Self compacting concrete (SCC) is gaining more and more popularity in the building and civil engineering construction field. Precast industry is looking at it with continuously growing interest, the elimination of vibration contributing to significantly improve the quality of its products and the efficacy of production processes, with positive effects also on the “friendliness” of the working environment (e.g. reduction of noises) and consequently on the wellness of workers. The possibility, now widely investigated, of successfully replacing a not negligible portion of the higher cement content with waste by-products, reducing the total cost for cubic meter, can give a further impulse to the use of SCC also for large scale and series production of structural elements. The higher cost, due to a higher demand of cementitious material and of high-range water reducing and viscosity enhancing admixtures, and which stand as the main drawback for a more and more widespread use of SCC in precast construction, can be in fact successfully reduced by a proper selection of finely ground materials, which enhancing packing density also enables for the reduction of water and HRWRA demand to achieve a required deformability and contemporary the VEA dosage necessary to guarantee stability, without any significant effect on strength. To the author’s knowledge scarce data are so far available on the statistical properties of self compacting concrete, being it relatively new to precast industry and its production, at the present time, having been mainly “limited” to dedicated, even if significant, structural applications. The possibility of extrapolating existing data on conventional concretes (1,2) has hence to be checked, mainly in the sight of extending to SCC quality control procedures calibrated on conventional concretes (3) and assessing material partial safety factors (strength reduction factors) as prescribed in current design codes (4,5,6). In this work data of quality control on steam-cured plant-produced SCC for precast prestressed long span roof elements are analyzed: one year of continuing production has been taken as a reference (01/11/2001-31/10/2002). The examined SCC is targeted class C45 (45 MPa characteristic compressive strength at 28 days) according to European Standards (7). Statistical evaluations on short-term and 28-days compressive strength have been performed, also in the sight of extending to SCC currently available models for evolution of concrete strength with time. An evaluation of material partial safety factor has been also performed, according to current Italian and International code prescriptions.
Quality control of plant produced SCC for precast prestressed roof elements
FERRARA, LIBERATO
2005-01-01
Abstract
Self compacting concrete (SCC) is gaining more and more popularity in the building and civil engineering construction field. Precast industry is looking at it with continuously growing interest, the elimination of vibration contributing to significantly improve the quality of its products and the efficacy of production processes, with positive effects also on the “friendliness” of the working environment (e.g. reduction of noises) and consequently on the wellness of workers. The possibility, now widely investigated, of successfully replacing a not negligible portion of the higher cement content with waste by-products, reducing the total cost for cubic meter, can give a further impulse to the use of SCC also for large scale and series production of structural elements. The higher cost, due to a higher demand of cementitious material and of high-range water reducing and viscosity enhancing admixtures, and which stand as the main drawback for a more and more widespread use of SCC in precast construction, can be in fact successfully reduced by a proper selection of finely ground materials, which enhancing packing density also enables for the reduction of water and HRWRA demand to achieve a required deformability and contemporary the VEA dosage necessary to guarantee stability, without any significant effect on strength. To the author’s knowledge scarce data are so far available on the statistical properties of self compacting concrete, being it relatively new to precast industry and its production, at the present time, having been mainly “limited” to dedicated, even if significant, structural applications. The possibility of extrapolating existing data on conventional concretes (1,2) has hence to be checked, mainly in the sight of extending to SCC quality control procedures calibrated on conventional concretes (3) and assessing material partial safety factors (strength reduction factors) as prescribed in current design codes (4,5,6). In this work data of quality control on steam-cured plant-produced SCC for precast prestressed long span roof elements are analyzed: one year of continuing production has been taken as a reference (01/11/2001-31/10/2002). The examined SCC is targeted class C45 (45 MPa characteristic compressive strength at 28 days) according to European Standards (7). Statistical evaluations on short-term and 28-days compressive strength have been performed, also in the sight of extending to SCC currently available models for evolution of concrete strength with time. An evaluation of material partial safety factor has been also performed, according to current Italian and International code prescriptions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
