Method of Test for Permeability of Cement Mortar and Concrete
1965 Edition

IS 3085 defines the procedures to measure permeability of cement mortar and concrete using a dedicated permeability cell. Dimensions for test cells vary based on specimen size, with specific measurements provided for diameters 100 mm, 150 mm, and 300 mm. The test setup includes components such as the permeability cell, pressure regulator with gauge, air bleeder valve, water reservoir equipped with a graduated glass and safety shield, and a collection container. Pressure conduits must be constructed from robust armored rubber hoses or appropriate metal tubing, ensuring airtight joints. Test reports must document specimen identification, mixture details, age, test duration, specimen dimensions, test pressure and temperature, and permeability coefficients both at test and corrected temperatures. Rounding of values follows IS 2-1960 standards. A representative schematic illustrates the water reservoir feeding into the pressure regulator and permeability cell, with outputs to collection bottles and air bleeder valves.

The test measures the coefficient of permeability by passing de-aerated water through concrete or mortar specimens under controlled hydrostatic pressure and temperature. Water used must be purified and de-aerated by boiling and subsequent cooling, stored in sealed containers to prevent air reintroduction. The test records specimen identification, mix design, age, size, pressure, temperature, duration, and permeability coefficients. Specimen sizes and corresponding cell dimensions are standardized. The coefficient of permeability is calculated using the formula k = (Q × L) / (A × t × h), where Q is the water volume passed, L specimen length, A cross-sectional area, t time, and h hydraulic head. The testing apparatus setup includes a water reservoir, pressure regulator, permeability cell, collection bottle, graduated gauge glass, and air bleeder valve.

The permeability testing apparatus per IS 3085 includes heavy-duty armored rubber hoses or metal tubing for pressure lines with leakproof joints. Specimen cell dimensions correspond to specimen size, with precise measurements listed for 100 mm, 150 mm, and 300 mm diameters. Essential components include threaded nipples, sealing compounds, sheet metal funnels, air bleeder valves, pressure regulators with gauges, graduated gauge glasses protected by safety shields, water reservoirs, and collection bottles. Assembly requires secure attachment of the funnel and proper filling of the system with de-aerated water through the operation of valves and drain cocks. Compressed air or nitrogen supplies at regulated pressures between 5 to 15 kg/cm² are used, with regulators and gauges ensuring precise control. Test reports must capture specimen details, test conditions, and permeability results.

The test setup utilizes heavy-duty armored rubber hoses or metal tubing with leakproof fittings for pressure lines. Permeability cell dimensions are standardized according to specimen diameters of 100 mm, 150 mm, and 300 mm. Other apparatus includes threaded nipples, sealing compounds, funnels, air bleeder valves, pressure regulators with gauges, graduated gauge glasses with safety shields, water reservoirs, and collection bottles. The testing water must be clean, de-aerated by boiling and cooling, and stored sealed to prevent air contamination. Test reports must detail specimen identification, mix design, age, size, test pressure, temperature, duration, and permeability coefficients. A simplified schematic illustrates the flow from water reservoir through the pressure regulator to the permeability cell and collection bottle, including air bleeder valves and graduated gauge glass.

Test specimens should be cylindrical with height equal to diameter, typically 150 mm for standard aggregates. For aggregates up to 20 mm, specimens of 100 mm diameter and height are used; for aggregates exceeding 40 mm, dimensions should be at least four times the nominal aggregate size. Reports must include specimen identification, mix details, age at test initiation, test duration, dimensions, pressure, temperature, and permeability coefficients at test and standard conditions. Permeability cell dimensions correspond to specimen sizes as specified. Testing water is de-aerated, boiled, cooled, and stored in closed containers to avoid air contact. A schematic provides a visual overview of the test setup.

The standard test pressure is set at 10 kg/cm² (~0.98 MPa). For specimens with higher permeability, pressure may be reduced to 5 kg/cm² to expedite steady flow achievement. For less permeable specimens, pressures up to 15 kg/cm² may be applied, provided sealing integrity is maintained. During testing, the system is filled with water, desired pressure is applied, and water percolation is monitored by measuring the volume collected in a weighed container. Steady state is reached when inflow equals outflow, followed by approximately 100 hours of collection for averaging flow rates. Specimen and cell dimensions are standardized. Test reports must include all relevant specimen and testing parameters.

Test reports must include specimen identification, mix details, age, test duration, specimen size, test pressure and temperature, and permeability coefficients at both test and standard temperatures. Specimen and cell dimensions are standardized for sizes 100 mm, 150 mm, and 300 mm diameters. Apparatus assembly requires heavy-duty armored rubber hoses or metal tubing with leakproof joints and the use of de-aerated water to prevent air bubbles. The permeability coefficient is corrected to standard temperature using the formula k_std = k_test × (μ_test / μ_std), where μ denotes water viscosity at respective temperatures. The setup schematic illustrates water reservoir, permeability cell, collection bottle, pressure regulator, air bleeder valve, and pressure gauge. Measurements and rounding conform to IS 2-1960.

The permeability coefficient (K) is calculated by the formula: K = (Q × L) / (A × T × H), where K is the permeability coefficient in cm/sec, Q is the volume of water passed in ml after steady state, L is specimen thickness in cm, A is specimen cross-sectional area in cm², T is the measurement time in seconds, and H is the hydraulic head to specimen thickness ratio (dimensionless). Specimen dimensions must be accurately known, and seals must be leak-tight to prevent erroneous readings. Water used should contain less than 0.2% dissolved air to avoid air lock. Tests are conducted at 27 ± 2°C, with permeability adjusted by ±10% for every 5°C deviation using the temperature correction formula K_corrected = K_measured × [1 + 0.10 × (T_actual - 27)/5]. Surface preparation includes removing impervious layers by sandblasting or chiseling. A flowchart illustrates the process from applying hydrostatic pressure through calculation and temperature correction.

Results must be rounded as prescribed by IS 2:1960, maintaining significant digits consistent with standard values. Each test report should include specimen identification, mixture details, age at testing commencement, duration, specimen size, test pressure, temperature, permeability coefficient at test temperature, and the corrected coefficient at standard temperature. Reference dimensions for permeability cells corresponding to specimen diameters of 100 mm, 150 mm, and 300 mm are provided. Leak-proof pressure lines and properly sealed joints are mandatory. A flow diagram outlines the reporting process from specimen identification to final report generation, ensuring accuracy and compliance with IS 3085.