Investigation on self-curing capacity of light weight concrete using red ash as an aggregate

Abstract

Concrete is most widely used construction material due to its good compressive strength and durability. According to (Nilson, 2004) depending upon the nature of the work cement, fine aggregate, coarse aggregate and water are mixed in specific proportions to produce plain concrete. Plain concrete needs amiable atmosphere by providing moisture for a minimum period of 28 days for good hydration and to attain desired strength. The properties of hardened concrete, especially the durability, are greatly influenced by curing since it has an effect on the hydration of the cement. Any carelessness activity in curing will badly affect the strength and durability of concrete. Self-curing concrete is one of the special concretes in mitigating insufficient curing due to human negligence, scarcity of water in arid areas, inaccessibility of structures in difficult terrains. This study was focused on the self- curing capacity of light weight concrete using red ash as an aggregate. The main objective of this study is to evaluate self- curing capacity of light weight concrete using red ash as an aggregate. This thesis deals with an experimental investigation on the self-curing capacity of light weight concrete replacing coarse and fine aggregate with light weight aggregate (LWA) specifically the red ash and natural sand. Two different concrete mixes having both natural sand and red ash sand with red ash coarse aggregate as a common for the two types of mixes and control mix by natural gravel and natural sand (i.e.RRCO 2, RNCO2 and GNCO2) were prepared for normal strength (C-25) using a water cement ratio and cement content of 0.48, 360kg/m3 respectively. Concrete was cured outside the water at ambient temperature for 7, 14 and 28 days. The results of the hardened properties of the mixes have shown that concrete mix with prewetted red ash coarse aggregate and natural sand achieve a higher self-curing capacity and compressive strength with the value 34.28 Mpa at the 28thday curing period than the normal concrete by self-method of curing. The self-curing capacity and the compressive strength of concrete mix with natural gravel and natural sand is less than the curing capacity mix by red ash aggregates. This study also reveal that potential of this technology in saving the waste time to showering or other conventional curing method, reduce waste of fresh water in the curing time of concrete as well as the costs saved to the manpower for the follow up curing activity and reduce costs for material. It is recommended that to use red ash, the quality test for each source of red ash must be taste and the government create an awareness for contractors, client and suppliers to use red ash coarse aggregate instead of natural coarse aggregate using the internal method of curing.