Crystalline Silica Dust and Respirable Particulate Matter During Indoor Concrete Grinding—Wet Grinding and Ventilated Grinding Compared with Uncontrolled Conventional Grinding

Abstract

The effectiveness of wet grinding (wet dust reduction method) and ventilated grinding (local exhaust ventilation method, LEV) in reducing the levels of respirable crystalline silica dust (quartz) and respirable suspended particulate matter (RSP) were compared with that of uncontrolled (no dust reduction method) conventional grinding. A field laboratory was set up to simulate concrete surface grinding using hand-held angle grinders in an enclosed workplace. A total of 34 personal samples (16 pairs side-by-side and 2 singles) and 5 background air samples were collected during 18 concrete grinding sessions ranging from 15-93 min. General ventilation had no statistically significant effect on operator's exposure to dust. Overall, the arithmetic mean concentrations of respirable crystalline silica dust and RSP in personal air samples during: (i) five sessions of uncontrolled conventional grinding were respectively 61.7 and 611 mg/m(3) (ii) seven sessions of wet grinding were 0.896 and 11.9 mg/m(3) and (iii) six sessions of LEV grinding were 0.155 and 1.99 mg/m(3). Uncontrolled conventional grinding generated relatively high levels of respirable silica dust and proportionally high levels of RSP. Wet grinding was effective in reducing the geometric mean concentrations of respirable silica dust 98.2% and RSP 97.6%. LEV grinding was even more effective and reduced the geometric mean concentrations of respirable silica dust 99.7% and RSP 99.6%. Nevertheless, the average level of respirable silica dust (i) during wet grinding was 0.959 mg/m(3) (38 times the American Conference of Governmental Industrial Hygienists [ACGIH] threshold limit value [TLV] of 0.025 mg/m(3)) and (ii) during LEV grinding was 0.155 mg/m(3) (6 times the ACGIH TLV). Further studies are needed to examine the effectiveness of a greater variety of models, types, and sizes of grinders on different types of cement in different positions and also to test the simulated field lab experimentation in the field.

Exposure Assessment of Particulate Matter from Abrasive Treatment of Carbon and Glass Fibre-Reinforced Epoxy-Composites - Two Case Studies

“…S2(D . This is consistent with what is reported by Akbar-Khanzadeh et al (2007) for silica dust during the grinding of concrete. We found that at the maximum LEV flow rate particle emissions were negligible, and during the process, the near field particle concentrations remained at the pre-activity level (Figs.…”

Quartz Measurement in Coal Dust with High-Flow Rate Samplers: Laboratory Study

“…In many occupational environments, engineering controls such as wet methods and local exhaust ventilation do provide substantial exposure reductions of respirable crystalline silica (Flynn and Susi, 2003;Akbar-Khanzadeh et al, 2007). Consequently, the silica mass on a typical air sample is reduced and often close to the detection limit.…”

Concrete Grinding Residue Characterization and Influence on Infiltration

“…Highway concrete grinding typically uses diamond‐impregnated grinding wheels stacked together on a shaft that produce a total grinding width ranging from 0.9 to 1.2 m. The thickness of the concrete that is removed is a function of the degree of highway roughness and can range from 1.6 to 12.7 mm. Water is introduced to the grinding wheels to increase their life expectancy, decrease dust emissions and increase worker safety (Akbar‐Khanzadeh et al, 2007; Sheinbaum, 1962), and facilitate the movement of the grinding residue away from the grinding surface. The resultant concrete grinding residue (CGR) can be disposed of below the road shoulder at the site of grinding, collected and moved to a containment pond where it is then dewatered and the solids are transported to a landfill, or recycled (Dosho, 2008; Goodwin and Roshek, 1992).…”