received the highest oil charge from the overlying lower Bakken black shale source rocks. The 13 NMR logs from the study area show that it has an average of 7.5% total porosity (compared to 8% measured core porosity), and ranges from 5% to 10%. SEM study shows that both intercrystalline pores and secondary moldic pores formed by selective partial dissolution of some grains are present. The intercrystalline pores are typically triangular and occur between euhedral dolomite rhombs that range in size from 10 to 20 microns. The dolomite crystals have distinct iron-rich (ferroan) rims. Many of the intercrystalline pores are partly filled with fibrous authigenic illite, but overall pore size typically ranges from 1 to 5 microns. As expected, the first bench has the highest oil saturations in the Three Forks Formation, averaging 50% with a range from 30% to 70%. The second bench is also about 35 ft thick and consists of silty and shaly dolomite mudstones and rip-up clast breccias with euhedral dolomite crystals that range in size from 10 to 25 microns. Its color is quite variable, ranging from green to tan to red. The reservoir quality of the second bench data set appears to change based on proximity to the Nesson anticline. In the wells off the southeast flank of the Nesson anticline, the water saturation averages 75%, ranging from 64% to 91%. On the crest of the Nesson anticline, the water saturation averages 55%, ranging from 40% to 70%. NMR porosity is consistent across the entire area of interest - averaging 7.3% and ranging from 5% to 9%. Porosity observed from samples collected on the southeast flank of the Nesson Anticline is mainly as intercrystalline pores that have been extensively filled with chlorite clay platelets. In the water saturated southeastern Nesson Anticline, this bench contains few or no secondary pores and the iron-rich rims on the dolomite crystals are less developed than those in the first bench. The chlorite platelets in the intercrystalline pores reduce average pore size to 500 to 800 nanometers. The third bench is about 55 ft thick and is the most calcareous of the Three Forks benches with 20 to 40% calcite and a proportionate reduction in dolomite content near its top. It is also quite silty and shaly with a distinct reddish color. Its dolomite crystals are 20 to 50 microns in size and partly abraded and dissolved. Ferroan dolomite rims are absent. This interval averages 7.1% porosity and ranges from 5% to 9%, but the pores average just 200 nanometers in size and occur mainly as microinterparticle pores between illite flakes in intracrystalline pores in the dolomite crystals. This interval has little or no oil saturation on the southern Nesson Anticline. Unlike other porosity tools, the NMR tool is a lithology independent measurement. The alignment of hydrogen nuclei to the applied magnetic field and the subsequent return to incoherence are described by two decay time constants, longitudinal relaxation time (T1) and transverse relaxation time (T2). T2 is essentially the rate at which hydrogen nuclei lose alignment to the external magnetic field. The logarithmic mean of T2 (T2 Log Mean) has been correlated to pore-size distribution. In this study, we show that the assumption that T2 Log Mean can be used as a proxy for pore-size distribution changes is valid in the Three Forks Formation. While the NMR total porosity from T2 remains relatively consistent in the three benches of the Three Forks, there are significant changes in the T2 Log Mean from bench to bench. There is a positive correlation between changes in T2 Log Mean and average pore size measured on SEM samples. Study of a “type” well, QEP’s Ernie 7-2-11 BHD (Sec. 11, T149N, R95W, McKenzie County), shows that the 1- to 5-micron pores in the first bench have a T2 Log Mean relaxation time of 10.2 msec, whereas the 500- to 800-nanometer pores in the chlorite-filled intercrystalline pores in the second bench have a T2 Log Mean of 4.96 msec. This compares with a T2 Log Mean of 2.86 msec in 3rd bench where pores average just 200 nanometers in size. These data suggest that the NMR log is a useful tool for quantifying average pore size in the various benches of the Three Forks Formation.

scholarly journals The Use of Sheet Glass Powder as Fine Aggregate Replacement in Concrete

2010 ◽  
Vol 4 (1) ◽  
pp. 65-71 ◽  
Author(s):  
M. Mageswari ◽  
Dr. B. Vidivelli
Keyword(s):  
Sheet Glass ◽  
Glass Powder ◽  
Fine Aggregate ◽  
Test Results ◽  
Natural Sand ◽  
Aggregate Concrete ◽  
Fine Aggregates ◽  
Interesting Possibility ◽  
Compact State ◽  
Conservation Of Natural Resources

Sheet glass powder (SGP) used in concrete making leads to greener environment. In shops, near by Chidambaram many sheet glass cuttings go to waste, which are not recycled at present and usually delivered to landfills for disposal. Using SGP in concrete is an interesting possibility for economy on waste disposal sites and conservation of natural resources. This paper examines the possibility of using SGP as a replacement in fine aggregate for a new concrete. Natural sand was partially replaced (10%, 20%, 30%, 40% and 50%) with SGP. Compressive strength, Tensile strength (cubes and cylinders) and Flexural strength up to 180 days of age were compared with those of concrete made with natural fine aggregates. Fineness modulus, specific gravity, moisture content, water absorption, bulk density, %voids, % porosity (loose and compact) state for sand (S) and SDA were also studied. The test results indicate that it is possible to manufacture concrete containing Sheet glass powder (SGP) with characteristics similar to those of natural sand aggregate concrete provided that the percentage of SGP as fine aggregate is limited to 10-20%, respectively.

Influence of Stone Dust in Manufactured Sand on Resisting Chloride Penetration in Marine Concretes

2012 ◽  
Vol 174-177 ◽  
pp. 1419-1423
Author(s):  
Jian Bo Xiong ◽  
Peng Ping Li ◽  
Sheng Nian Wang
Keyword(s):  
Diffusion Coefficient ◽  
Pore Structure ◽  
Binding Capacity ◽  
Chloride Penetration ◽  
Dust Content ◽  
Chloride Diffusion ◽  
Fine Aggregate ◽  
Chloride Diffusion Coefficient ◽  
Manufactured Sand ◽  
Stone Dust

In China, manufactured sand has been widely used as fine aggregate in concrete. Therefore, it is necessary to investigate the effect of manufactured sand on durability of concrete. This research studies the influence of stone dust content in manufactured sand on resisting chloride penetration in marine concrete by strength and other physical mechanical tests, XRD, TGA and pore structure analysis. Test results have shown that the chloride diffusion coefficient increased with increasing the stone dust content in manufactured sand when the stone dust content increasing from 3% to 13%. The stone dust in fine aggregate was participated in hydration procedure of cementitious, which will promote the hydration degree of cementitious and increase the chloride binding capacity of hydration product. The influence of stone dust in fine aggregate on chloride diffusion coefficient were the combined effects of concrete pore structure and cementitious hydration products, and the porosity and pore size distribution were the main factors that influence the changes of diffusion coefficient.

scholarly journals Mechanical and Durability Properties of Concrete Made with Used Foundry Sand as Fine Aggregate

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
G. Ganesh Prabhu ◽  
Jin Wook Bang ◽  
Byung Jae Lee ◽  
Jung Hwan Hyun ◽  
Yun Yong Kim
Keyword(s):  
Substitution Rate ◽  
International Standards ◽  
Fine Aggregate ◽  
Test Results ◽  
Natural Sand ◽  
Foundry Sand ◽  
Durability Properties ◽  
Concrete Mixtures ◽  
Concrete Production ◽  
Strength And Durability

In recent years, the construction industry has been faced with a decline in the availability of natural sand due to the growth of the industry. On the other hand, the metal casting industries are being forced to find ways to safely dispose of waste foundry sand (FS). With the aim of resolving both of these issues, an investigation was carried out on the reuse of waste FS as an alternative material to natural sand in concrete production, satisfied with relevant international standards. The physical and chemical properties of the FS were addressed. The influence of FS on the behaviour of concrete was evaluated through strength and durability properties. The test results revealed that compared to the concrete mixtures with a substitution rate of 30%, the control mixture had a strength value that was only 6.3% higher, and this enhancement is not particularly high. In a similar manner, the durability properties of the concrete mixtures containing FS up to 30% were relatively close to those of control mixture. From the test results, it is suggested that FS with a substitution rate of up to 30% can be effectively used in concrete production without affecting the strength and durability properties of the concrete.

Prediction of tensile strength of concrete produced by using pozzolanic materials and partly replacing natural sand by manufactured sand

2019 ◽  
Vol 10 (3) ◽  
pp. 50
Author(s):  
Kiran Mansingrao Mane ◽  
Dilip K. Kulkarni ◽  
K. B. Prakash
Keyword(s):  
Tensile Strength ◽  
Industrial Wastes ◽  
Test Results ◽  
Ann Model ◽  
Natural Sand ◽  
Manufactured Sand ◽  
Tensile Strength Test ◽  
Pozzolanic Materials ◽  
By Products ◽  
Potential Use

The overuse level of cement and natural sand for civil industry has several undesirable social and ecological consequences. As an answer for this, industrial wastes or by-products (pozzolanic materials) such as fly ash, GGBFS, silica fume and metakaolin can be used to interchange partially cement and natural sand by manufacturing sand (M-sand). In this study, Artificial Neural Networks (ANNs) models were developed for predicting the tensile strength, at the age of 28 days, of concretes containing partly pozzolanic materials and partly replacing natural sand by manufactured sand. Tensile strength test were performed and test results were used to construct ANN model. A total of 131 values was used for modeling ANN, 80% in the training phase, and 20% in the testing phase. To construct the model, 25 input parameters were used to achieve one output parameter, referred to as the tensile strength of concrete containing partly pozzolanic materials and manufactured sand. The results obtained in both, the training and testing phases strongly show the potential use of ANN to predict 28 days tensile strength of concretes containing partly pozzolanic materials and manufactured sand.

Pore space characteristics of soil microaggregates – Possible implications for functioning

2020 ◽  
Author(s):  
Stefan Dultz ◽  
Vincent Felde ◽  
Susanne K. Woche ◽  
Robert Mikutta ◽  
Daniel Uteau ◽  
...  
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Euler Number ◽  
Pore Space ◽  
Size Fraction ◽  
Clay Content ◽  
Total Porosity ◽  
Microbial Colonization ◽  
Small Scale ◽  
Fine Aggregate

<p>Soil microaggregates (SMA) are characterized by a pronounced small-scale structural heterogeneity, with recognizable chemical differences between the aggregate`s interior and its surface. Latter suggests a deterministic spatial pattern with respect to C stabilization, element exchange, and habitat function for microorganisms. Here, a detailed characterization of the pore space is crucial for the understanding of element transfer and microbial colonization in SMA. In our study, the 53-250 µm size fraction of SMA isolated along a soil clay content gradient (19-35%) were investigated in terms of their pore space characteristics. For the visualization of connected “open” pore structures as well as “closed” pores, a modified Hg-porosimetry technique utilizing Wood´s metal was used (WIP). The molten alloy was pressed into accessible connective pores by applying an argon pressure of 55 MPa, filling up pores with a diameter down to ≈20 nm. After solidification of the alloy, polished sections of SMA were analyzed by laser scanning confocal microscopy (Keyence, VK-9700). To image and quantify open and closed pores, grayscale-histograms were segmented and three pore size classes (<10, 10-100, and >100 µm²) were distinguished for open and closed pore systems. Additionally, we scanned 27 samples with high-resolution X-ray tomography (CT, Zeiss Xradia 520 versa) to characterize the 3D pore features at resolutions between 480 and 928 nm. SMA typically consist of two different sections, where particle arrangements are loose or dense. Relatively coarse-sized aggregate-forming materials were observed in sections with loose particle arrangements, where pores appear well connected. To some extent, these coarse aggregate-forming materials are arranged in larger circular structures. In contrast, dense particle arrangements consist primarily of fine aggregate-forming materials. The total porosity of the SMA derived by WIP was highly variable with a maximum of 40 area-%. While CT aggregate volume and CT aggregate surface area did not change with clay content, CT-porosity (vol.-%) increased with increasing clay content. Maximum CT porosity of 27 % was found in the samples with the highest clay content. Maximum pore diameter was similar across all clay contents, but the share of macropores with diameters >10 µm increased with increasing clay content. The Euler number decreased with increasing clay content, which indicates an increased connectivity of the pore space. Another parameter that increased with increasing clay content was the CT aggregate volume / CT internal pore surface area ratio, signifying more accessible surfaces for element exchange and/or C storage. While pores exceeding 100 µm² had the highest share within the open pores, it was the pore system <10 µm² for the closed pores. The proportion of closed pores of total porosity was smaller for the finer SMA sizes within the 53-250 µm fraction, which confirms the CT results (increasing Euler number). Our WIP data reveal that higher shares of clay minerals in SMA cause a narrower pore size distribution with smaller average diameters and increased tortuosity. Consequently, element transport and habitation by microorganisms might be slowed down in smaller, more clay-rich SMA, potentially resulting in larger C conservation within the interior of smaller SMA.</p>

scholarly journals Effect of Pore Structure on Thermal Conductivity and Mechanical Properties of Autoclaved Aerated Concrete

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 339
Author(s):  
Gonglian Chen ◽  
Fenglan Li ◽  
Pengfei Jing ◽  
Jingya Geng ◽  
Zhengkai Si
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Pore Structure ◽  
Pore Size ◽  
Base Material ◽  
Test Results ◽  
Foam Stabilizer ◽  
Base Materials ◽  
Aerated Concrete

With the premise of investigating mechanical properties, the thermal conductivity of autoclaved aerated concrete (AAC) is a key index of self-insulation block walls for building energy conservation. This study focused on the effect of pore structures on the mechanical performance and thermal conductivity of AAC with the comparison of AAC base materials. Different kinds of AAC and their base materials were prepared and experimentally investigated. While maintaining a consistent mix proportion of the AAC base material, the pore structure of AAC was changed by the dosage of aluminum power/paste, foam stabilizer, and varying the stirring time of aluminum paste. The steam curing systems of AAC and the base material were determined based on SEM (Scanning Electronic Microscopy) and XRD (X-Ray Diffraction) tests. With almost the same apparent density, the pore size decreased with the increasing content of foam stabilizer, and the mixing time of aluminum paste and foam stabilizer has a great influence on pore size. The thermal conductivity test and compressive test results indicated that that pore size had an effect on the thermal conductivity, but it had little effect on the compressive strength, and the thermal conductivity of sand aeration AAC was 8.3% higher than that of fly ash aeration AAC; the compressive strength was 10.4% higher, too. With almost the same apparent density, the regression mathematical model indicates that the thermal conductivity of AAC increased gradually with the increase of pore size, but it had little effect on the compressive strength. From the test results of basic mechanical properties, the mechanical model of cubic compressive strength, elastic modulus, axial compressive strength, and splitting tensile strength was obtained. The proposed stress–strain relationship model could well describe the relationship of AAC and the base material at the rising section of the curve.

scholarly journals Combined effect of limestone fine aggregate and pozzolan on properties of high performance fine-grained concrete

2019 ◽  
Vol 97 ◽  
pp. 02004
Author(s):  
Lam Tang Van ◽  
Dien Vu Kim ◽  
Hung Ngo Xuan ◽  
Doan Tung Lam Nguyen ◽  
Boris Bulgakov ◽  
...  
Keyword(s):  
High Performance ◽  
Corrosion Damage ◽  
Concrete Mixture ◽  
Fine Aggregate ◽  
Test Results ◽  
Natural Sand ◽  
Fine Grained ◽  
Absolute Volume ◽  
Study Support ◽  
Volume Method

This paper used the absolute volume method combined with the experiment to determine the compositions of high performance fine-grained concrete (HPFC) and presented the effect of limestone fine aggregate (LFA) and pozzolan (PU) on the HPFC properties. Test results showed that by increasing the LFA and PU, the workability of the concrete mixture decreased, the maximum slump loss after 90 minutes of mixing was 37.84%, whereas the mechanical properties of HPFC increased. The fine-grained concrete mixture containing 40% PU and LFA completely replaced material for natural sand, the compressive strength of concrete at 28-day increased about 23.87% in comparison to the control mixture. By using the standard NT Build 356, the destruction time of the four specimens tested was of 45, 63, 60 and 61 days, respectively. This result is due to the presence of PU increased the volume of the C-S-H, as well as the density of concrete structure and enhanced the strength of HPFC, thus increased destruction time of specimens used for the assessment of corrosion damage of reinforced in the concrete. The results of the current study support the use of the waste limestone from the quarries as a fine aggregate of green concrete in the future.

Effects of pore structure and wettability on the electrical resistivity of partially saturated rocks—A network study

Geophysics ◽  
1997 ◽  
Vol 62 (4) ◽  
pp. 1151-1162 ◽  
Author(s):  
Ravi J. Suman ◽  
Rosemary J. Knight
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Network Model ◽  
Water Saturation ◽  
Archie’S Law ◽  
Partially Saturated ◽  
Saturation Exponent ◽  
Wetting Film

A network model of porous media is used to assess the effects of pore structure and matrix wettability on the resistivity of partially saturated rocks. Our focus is the magnitude of the saturation exponent n from Archie's law and the hysteresis in resistivity between drainage and imbibition cycles. Wettability is found to have the dominant effect on resistivity. The network model is used to investigate the role of a wetting film in water‐wet systems, and the behavior of oil‐wet systems. In the presence of a thin wetting film in water‐wet systems, the observed variation in n with saturation is reduced significantly resulting in lower n values and reduced hysteresis. This is attributed to the electrical continuity provided by the film at low‐water saturation between otherwise physically isolated portions of water. Oil‐wet systems, when compared with the water‐wet systems, are found to have higher n values. In addition, the oil‐wet systems exhibit a different form of hysteresis and more pronounced hysteresis. These differences in the resistivity response are attributed to differences in the pore scale distribution of water. The effects of pore structure are assessed by varying pore size distribution and standard deviation of the pore size distribution and considering networks with pore size correlation. The most significant parameter is found to be the pore size correlation. When the sizes of the neighboring pores of the network are correlated positively, the magnitude of n and hysteresis are reduced substantially in both the water‐wet and oil‐wet systems. This is attributed to higher pore accessibility in the correlated networks. The results of the present study emphasize the importance of conducting laboratory measurements on core samples with reservoir fluids and wettability that is representative of the reservoir. Hysteresis in resistivity can be present, particularly in oil‐wet systems, and should be considered in the interpretation of resistivity data.

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