TY  - BOOK
AU  - Ceniza, John Gerard S.
TI  - Comparative study of the production of concrete hollow blocks in Cebu as basis for improvement
U1  - T C3324 2014 
CY  - 3
N1  - 000-099
N2  - As the construction industry booms in the city, the demand of Concrete Hollow Blocks (CHB) also increases relatively. However, the existing CHB are not that strong making it unreliable as defense against natural and manmade calamities. Things were done to make CHB compressively strong; adding other materials to the original ingredients are one of the innovations that are believed to make the CHB strong, but the common problem of these innovations is the additional cost of the CHB. Realizing this problem brought the proponents to the idea of dropping all the innovations and focusing on the proper production process.
	The proponents surveyed some manufacturers in Cebu to know and study their production processes asking them the following questions:
1.	How are CHB produced in different manufacturers in Cebu? What are their similarities and differences?
2.	What should be the proportion of the hereinafter listed ingredients for economically feasible CHB products?
a.	Cement
b.	Washed sand 
c.	Stone Chips
d.	Water
3.	How should the following procedures be properly executed to produce good quality CHB?
a.	Handling and storage of materials
b.	Mixing
c.	Molding
d.	Curing
e.	Stacking
The proponents conducted experimental studies about the production process that manufacturers followed and pinpointed the probable lapses that caused the CHB to attain unsatisfactory strength. Samples were procured from these manufacturers and were then tested using a Universal testing Machine (UTM) to know their compressive strengths. The results were unsatisfactory, ranging from 150 psi to 320 psi. These poor results might have been caused by these lapses in production:
1.	The proportioning of ingredients was solely base on experience and exact measurement was neglected.
2.	Ingredients were improperly stored making them mix prior to the mixing process making the C:S:G:W ratio erroneous.
3.	Curing was not strictly followed.
4.	Inconsistency in the duration of molding via vibration was also observed.
5.	Excessive stacking of CHB.

The proponents also considered the type and sources of the ingredients and its properties that may affect the strength of the CHB. An Abrasion test was done to the aggregates to determine the strength of the aggregates. All the data collected from the interviews and tests were then used to formulate a recommended ratio and production process that will yield higher strength CHB than those existing in the market. After formulating the desired ratio and preparing the step-by-step process in attaining the high strength CHB, production of CHB then started. The proponents produced the modified CHB and were tested against compression. Although the modified CHB cost approximately 40% more expensive, it yielded 30% to 50% higher strength than the existing CHB in the market.
However, despite of these positive results lapses were still present. In order to prevent, a set of recommendations are listed below:
1.	Curing must be implemented strictly and skipping of curing days must be avoided
2.	Storage must be in a less disturbance prone area.
3.	Procure ingredients from primary sources and not from retailers in order to spend less
ER  -