Screed
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Types and Durability
Description
Screed |
Expected Lifespan
(Years) |
Adjustment Factors |
Cementitious Screed | ||
Direct finished concrete slab to BS 8204: Part 2. High alumina cement to BS 915 (not suitable for use in structural concrete or in monolithic toppings or Portland cement concrete) | 35+ | Constantly immersed in water or exposed to extreme moisture: – 15% years
Addition of water reducing admixture to BS 5075: Part 1: + 15% years |
Direct finished concrete slab to BS 8204: part 2. Portland-blast furnace cement to BS 146 | 35+ | |
Direct finished concrete slab to BS 8204: part 2. Portland pulverized-fuel ash cement to BS 6588 | 35+ | |
Direct finished concrete slab to BS 8204: part 2. Combination of Portland cement with granulated blastfurnace slag or pulverised fuel ash. | 35+ | |
Direct finished concrete slab to BS 8204: part 2. Portland Cement to BS 12 | 35 | |
Direct finished concrete slab to BS 8204: part 2. Portland Cement to BS 12 | 35 | |
Proprietary Screed | ||
Preblended polymer-modified topping. Thickness and installation of topping in strict accordance with manufacturer’s recommendation. | 25 | Constantly immersed in water or exposed to extreme moisture: – 15% years,Test certificate from approved local testing authority: +15% years
Addition of water reducing admixture to BS 5075: Part 1: + 15% years (for cementitious based only) |
Proprietary metallic non-ferrous aggregate topping. Laid monolithically with concrete base/ screed. Cement to comply with the requirements of BS 12, Class 42.5, BS 915: Part 2, or BS 4027 Class 42.5N. Sand to BS 882, grades C or M, but with not more than 10% passing sieve size 75 micrometers. Mixing & laying in strict accordance with manufacturer’s instructions. | 25 | |
Proprietary polymer-modified topping. Cement to comply with the requirement of BS 12, Class 42.5N, BS 915: Part 2, or BS 4027 Class 42.5N. Sand to BS 882, grades C or M, but with not more than 10% passing sieve size 75 micrometers. Coarse aggregate to table 2 of BS 63: Part 1 or table 3 of BS 882. Thickness and mix proportion in accordance with table 1 of BS 8204: Part 3. | 20 | |
Proprietary metallic non-ferrous aggregate topping. Laid monolithically with a minimum 25mm thick 1:1.5:2.5 concrete bonding layer. Cement to comply with the requirement of BS 12, class 42.5N, BS 915: Part 2, or BS 4027 Class 42.5N. Sand to BS 882, grades C or M, but with not more than 10% passing sieve size 75 micrometers. Mixing/ laying in strict accordance with manufacture’s instruction. | 20 | |
Proprietary epoxy-reinforced cementitious topping. Minimum thickness 10mm. Mixing and application strict accordance with manufacturer’s instruction. | 20 | |
Proprietary epoxy-reinforced cementitious topping. Minimum thickness 5mm. Mixing and application strict accordance with manufacturer’s instruction. | 10 | |
Unclassified, i.e. proprietary polymer-modified topping, cement not to BS 12/ BS 915/ BS 4027, sand not to BS 882, aggregate not to BS 63/ BS 882 and/ or thickness/ mix proportion not to BS 8204 Part 3. | < 10 | |
Unclassified, i.e. proprietary metallic aggregate topping not laid monolithically with concrete base or bonding layer, and/ or cement not BS 12/ BS 915/ BS 4027, sand not to BS 882, aggregate not to BS 63/ BS 882, and/or not mixed/ laid in accordance with manufacturer’s instruction. | < 10 | |
Unclassified, i.e. proprietary epoxy reinforced cementitious topping, thickness less than 1.5mm, and/ or mixing/ application not in accordance to manufacturer’s instructions. | < 10 |
In the case of 2 or more condition of adjustment factor occur, the percentage of year shall be added to obtain the durability value.