Naqvi A A, Maslehuddin M, Garwan M A, Nagadi M M, Al-Amoudi O S B, Raashid M
Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia.
Appl Radiat Isot. 2010 Mar;68(3):412-7. doi: 10.1016/j.apradiso.2009.11.044. Epub 2009 Dec 29.
Pozzolanic materials, such as fly ash (FA), silica fume (SF), and blast furnace slag (BFS) are added to Portland cement in concrete to prevent reinforcement steel corrosion in concrete. Further preventive measure against reinforcement steel corrosion require monitoring of chloride salts concentration in concrete using non-destructive techniques, such as the prompt gamma-ray neutron activation analysis (PGNAA) technique. Due to interferences between gamma-rays from chlorine and calcium in PGNAA technique, detection limit of chlorine in concrete strongly depends upon calcium concentration in concrete. SF mainly contains silica and its addition to cement concrete reduces overall concentration of calcium in concrete. This may result in an improvement in detection limit of chlorine in SF-based concrete in PGNAA studies. Particularly for chlorine detection using 6.11 and 6.62 MeV prompt gamma-rays that strongly interfere with 6.42 MeV prompt gamma-rays from calcium. In this study, SF was added to Portland cement to prevent concrete reinforcement steel from corrosion. The chlorine concentration in SF cement concrete specimens containing 0.2-3.0 wt% chlorine was measured through yield of 1.16, 1.95, 6.11, 6.62, 7.41, 7.79, and 8.58 MeV chlorine gamma-rays using PGNAA technique. An excellent agreement was noted between the experimental yield of the prompt gamma-rays and the gamma-ray yield calculated through the Monte Carlo simulations. Further the minimum detectable concentration (MDC) of chlorine in SF cement concrete was calculated and compared with the MDC values of chlorine in plain concrete and concrete mixed with fly ash cement. The MDC of chlorine in SF-based concrete through 6.11 MeV, and 6.62 MeV chlorine gamma-rays was found to be improved as compared to those in plain concrete and concrete mixed with fly ash cement.
火山灰质材料，如粉煤灰（FA）、硅灰（SF）和高炉矿渣（BFS），被添加到混凝土中的波特兰水泥中，以防止混凝土中的钢筋腐蚀。防止钢筋腐蚀的进一步预防措施需要使用无损技术，如瞬发伽马射线中子活化分析（PGNAA）技术来监测混凝土中氯化物盐的浓度。由于PGNAA技术中来自氯和钙的伽马射线之间的干扰，混凝土中氯的检测限很大程度上取决于混凝土中的钙浓度。硅灰主要含有二氧化硅，将其添加到水泥混凝土中会降低混凝土中钙的总体浓度。这可能会导致在PGNAA研究中提高基于硅灰的混凝土中氯的检测限。特别是对于使用6.11和6.62 MeV瞬发伽马射线检测氯，这两种射线会强烈干扰来自钙的6.42 MeV瞬发伽马射线。在本研究中，将硅灰添加到波特兰水泥中以防止混凝土钢筋腐蚀。通过使用PGNAA技术，通过1.16、1.95、6.11、6.62、7.41、7.79和8.58 MeV氯伽马射线的产率，测量了含0.2 - 3.0 wt%氯的硅灰水泥混凝土试件中的氯浓度。观察到瞬发伽马射线的实验产率与通过蒙特卡罗模拟计算的伽马射线产率之间有很好的一致性。此外，计算了硅灰水泥混凝土中氯的最低可检测浓度（MDC），并与普通混凝土和掺粉煤灰水泥混凝土中氯的MDC值进行了比较。发现基于硅灰的混凝土中通过6.11 MeV和6.62 MeV氯伽马射线的氯MDC与普通混凝土和掺粉煤灰水泥混凝土相比有所提高。
