scholarly journals Shrinkage cracking and strength deterioration of red clay under cyclic drying and wetting

Author(s):  
Yanhua Xie ◽  
Binghui Zhang ◽  
Baochen Liu ◽  
Zhaotian Zeng ◽  
Yan Zhang ◽  
...  
2019 ◽  
Vol 26 (4) ◽  
pp. 197-208
Author(s):  
Leo Gu Li ◽  
Albert Kwok Hung Kwan

Previous research studies have indicated that using fibres to improve crack resistance and applying expansive agent (EA) to compensate shrinkage are both effective methods to mitigate shrinkage cracking of concrete, and the additions of both fibres and EA can enhance the other performance attributes of concrete. In this study, an EA was added to fibre reinforced concrete (FRC) to produce concrete mixes with various water/binder (W/B) ratios, steel fibre (SF) contents and EA contents for testing of their workability and compressive properties. The test results showed that adding EA would slightly increase the superplasticiser (SP) demand and decrease the compressive strength, Young’s modulus and Poisson’s ratio, but significantly improve the toughness and specific toughness of the steel FRC produced. Such improvement in toughness may be attributed to the pre-stress of the concrete matrix and the confinement effect of the SFs due to the expansion of the concrete and the restraint of the SFs against such expansion.


1960 ◽  
Vol 25 (3) ◽  
pp. 199-204 ◽  
Author(s):  
Bert E. Bradley
Keyword(s):  

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3855
Author(s):  
Amirmohamad Abolhasani ◽  
Bijan Samali ◽  
Fatemeh Aslani

One commonly used cement type for thermal applications is CAC containing 38–40% alumina, although the postheated behavior of this cement subjected to elevated temperature has not been studied yet. Here, through extensive experimentation, the postheated mineralogical and physicochemical features of calcium aluminate cement concrete (CACC) were examined via DTA/TGA, X-ray diffraction (XRD), and scanning electron microscopy (SEM) imaging and the variation in the concrete physical features and the compressive strength deterioration with temperature rise were examined through ultrasonic pulse velocity (UPV) values. In addition, other mechanical features that were addressed were the residual tensile strength and elastic modulus. According to the XRD test results, with the temperature rise, the dehydration of the C3AH6 structure occurred, which, in turn, led to the crystallization of the monocalcium dialuminate (CA2) and alumina (Al2O3) structures. The SEM images indicated specific variations in morphology that corresponded to concrete deterioration due to heat.


Author(s):  
Murugan Paradesi Chockalingam ◽  
Navaneethakrishnan Palanisamy ◽  
Saji Raveendran Padmavathy ◽  
Edwin Mohan ◽  
Beno Wincy Winsly ◽  
...  

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 846
Author(s):  
Hastia Asadi ◽  
Joerg Uhlemann ◽  
Natalie Stranghoener ◽  
Mathias Ulbricht

Polytetrafluoroethylene (PTFE)-coated glass fiber fabrics are used for long-lasting membrane structures due to their outstanding mechanical properties, chemical stabilities, and satisfying service life. During their operation time, different environmental impacts might influence their performance, especially regarding the mechanical properties. In this contribution, the impact of water on the tensile strength deterioration was assessed experimentally, providing evidence of considerable but partially reversible loss of strength by up to 20% among the various types of investigated industrially established fabrics.


1989 ◽  
Vol 40 (2) ◽  
pp. 255 ◽  
Author(s):  
ICR Holford

Long-term yields, nitrogen uptake and responsiveness of grain sorghum following three lucerne rotations, an annual legume rotation, long fallowing, and continuous wheat growing were measured on a black earth and red clay in northern New South Wales. The three lucerne rotations compared two methods of lucerne establishment (with or without a cover crop) and two methods of grazing management (short or extended grazing).There were large beneficial effects of lucerne leys on the first grain sorghum crop, whether they were measured as grain yield, nitrogen content of the foliage and grain, or nitrogen uptake. The effect was much smaller in the second year but it increased in the third and fourth years, in direct relation to the rainfall during the sorghum flowering period. The effect was larger on the black earth than on the red clay, reflecting the much higher lucerne yields on the former soil. Evidence indicated that the nitrogen contribution from lucerne after the first year was no greater than the nitrogen accumulated by long fallowing, and this was attributed to very low rainfall and lucerne yields during the four year ley period.The annual legume rotation suffered from drought and insect damage in most years, and following sorghum yields tended to be lower than those achieved by long fallowing.Differences in the effects of establishment method and grazing management on total lucerne yields were reflected in the differences in subsequent grain sorghum yields. Largest differences were on the black earth where extended grazing lowered the total yields of lucerne and subsequent grain sorghum. Sowing lucerne under wheat had little effect on total yields of lucerne or sorghum.


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