Mt Pinatubo Case Study

CHAPTER I
THE PROBLEM AND ITS BACKGROUND
Introduction
The eruption of Mt. Pinatubo, in Central Luzon on 12 to 15 of June 1991 is recorded as the second largest volcanic eruption of 20th Century. It results in the deposition of Billion cubic meters of volcanic ash over its surrounding area including rivers in Tarlac, Pampanga, and Zambales. These loose materials that composed of volcanic ash, rocks, and debris were rapidly flown by rainfalls in the form of lahar to the surrounding of Mt. Pinatubo, especially in river valleys. It caused the devastation of low-lying areas and destruction of structures along its path. To protect the residential areas and farmlands during heavy rainfall, River embankments also known as mega-dikes were constructed.

Mega-dikes, serve as protection against the devastation that can be caused by the lahar, have channels where lahar settle and deposit. These Lahar deposits were flown by rainwater where silt washed away if so lahar became washed sand. With the help of mega-dikes, they can quarry the lahar sand deposits in the riverbanks. Now, it is one of the primary sources of income in those provinces. Lahar aggregates and sand are mostly used in construction industry like fine aggregates in concrete, making concrete hollow blocks, sub-base and base course, and asphalt mix in road construction. Despite the many things can be done in lahar, it is rarely used as backfill materials. Because it is a porous lightweight material where can may undergo large settlements when utilized as geotechnical structures.
Many methods and laboratory experiments can be used to improve lahar as backfill materials. One of them is the determination of compaction properties of soil namely the maximum dry density and optimum moisture content. Determination of compaction properties of soil is common soil modification method to improve the engineering properties of soils. The effectiveness of the compaction is usually measured by soil's optimum moisture content and maximum dry density. It is important in the construction projects such as earth dams, road and railway embankments, landfill liners and backfills of retaining

What are the possible soil improvement techniques to use lahar as backfill materials?
Significance of the Study
This research assessed the optimum moisture content and maximum dry density of lahar as backfill material, due to limited research on the geotechnical properties of lahar and non-existent design methodologies regarding its use as earth backfill or embankment.
By determining the compaction properties of lahar, it can be more effective as backfill materials. It can be determined the possible soil improvement techniques to use lahar as backfill materials.
It helps the provinces having the deposits of lahars and the construction industry to maximize lahar's potential use as backfill materials without worrying large settlement.
For Civil Engineering, students and researchers, this will help them to get more information about lahar as backfill materials. It can give them knowledge and idea on how to improve lahar in the geotechnical field of study.
Scope and