Compressive Strength and Water Absorption of Pervious Concrete that Using the Fragments of Ceramics and Roof Tiles

Pervious concrete was introduced in America in 2003, popularized by Dan Brown and used as a rigid pavement in the open parking lot. Rigid pavement using pervious concrete can absorb water in the surface to go straight through the concrete to the ground below.This water flow is one of the benefit of using the pervious concrete. Using of wastes such as broken roof and ceramics tiles are not commonly used in Indonesia. Utilization these kind of wastes is predicted lower the compressive strength of pervious concrete as they are used as a substitute for coarse aggregate.In this research, pervious concrete is made using a mixture of the fragment of ceramics and roof tiles.This research using broken ceramics and roof tiles with a grain size that loose from 38 mm sieve, retained on 19 mm sieve and the coarse aggregate from crushed stone that loose 12.5 mm sieve, retained on 9.5 mm sieve. The water cement ratio is 0.3 and to assist the mixing process, the addition of addictive in pervious concrete is used.The size of coarse aggregate used in the mixture affects the strength of pervious concrete. The larger the size of aggregate, the obtained compressive strength becomes smaller. It also affects the density of pervious concrete. The using of mixture of ceramics and roof tiles only reduce 2 MPa of pervious concrete compressive strength so this mixture can be used as a substitute for coarse aggregate with a maximum portion of 30 %. The high porosity of the specimens causes the reduction of pervious concrete density that affect the compressive strength. This high level of porosity can be seen from the high level of water absorption that exceed the required limit of water infiltration.


Introduction
Pervious concrete is an alternative that can help to enter a new era in the field of construction. This construction material has characteristic that can be penetrated by water, because of its concrete pores.It can be used as a means of soil water absorption so it can reduce surface runoff and add the groundwater reserves.The using of ceramics and roof tile fragments is one way to reuse wasted materials. But the use of substitute materials is still not popular in Indonesia. Maybe, this is because of the coarse and fine aggregate materials are easily obtained, but sooner or later these materials will be depleted so the price of these materials from year to year will be more expensive. The volume of coarse aggregate in concrete mixture reaches 78 % and coarse aggregate is the main filler in concrete mixture. Utilization the fragments of ceramics and roof tile as the substitution of coarse aggregate is expected to be one alternative in reusing the waste materials.

Research Significance
The objective of this research is to find out the compressive strength of pervious concrete that using the waste materials (such as the ceramics and roof tile fragments) as a coarse aggregate substitute and determine the ability of water absorption. This research has an added value by using waste material such as ceramic and roof tile as a subtitute of coarse aggregate.

Implementation of Research
This research was conducted based on the scope as follows: 1. Using Portland cement type I. 2. This research using broken ceramics and roof tiles with a grain size that loose from 38 mm sieve, retained on 19 mm sieve and the coarse aggregate from crushed stone that loose 12.5 mm sieve, retained on 9.5 mm sieve.
3.Local clay tile is made from molded clay, heated with hot coals with a certain degree, so it has good durability. The tile was destroyed following the coarse aggregate size at the number 2, loose from 38 mm sieve, retained on 19 mm sieve ( for size 2-3 cm tile size fraction), and loose from the 12.5 mm sieve,retained on 9.5 mm sieve (for size of tile fragments 9 -12 mm). 4.Ceramic (porcelain tiles) is the tile with the strongest resistance compared to another kind of tile, created by burning at high temperatures. In addition, the ceramic has a strong durability, low power absorption and suitable for use in the open space. The ceramic was destroyed following the coarse aggregate size at the number 2, loose from 38 mm sieve, retained on 19 mm sieve (for size 2-3 cm tile size fraction), and loose from the 12.5 mm sieve, retained on 9.5 mm sieve (for size of tile fragments 9 -12 mm).

The Variation of Specimens
The specimens made of pervious concrete cube molds shaped to the size of 15x15x15 cm, with two stages: 1. Two variations of preliminary specimens, made without ceramics and roof tiles. 2. Research speciments with six variations of roof tile fragments and six variations with ceramics tile fragments. Time of water seepage will be tested to all specimens.  -1968-1990 about coarse aggregate sieve analysis. Specivic gravity and coarse aggregate testing procedure is according to SNI-03-1969SNI-03- -1990 about specific gravity and absorption of coarse aggregate.

Test Results
Pervious concrete has void content of 20% and water cement ratio of 0.38. The spesification test results of coarse aggregate with 9-12 mm diameter are as follow: the density obtained is 1.184 kg/dm3 with specific gravity of 2.53 and the water absorption rate of 3.06%. The spesification test results of coarse aggregate with 19-31 mm diameter are as follow: the density obtained is 1.211 kg/dm3 with specific gravity of 2.53 and the water absorption rate of 3.06% While the density of roof tile fragment is 0.899 kg/dm3 and 0.996 kg/dm3 for ceramics tile fragment.The result of A and B variation can be seen in following table:  From the analysis result, it's seen that the density of the proportion was still below the required 1780 -1890 kg/m3 , automatically the compression strength result is also below the initial estimation.

Concrete Compressive Strength Test for A Variation and B Variation (Without Mixed Ceramics and roof Tile fragment)
Comparison of compressive strength test results between A and B variations can be seen in the following figure:

Fig. 1. Comparison compressive strength of A and B variations
The A variation with 9.5-12.5 mm sized aggregate has higher compressive strength compared to B variation, although the difference was not significant (approximately 1 Mpa).

Concrete Compressive Strength Testing With Roof Tile Fragment
Comparison of compressive strength beween variations with 9.5-12.5 mm coarse aggregate can be seen in the following figure:   Fig. 2. Comparison compressive strength of each variation for 9.5-12.5 mm aggregate There is a significant decrease (about 2 Mpa) for the concrete mixture with roof tile fragments. While the comparison of compressive strength between variations using roof tile fragments only has 0.1 Mpa difference.
Comparison of compressive strength beween variations with 19-31 mm coarse aggregate can be seen in the following figure:  There is a significant decrease (about 2 Mpa) for the concrete mixture with ceramic tile fragments. While the comparison of compressive strength between variations using ceramic tile fragments only has 0.2 MPa difference.
Comparison of compressive strength beween variations with 19-31 mm coarse aggregate can be seen in the following figure:

Water Infiltration Test
The test is done by pouring one liter of water and measure the time required by water to flow through the specimen (in seconds). All the specimens are tested with water infiltration test and the average from each variation is noted. The water infiltration test is done as follow:

Fig. 6. Water infiltration test
The water infiltration test result for each variation and the average flow time can be seen as follow:

Conclusions and suggestions
Based on the test results, the following conclusions are drawn: 1. The size of coarse aggregate used in the mixture affects the concrete compressive strength. The larger the size of the aggregate, the compressive strength obtained becomes smaller. It also afects the pervious concrete density. 2. The using of the mixture of ceramics and roof tile fragments only decreases the compressive strength around 2 MPa, so the using of the mixture of ceramics and roof tile fragments can be done for maximum 30 % 3. The specimens' high porosity decreases the concrete density, affecting the compressive strength.The high level of porosity can be seen from the high water absorption that exceeds the required limit of water infiltration.

Suggestions
1. To reach the required compressive strength, the pervious concrete density should be maintained at about 1780 to 1890 kg/m3 or about 22% lower than normal concrete. This density can be achieved by using the aggregate size of about 9.5 to 12.5 mm.
2. Considering that water absorption of specimen is high, automatically the level of porosity is high and the density of the specimen is low. The required water absorption is 100-750 liter per m3 per m2. By increasing the concrete density, it's expected that the concrete compressive strength becomes higher.