scholarly journals Effect of Lightweight Aggregate Impregnation on Selected Concrete Properties

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 198
Author(s):  
Lucyna Domagała ◽  
Agnieszka Podolska
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Cement Paste ◽  
Initial Moisture Content ◽  
Lightweight Aggregate ◽  
The Other ◽  
Lightweight Aggregates ◽  
Cement Pastes ◽  
Water Absorption Test ◽  
The One

The impregnation of lightweight aggregate (LWA) is an alternative method to its pre-moistening, which is used to limit the loss of fresh concrete workability due to the aggregate’s ability to absorb a great amount of mixing water. The aim of this study was to access the effectiveness, by pre-coating LWAs with cement paste, in modifying the properties of concrete composites. Two types of lightweight aggregates (Lytag and Leca) characterized with a relatively open-structure shell were selected. The other changeable parameters taken into consideration in this research were: LWA size, initial moisture of aggregate before the impregnation process and type of cement paste applied as an impregnant. Sixteen concretes prepared with pre-moistened and pre-coated lightweight aggregates were subject to a density test in different moisture conditions, a water absorption test and a compressive strength test. On the one hand, the pre-coating of LWAs with cement paste resulted in a relatively slight increase in concrete density (by up to 19%) compared to the pre-moistening of LWAs. On the other hand, it caused a very significant reduction (by up to 52%) in the composite’s water absorption and an incomparably greater growth (by up to 107%) in compressive strength. The most crucial factors determining the effectiveness of impregnation of LWAs with cement pastes in improvement of composite properties were the aggregate type and its size. The composition of impregnating slurry and the initial moisture content of LWA before pre-coating also mattered.

scholarly journals Investigation of Physical Characteristics of Non-Structural Lightweight Aggregate Blocks

2016 ◽  
Author(s):  
Hamid Reza Ashrafi ◽  
Marzieh Sadat Moayyeri ◽  
Peyman Beiranvand
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Construction Materials ◽  
Lightweight Aggregate ◽  
Coarse Grained ◽  
Mechanical Resistance ◽  
Lightweight Aggregates ◽  
Dead Load ◽  
Load Bearing ◽  
Materials Used

Today, the style of light construction materials used in building is one of the most important factors in reducing building's dead load and better performance of the structures in the earthquake. One of the ways to reduce the structure weight is to use lightweight blocks instead of using traditional materials. The main purpose of this research is to compare density, compressive strength and water absorption volume of non-load-bearing lightweight blocks made of natural and artificial lightweight aggregates. Scoria lightweight aggregates of Sanandaj, Ghorveh mine, pumice in Tabriz, Bostanabad mine, and Leca in Leca enterprise have been used to make the samples. Given the importance of the materials used, grading of coarse-grained materials has been conducted based on the standard of 7657 and grading of fine materials have been conducted based on the standard of 302.The experiments' results show that Scoria blocks due to hard texture, and high mechanical resistance of their lightweight aggregates, have had higher compressive strength, and density and lower water absorption volume compared to pumice and Lika lightweight aggregate blocks. Pumice blocks despite having desirable compressive strength and lower density compared to the two other blocks have higher water absorption volume, and do not meet the standard conditions. This same factor causes it faces with less interest. Among these Lika blocks with density of 1151.94 (kg per cubic meter) below 2000 kilograms per cubic meter of Iran density standard of 7782 (28-day compressive strength of 2.57 MPa), higher than 2.5 MPa of Iran compressive strength standard of 7782 (and water absorption volume of 282.92 kg per cubic meter) below 288 kilograms per cubic meter of Iran water absorption volume standard of 7782 (as a non-load-bearing lightweight block) have been diagnosed desirable.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

scholarly journals USE OF SLUDGE FROM SANITARY SEWAGE TREATMENT PLANTS (S.T.P) AND THEIR USE AS RAW MATERIAL IN THE MANUFACTURE OF BRICKS

2019 ◽  
Vol 16 (33) ◽  
pp. 823-840
Author(s):  
M. K. TARABAI ◽  
S. G. de AZEVEDO
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Sewage Treatment ◽  
Point Of View ◽  
Test Method ◽  
Raw Material ◽  
Environmental Preservation ◽  
Ceramic Block ◽  
Environmental Requirements ◽  
The One

This paper discusses a possible solution regarding the final disposal of sludge from Sanitary Sewage Treatment Stations (ET), aiming at environmental preservation. The solid waste generated after the wastewater treatment processes is highly contaminating and detrimental to the area in which it is deposited. Given this, the use of sludge with the application of reuse techniques becomes pertinent, both from the economic point of view and from the ecological point of view. By replacing the use of aggregates from mineral deposits, the main clay raw material in the manufacture of ceramic products (Vieira, 2000), by the treated sludge of WWTP we will save on the sources of granular materials. Aiming its reintegration to the production cycle through the introduction of sludge as raw material incorporated in the ceramic mass in the manufacture of hollow bricks, the viability of use was verified through performance analysis, compared to the control brick made of pottery, without the addition of sludge. Specimens were prepared with three types of samples: 90% clay and 10% sludge; 80% clay and 20% sludge; 70% clay and 30% sludge. Mass loss, water absorption index and compressive strength tests were performed. As for the tests, the specimens with 10% and 20% of sludge were the ones that had better adaptation to the technical requirements, but because it is a larger volume of the residue for the application of reuse techniques, the brick with 20% sludge dosage. is the most suitable. NBR7.171, November 1992: Ceramic Block for masonry; Specification NBR 6.461, June 1983: Masonry Ceramic Block - Compressive Strength Check: Test Method; NBR 8.947, November 1992: Ceramic Tile- Determination of Mass and Water Absorption: Test Method. As for the tests, the specimen with 20% of sludge was the one that had the best adaptation to technical and environmental requirements. The present article approaches a possible solution regarding the destination of the sludge coming from Sanitary Sewage Treatment Stations, aiming at environmental preservation. Aiming at its reintegration into the productive cycle through applications of reuse techniques, the sludge became raw material when the ceramic mass was incorporated into the brick fabrication. Three types of samples were elaborated: 90% of clay and 10% of mud; 80% clay and 20% sludge; 70% clay and 30% sludge. As for the tests, the test specimen with 20% of sludge was the one that had more adequacy to the technical and environmental requirements.

High Volume Slag and Slag-Fly Ash Blended Cement Pastes Containing Nano Silica

2019 ◽  
Vol 967 ◽  
pp. 205-213
Author(s):  
Faiz U.A. Shaikh ◽  
Anwar Hosan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Cement Paste ◽  
Ordinary Portland Cement ◽  
Blended Cement ◽  
High Volume ◽  
Ash Content ◽  
Partial Replacement ◽  
Nano Silica ◽  
Cement Pastes

This paper presents the effect of nanosilica (NS) on compressive strength and microstructure of cement paste containing high volume slag and high volume slag-fly ash blend as partial replacement of ordinary Portland cement (OPC). Results show that high volume slag (HVS) cement paste containing 60% slag exhibited about 4% higher compressive strength than control cement paste, while the HVS cement paste containing 70% slag maintained the similar compressive strength to control cement paste. However, about 9% and 37% reduction in compressive strength in HVS cement pastes is observed due to use of 80% and 90% slag, respectively. The high volume slag-fly ash (HVSFA) cement pastes containing total slag and fly ash content of 60% exhibited about 5%-16% higher compressive strength than control cement paste. However, significant reduction in compressive strength is observed in higher slag-fly ash blends with increasing in fly ash contents. Results also show that the addition of 1-4% NS improves the compressive strength of HVS cement paste containing 70% slag by about 9-24%. However, at higher slag contents of 80% and 90% this improvement is even higher e.g. 11-29% and 17-41%, respectively. The NS addition also improves the compressive strength by about 1-59% and 5-21% in high volume slag-fly ash cement pastes containing 21% fly ash+49%slag and 24% fly ash+56%slag, respectively. The thermogravimetric analysis (TGA) results confirm the reduction of calcium hydroxide (CH) in HVS/HVSFA pastes containing NS indicating the formation of additional calcium silicate hydrate (CSH) gels in the system. By combining slag, fly ash and NS in high volumes e.g. 70-80%, the carbon footprint of cement paste is reduced by 66-76% while maintains the similar compressive strength of control cement paste. Keywords: high volume slag, nanosilica, compressive strength, TGA, high volume slag-fly ash blend, CO2 emission.

Study on the Waterproofing Properties of Cement-Based Composite Thermal Insulation Materials

2014 ◽  
Vol 711 ◽  
pp. 166-169
Author(s):  
Jing Li ◽  
Guo Zhong Li
Keyword(s):  
Compressive Strength ◽  
Stearic Acid ◽  
Water Absorption ◽  
Thermal Insulation ◽  
Lightweight Aggregate ◽  
Insulation Materials ◽  
Strengthen Effect ◽  
Cementing Material

Polystyrene granules (EPS) for lightweight aggregate and cement for cementing material, while adding a variety of additives, were used to prepare cement-based composite thermal insulation materials by the method of vibration molding. The effects of different waterproof agent on water absorption and strength of cement-based composite thermal insulation materials were studied contrastively by adding emulsified stearic acid and emulsified composite waterproofing agent, and the related mechanisms were analyzed. Results showed that the waterproofing effect and strengthen effect of emulsified composite waterproofing agent is superior to emulsified stearic acid, when the content of emulsified stearic acid and emulsified composite waterproofing agent are 5% and 5%, respectively, the 2h, 24h water absorption of samples are 20.59%, 47.64% and 15.53%, 34.53%, the flexural and compressive strength of samples are 0.32MPa, 0.42MPa and 0.35MPa, 0.47MPa.

scholarly journals Surface Roughness and Porosity of Hydrated Cement Pastes

10.14311/1374 ◽  
2011 ◽  
Vol 51 (3) ◽  
Author(s):  
T. Ficker ◽  
D. Martišek ◽  
H. M. Jennings
Keyword(s):  
The Other ◽  
Porous Solids ◽  
Surface Irregularity ◽  
Hydrated Cement ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Fracture Surfaces ◽  
Water To Cement Ratio ◽  
The One ◽  
Highly Porous

. Seventy-eight graphs were plotted to describe and analyze the dependences of the height and roughness irregularities on the water-to-cement ratio and on the porosity of the cement hydrates. The results showed unambiguously that the water-to-cement ratio or equivalently the porosity of the specimens has a decisive influence on the irregularities of the fracture surfaces of this material. The experimental results indicated the possibility that the porosity or the value of the water-to-cement ratio might be inferred from the height irregularities of the fracture surfaces. It was hypothesized that there may be a similarly strong correlation between porosity and surface irregularity, on the one hand, and some other highly porous solids, on the other, and thus the same possibility to infer porosity from the surfaces of their fracture remnants.

scholarly journals Hydrochloric Acid Pretreatment of Different Types of Rice Husk Ash Influence on the Properties of Cement Paste

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1524 ◽  
Author(s):  
Jing Liu ◽  
Chunyan Xie ◽  
Chao Fu ◽  
Xiuli Wei ◽  
Dake Wu
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Cement Paste ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Control Sample ◽  
Control Group ◽  
Rice Husks ◽  
Acid Pretreatment ◽  
Blank Control Group

When properly processed, rice husk ash (RHA) comprises a large amount of SiO2, which exhibits a high pozzolanic activity and acts as a good building filler. In this paper, the effects of rice husk ash content, acid pretreatment, and production regions on the compressive and flexural properties and water absorption of a cement paste were studied. The experimental results showed that the compressive strength of the rice husk ash was the highest with a 10% content level, which was about 16.22% higher than that of the control sample. The rice husk after acid pretreatment displayed a higher strength than that of the sample without the acid treatment, and the rice husk from the Inner Mongolia region indicated a higher strength than that from the Guangdong province. However, the flexural strength of each group was not significantly different from that of the blank control group. The trend observed for the water absorption was similar to that of the compressive strength. The variation in the RHA proportions had the greatest influence on the properties of the paste specimens, followed by the acid pretreatments of the rice husks. The production regions of the rice husks indicated the least influence.

scholarly journals Study of the resistance, porosity, and migration of chloride ions of BAPbased crushing sand

2018 ◽  
Vol 149 ◽  
pp. 01093
Author(s):  
Benyamina Smain ◽  
Siham Kamali-Bernard ◽  
Kenai Said ◽  
Menadi Belkacem
Keyword(s):  
Compressive Strength ◽  
Physical And Mechanical Properties ◽  
Chloride Ions ◽  
The Other ◽  
High Demand ◽  
Alternative Source ◽  
And Migration ◽  
The One ◽  
The Cost ◽  
Limestone Fines

Self-compacting concretes (SCC), are hyper-fluid concretes, placed without vibration and are considered as one of the most important innovations of the last decade in construction. SCCs offer many advantages, due to their exceptional characteristics of flow and filling of formwork. Their compositions require a large quantity of fines in order to limit bleeding and segregation. Hence, the use of crushed sand (SC), rich in limestone fines (CF) in the manufacture of self-placing concretes (SCC), can be considered as an alternative source of fillers. These sands reduce the cost of SCC by reducing the high demand for fillers on the one hand and on the other hand, obtaining SCC with good physical and mechanical properties. The main purpose of this paper is to examine the effect of different percentages (0, 5, 10, 15, and 20%) of (CF) in crushed sand on SCC performance. The evolution of the compressive strength, the porosity accessible to water and the migration coefficient of the chloride ions were evaluated. The Okamura method was used for the formulation of all SCC mixtures. Sand/mortar (S/M), water/cement (W / C) ratios and superplasticizer content were kept constant. The results show that (CF) reduce the compressive strength but contribute to the reduction of porosity and migration of chloride ions.

Effect of Cement Type and Air-Entraining Agent on Microbially Induced Carbonate Precipitation in Cement Paste

2013 ◽  
Vol 816-817 ◽  
pp. 758-761
Author(s):  
Xiao Lu Yuan ◽  
Shi Hua Zhou ◽  
Wei Min Hu ◽  
Sen Yao Tan ◽  
Deng Pan
Keyword(s):  
Growth Rate ◽  
Compressive Strength ◽  
Cement Paste ◽  
Carbonate Precipitation ◽  
Cement Type ◽  
Cement Pastes ◽  
Sulphoaluminate Cement ◽  
Microbially Induced Carbonate Precipitation

The effect of cement type and the air-entraining agent on microbially induced carbonate precipitation in cement paste has been studied. Results indicate that after biodeposition treatment, Sulphoaluminate cement paste behaved with a higher growth rate of compressive strength than OPC paste. Incorporation of air-entraining agent increased the growth rate of compressive strength of sulphoaluminate cement paste. Calcite was formed through microbially induced carbonate precipitation in cement pastes. Sulphoaluminate cement paste achieved a larger amount of calcite than OPC paste.

Sign in / Sign up

Export Citation Format

Share Document