Code of practice for preparation and use of lime-pozzolana mixture concrete in buildings and roads
1992 Edition

IS 5817:1992 mandates that lime-pozzolana mixtures comply with IS 4098:1983 standards. If quick-setting mixtures are employed, they must meet IS 10772:1983 criteria. Strength requirements depend on the mixture type, water-to-binder ratio, and binder-to-aggregate ratio. Typically, minimum compressive and flexural strengths are specified in Table 1 of the standard based on intended usage in buildings or roads. Pulverized fuel ash conforming to IS 15648:2006 may be used as part of fine aggregate. Additionally, the bond strength between lime-pozzolana concrete and cement concrete ranges from 1.5 to 2.0 MPa, crucial for composite pavement layers. These criteria ensure adequate durability, workability, and strength for structural and pavement applications.

For road base construction using lime-pozzolana concrete, suitable mix proportions as outlined in Table 1 (Serial Nos. 2 or 3) should be selected based on the application. The mixing process involves thoroughly blending lime, pozzolana, and aggregates in a mechanical mixer for uniformity. Once mixed, the concrete is placed to the required thickness and subjected to sufficient surcharge. Compaction is achieved by using a notched screed vibrator to ensure full consolidation of the material. This method enhances the flexural capacity and strain distribution, effectively spreading loads and reducing stresses on the subgrade, thereby improving pavement performance.

IS 5817 advises an initial curing phase where freshly laid lime-pozzolana concrete is covered with wet hessian for 48 hours to preserve moisture. Following this, the surface should be covered with wet sand or gunny bags and kept frequently moistened for a minimum period of 10 days. Clean and potable water must be used for both mixing and curing to avoid any adverse effects. Since lime-pozzolana concrete cures slower than cement concrete, this extended curing ensures optimal hydration, strength gain, and resistance to sulphate attack. For structural elements like foundations, commencement of superstructure work should be delayed until at least 7 days post laying.

Yes, IS 5817 specifies the use of lime-pozzolana mixture concrete as a bonded underlay beneath thin cement concrete overlays in composite rigid pavements. This application is detailed in Clause 8.6.1, highlighting its high flexural strength and strain capacity, which facilitates efficient load distribution and reduces subgrade deflections. The mix proportions for such bonded underlays are provided in Serial No. 3 of Table 1. Its use enhances pavement durability by providing a rigid base layer that adheres well to the overlay, improving overall pavement performance.

The strength of lime-pozzolana concrete varies based on the mixture type (per IS 4098:1983 or IS 10772:1983), water-to-binder ratio, and binder-to-aggregate ratio. IS 5817 Table 1 specifies minimum compressive and flexural strengths tailored to application needs: foundations generally require lower strengths suitable for moderate loads, while floors, pavements, and roads demand higher strength values due to traffic and wear. The concrete is known for its durability and resistance to sulphate attack, making it appropriate for foundations in aggressive soil conditions. Bond strength with cement concrete overlays is typically between 1.5 and 2.0 MPa when layers are placed promptly. For precise strength values, consulting Table 1 of IS 5817 is essential.