Suitability of Crushed Sandcrete Block (Csb) as Fine Aggregate for Masonry Works
Abstract
This paper focuses on the prospects of recycled broken sand Crete hollow blocks as fine aggregate for masonry works. Sandcrete hollow blocks were taken from dealers in Zaria and tested for density, water absorption, dimension tolerances, drying shrinkage, wetting expansion and compressive strength as compared to hand moulded blocks which were moulded in the laboratory to NIS 87(2004) specification. Density ranges from 1797.37Kg/m3 – 1974.00Kg/m3 , water absorption ranges from 5.38% - 10.38%, drying shrinkage ranges from 0.028% - 0.044%, wetting expansion ranges from 0.042% - 0.059% and the 28th day compressive strength ranges from 0.45N/mm2 - 0.85N/mm2 . Results showed that density, water absorption, drying shrinkage, wetting expansion and 28th -day compressive strength of block samples manufactured from quarry fine collected from one of the industries was 2070.11Kg/m3 , 9.54%, 0.034%, 0.05%, and 1.38N/mm2 respectively. The study confirmed that the quality of sand Crete blocks manufactured in Zaria does not meet the specified standard in respect of strength.
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Introduction
In most construction sites today, broken Sandcrete blocks are being disposed of as waste materials. The application of recycled aggregates from construction and demolition wastes is viewing the potential presentation in construction as another to primary (natural) aggregates. It saves usual resources and decreases the space essential for landfill removal (Buchner and Scholten, 1992). In Nigeria and many other developing countries, the building construction industry is exploring and still combining materials within its immediate surroundings in search of suitable materials that can combine to facilitate the building of civil engineering structures.
It is a recognised detail that the non-stop generation of solid waste materials gives a serious environmental challenge. For this motive, it is very significant to study and develop any technology, procedure or method that may help to exploit their use efficiently (Bolden, 2013). Due to the high cost of building materials in Nigeria, the average citizen finds it difficult to afford good housing in the country. This trouble has led to the use of local wastes as alternatives to conventional materials in the construction industry. One of the main challenges of our current society is to safeguard the environment. The significant features in this respect are the decrease in the consumption of energy and natural raw materials and the consumption of waste materials.
Conclusion
The suitability of crushed Sandcrete block as fine aggregate for masonry work has been carried out, based on the findings the resulting conclusions can be noted:
1. The lack of adequate knowledge, non-adherence to established standard and poor quality control measures on the part of Sandcrete block manufacturers in Zaria is responsible for the considerable variations and low compressive strength.
2. The cement-sand mix ratio used by the manufacturers in Zaria is one-part cement to ten or fourteen parts of sand (1:10 to 1:14) compared to one-part cement to six or eight parts of sand (1:6 to 1:8) and is below codes requirements.
3. A curing period of 1 to 3 days has been adopted by Sandcrete hollow blocks manufacturers in Zaria instead of a minimum of seven (7) days.
4. The water absorption of Sandcrete hollow blocks in Zaria satisfies the code requirements.
5. The densities of Sandcrete blocks manufactured in Zaria are greater than 1500Kg/m3 which makes them be classified as Type A blocks.
6. The density, water absorption, drying shrinkage, wetting expansion and 28th -day compressive strength of block samples manufactured from quarry fine collected from a manufacturer in Zaria is 2070.11Kg/m3 , 9.54%, 0.034%, 0.05%, and 1.38N/mm2 respectively.