This chapter presents the related literature and related studies taken from several sources, with varying local and foreign authors. It also includes the theoretical framework and the bibliography of the study. All the information provided in this chapter is intended to further help the readers understand the weight of the importance and the gravity of the responsibility that is upon the study.
Review of Literature
In the Philippines, construction is among the major industries to date; alongside BPO (business process outsourcing), retail, gaming, hospitality & leisure, real estate, manufacturing, shipbuilding, and energy & automotive. The Asian Development Bank reported in 2013 that construction contributed more than 40% of GDP growth. It is forecasted to remain buoyant with double-digit growth, with increases in both the public and the private sectors.
On the other hand, our country, like the rest of the world, is suffering from human-caused environmental degradation. There are many factors attributing to this, one of them being the improper disposal of solid and toxic wastes. This then leads to creating sustainable methods in order to omit old but erroneous practices. The World Commission on Environment and Development defines sustainability as a “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”
One of the local initiatives applying the said practice is the RiceStrawPH or the “Sustainable Rice Straw Management for Food, Bioenergy, and Feed in the Philippines”. It aims the “development of sustainable rice straw technologies and practices on the productions of animal feed, mushroom and bioenergy.” The implementation of this program has already started last April 2008, and it will end on 2020. The Bureau of Agricultural Research is funding this project. However, this program focuses on improved rice straw quality for animal feeding and about 60-80% of rice straw is burned for speedy management.
Filipinos, being the world’s biggest rice consumers, are also major contributors to the worldwide lignocellulosic wastes with the rice straws. Rice straw is separated from the grains after the plants are threshed. Traditionally, rice straws and husks are either dumped into rivers or burned in the field, causing GHG emissions, contamination, and pollution. In the absence of proper management, these wastes lead to serious environmental issues. Recently, sustainable practices are being developed for rice residues to be processed and managed properly. One of them being the goal of this study: the conversion of rice straws as cement reinforcement.
A cement is a substance used for construction that sets, hardens, and adheres to other materials to bind them together. When it is mixed with fine aggregate, it produces mortar for masonry. Furthermore, it produces concrete when mixed with sand and gravel. Inorganic cements, like lime- or calcium silicate-based, are usually used. They are highly dangerous to one’s health, especially with direct and unguarded contact. Heavy airborne pollution is brought about by the cement industry as it is one of the primary producers of carbon dioxide, a potent greenhouse gas. Every stage of its process brings a negative impact on the environment in the form of dust, gases, noise and vibration of machineries when operating, and damage to the countryside from quarrying. Concrete also has unwanted additives that can cause health concerns due to toxicity and radioactivity.
New manufacturing process is utilizing the use of ‘green cement’ by incorporating and optimizing recycled materials. It aims to reduce, possibly eliminate, the release of damaging pollutants and greenhouse gasses.
With the estimated 580 million tons production of rice straws every year, this ‘farm waste’ becomes an abundant and cheap source for high-value fibrous applications. Natural cellulose fibers are obtained from rice straw, it is reported to contain better properties than any other agricultural byproduct.
According to the study conducted by N. Stevulova, et al, “fiber reinforced cement composites exhibit improved toughness, ductility, flexural capacity and crack resistance compared with non-fiber reinforced cement-based materials”. Moreover, cellulosic fibers provide adequate bonding capacity for the substantial enhancement of the cement-based material’s flexural strength, toughness and impact resistance. Their results show positive performance in the use of cellulosic and lignocellulosic fibers reinforced into cement-based mortars, concluding the potential contribution of the said composites to sustainable development.
A review of recent research in the area of cement-based composites reinforced with cellulose fibers conducted by Monica Ardanuy, et al., it recognizes the exhibited set of important advantages of vegetable or cellulose fibers, “such as wide availability at relatively low cost, bio-renewability, ability to be recycled, bioderadability, non-hazardous nature, zero carbon footprint, and interesting physical and mechanical properties”.
In a related study, Yahya Hamzeh, et al. utilized white rice husk ash and other fibrous materials as reinforcing agents on cement composites. Their obtained data contains comparable effects in the compressive strength, water absorption, and density on the incorporation of the white rice husk ash and various pulp fibers into normal Portland cement.