Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.1.5
H. R. Darvishvand, S. A. H. S. Taghia, M. Ebrahimi
The issue of the size and shape of the aggregates in concrete is one of the most challenging subjects in the building industry, in order to reach maximum strength and ductility. To investigate this issue, two types of aggregate were selected. One was the river aggregate - gravel with rounded grains and the second was a crushed stone with sharp-edged grains, both with the maximum sizes of 9.5, 12.5, 19, and 25 mm respectively. The cement content was 250, 350, 450, and 550 kg/m3, and the water to cement ratio was equal to 0.4. At first, the compressive strength and stress-strain relationship were examined. According to the test results, the compressive strength increases with increasing cement content, as expected. The aggregate with the largest grain size of 12.5 mm gives the highest compressive strength and ductility compared to other grain sizes and it was selected as the optimal choice and finally, the sharp-edged aggregates have higher compressive strength and ductility in comparing to the rounded grain aggregates.
{"title":"The effect of size and shape of aggregate on compressive strength and ductility of concrete","authors":"H. R. Darvishvand, S. A. H. S. Taghia, M. Ebrahimi","doi":"10.32047/cwb.2021.26.1.5","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.1.5","url":null,"abstract":"The issue of the size and shape of the aggregates in concrete is one of the most challenging subjects in the building industry, in order to reach maximum strength and ductility. To investigate this issue, two types of aggregate were selected. One was the river aggregate - gravel with rounded grains and the second was a crushed stone with sharp-edged grains, both with the maximum sizes of 9.5, 12.5, 19, and 25 mm respectively. The cement content was 250, 350, 450, and 550 kg/m3, and the water to cement ratio was equal to 0.4. At first, the compressive strength and stress-strain relationship were examined. According to the test results, the compressive strength increases with increasing cement content, as expected. The aggregate with the largest grain size of 12.5 mm gives the highest compressive strength and ductility compared to other grain sizes and it was selected as the optimal choice and finally, the sharp-edged aggregates have higher compressive strength and ductility in comparing to the rounded grain aggregates.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"44 10 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82694777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.3.6
S. Lecheb, A. Chellil, K. Chahour, B. Safi
The foamed glass is currently used in the manufacture of concretes as aggregate to produce lightweight concrete. The lightness of the concrete is assured by the important porosity of foamed glass granulates [GFG], however, they have a closed porosity with a smooth surface. In this respect, this study aims to use foam glass granulates with open-porosity, to produce lightweight self-compacting mortars. GFG were prepared from the glass powder – glass cullet and foaming agent – limestone, according to the current applied process for GFG – heat treatment at 850°C for 20 min. Then from GFG the sand fine aggregate – 0/5 mm was prepared by crushing and sieving. The self-compacting mortars were obtained using natural sand as fine aggregate and other mortars with granulated foam glass substituting sand at volume ratios: 30, 50 and 100 %. Rheological tests of fluidity and physical properties, i.e. density and porosity, by measuring absorption of water and mechanical tests were carried out on studied mortars. The interface of cementitious matrix/GFG granules study shows that open-porosity of GFG sand has favored adhesion to cement matrix, without causing the segregation of the mortar phases. Also, the decrease of the compressive strength for mortars exhibiting a specific lightness, was found. It should be noted that the latter property is very important in construction.
{"title":"Foamed glass granulated-based self-compacting mortars: open-porosity effect on rheological and mechanical properties","authors":"S. Lecheb, A. Chellil, K. Chahour, B. Safi","doi":"10.32047/cwb.2021.26.3.6","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.3.6","url":null,"abstract":"The foamed glass is currently used in the manufacture of concretes as aggregate to produce lightweight concrete. The lightness of the concrete is assured by the important porosity of foamed glass granulates [GFG], however, they have a closed porosity with a smooth surface. In this respect, this study aims to use foam glass granulates with open-porosity, to produce lightweight self-compacting mortars. GFG were prepared from the glass powder – glass cullet and foaming agent – limestone, according to the current applied process for GFG – heat treatment at 850°C for 20 min. Then from GFG the sand fine aggregate – 0/5 mm was prepared by crushing and sieving. The self-compacting mortars were obtained using natural sand as fine aggregate and other mortars with granulated foam glass substituting sand at volume ratios: 30, 50 and 100 %. Rheological tests of fluidity and physical properties, i.e. density and porosity, by measuring absorption of water and mechanical tests were carried out on studied mortars. The interface of cementitious matrix/GFG granules study shows that open-porosity of GFG sand has favored adhesion to cement matrix, without causing the segregation of the mortar phases. Also, the decrease of the compressive strength for mortars exhibiting a specific lightness, was found. It should be noted that the latter property is very important in construction.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"83 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90249803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.2.4
N. K. Degloorkar, Ratish K. Pancharathi
Restoration and preservation of Heritage Structures in any countryis a challenging task and sometimes requires urgent attention. Moreover, it is important for sustenance of culture and heritage of the society. But many times, it is very diffi cult to find matching materials used in the past and hence due to use of available cementitious materials there can be degeneration of existing material. In view of this, there is a need to characterize these ancient materials and develop alternate materials with almost similar characteristics. With this knowledge, an alternate material similar in mineral composition and physical properties need to be developed, which will not have compatibility issues during and after repair. In the present study, the material characterization of an ancient floating brick at an Indian Heritage site was examined using modern analytical techniques like SEM-EDS, XRD and FTIR. In addition, the physical properties like specific gravity, bulk density, voids ratio and porosity were also determined. From the analysis, it could be confirmed that the bricks were light in weight due to the pores content and could float in water due to the non-interconnected porosity. Also, the presence of quartz, alumina and hematite from SEM-EDS analysis confirmed that these bricks were made of firing the clay, at lower temperatures, to induce pores. This low temperature firing of clay was supported by FTIR analysis indicating the presence of Si-O bond that would have disappeared at higher temperature.
{"title":"Material properties of the light mass bricks from an 800 year old Heritage site in India","authors":"N. K. Degloorkar, Ratish K. Pancharathi","doi":"10.32047/cwb.2021.26.2.4","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.2.4","url":null,"abstract":"Restoration and preservation of Heritage Structures in any countryis a challenging task and sometimes requires urgent attention. Moreover, it is important for sustenance of culture and heritage of the society. But many times, it is very diffi cult to find matching materials used in the past and hence due to use of available cementitious materials there can be degeneration of existing material. In view of this, there is a need to characterize these ancient materials and develop alternate materials with almost similar characteristics. With this knowledge, an alternate material similar in mineral composition and physical properties need to be developed, which will not have compatibility issues during and after repair. In the present study, the material characterization of an ancient floating brick at an Indian Heritage site was examined using modern analytical techniques like SEM-EDS, XRD and FTIR. In addition, the physical properties like specific gravity, bulk density, voids ratio and porosity were also determined. From the analysis, it could be confirmed that the bricks were light in weight due to the pores content and could float in water due to the non-interconnected porosity. Also, the presence of quartz, alumina and hematite from SEM-EDS analysis confirmed that these bricks were made of firing the clay, at lower temperatures, to induce pores. This low temperature firing of clay was supported by FTIR analysis indicating the presence of Si-O bond that would have disappeared at higher temperature.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"9 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87057618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.1.2
Alkan Hafçi, L. Turanli, F. Bektaş
In this experimental study the effect of alkali silica reaction [ASR] on the mechanical properties of concrete namely compressive strength, fl exural strength, splitting tensile strength, modulus of elasticity and pull-out strength is presented. The effect of the specimens’ geometry on ASR expansion has also been studied. The results confirm that ASR expansion of over 0.04% causes significant losses in the mechanical properties of concrete, albeit at differing rates. Moreover, this study proves that the specimen geometry has an important role on ASR expansion rate.
{"title":"Effect of ASR expansion on mechanical properties of concrete","authors":"Alkan Hafçi, L. Turanli, F. Bektaş","doi":"10.32047/cwb.2021.26.1.2","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.1.2","url":null,"abstract":"In this experimental study the effect of alkali silica reaction [ASR] on the mechanical properties of concrete namely compressive strength, fl exural strength, splitting tensile strength, modulus of elasticity and pull-out strength is presented. The effect of the specimens’ geometry on ASR expansion has also been studied. The results confirm that ASR expansion of over 0.04% causes significant losses in the mechanical properties of concrete, albeit at differing rates. Moreover, this study proves that the specimen geometry has an important role on ASR expansion rate.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"67 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87413554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.2.5
W. Kurdowski
The basis for the geopolymers production was drawn up by prof. Kühl, well known to present day from the introduction of the modulus of clinker lime saturation: This Kühl’s formula was lined on the assumption that the best clinker should be composed of C3S, C3A and C2F and the mass ratio of CaO in respect to other components is equal adequately: 2.8, 1.65 and 0.70. The analyses of the equilibrium condition in the four components system led Kühl to the so-called lime criterion, equal to the permissible maximal lime content in clinker, in the conditions far from the equilibrium: One of the unfavourable properties of concrete is shrinkage which is linked with the volume changes of cement paste. We distinguish the following kinds of shrinkage: – “chemical” shrinkage called also the contraction or Le Chatelier shrinkage, – plastic shrinkage, – autogenic shrinkage or spontaneous, sometimes called auto drying, – drying shrinkage. There are several methods to eliminate concrete shrinkage. The ettringite crystallization is one of the inorganic compounds methods and is based on Klein’s complex addition to cement. This complex is causing the rapid ettringite formation and the shrinkage is diminished. There are also organic admixtures which action is the reduction of the water surface tension. There are surface-active additions that are reducing this tension, in capillaries. The organic admixtures which are diminishing the shrinkage are based on neopentyl glycol or similar chemical compounds. In the study, the shrinkage-reducing admixture BASF Master Life SRA 815 alone and with CaO addition were examined. It was shown that CaO addition is giving very low diminishing of cement shrinkage, contrary to the fluid admixture Master Life SRA 815 which has a high diminishing influence on cement shrinkage. However, the simultaneous addition of CaO is increasing the diminishing influence of this fluid admixture. The addition of Klein’s complex does not influence of shrinkage but its simultaneous addition with Master Life SRA 815 gives higher shrinkage diminishing.
地聚合物生产的基础是由k hl教授提出的，他从熟料石灰饱和模量的引入到今天都很出名:k hl的公式是基于最好的熟料应该由C3S、C3A和C2F组成，CaO相对于其他组分的质量比是充分相等的:2.8、1.65和0.70。通过对四组分体系平衡条件的分析，k hl得出了所谓的石灰准则，即熟料中允许的最大石灰含量，在远离平衡的条件下:混凝土的不利性能之一是收缩，这与水泥浆体的体积变化有关。我们区分以下几种收缩:-“化学”收缩也称为收缩或勒夏特列收缩，-塑性收缩，-自生收缩或自发，有时称为自动干燥，-干燥收缩。消除混凝土收缩的方法有几种。钙矾石结晶法是一种无机化合物方法，其基础是水泥中克莱因络合物的加入。这种复合体导致钙矾石快速形成，收缩减少。也有有机外加剂，其作用是降低水的表面张力。在毛细血管中，有表面活性添加剂可以降低这种张力。减少收缩的有机外加剂是基于新戊二醇或类似的化合物。研究了巴斯夫主寿命减水剂SRA 815单独和添加CaO的减水剂。结果表明，CaO的加入对水泥收缩的抑制作用很小，而Master Life SRA 815对水泥收缩的抑制作用很大。然而，同时加入CaO会增加这种流体混合物的影响。克莱因配合物的加入对收缩率没有影响，但与主寿命SRA 815同时加入后，收缩率减小较大。
{"title":"Kinds of concrete shrinkages, their importance and prevention methods","authors":"W. Kurdowski","doi":"10.32047/cwb.2021.26.2.5","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.2.5","url":null,"abstract":"The basis for the geopolymers production was drawn up by prof. Kühl, well known to present day from the introduction of the modulus of clinker lime saturation: This Kühl’s formula was lined on the assumption that the best clinker should be composed of C3S, C3A and C2F and the mass ratio of CaO in respect to other components is equal adequately: 2.8, 1.65 and 0.70. The analyses of the equilibrium condition in the four components system led Kühl to the so-called lime criterion, equal to the permissible maximal lime content in clinker, in the conditions far from the equilibrium: One of the unfavourable properties of concrete is shrinkage which is linked with the volume changes of cement paste. We distinguish the following kinds of shrinkage: – “chemical” shrinkage called also the contraction or Le Chatelier shrinkage, – plastic shrinkage, – autogenic shrinkage or spontaneous, sometimes called auto drying, – drying shrinkage. There are several methods to eliminate concrete shrinkage. The ettringite crystallization is one of the inorganic compounds methods and is based on Klein’s complex addition to cement. This complex is causing the rapid ettringite formation and the shrinkage is diminished. There are also organic admixtures which action is the reduction of the water surface tension. There are surface-active additions that are reducing this tension, in capillaries. The organic admixtures which are diminishing the shrinkage are based on neopentyl glycol or similar chemical compounds. In the study, the shrinkage-reducing admixture BASF Master Life SRA 815 alone and with CaO addition were examined. It was shown that CaO addition is giving very low diminishing of cement shrinkage, contrary to the fluid admixture Master Life SRA 815 which has a high diminishing influence on cement shrinkage. However, the simultaneous addition of CaO is increasing the diminishing influence of this fluid admixture. The addition of Klein’s complex does not influence of shrinkage but its simultaneous addition with Master Life SRA 815 gives higher shrinkage diminishing.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"5 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89682134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.3.5
A. Pehlivan
In this experimental study, the effect of basalt fibers on the mechanical properties of magnesium phosphate cement [MPC] was investigated. Compressive strength, splitting tensile strength, flexural strength and modulus of elasticity, were introduced. It was observed that mechanical properties were significantly enhanced with the addition of silica fume, especially splitting tensile and flexural strength were enhanced with the increase of basalt fibers. However, for mixtures without silica fume addition, high content of fibers adversely affected the mechanical properties. Silica fume addition was found to be significant in increasing the bonding mechanism between basalt fibers and the MPC matrix. Thus, combined usage of silica fume and basalt fibers was found to be effective. A molar ratio of magnesia to ammonium dihydrogen phosphate of 8 was observed to have better results with respect to a molar ratio of 6, however, this distinction was not very apparent, when silica fume was added to both mixtures.
{"title":"Mechanical properties of magnesium phosphate cement incorporating basalt fibers","authors":"A. Pehlivan","doi":"10.32047/cwb.2021.26.3.5","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.3.5","url":null,"abstract":"In this experimental study, the effect of basalt fibers on the mechanical properties of magnesium phosphate cement [MPC] was investigated. Compressive strength, splitting tensile strength, flexural strength and modulus of elasticity, were introduced. It was observed that mechanical properties were significantly enhanced with the addition of silica fume, especially splitting tensile and flexural strength were enhanced with the increase of basalt fibers. However, for mixtures without silica fume addition, high content of fibers adversely affected the mechanical properties. Silica fume addition was found to be significant in increasing the bonding mechanism between basalt fibers and the MPC matrix. Thus, combined usage of silica fume and basalt fibers was found to be effective. A molar ratio of magnesia to ammonium dihydrogen phosphate of 8 was observed to have better results with respect to a molar ratio of 6, however, this distinction was not very apparent, when silica fume was added to both mixtures.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89758322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.5.3
S. Siva Chandran, K. Chinnaraju
Conservation of natural resources and effective management of waste materials that can harm our environment is a challenging phenomenon. This paper is focused to study the different properties of M30 grade concrete where the coarse aggregate has been completely replaced by commercially available sintered fly ash aggregate and it has proved to meet the target strength. To further improve the crack resisting behavior and tensile strength,basalt fibers was incorporated. The incorporation of fibers has improved the mechanical properties to around 3-4%. The RCPT and water absorption test has proved that the durability properties of sintered fly ash aggregate are within the standard specified.
{"title":"Mechanical and durability properties of sintered fly ash aggregate concrete","authors":"S. Siva Chandran, K. Chinnaraju","doi":"10.32047/cwb.2021.26.5.3","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.5.3","url":null,"abstract":"Conservation of natural resources and effective management of waste materials that can harm our environment is a challenging phenomenon. This paper is focused to study the different properties of M30 grade concrete where the coarse aggregate has been completely replaced by commercially available sintered fly ash aggregate and it has proved to meet the target strength. To further improve the crack resisting behavior and tensile strength,basalt fibers was incorporated. The incorporation of fibers has improved the mechanical properties to around 3-4%. The RCPT and water absorption test has proved that the durability properties of sintered fly ash aggregate are within the standard specified.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"73 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80604966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.3.7
K. Yuvaraj, S. Ramesh
In the present era, the consumption of electricity has increased rapidly with each passing year, due to the industrialization. Coal is a raw material for the production of electricity in the thermal power stations. Particularly, a large amount of unused ash is dumped in ponds, which are major problem concerning many developing countries. Further, dumping of ash in ponds causes environmental hazards effects such as soil, land and water pollution. Identifying a viable alternative to utilize pond ash becomes a necessity, to avoid these environmental hazards. In this research work, an attempt has been made to partially replace cement by the pond ash as a supplementary cementitious material [SCM] in concrete, which will considerably reduce the hazardous effects of pond ash, to the environment. The pond ash was ground to 45 μm and it was used to replace the cement in concrete by proportions of 5, 10, 15, 20 and 25% by mass. Test on compressive strength, split tensile strength and modulus of rupture were conducted on concrete mixes. The result indicate that the addition of 10% pond ash to concrete significantly increased the strength properties of the concrete at the age of 7, 28, 56 and 90 days.
{"title":"Experimental investigation on strength properties of concrete incorporating ground pond ash","authors":"K. Yuvaraj, S. Ramesh","doi":"10.32047/cwb.2021.26.3.7","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.3.7","url":null,"abstract":"In the present era, the consumption of electricity has increased rapidly with each passing year, due to the industrialization. Coal is a raw material for the production of electricity in the thermal power stations. Particularly, a large amount of unused ash is dumped in ponds, which are major problem concerning many developing countries. Further, dumping of ash in ponds causes environmental hazards effects such as soil, land and water pollution. Identifying a viable alternative to utilize pond ash becomes a necessity, to avoid these environmental hazards. In this research work, an attempt has been made to partially replace cement by the pond ash as a supplementary cementitious material [SCM] in concrete, which will considerably reduce the hazardous effects of pond ash, to the environment. The pond ash was ground to 45 μm and it was used to replace the cement in concrete by proportions of 5, 10, 15, 20 and 25% by mass. Test on compressive strength, split tensile strength and modulus of rupture were conducted on concrete mixes. The result indicate that the addition of 10% pond ash to concrete significantly increased the strength properties of the concrete at the age of 7, 28, 56 and 90 days.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"32 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87941521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.5.5
K. Furtak
Modern challenges of science and technology should not be considered in isolation from the past and changes that have taken place over the centuries. They have occurred in different ways in various periods of human history and in various spheres of human activity, including technology. The changes also concern construction and construction materials. All changes have been stimulated by, inter alia, science and they, in turn, have determined and stimulated the development of science. The soaring growth in science and technological development result in a rising social awareness of increasing and new issues both technological and social that must be addressed. At the present stage of civilisation evelopment, they cannot be solved separately. The environmental and energy impacts must also be included. Special attention was focused on construction materials and products, as well as technological aspects including the application of 3D printing technology in construction. They all belong to the development of civilisation in a broad sense. In construction, there is room for traditional materials and technologies and their new versions with the primacy, however, of new generation materials. The need to apply the achievements in disciplines other than construction has been emphasised.
{"title":"Contemporary challenges of science and technology – selected reflections","authors":"K. Furtak","doi":"10.32047/cwb.2021.26.5.5","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.5.5","url":null,"abstract":"Modern challenges of science and technology should not be considered in isolation from the past and changes that have taken place over the centuries. They have occurred in different ways in various periods of human history and in various spheres of human activity, including technology. The changes also concern construction and construction materials. All changes have been stimulated by, inter alia, science and they, in turn, have determined and stimulated the development of science. The soaring growth in science and technological development result in a rising social awareness of increasing and new issues both technological and social that must be addressed. At the present stage of civilisation evelopment, they cannot be solved separately. The environmental and energy impacts must also be included. Special attention was focused on construction materials and products, as well as technological aspects including the application of 3D printing technology in construction. They all belong to the development of civilisation in a broad sense. In construction, there is room for traditional materials and technologies and their new versions with the primacy, however, of new generation materials. The need to apply the achievements in disciplines other than construction has been emphasised.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79904934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.32047/cwb.2021.26.3.3
Ru Wang, Ziyan Xi, Gaoyong Wang
Styrene-butadiene copolymer [SB] modified cement-based materials are widely used, but the addition of SB can delay the setting and hardening of cement, which limits its application in some projects. In this paper, nanosilica was selected as the modifying component to study its influence on the early hydration, setting and hardening of SB/cement composite material. By measuring the setting time and early strength of nanosilica modified SB/cement composite material, the influence of nanosilica on the setting and hardening process of composite cementitious material was analyzed. The hydration heat of nanosilica modified SB/cement composite material was determined by isothermal calorimetry, and its hydration products were examined by X-ray diffraction, so as to analyze the influence of nanosilica on the early hydration process of composite cementitious material. The results show that the addition of nanosilica can effectively promote the setting and hardening process of composite cementitious material, and the higher the dosage is, the more significant the effect is. It also indicates that addition of nanosilica accelerates the formation of ettringite and calcium hydroxide, by promoting the hydration of tricalcium aluminate and tricalcium silicate. Shortens the hydration induction period and acceleration period of the composite cementitious material and accelerates the hydration process, thereby shortening the setting time and increasing the early strength.
{"title":"Unground granulated slag as a substitute for natural aggregate during concrete production","authors":"Ru Wang, Ziyan Xi, Gaoyong Wang","doi":"10.32047/cwb.2021.26.3.3","DOIUrl":"https://doi.org/10.32047/cwb.2021.26.3.3","url":null,"abstract":"Styrene-butadiene copolymer [SB] modified cement-based materials are widely used, but the addition of SB can delay the setting and hardening of cement, which limits its application in some projects. In this paper, nanosilica was selected as the modifying component to study its influence on the early hydration, setting and hardening of SB/cement composite material. By measuring the setting time and early strength of nanosilica modified SB/cement composite material, the influence of nanosilica on the setting and hardening process of composite cementitious material was analyzed. The hydration heat of nanosilica modified SB/cement composite material was determined by isothermal calorimetry, and its hydration products were examined by X-ray diffraction, so as to analyze the influence of nanosilica on the early hydration process of composite cementitious material. The results show that the addition of nanosilica can effectively promote the setting and hardening process of composite cementitious material, and the higher the dosage is, the more significant the effect is. It also indicates that addition of nanosilica accelerates the formation of ettringite and calcium hydroxide, by promoting the hydration of tricalcium aluminate and tricalcium silicate. Shortens the hydration induction period and acceleration period of the composite cementitious material and accelerates the hydration process, thereby shortening the setting time and increasing the early strength.","PeriodicalId":55632,"journal":{"name":"Cement Wapno Beton","volume":"194 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76784299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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